Implement TIP 445

199 files changed, 1545 insertions, 971 deletions

diff --git a/compat/zlib/win32/zlib1.dll b/compat/zlib/win32/zlib1.dll
index 3196f4a..3196f4a 100755..100644
--- a/compat/zlib/win32/zlib1.dll
+++ b/compat/zlib/win32/zlib1.dll
diff --git a/compat/zlib/win64/zlib1.dll b/compat/zlib/win64/zlib1.dll
index 81195c3..81195c3 100755..100644
--- a/compat/zlib/win64/zlib1.dll
+++ b/compat/zlib/win64/zlib1.dll
diff --git a/compat/zlib/zlib2ansi b/compat/zlib/zlib2ansi
index 15e3e16..15e3e16 100755..100644
--- a/compat/zlib/zlib2ansi
+++ b/compat/zlib/zlib2ansi
diff --git a/doc/GetCwd.3 b/doc/GetCwd.3
index f4f37a1..f4f37a1 100644..100755
--- a/doc/GetCwd.3
+++ b/doc/GetCwd.3
diff --git a/doc/GetVersion.3 b/doc/GetVersion.3
index 3672382..3672382 100644..100755
--- a/doc/GetVersion.3
+++ b/doc/GetVersion.3
diff --git a/doc/lset.n b/doc/lset.n
index e425274..e425274 100644..100755
--- a/doc/lset.n
+++ b/doc/lset.n
diff --git a/generic/tcl.decls b/generic/tcl.decls
index dfcb822..0bc43e8 100644
--- a/generic/tcl.decls
+++ b/generic/tcl.decls
@@ -2346,6 +2346,24 @@ declare 635 {
 	    unsigned char *data, size_t datalen, int copy)
 }
 
+# TIP #445
+declare 636 {
+    void Tcl_FreeIntRep(Tcl_Obj *objPtr)
+}
+declare 637 {
+    char *Tcl_InitStringRep(Tcl_Obj *objPtr, const char *bytes,
+	    unsigned int numBytes)
+}
+declare 638 {
+    Tcl_ObjIntRep *Tcl_FetchIntRep(Tcl_Obj *objPtr, const Tcl_ObjType *typePtr)
+}
+declare 639 {
+    void Tcl_StoreIntRep(Tcl_Obj *objPtr, const Tcl_ObjType *typePtr,
+	    const Tcl_ObjIntRep *irPtr)
+}
+declare 640 {
+    int Tcl_HasStringRep(Tcl_Obj *objPtr)
+}
 # ----- BASELINE -- FOR -- 8.7.0 ----- #
 
 ##############################################################################
diff --git a/generic/tcl.h b/generic/tcl.h
index 0971066..35edebb 100644
--- a/generic/tcl.h
+++ b/generic/tcl.h
@@ -751,6 +751,29 @@ typedef struct Tcl_ObjType {
 } Tcl_ObjType;
 
 /*
+ * The following structure stores an internal representation (intrep) for
+ * a Tcl value. An intrep is associated with an Tcl_ObjType when both
+ * are stored in the same Tcl_Obj.  The routines of the Tcl_ObjType govern
+ * the handling of the intrep.
+ */
+
+typedef union Tcl_ObjIntRep {	/* The internal representation: */
+    long longValue;		/*   - an long integer value. */
+    double doubleValue;		/*   - a double-precision floating value. */
+    void *otherValuePtr;	/*   - another, type-specific value, */
+				/*     not used internally any more. */
+    Tcl_WideInt wideValue;	/*   - an integer value >= 64bits */
+    struct {			/*   - internal rep as two pointers. */
+	void *ptr1;		
+	void *ptr2;
+    } twoPtrValue;
+    struct {			/*   - internal rep as a pointer and a long, */
+	void *ptr;		/*     not used internally any more. */
+	unsigned long value;
+    } ptrAndLongRep;
+} Tcl_ObjIntRep;
+
+/*
  * One of the following structures exists for each object in the Tcl system.
  * An object stores a value as either a string, some internal representation,
  * or both.
@@ -775,27 +798,7 @@ typedef struct Tcl_Obj {
 				 * corresponds to the type of the object's
 				 * internal rep. NULL indicates the object has
 				 * no internal rep (has no type). */
-    union {			/* The internal representation: */
-	long longValue;		/*   - an long integer value. */
-	double doubleValue;	/*   - a double-precision floating value. */
-	void *otherValuePtr;	/*   - another, type-specific value, not used
-				 *     internally any more. */
-	Tcl_WideInt wideValue;	/*   - a long long value. */
-	struct {		/*   - internal rep as two pointers.
-				 *     Many uses in Tcl, including a bignum's
-				 *     tightly packed fields, where the alloc,
-				 *     used and signum flags are packed into
-				 *     ptr2 with everything else hung off
-				 *     ptr1. */
-	    void *ptr1;
-	    void *ptr2;
-	} twoPtrValue;
-	struct {		/*   - internal rep as a pointer and a long,
-				 *     not used internally any more. */
-	    void *ptr;
-	    unsigned long value;
-	} ptrAndLongRep;
-    } internalRep;
+    Tcl_ObjIntRep internalRep;	/* The internal representation: */
 } Tcl_Obj;
 
 /*
diff --git a/generic/tclAssembly.c b/generic/tclAssembly.c
index 6356a00..5ac9a55 100644
--- a/generic/tclAssembly.c
+++ b/generic/tclAssembly.c
@@ -32,6 +32,7 @@
 #include "tclInt.h"
 #include "tclCompile.h"
 #include "tclOOInt.h"
+#include <assert.h>
 
 /*
  * Structure that represents a range of instructions in the bytecode.
@@ -271,15 +272,12 @@ static void		CompileEmbeddedScript(AssemblyEnv*, Tcl_Token*,
 			    const TalInstDesc*);
 static int		DefineLabel(AssemblyEnv* envPtr, const char* label);
 static void		DeleteMirrorJumpTable(JumptableInfo* jtPtr);
-static void		DupAssembleCodeInternalRep(Tcl_Obj* src,
-			    Tcl_Obj* dest);
 static void		FillInJumpOffsets(AssemblyEnv*);
 static int		CreateMirrorJumpTable(AssemblyEnv* assemEnvPtr,
 			    Tcl_Obj* jumpTable);
 static int		FindLocalVar(AssemblyEnv* envPtr,
 			    Tcl_Token** tokenPtrPtr);
 static int		FinishAssembly(AssemblyEnv*);
-static void		FreeAssembleCodeInternalRep(Tcl_Obj *objPtr);
 static void		FreeAssemblyEnv(AssemblyEnv*);
 static int		GetBooleanOperand(AssemblyEnv*, Tcl_Token**, int*);
 static int		GetListIndexOperand(AssemblyEnv*, Tcl_Token**, int*);
@@ -318,6 +316,9 @@ static void		UnstackExpiredCatches(CompileEnv*, BasicBlock*, int,
  * Tcl_ObjType that describes bytecode emitted by the assembler.
  */
 
+static Tcl_FreeInternalRepProc	FreeAssembleCodeInternalRep;
+static Tcl_DupInternalRepProc	DupAssembleCodeInternalRep;
+
 static const Tcl_ObjType assembleCodeType = {
     "assemblecode",
     FreeAssembleCodeInternalRep, /* freeIntRepProc */
@@ -847,15 +848,15 @@ CompileAssembleObj(
     const char* source;		/* String representation of the source code */
     int sourceLen;		/* Length of the source code in bytes */
 
-
     /*
      * Get the expression ByteCode from the object. If it exists, make sure it
      * is valid in the current context.
      */
 
-    if (objPtr->typePtr == &assembleCodeType) {
+    ByteCodeGetIntRep(objPtr, &assembleCodeType, codePtr);
+
+    if (codePtr) {
 	namespacePtr = iPtr->varFramePtr->nsPtr;
-	codePtr = objPtr->internalRep.twoPtrValue.ptr1;
 	if (((Interp *) *codePtr->interpHandle == iPtr)
 		&& (codePtr->compileEpoch == iPtr->compileEpoch)
 		&& (codePtr->nsPtr == namespacePtr)
@@ -869,7 +870,7 @@ CompileAssembleObj(
 	 * Not valid, so free it and regenerate.
 	 */
 
-	TclFreeIntRep(objPtr);
+	Tcl_StoreIntRep(objPtr, &assembleCodeType, NULL);
     }
 
     /*
@@ -4332,7 +4333,10 @@ static void
 FreeAssembleCodeInternalRep(
     Tcl_Obj *objPtr)
 {
-    ByteCode *codePtr = objPtr->internalRep.twoPtrValue.ptr1;
+    ByteCode *codePtr;
+
+    ByteCodeGetIntRep(objPtr, &assembleCodeType, codePtr);
+    assert(codePtr != NULL);
 
     TclReleaseByteCode(codePtr);
 }
diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index 179306d..75c467b 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -3867,9 +3867,14 @@ OldMathFuncProc(
 	valuePtr = objv[j];
 	result = Tcl_GetDoubleFromObj(NULL, valuePtr, &d);
 #ifdef ACCEPT_NAN
-	if ((result != TCL_OK) && (valuePtr->typePtr == &tclDoubleType)) {
-	    d = valuePtr->internalRep.doubleValue;
-	    result = TCL_OK;
+	if (result != TCL_OK) {
+	    const Tcl_ObjIntRep *irPtr
+		    = Tcl_FetchIntRep(valuePtr, &tclDoubleType);
+
+	    if (irPtr) {
+		d = irPtr->doubleValue;
+		result = TCL_OK;
+	    }
 	}
 #endif
 	if (result != TCL_OK) {
@@ -6151,7 +6156,7 @@ TclArgumentGet(
      * up by the caller. It knows better than us.
      */
 
-    if ((obj->bytes == NULL) || TclListObjIsCanonical(obj)) {
+    if (!TclHasStringRep(obj) || TclListObjIsCanonical(obj)) {
 	return;
     }
 
@@ -7428,9 +7433,13 @@ ExprCeilFunc(
     }
     code = Tcl_GetDoubleFromObj(interp, objv[1], &d);
 #ifdef ACCEPT_NAN
-    if ((code != TCL_OK) && (objv[1]->typePtr == &tclDoubleType)) {
-	Tcl_SetObjResult(interp, objv[1]);
-	return TCL_OK;
+    if (code != TCL_OK) {
+	const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(objv[1], &tclDoubleType);
+
+	if (irPtr) {
+	    Tcl_SetObjResult(interp, objv[1]);
+	    return TCL_OK;
+	}
     }
 #endif
     if (code != TCL_OK) {
@@ -7464,9 +7473,13 @@ ExprFloorFunc(
     }
     code = Tcl_GetDoubleFromObj(interp, objv[1], &d);
 #ifdef ACCEPT_NAN
-    if ((code != TCL_OK) && (objv[1]->typePtr == &tclDoubleType)) {
-	Tcl_SetObjResult(interp, objv[1]);
-	return TCL_OK;
+    if (code != TCL_OK) {
+	const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(objv[1], &tclDoubleType);
+
+	if (irPtr) {
+	    Tcl_SetObjResult(interp, objv[1]);
+	    return TCL_OK;
+	}
     }
 #endif
     if (code != TCL_OK) {
@@ -7600,9 +7613,13 @@ ExprSqrtFunc(
     }
     code = Tcl_GetDoubleFromObj(interp, objv[1], &d);
 #ifdef ACCEPT_NAN
-    if ((code != TCL_OK) && (objv[1]->typePtr == &tclDoubleType)) {
-	Tcl_SetObjResult(interp, objv[1]);
-	return TCL_OK;
+    if (code != TCL_OK) {
+	const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(objv[1], &tclDoubleType);
+
+	if (irPtr) {
+	    Tcl_SetObjResult(interp, objv[1]);
+	    return TCL_OK;
+	}
     }
 #endif
     if (code != TCL_OK) {
@@ -7643,10 +7660,14 @@ ExprUnaryFunc(
     }
     code = Tcl_GetDoubleFromObj(interp, objv[1], &d);
 #ifdef ACCEPT_NAN
-    if ((code != TCL_OK) && (objv[1]->typePtr == &tclDoubleType)) {
-	d = objv[1]->internalRep.doubleValue;
-	Tcl_ResetResult(interp);
-	code = TCL_OK;
+    if (code != TCL_OK) {
+	const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(objv[1], &tclDoubleType);
+
+	if (irPtr) {
+	    d = irPtr->doubleValue;
+	    Tcl_ResetResult(interp);
+	    code = TCL_OK;
+	}
     }
 #endif
     if (code != TCL_OK) {
@@ -7703,10 +7724,14 @@ ExprBinaryFunc(
     }
     code = Tcl_GetDoubleFromObj(interp, objv[1], &d1);
 #ifdef ACCEPT_NAN
-    if ((code != TCL_OK) && (objv[1]->typePtr == &tclDoubleType)) {
-	d1 = objv[1]->internalRep.doubleValue;
-	Tcl_ResetResult(interp);
-	code = TCL_OK;
+    if (code != TCL_OK) {
+	const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(objv[1], &tclDoubleType);
+
+	if (irPtr) {
+	    d1 = irPtr->doubleValue;
+	    Tcl_ResetResult(interp);
+	    code = TCL_OK;
+	}
     }
 #endif
     if (code != TCL_OK) {
@@ -7714,10 +7739,14 @@ ExprBinaryFunc(
     }
     code = Tcl_GetDoubleFromObj(interp, objv[2], &d2);
 #ifdef ACCEPT_NAN
-    if ((code != TCL_OK) && (objv[2]->typePtr == &tclDoubleType)) {
-	d2 = objv[2]->internalRep.doubleValue;
-	Tcl_ResetResult(interp);
-	code = TCL_OK;
+    if (code != TCL_OK) {
+	const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(objv[1], &tclDoubleType);
+
+	if (irPtr) {
+	    d2 = irPtr->doubleValue;
+	    Tcl_ResetResult(interp);
+	    code = TCL_OK;
+	}
     }
 #endif
     if (code != TCL_OK) {
@@ -7754,14 +7783,16 @@ ExprAbsFunc(
 	if (l > (Tcl_WideInt)0) {
 	    goto unChanged;
 	} else if (l == (Tcl_WideInt)0) {
-	    const char *string = objv[1]->bytes;
-	    if (string) {
-		while (*string != '0') {
-		    if (*string == '-') {
+	    if (TclHasStringRep(objv[1])) {
+		int numBytes;
+		const char *bytes = TclGetStringFromObj(objv[1], &numBytes);
+
+		while (numBytes) {
+		    if (*bytes == '-') {
 			Tcl_SetObjResult(interp, Tcl_NewLongObj(0));
 			return TCL_OK;
 		    }
-		    string++;
+		    bytes++; numBytes--;
 		}
 	    }
 	    goto unChanged;
@@ -7857,7 +7888,7 @@ ExprDoubleFunc(
     }
     if (Tcl_GetDoubleFromObj(interp, objv[1], &dResult) != TCL_OK) {
 #ifdef ACCEPT_NAN
-	if (objv[1]->typePtr == &tclDoubleType) {
+	if (Tcl_FetchIntRep(objv[1], &tclDoubleType)) {
 	    Tcl_SetObjResult(interp, objv[1]);
 	    return TCL_OK;
 	}
diff --git a/generic/tclBinary.c b/generic/tclBinary.c
index fdc60e7..96adff0 100644
--- a/generic/tclBinary.c
+++ b/generic/tclBinary.c
@@ -15,6 +15,7 @@
 #include "tommath.h"
 
 #include <math.h>
+#include <assert.h>
 
 /*
  * The following constants are used by GetFormatSpec to indicate various
@@ -56,9 +57,12 @@
 
 static void		DupByteArrayInternalRep(Tcl_Obj *srcPtr,
 			    Tcl_Obj *copyPtr);
+static void		DupProperByteArrayInternalRep(Tcl_Obj *srcPtr,
+			    Tcl_Obj *copyPtr);
 static int		FormatNumber(Tcl_Interp *interp, int type,
 			    Tcl_Obj *src, unsigned char **cursorPtr);
 static void		FreeByteArrayInternalRep(Tcl_Obj *objPtr);
+static void		FreeProperByteArrayInternalRep(Tcl_Obj *objPtr);
 static int		GetFormatSpec(const char **formatPtr, char *cmdPtr,
 			    int *countPtr, int *flagsPtr);
 static Tcl_Obj *	ScanNumber(unsigned char *buffer, int type,
@@ -246,8 +250,8 @@ static const EnsembleImplMap decodeMap[] = {
 
 static const Tcl_ObjType properByteArrayType = {
     "bytearray",
-    FreeByteArrayInternalRep,
-    DupByteArrayInternalRep,
+    FreeProperByteArrayInternalRep,
+    DupProperByteArrayInternalRep,
     UpdateStringOfByteArray,
     NULL
 };
@@ -268,9 +272,9 @@ const Tcl_ObjType tclByteArrayType = {
  */
 
 typedef struct ByteArray {
-    int used;			/* The number of bytes used in the byte
+    unsigned int used;		/* The number of bytes used in the byte
 				 * array. */
-    int allocated;		/* The amount of space actually allocated
+    unsigned int allocated;	/* The amount of space actually allocated
 				 * minus 1 byte. */
     unsigned char bytes[1];	/* The array of bytes. The actual size of this
 				 * field depends on the 'allocated' field
@@ -279,16 +283,15 @@ typedef struct ByteArray {
 
 #define BYTEARRAY_SIZE(len) \
 		((unsigned) (TclOffset(ByteArray, bytes) + (len)))
-#define GET_BYTEARRAY(objPtr) \
-		((ByteArray *) (objPtr)->internalRep.twoPtrValue.ptr1)
-#define SET_BYTEARRAY(objPtr, baPtr) \
-		(objPtr)->internalRep.twoPtrValue.ptr1 = (void *) (baPtr)
+#define GET_BYTEARRAY(irPtr) ((ByteArray *) (irPtr)->twoPtrValue.ptr1)
+#define SET_BYTEARRAY(irPtr, baPtr) \
+		(irPtr)->twoPtrValue.ptr1 = (void *) (baPtr)
 
 int
 TclIsPureByteArray(
     Tcl_Obj * objPtr)
 {
-    return (objPtr->typePtr == &properByteArrayType);
+    return (NULL != Tcl_FetchIntRep(objPtr, &properByteArrayType));
 }
 
 /*
@@ -403,11 +406,11 @@ Tcl_SetByteArrayObj(
 				   be >= 0. */
 {
     ByteArray *byteArrayPtr;
+    Tcl_ObjIntRep ir;
 
     if (Tcl_IsShared(objPtr)) {
 	Tcl_Panic("%s called with shared object", "Tcl_SetByteArrayObj");
     }
-    TclFreeIntRep(objPtr);
     TclInvalidateStringRep(objPtr);
 
     if (length < 0) {
@@ -420,8 +423,9 @@ Tcl_SetByteArrayObj(
     if ((bytes != NULL) && (length > 0)) {
 	memcpy(byteArrayPtr->bytes, bytes, (size_t) length);
     }
-    objPtr->typePtr = &properByteArrayType;
-    SET_BYTEARRAY(objPtr, byteArrayPtr);
+    SET_BYTEARRAY(&ir, byteArrayPtr);
+
+    Tcl_StoreIntRep(objPtr, &properByteArrayType, &ir);
 }
 
 /*
@@ -449,17 +453,24 @@ Tcl_GetByteArrayFromObj(
 				 * array of bytes in the ByteArray object. */
 {
     ByteArray *baPtr;
+    const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(objPtr, &properByteArrayType);
 
-    if ((objPtr->typePtr != &properByteArrayType)
-	    && (objPtr->typePtr != &tclByteArrayType)) {
-	SetByteArrayFromAny(NULL, objPtr);
+    if (irPtr == NULL) {
+	irPtr = Tcl_FetchIntRep(objPtr, &tclByteArrayType);
+	if (irPtr == NULL) {
+	    SetByteArrayFromAny(NULL, objPtr);
+	    irPtr = Tcl_FetchIntRep(objPtr, &properByteArrayType);
+	    if (irPtr == NULL) {
+		irPtr = Tcl_FetchIntRep(objPtr, &tclByteArrayType);
+	    }
+	}
     }
-    baPtr = GET_BYTEARRAY(objPtr);
+    baPtr = GET_BYTEARRAY(irPtr);
 
     if (lengthPtr != NULL) {
 	*lengthPtr = baPtr->used;
     }
-    return (unsigned char *) baPtr->bytes;
+    return baPtr->bytes;
 }
 
 /*
@@ -490,23 +501,36 @@ Tcl_SetByteArrayLength(
     int length)			/* New length for internal byte array. */
 {
     ByteArray *byteArrayPtr;
+    unsigned newLength;
+    Tcl_ObjIntRep *irPtr;
+
+    assert(length >= 0);
+    newLength = (unsigned int)length;
 
     if (Tcl_IsShared(objPtr)) {
 	Tcl_Panic("%s called with shared object", "Tcl_SetByteArrayLength");
     }
-    if ((objPtr->typePtr != &properByteArrayType)
-	    && (objPtr->typePtr != &tclByteArrayType)) {
-	SetByteArrayFromAny(NULL, objPtr);
+
+    irPtr = Tcl_FetchIntRep(objPtr, &properByteArrayType);
+    if (irPtr == NULL) {
+	irPtr = Tcl_FetchIntRep(objPtr, &tclByteArrayType);
+	if (irPtr == NULL) {
+	    SetByteArrayFromAny(NULL, objPtr);
+	    irPtr = Tcl_FetchIntRep(objPtr, &properByteArrayType);
+	    if (irPtr == NULL) {
+		irPtr = Tcl_FetchIntRep(objPtr, &tclByteArrayType);
+	    }
+	}
     }
 
-    byteArrayPtr = GET_BYTEARRAY(objPtr);
-    if (length > byteArrayPtr->allocated) {
-	byteArrayPtr = ckrealloc(byteArrayPtr, BYTEARRAY_SIZE(length));
-	byteArrayPtr->allocated = length;
-	SET_BYTEARRAY(objPtr, byteArrayPtr);
+    byteArrayPtr = GET_BYTEARRAY(irPtr);
+    if (newLength > byteArrayPtr->allocated) {
+	byteArrayPtr = ckrealloc(byteArrayPtr, BYTEARRAY_SIZE(newLength));
+	byteArrayPtr->allocated = newLength;
+	SET_BYTEARRAY(irPtr, byteArrayPtr);
     }
     TclInvalidateStringRep(objPtr);
-    byteArrayPtr->used = length;
+    byteArrayPtr->used = newLength;
     return byteArrayPtr->bytes;
 }
 
@@ -536,12 +560,12 @@ SetByteArrayFromAny(
     const char *src, *srcEnd;
     unsigned char *dst;
     ByteArray *byteArrayPtr;
-    Tcl_UniChar ch = 0;
+    Tcl_ObjIntRep ir;
 
-    if (objPtr->typePtr == &properByteArrayType) {
+    if (Tcl_FetchIntRep(objPtr, &properByteArrayType)) {
 	return TCL_OK;
     }
-    if (objPtr->typePtr == &tclByteArrayType) {
+    if (Tcl_FetchIntRep(objPtr, &tclByteArrayType)) {
 	return TCL_OK;
     }
 
@@ -551,6 +575,7 @@ SetByteArrayFromAny(
 
     byteArrayPtr = ckalloc(BYTEARRAY_SIZE(length));
     for (dst = byteArrayPtr->bytes; src < srcEnd; ) {
+	Tcl_UniChar ch = 0;
 	src += TclUtfToUniChar(src, &ch);
 	improper = improper || (ch > 255);
 	*dst++ = UCHAR(ch);
@@ -559,9 +584,9 @@ SetByteArrayFromAny(
     byteArrayPtr->used = dst - byteArrayPtr->bytes;
     byteArrayPtr->allocated = length;
 
-    TclFreeIntRep(objPtr);
-    objPtr->typePtr = improper ? &tclByteArrayType : &properByteArrayType;
-    SET_BYTEARRAY(objPtr, byteArrayPtr);
+    SET_BYTEARRAY(&ir, byteArrayPtr);
+    Tcl_StoreIntRep(objPtr,
+	    improper ? &tclByteArrayType : &properByteArrayType, &ir);
     return TCL_OK;
 }
 
@@ -586,8 +611,14 @@ static void
 FreeByteArrayInternalRep(
     Tcl_Obj *objPtr)		/* Object with internal rep to free. */
 {
-    ckfree(GET_BYTEARRAY(objPtr));
-    objPtr->typePtr = NULL;
+    ckfree(GET_BYTEARRAY(Tcl_FetchIntRep(objPtr, &tclByteArrayType)));
+}
+
+static void
+FreeProperByteArrayInternalRep(
+    Tcl_Obj *objPtr)		/* Object with internal rep to free. */
+{
+    ckfree(GET_BYTEARRAY(Tcl_FetchIntRep(objPtr, &properByteArrayType)));
 }
 
 /*
@@ -612,19 +643,41 @@ DupByteArrayInternalRep(
     Tcl_Obj *srcPtr,		/* Object with internal rep to copy. */
     Tcl_Obj *copyPtr)		/* Object with internal rep to set. */
 {
-    int length;
+    unsigned int length;
+    ByteArray *srcArrayPtr, *copyArrayPtr;
+    Tcl_ObjIntRep ir;
+
+    srcArrayPtr = GET_BYTEARRAY(Tcl_FetchIntRep(srcPtr, &tclByteArrayType));
+    length = srcArrayPtr->used;
+
+    copyArrayPtr = ckalloc(BYTEARRAY_SIZE(length));
+    copyArrayPtr->used = length;
+    copyArrayPtr->allocated = length;
+    memcpy(copyArrayPtr->bytes, srcArrayPtr->bytes, (size_t) length);
+
+    SET_BYTEARRAY(&ir, copyArrayPtr);
+    Tcl_StoreIntRep(copyPtr, &tclByteArrayType, &ir);
+}
+
+static void
+DupProperByteArrayInternalRep(
+    Tcl_Obj *srcPtr,		/* Object with internal rep to copy. */
+    Tcl_Obj *copyPtr)		/* Object with internal rep to set. */
+{
+    unsigned int length;
     ByteArray *srcArrayPtr, *copyArrayPtr;
+    Tcl_ObjIntRep ir;
 
-    srcArrayPtr = GET_BYTEARRAY(srcPtr);
+    srcArrayPtr = GET_BYTEARRAY(Tcl_FetchIntRep(srcPtr, &properByteArrayType));
     length = srcArrayPtr->used;
 
     copyArrayPtr = ckalloc(BYTEARRAY_SIZE(length));
     copyArrayPtr->used = length;
     copyArrayPtr->allocated = length;
     memcpy(copyArrayPtr->bytes, srcArrayPtr->bytes, (size_t) length);
-    SET_BYTEARRAY(copyPtr, copyArrayPtr);
 
-    copyPtr->typePtr = srcPtr->typePtr;
+    SET_BYTEARRAY(&ir, copyArrayPtr);
+    Tcl_StoreIntRep(copyPtr, &properByteArrayType, &ir);
 }
 
 /*
@@ -632,9 +685,7 @@ DupByteArrayInternalRep(
  *
  * UpdateStringOfByteArray --
  *
- *	Update the string representation for a ByteArray data object. Note:
- *	This procedure does not invalidate an existing old string rep so
- *	storage will be lost if this has not already been done.
+ *	Update the string representation for a ByteArray data object.
  *
  * Results:
  *	None.
@@ -643,9 +694,6 @@ DupByteArrayInternalRep(
  *	The object's string is set to a valid string that results from the
  *	ByteArray-to-string conversion.
  *
- *	The object becomes a string object -- the internal rep is discarded
- *	and the typePtr becomes NULL.
- *
  *----------------------------------------------------------------------
  */
 
@@ -654,41 +702,35 @@ UpdateStringOfByteArray(
     Tcl_Obj *objPtr)		/* ByteArray object whose string rep to
 				 * update. */
 {
-    int i, length, size;
-    unsigned char *src;
-    char *dst;
-    ByteArray *byteArrayPtr;
-
-    byteArrayPtr = GET_BYTEARRAY(objPtr);
-    src = byteArrayPtr->bytes;
-    length = byteArrayPtr->used;
+    const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(objPtr, &properByteArrayType);
+    ByteArray *byteArrayPtr = GET_BYTEARRAY(irPtr);
+    unsigned char *src = byteArrayPtr->bytes;
+    unsigned int i, length = byteArrayPtr->used;
+    unsigned int size = length;
 
     /*
      * How much space will string rep need?
      */
 
-    size = length;
-    for (i = 0; i < length && size >= 0; i++) {
+    for (i = 0; i < length && size <= INT_MAX; i++) {
 	if ((src[i] == 0) || (src[i] > 127)) {
 	    size++;
 	}
     }
-    if (size < 0) {
+    if (size > INT_MAX) {
 	Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
     }
 
-    dst = ckalloc(size + 1);
-    objPtr->bytes = dst;
-    objPtr->length = size;
-
     if (size == length) {
-	memcpy(dst, src, (size_t) size);
-	dst[size] = '\0';
+	char *dst = Tcl_InitStringRep(objPtr, (char *)src, size);
+	TclOOM(dst, size);
     } else {
+	char *dst = Tcl_InitStringRep(objPtr, NULL, size);
+	TclOOM(dst, size);
 	for (i = 0; i < length; i++) {
 	    dst += Tcl_UniCharToUtf(src[i], dst);
 	}
-	*dst = '\0';
+	(void)Tcl_InitStringRep(objPtr, NULL, size);
     }
 }
 
@@ -718,7 +760,8 @@ TclAppendBytesToByteArray(
     int len)
 {
     ByteArray *byteArrayPtr;
-    int needed;
+    unsigned int length, needed;
+    Tcl_ObjIntRep *irPtr;
 
     if (Tcl_IsShared(objPtr)) {
 	Tcl_Panic("%s called with shared object","TclAppendBytesToByteArray");
@@ -731,24 +774,34 @@ TclAppendBytesToByteArray(
 	/* Append zero bytes is a no-op. */
 	return;
     }
-    if ((objPtr->typePtr != &properByteArrayType)
-	    && (objPtr->typePtr != &tclByteArrayType)) {
-	SetByteArrayFromAny(NULL, objPtr);
+
+    length = (unsigned int)len;
+
+    irPtr = Tcl_FetchIntRep(objPtr, &properByteArrayType);
+    if (irPtr == NULL) {
+	irPtr = Tcl_FetchIntRep(objPtr, &tclByteArrayType);
+	if (irPtr == NULL) {
+	    SetByteArrayFromAny(NULL, objPtr);
+	    irPtr = Tcl_FetchIntRep(objPtr, &properByteArrayType);
+	    if (irPtr == NULL) {
+		irPtr = Tcl_FetchIntRep(objPtr, &tclByteArrayType);
+	    }
+	}
     }
-    byteArrayPtr = GET_BYTEARRAY(objPtr);
+    byteArrayPtr = GET_BYTEARRAY(irPtr);
 
-    if (len > INT_MAX - byteArrayPtr->used) {
+    if (length > INT_MAX - byteArrayPtr->used) {
 	Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
     }
 
-    needed = byteArrayPtr->used + len;
+    needed = byteArrayPtr->used + length;
     /*
      * If we need to, resize the allocated space in the byte array.
      */
 
     if (needed > byteArrayPtr->allocated) {
 	ByteArray *ptr = NULL;
-	int attempt;
+	unsigned int attempt;
 
 	if (needed <= INT_MAX/2) {
 	    /* Try to allocate double the total space that is needed. */
@@ -758,7 +811,7 @@ TclAppendBytesToByteArray(
 	if (ptr == NULL) {
 	    /* Try to allocate double the increment that is needed (plus). */
 	    unsigned int limit = INT_MAX - needed;
-	    unsigned int extra = len + TCL_MIN_GROWTH;
+	    unsigned int extra = length + TCL_MIN_GROWTH;
 	    int growth = (int) ((extra > limit) ? limit : extra);
 
 	    attempt = needed + growth;
@@ -771,13 +824,13 @@ TclAppendBytesToByteArray(
 	}
 	byteArrayPtr = ptr;
 	byteArrayPtr->allocated = attempt;
-	SET_BYTEARRAY(objPtr, byteArrayPtr);
+	SET_BYTEARRAY(irPtr, byteArrayPtr);
     }
 
     if (bytes) {
-	memcpy(byteArrayPtr->bytes + byteArrayPtr->used, bytes, len);
+	memcpy(byteArrayPtr->bytes + byteArrayPtr->used, bytes, length);
     }
-    byteArrayPtr->used += len;
+    byteArrayPtr->used += length;
     TclInvalidateStringRep(objPtr);
 }
 
@@ -1978,10 +2031,11 @@ FormatNumber(
 	 */
 
 	if (Tcl_GetDoubleFromObj(interp, src, &dvalue) != TCL_OK) {
-	    if (src->typePtr != &tclDoubleType) {
+	    const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(src, &tclDoubleType);
+	    if (irPtr == NULL) {
 		return TCL_ERROR;
 	    }
-	    dvalue = src->internalRep.doubleValue;
+	    dvalue = irPtr->doubleValue;
 	}
 	CopyNumber(&dvalue, *cursorPtr, sizeof(double), type);
 	*cursorPtr += sizeof(double);
@@ -1997,10 +2051,11 @@ FormatNumber(
 	 */
 
 	if (Tcl_GetDoubleFromObj(interp, src, &dvalue) != TCL_OK) {
-	    if (src->typePtr != &tclDoubleType) {
+	    const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(src, &tclDoubleType);
+	    if (irPtr == NULL) {
 		return TCL_ERROR;
 	    }
-	    dvalue = src->internalRep.doubleValue;
+	    dvalue = irPtr->doubleValue;
 	}
 
 	/*
diff --git a/generic/tclClock.c b/generic/tclClock.c
index bbfc83b..7f4f592 100644
--- a/generic/tclClock.c
+++ b/generic/tclClock.c
@@ -452,7 +452,7 @@ ClockGetdatefieldsObjCmd(
      * that it isn't.
      */
 
-    if (objv[1]->typePtr == &tclBignumType) {
+    if (Tcl_FetchIntRep(objv[1], &tclBignumType)) {
 	Tcl_SetObjResult(interp, literals[LIT_INTEGER_VALUE_TOO_LARGE]);
 	return TCL_ERROR;
     }
diff --git a/generic/tclCmdIL.c b/generic/tclCmdIL.c
index 434840e..ac2288e 100644
--- a/generic/tclCmdIL.c
+++ b/generic/tclCmdIL.c
@@ -539,9 +539,9 @@ InfoBodyCmd(
     Tcl_Obj *const objv[])	/* Argument objects. */
 {
     register Interp *iPtr = (Interp *) interp;
-    const char *name;
+    const char *name, *bytes;
     Proc *procPtr;
-    Tcl_Obj *bodyPtr, *resultPtr;
+    int numBytes;
 
     if (objc != 2) {
 	Tcl_WrongNumArgs(interp, 1, objv, "procname");
@@ -566,18 +566,8 @@ InfoBodyCmd(
      * the object do not invalidate the internal rep.
      */
 
-    bodyPtr = procPtr->bodyPtr;
-    if (bodyPtr->bytes == NULL) {
-	/*
-	 * The string rep might not be valid if the procedure has never been
-	 * run before. [Bug #545644]
-	 */
-
-	TclGetString(bodyPtr);
-    }
-    resultPtr = Tcl_NewStringObj(bodyPtr->bytes, bodyPtr->length);
-
-    Tcl_SetObjResult(interp, resultPtr);
+    bytes = Tcl_GetStringFromObj(procPtr->bodyPtr, &numBytes);
+    Tcl_SetObjResult(interp, Tcl_NewStringObj(bytes, numBytes));
     return TCL_OK;
 }
 
diff --git a/generic/tclCmdMZ.c b/generic/tclCmdMZ.c
index f94c094..e113412 100644
--- a/generic/tclCmdMZ.c
+++ b/generic/tclCmdMZ.c
@@ -1593,9 +1593,9 @@ StringIsCmd(
 	chcomp = Tcl_UniCharIsDigit;
 	break;
     case STR_IS_DOUBLE: {
-	if ((objPtr->typePtr == &tclDoubleType) ||
-		(objPtr->typePtr == &tclIntType) ||
-		(objPtr->typePtr == &tclBignumType)) {
+	if (Tcl_FetchIntRep(objPtr, &tclDoubleType) ||
+		Tcl_FetchIntRep(objPtr, &tclIntType) ||
+		Tcl_FetchIntRep(objPtr, &tclBignumType)) {
 	    break;
 	}
 	string1 = TclGetStringFromObj(objPtr, &length1);
@@ -1624,8 +1624,8 @@ StringIsCmd(
 	break;
     case STR_IS_INT:
     case STR_IS_ENTIER:
-	if ((objPtr->typePtr == &tclIntType) ||
-		(objPtr->typePtr == &tclBignumType)) {
+	if (Tcl_FetchIntRep(objPtr, &tclIntType) ||
+		Tcl_FetchIntRep(objPtr, &tclBignumType)) {
 	    break;
 	}
 	string1 = TclGetStringFromObj(objPtr, &length1);
@@ -1903,7 +1903,8 @@ StringMapCmd(
      * inconsistencies (see test string-10.20.1 for illustration why!)
      */
 
-    if (objv[objc-2]->typePtr == &tclDictType && objv[objc-2]->bytes == NULL){
+    if (!TclHasStringRep(objv[objc-2]) 
+	    && Tcl_FetchIntRep(objv[objc-2], &tclDictType)){
 	int i, done;
 	Tcl_DictSearch search;
 
diff --git a/generic/tclCompExpr.c b/generic/tclCompExpr.c
index f8835b9..e96e264 100644
--- a/generic/tclCompExpr.c
+++ b/generic/tclCompExpr.c
@@ -2476,11 +2476,13 @@ CompileExprTree(
 		     * already, then use it to share via the literal table.
 		     */
 
-		    if (objPtr->bytes) {
+		    if (TclHasStringRep(objPtr)) {
 			Tcl_Obj *tableValue;
+			int numBytes;
+			const char *bytes
+				= Tcl_GetStringFromObj(objPtr, &numBytes);
 
-			index = TclRegisterLiteral(envPtr, objPtr->bytes,
-				objPtr->length, 0);
+			index = TclRegisterLiteral(envPtr, bytes, numBytes, 0);
 			tableValue = TclFetchLiteral(envPtr, index);
 			if ((tableValue->typePtr == NULL) &&
 				(objPtr->typePtr != NULL)) {
diff --git a/generic/tclCompile.c b/generic/tclCompile.c
index b5de230..f6e6b81 100644
--- a/generic/tclCompile.c
+++ b/generic/tclCompile.c
@@ -725,13 +725,14 @@ static const Tcl_ObjType substCodeType = {
     NULL,			/* updateStringProc */
     NULL,			/* setFromAnyProc */
 };
+#define SubstFlags(objPtr) (objPtr)->internalRep.twoPtrValue.ptr2
 
 /*
  * Helper macros.
  */
 
 #define TclIncrUInt4AtPtr(ptr, delta) \
-    TclStoreInt4AtPtr(TclGetUInt4AtPtr(ptr)+(delta), (ptr));
+    TclStoreInt4AtPtr(TclGetUInt4AtPtr(ptr)+(delta), (ptr))
 
 /*
  *----------------------------------------------------------------------
@@ -974,7 +975,10 @@ static void
 FreeByteCodeInternalRep(
     register Tcl_Obj *objPtr)	/* Object whose internal rep to free. */
 {
-    register ByteCode *codePtr = objPtr->internalRep.twoPtrValue.ptr1;
+    ByteCode *codePtr;
+
+    ByteCodeGetIntRep(objPtr, &tclByteCodeType, codePtr);
+    assert(codePtr != NULL);
 
     TclReleaseByteCode(codePtr);
 }
@@ -1304,21 +1308,23 @@ CompileSubstObj(
     Interp *iPtr = (Interp *) interp;
     ByteCode *codePtr = NULL;
 
-    if (objPtr->typePtr == &substCodeType) {
+    ByteCodeGetIntRep(objPtr, &substCodeType, codePtr);
+
+    if (codePtr != NULL) {
 	Namespace *nsPtr = iPtr->varFramePtr->nsPtr;
 
-	codePtr = objPtr->internalRep.twoPtrValue.ptr1;
-	if (flags != PTR2INT(objPtr->internalRep.twoPtrValue.ptr2)
+	if (flags != PTR2INT(SubstFlags(objPtr))
 		|| ((Interp *) *codePtr->interpHandle != iPtr)
 		|| (codePtr->compileEpoch != iPtr->compileEpoch)
 		|| (codePtr->nsPtr != nsPtr)
 		|| (codePtr->nsEpoch != nsPtr->resolverEpoch)
 		|| (codePtr->localCachePtr !=
 		iPtr->varFramePtr->localCachePtr)) {
-	    TclFreeIntRep(objPtr);
+	    Tcl_StoreIntRep(objPtr, &substCodeType, NULL);
+	    codePtr = NULL;
 	}
     }
-    if (objPtr->typePtr != &substCodeType) {
+    if (codePtr == NULL) {
 	CompileEnv compEnv;
 	int numBytes;
 	const char *bytes = TclGetStringFromObj(objPtr, &numBytes);
@@ -1332,8 +1338,7 @@ CompileSubstObj(
 	codePtr = TclInitByteCodeObj(objPtr, &substCodeType, &compEnv);
 	TclFreeCompileEnv(&compEnv);
 
-	objPtr->internalRep.twoPtrValue.ptr1 = codePtr;
-	objPtr->internalRep.twoPtrValue.ptr2 = INT2PTR(flags);
+	SubstFlags(objPtr) = INT2PTR(flags);
 	if (iPtr->varFramePtr->localCachePtr) {
 	    codePtr->localCachePtr = iPtr->varFramePtr->localCachePtr;
 	    codePtr->localCachePtr->refCount++;
@@ -1372,7 +1377,10 @@ static void
 FreeSubstCodeInternalRep(
     register Tcl_Obj *objPtr)	/* Object whose internal rep to free. */
 {
-    register ByteCode *codePtr = objPtr->internalRep.twoPtrValue.ptr1;
+    register ByteCode *codePtr;
+
+    ByteCodeGetIntRep(objPtr, &substCodeType, codePtr);
+    assert(codePtr != NULL);
 
     TclReleaseByteCode(codePtr);
 }
@@ -2912,9 +2920,7 @@ TclInitByteCodeObj(
      * by making its internal rep point to the just compiled ByteCode.
      */
 
-    TclFreeIntRep(objPtr);
-    objPtr->internalRep.twoPtrValue.ptr1 = codePtr;
-    objPtr->typePtr = typePtr;
+    ByteCodeSetIntRep(objPtr, typePtr, codePtr);
     return codePtr;
 }
 
diff --git a/generic/tclCompile.h b/generic/tclCompile.h
index d827382..3e349b2 100644
--- a/generic/tclCompile.h
+++ b/generic/tclCompile.h
@@ -514,6 +514,23 @@ typedef struct ByteCode {
 				 * created. */
 #endif /* TCL_COMPILE_STATS */
 } ByteCode;
+
+#define ByteCodeSetIntRep(objPtr, typePtr, codePtr)			\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	ir.twoPtrValue.ptr1 = (codePtr);				\
+	ir.twoPtrValue.ptr2 = NULL;					\
+	Tcl_StoreIntRep((objPtr), (typePtr), &ir);			\
+    } while (0)
+
+
+
+#define ByteCodeGetIntRep(objPtr, typePtr, codePtr)			\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep((objPtr), (typePtr));			\
+	(codePtr) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+    } while (0)
 
 /*
  * Opcodes for the Tcl bytecode instructions. These must correspond to the
diff --git a/generic/tclDecls.h b/generic/tclDecls.h
index e20782e..c79a408 100644
--- a/generic/tclDecls.h
+++ b/generic/tclDecls.h
@@ -1875,6 +1875,20 @@ EXTERN Tcl_Obj *	TclZipfs_TclLibrary(void);
 EXTERN int		TclZipfs_MountBuffer(Tcl_Interp *interp,
 				const char *mountPoint, unsigned char *data,
 				size_t datalen, int copy);
+/* 636 */
+EXTERN void		Tcl_FreeIntRep(Tcl_Obj *objPtr);
+/* 637 */
+EXTERN char *		Tcl_InitStringRep(Tcl_Obj *objPtr, const char *bytes,
+				unsigned int numBytes);
+/* 638 */
+EXTERN Tcl_ObjIntRep *	Tcl_FetchIntRep(Tcl_Obj *objPtr,
+				const Tcl_ObjType *typePtr);
+/* 639 */
+EXTERN void		Tcl_StoreIntRep(Tcl_Obj *objPtr,
+				const Tcl_ObjType *typePtr,
+				const Tcl_ObjIntRep *irPtr);
+/* 640 */
+EXTERN int		Tcl_HasStringRep(Tcl_Obj *objPtr);
 
 typedef struct {
     const struct TclPlatStubs *tclPlatStubs;
@@ -2546,6 +2560,11 @@ typedef struct TclStubs {
     int (*tclZipfs_Unmount) (Tcl_Interp *interp, const char *mountPoint); /* 633 */
     Tcl_Obj * (*tclZipfs_TclLibrary) (void); /* 634 */
     int (*tclZipfs_MountBuffer) (Tcl_Interp *interp, const char *mountPoint, unsigned char *data, size_t datalen, int copy); /* 635 */
+    void (*tcl_FreeIntRep) (Tcl_Obj *objPtr); /* 636 */
+    char * (*tcl_InitStringRep) (Tcl_Obj *objPtr, const char *bytes, unsigned int numBytes); /* 637 */
+    Tcl_ObjIntRep * (*tcl_FetchIntRep) (Tcl_Obj *objPtr, const Tcl_ObjType *typePtr); /* 638 */
+    void (*tcl_StoreIntRep) (Tcl_Obj *objPtr, const Tcl_ObjType *typePtr, const Tcl_ObjIntRep *irPtr); /* 639 */
+    int (*tcl_HasStringRep) (Tcl_Obj *objPtr); /* 640 */
 } TclStubs;
 
 extern const TclStubs *tclStubsPtr;
@@ -3848,6 +3867,16 @@ extern const TclStubs *tclStubsPtr;
 	(tclStubsPtr->tclZipfs_TclLibrary) /* 634 */
 #define TclZipfs_MountBuffer \
 	(tclStubsPtr->tclZipfs_MountBuffer) /* 635 */
+#define Tcl_FreeIntRep \
+	(tclStubsPtr->tcl_FreeIntRep) /* 636 */
+#define Tcl_InitStringRep \
+	(tclStubsPtr->tcl_InitStringRep) /* 637 */
+#define Tcl_FetchIntRep \
+	(tclStubsPtr->tcl_FetchIntRep) /* 638 */
+#define Tcl_StoreIntRep \
+	(tclStubsPtr->tcl_StoreIntRep) /* 639 */
+#define Tcl_HasStringRep \
+	(tclStubsPtr->tcl_HasStringRep) /* 640 */
 
 #endif /* defined(USE_TCL_STUBS) */
 
diff --git a/generic/tclDictObj.c b/generic/tclDictObj.c
index 1d952ec..13ff0f8 100644
--- a/generic/tclDictObj.c
+++ b/generic/tclDictObj.c
@@ -12,6 +12,7 @@
 
 #include "tclInt.h"
 #include "tommath.h"
+#include <assert.h>
 
 /*
  * Forward declaration.
@@ -149,13 +150,6 @@ typedef struct Dict {
 } Dict;
 
 /*
- * Accessor macro for converting between a Tcl_Obj* and a Dict. Note that this
- * must be assignable as well as readable.
- */
-
-#define DICT(dictObj)   ((dictObj)->internalRep.twoPtrValue.ptr1)
-
-/*
  * The structure below defines the dictionary object type by means of
  * functions that can be invoked by generic object code.
  */
@@ -168,6 +162,21 @@ const Tcl_ObjType tclDictType = {
     SetDictFromAny			/* setFromAnyProc */
 };
 
+#define DictSetIntRep(objPtr, dictRepPtr)				\
+    do {                                                                \
+        Tcl_ObjIntRep ir;                                               \
+        ir.twoPtrValue.ptr1 = (dictRepPtr);                             \
+        ir.twoPtrValue.ptr2 = NULL;                                     \
+        Tcl_StoreIntRep((objPtr), &tclDictType, &ir);                   \
+    } while (0)
+
+#define DictGetIntRep(objPtr, dictRepPtr)				\
+    do {                                                                \
+        const Tcl_ObjIntRep *irPtr;                                     \
+        irPtr = Tcl_FetchIntRep((objPtr), &tclDictType);                \
+        (dictRepPtr) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;          \
+    } while (0)
+
 /*
  * The type of the specially adapted version of the Tcl_Obj*-containing hash
  * table defined in the tclObj.c code. This version differs in that it
@@ -363,10 +372,11 @@ DupDictInternalRep(
     Tcl_Obj *srcPtr,
     Tcl_Obj *copyPtr)
 {
-    Dict *oldDict = DICT(srcPtr);
-    Dict *newDict = ckalloc(sizeof(Dict));
+    Dict *oldDict, *newDict = ckalloc(sizeof(Dict));
     ChainEntry *cPtr;
 
+    DictGetIntRep(srcPtr, oldDict);
+
     /*
      * Copy values across from the old hash table.
      */
@@ -398,9 +408,7 @@ DupDictInternalRep(
      * Store in the object.
      */
 
-    DICT(copyPtr) = newDict;
-    copyPtr->internalRep.twoPtrValue.ptr2 = NULL;
-    copyPtr->typePtr = &tclDictType;
+    DictSetIntRep(copyPtr, newDict);
 }
 
 /*
@@ -425,12 +433,13 @@ static void
 FreeDictInternalRep(
     Tcl_Obj *dictPtr)
 {
-    Dict *dict = DICT(dictPtr);
+    Dict *dict;
+
+    DictGetIntRep(dictPtr, dict);
 
     if (dict->refCount-- <= 1) {
 	DeleteDict(dict);
     }
-    dictPtr->typePtr = NULL;
 }
 
 /*
@@ -489,7 +498,7 @@ UpdateStringOfDict(
 {
 #define LOCAL_SIZE 64
     char localFlags[LOCAL_SIZE], *flagPtr = NULL;
-    Dict *dict = DICT(dictPtr);
+    Dict *dict;
     ChainEntry *cPtr;
     Tcl_Obj *keyPtr, *valuePtr;
     int i, length, bytesNeeded = 0;
@@ -501,12 +510,17 @@ UpdateStringOfDict(
      * is not exposed by any API function...
      */
 
-    int numElems = dict->table.numEntries * 2;
+    int numElems;
+
+    DictGetIntRep(dictPtr, dict);
+
+    assert (dict != NULL);
+
+    numElems = dict->table.numEntries * 2;
 
     /* Handle empty list case first, simplifies what follows */
     if (numElems == 0) {
-	dictPtr->bytes = &tclEmptyString;
-	dictPtr->length = 0;
+	Tcl_InitStringRep(dictPtr, NULL, 0);
 	return;
     }
 
@@ -550,9 +564,8 @@ UpdateStringOfDict(
      * Pass 2: copy into string rep buffer.
      */
 
-    dictPtr->length = bytesNeeded - 1;
-    dictPtr->bytes = ckalloc(bytesNeeded);
-    dst = dictPtr->bytes;
+    dst = Tcl_InitStringRep(dictPtr, NULL, bytesNeeded - 1);
+    TclOOM(dst, bytesNeeded);
     for (i=0,cPtr=dict->entryChainHead; i<numElems; i+=2,cPtr=cPtr->nextPtr) {
 	flagPtr[i] |= ( i ? TCL_DONT_QUOTE_HASH : 0 );
 	keyPtr = Tcl_GetHashKey(&dict->table, &cPtr->entry);
@@ -566,7 +579,7 @@ UpdateStringOfDict(
 	dst += TclConvertElement(elem, length, dst, flagPtr[i+1]);
 	*dst++ = ' ';
     }
-    dictPtr->bytes[dictPtr->length] = '\0';
+    (void)Tcl_InitStringRep(dictPtr, NULL, bytesNeeded - 1);
 
     if (flagPtr != localFlags) {
 	ckfree(flagPtr);
@@ -610,7 +623,7 @@ SetDictFromAny(
      * the conversion from lists to dictionaries.
      */
 
-    if (objPtr->typePtr == &tclListType) {
+    if (Tcl_FetchIntRep(objPtr, &tclListType)) {
 	int objc, i;
 	Tcl_Obj **objv;
 
@@ -665,10 +678,14 @@ SetDictFromAny(
 		TclNewStringObj(keyPtr, elemStart, elemSize);
 	    } else {
 		/* Avoid double copy */
+		char *dst;
+
 		TclNewObj(keyPtr);
-		keyPtr->bytes = ckalloc((unsigned) elemSize + 1);
-		keyPtr->length = TclCopyAndCollapse(elemSize, elemStart,
-			keyPtr->bytes);
+		Tcl_InvalidateStringRep(keyPtr);
+		dst = Tcl_InitStringRep(keyPtr, NULL, elemSize);
+		TclOOM(dst, elemSize); /* Consider error */
+		(void)Tcl_InitStringRep(keyPtr, NULL,
+			TclCopyAndCollapse(elemSize, elemStart, dst));
 	    }
 
 	    if (TclFindDictElement(interp, nextElem, (limit - nextElem),
@@ -681,10 +698,14 @@ SetDictFromAny(
 		TclNewStringObj(valuePtr, elemStart, elemSize);
 	    } else {
 		/* Avoid double copy */
+		char *dst;
+
 		TclNewObj(valuePtr);
-		valuePtr->bytes = ckalloc((unsigned) elemSize + 1);
-		valuePtr->length = TclCopyAndCollapse(elemSize, elemStart,
-			valuePtr->bytes);
+		Tcl_InvalidateStringRep(valuePtr);
+		dst = Tcl_InitStringRep(valuePtr, NULL, elemSize);
+		TclOOM(dst, elemSize); /* Consider error */
+		(void)Tcl_InitStringRep(valuePtr, NULL,
+			TclCopyAndCollapse(elemSize, elemStart, dst));
 	    }
 
 	    /* Store key and value in the hash table we're building. */
@@ -706,13 +727,10 @@ SetDictFromAny(
      * Tcl_GetStringFromObj, to use that old internalRep.
      */
 
-    TclFreeIntRep(objPtr);
     dict->epoch = 1;
     dict->chain = NULL;
     dict->refCount = 1;
-    DICT(objPtr) = dict;
-    objPtr->internalRep.twoPtrValue.ptr2 = NULL;
-    objPtr->typePtr = &tclDictType;
+    DictSetIntRep(objPtr, dict);
     return TCL_OK;
 
   missingValue:
@@ -726,6 +744,23 @@ SetDictFromAny(
     ckfree(dict);
     return TCL_ERROR;
 }
+
+static Dict *
+GetDictFromObj(
+    Tcl_Interp *interp,
+    Tcl_Obj *dictPtr)
+{
+    Dict *dict;
+
+    DictGetIntRep(dictPtr, dict);
+    if (dict == NULL) {
+	if (SetDictFromAny(interp, dictPtr) != TCL_OK) {
+	    return NULL;
+	}
+	DictGetIntRep(dictPtr, dict);
+    }
+    return dict;
+}
 
 /*
  *----------------------------------------------------------------------
@@ -770,11 +805,13 @@ TclTraceDictPath(
     Dict *dict, *newDict;
     int i;
 
-    if (dictPtr->typePtr != &tclDictType
-	    && SetDictFromAny(interp, dictPtr) != TCL_OK) {
-	return NULL;
+    DictGetIntRep(dictPtr, dict);
+    if (dict == NULL) {
+	if (SetDictFromAny(interp, dictPtr) != TCL_OK) {
+	    return NULL;
+	}
+	DictGetIntRep(dictPtr, dict);
     }
-    dict = DICT(dictPtr);
     if (flags & DICT_PATH_UPDATE) {
 	dict->chain = NULL;
     }
@@ -810,13 +847,17 @@ TclTraceDictPath(
 	    Tcl_SetHashValue(hPtr, tmpObj);
 	} else {
 	    tmpObj = Tcl_GetHashValue(hPtr);
-	    if (tmpObj->typePtr != &tclDictType
-		    && SetDictFromAny(interp, tmpObj) != TCL_OK) {
-		return NULL;
+
+	    DictGetIntRep(tmpObj, newDict);
+
+	    if (newDict == NULL) {
+		if (SetDictFromAny(interp, tmpObj) != TCL_OK) {
+		    return NULL;
+		}
 	    }
 	}
 
-	newDict = DICT(tmpObj);
+	DictGetIntRep(tmpObj, newDict);
 	if (flags & DICT_PATH_UPDATE) {
 	    if (Tcl_IsShared(tmpObj)) {
 		TclDecrRefCount(tmpObj);
@@ -824,7 +865,7 @@ TclTraceDictPath(
 		Tcl_IncrRefCount(tmpObj);
 		Tcl_SetHashValue(hPtr, tmpObj);
 		dict->epoch++;
-		newDict = DICT(tmpObj);
+		DictGetIntRep(tmpObj, newDict);
 	    }
 
 	    newDict->chain = dictPtr;
@@ -859,17 +900,24 @@ static void
 InvalidateDictChain(
     Tcl_Obj *dictObj)
 {
-    Dict *dict = DICT(dictObj);
+    Dict *dict;
+
+    DictGetIntRep(dictObj, dict);
+    assert( dict != NULL);
 
     do {
+	dict->refCount++;
 	TclInvalidateStringRep(dictObj);
+	TclFreeIntRep(dictObj);
+	DictSetIntRep(dictObj, dict);
+
 	dict->epoch++;
 	dictObj = dict->chain;
 	if (dictObj == NULL) {
 	    break;
 	}
 	dict->chain = NULL;
-	dict = DICT(dictObj);
+	DictGetIntRep(dictObj, dict);
     } while (dict != NULL);
 }
 
@@ -907,16 +955,16 @@ Tcl_DictObjPut(
 	Tcl_Panic("%s called with shared object", "Tcl_DictObjPut");
     }
 
-    if (dictPtr->typePtr != &tclDictType
-	    && SetDictFromAny(interp, dictPtr) != TCL_OK) {
+    dict = GetDictFromObj(interp, dictPtr);
+    if (dict == NULL) {
 	return TCL_ERROR;
     }
 
-    if (dictPtr->bytes != NULL) {
-	TclInvalidateStringRep(dictPtr);
-    }
-    dict = DICT(dictPtr);
+    TclInvalidateStringRep(dictPtr);
     hPtr = CreateChainEntry(dict, keyPtr, &isNew);
+    dict->refCount++;
+    TclFreeIntRep(dictPtr)
+    DictSetIntRep(dictPtr, dict);
     Tcl_IncrRefCount(valuePtr);
     if (!isNew) {
 	Tcl_Obj *oldValuePtr = Tcl_GetHashValue(hPtr);
@@ -958,13 +1006,12 @@ Tcl_DictObjGet(
     Dict *dict;
     Tcl_HashEntry *hPtr;
 
-    if (dictPtr->typePtr != &tclDictType
-	    && SetDictFromAny(interp, dictPtr) != TCL_OK) {
+    dict = GetDictFromObj(interp, dictPtr);
+    if (dict == NULL) {
 	*valuePtrPtr = NULL;
 	return TCL_ERROR;
     }
 
-    dict = DICT(dictPtr);
     hPtr = Tcl_FindHashEntry(&dict->table, keyPtr);
     if (hPtr == NULL) {
 	*valuePtrPtr = NULL;
@@ -1005,16 +1052,13 @@ Tcl_DictObjRemove(
 	Tcl_Panic("%s called with shared object", "Tcl_DictObjRemove");
     }
 
-    if (dictPtr->typePtr != &tclDictType
-	    && SetDictFromAny(interp, dictPtr) != TCL_OK) {
+    dict = GetDictFromObj(interp, dictPtr);
+    if (dict == NULL) {
 	return TCL_ERROR;
     }
 
-    dict = DICT(dictPtr);
     if (DeleteChainEntry(dict, keyPtr)) {
-	if (dictPtr->bytes != NULL) {
-	    TclInvalidateStringRep(dictPtr);
-	}
+	TclInvalidateStringRep(dictPtr);
 	dict->epoch++;
     }
     return TCL_OK;
@@ -1046,12 +1090,11 @@ Tcl_DictObjSize(
 {
     Dict *dict;
 
-    if (dictPtr->typePtr != &tclDictType
-	    && SetDictFromAny(interp, dictPtr) != TCL_OK) {
+    dict = GetDictFromObj(interp, dictPtr);
+    if (dict == NULL) {
 	return TCL_ERROR;
     }
 
-    dict = DICT(dictPtr);
     *sizePtr = dict->table.numEntries;
     return TCL_OK;
 }
@@ -1098,12 +1141,11 @@ Tcl_DictObjFirst(
     Dict *dict;
     ChainEntry *cPtr;
 
-    if (dictPtr->typePtr != &tclDictType
-	    && SetDictFromAny(interp, dictPtr) != TCL_OK) {
+    dict = GetDictFromObj(interp, dictPtr);
+    if (dict == NULL) {
 	return TCL_ERROR;
     }
 
-    dict = DICT(dictPtr);
     cPtr = dict->entryChainHead;
     if (cPtr == NULL) {
 	searchPtr->epoch = 0;
@@ -1277,7 +1319,8 @@ Tcl_DictObjPutKeyList(
 	return TCL_ERROR;
     }
 
-    dict = DICT(dictPtr);
+    DictGetIntRep(dictPtr, dict);
+    assert(dict != NULL);
     hPtr = CreateChainEntry(dict, keyv[keyc-1], &isNew);
     Tcl_IncrRefCount(valuePtr);
     if (!isNew) {
@@ -1334,7 +1377,8 @@ Tcl_DictObjRemoveKeyList(
 	return TCL_ERROR;
     }
 
-    dict = DICT(dictPtr);
+    DictGetIntRep(dictPtr, dict);
+    assert(dict != NULL);
     DeleteChainEntry(dict, keyv[keyc-1]);
     InvalidateDictChain(dictPtr);
     return TCL_OK;
@@ -1380,9 +1424,7 @@ Tcl_NewDictObj(void)
     dict->epoch = 1;
     dict->chain = NULL;
     dict->refCount = 1;
-    DICT(dictPtr) = dict;
-    dictPtr->internalRep.twoPtrValue.ptr2 = NULL;
-    dictPtr->typePtr = &tclDictType;
+    DictSetIntRep(dictPtr, dict);
     return dictPtr;
 #endif
 }
@@ -1430,9 +1472,7 @@ Tcl_DbNewDictObj(
     dict->epoch = 1;
     dict->chain = NULL;
     dict->refCount = 1;
-    DICT(dictPtr) = dict;
-    dictPtr->internalRep.twoPtrValue.ptr2 = NULL;
-    dictPtr->typePtr = &tclDictType;
+    DictSetIntRep(dictPtr, dict);
     return dictPtr;
 #else /* !TCL_MEM_DEBUG */
     return Tcl_NewDictObj();
@@ -1618,16 +1658,13 @@ DictReplaceCmd(
     }
 
     dictPtr = objv[1];
-    if (dictPtr->typePtr != &tclDictType
-	    && SetDictFromAny(interp, dictPtr) != TCL_OK) {
+    if (GetDictFromObj(interp, dictPtr) == NULL) {
 	return TCL_ERROR;
     }
     if (Tcl_IsShared(dictPtr)) {
 	dictPtr = Tcl_DuplicateObj(dictPtr);
     }
-    if (dictPtr->bytes != NULL) {
-	TclInvalidateStringRep(dictPtr);
-    }
+    TclInvalidateStringRep(dictPtr);
     for (i=2 ; i<objc ; i+=2) {
 	Tcl_DictObjPut(NULL, dictPtr, objv[i], objv[i+1]);
     }
@@ -1669,16 +1706,13 @@ DictRemoveCmd(
     }
 
     dictPtr = objv[1];
-    if (dictPtr->typePtr != &tclDictType
-	    && SetDictFromAny(interp, dictPtr) != TCL_OK) {
+    if (GetDictFromObj(interp, dictPtr) == NULL) {
 	return TCL_ERROR;
     }
     if (Tcl_IsShared(dictPtr)) {
 	dictPtr = Tcl_DuplicateObj(dictPtr);
     }
-    if (dictPtr->bytes != NULL) {
-	TclInvalidateStringRep(dictPtr);
-    }
+    TclInvalidateStringRep(dictPtr);
     for (i=2 ; i<objc ; i++) {
 	Tcl_DictObjRemove(NULL, dictPtr, objv[i]);
     }
@@ -1729,8 +1763,7 @@ DictMergeCmd(
      */
 
     targetObj = objv[1];
-    if (targetObj->typePtr != &tclDictType
-	    && SetDictFromAny(interp, targetObj) != TCL_OK) {
+    if (GetDictFromObj(interp, targetObj) == NULL) {
 	return TCL_ERROR;
     }
 
@@ -1813,8 +1846,7 @@ DictKeysCmd(
      * need. [Bug 1705778, leak K04]
      */
 
-    if (objv[1]->typePtr != &tclDictType
-	    && SetDictFromAny(interp, objv[1]) != TCL_OK) {
+    if (GetDictFromObj(interp, objv[1]) == NULL) {
 	return TCL_ERROR;
     }
 
@@ -2021,7 +2053,6 @@ DictInfoCmd(
     int objc,
     Tcl_Obj *const *objv)
 {
-    Tcl_Obj *dictPtr;
     Dict *dict;
     char *statsStr;
 
@@ -2030,12 +2061,10 @@ DictInfoCmd(
 	return TCL_ERROR;
     }
 
-    dictPtr = objv[1];
-    if (dictPtr->typePtr != &tclDictType
-	    && SetDictFromAny(interp, dictPtr) != TCL_OK) {
+    dict = GetDictFromObj(interp, objv[1]);
+    if (dict == NULL) {
 	return TCL_ERROR;
     }
-    dict = DICT(dictPtr);
 
     statsStr = Tcl_HashStats(&dict->table);
     Tcl_SetObjResult(interp, Tcl_NewStringObj(statsStr, -1));
@@ -2096,12 +2125,11 @@ DictIncrCmd(
 	 * soon be no good.
 	 */
 
-	char *saved = dictPtr->bytes;
 	Tcl_Obj *oldPtr = dictPtr;
 
-	dictPtr->bytes = NULL;
-	dictPtr = Tcl_DuplicateObj(dictPtr);
-	oldPtr->bytes = saved;
+	TclNewObj(dictPtr);
+	TclInvalidateStringRep(dictPtr);
+	DupDictInternalRep(oldPtr, dictPtr);
     }
     if (valuePtr == NULL) {
 	/*
@@ -2238,7 +2266,7 @@ DictLappendCmd(
 
     if (allocatedValue) {
 	Tcl_DictObjPut(NULL, dictPtr, objv[2], valuePtr);
-    } else if (dictPtr->bytes != NULL) {
+    } else {
 	TclInvalidateStringRep(dictPtr);
     }
 
diff --git a/generic/tclDisassemble.c b/generic/tclDisassemble.c
index 6580d59..6ea3397 100644
--- a/generic/tclDisassemble.c
+++ b/generic/tclDisassemble.c
@@ -38,7 +38,7 @@ static void		UpdateStringOfInstName(Tcl_Obj *objPtr);
  * reporting of inner contexts in errorstack without string allocation.
  */
 
-static const Tcl_ObjType tclInstNameType = {
+static const Tcl_ObjType instNameType = {
     "instname",			/* name */
     NULL,			/* freeIntRepProc */
     NULL,			/* dupIntRepProc */
@@ -46,12 +46,21 @@ static const Tcl_ObjType tclInstNameType = {
     NULL,			/* setFromAnyProc */
 };
 
-/*
- * How to get the bytecode out of a Tcl_Obj.
- */
+#define InstNameSetIntRep(objPtr, inst)				\
+    do {							\
+	Tcl_ObjIntRep ir;					\
+	ir.wideValue = (inst);					\
+	Tcl_StoreIntRep((objPtr), &instNameType, &ir);		\
+    } while (0)
+
+#define InstNameGetIntRep(objPtr, inst)				\
+    do {							\
+	const Tcl_ObjIntRep *irPtr;				\
+	irPtr = Tcl_FetchIntRep((objPtr), &instNameType);	\
+	assert(irPtr != NULL);					\
+	(inst) = (size_t)irPtr->wideValue;			\
+    } while (0)
 
-#define BYTECODE(objPtr)					\
-    ((ByteCode *) (objPtr)->internalRep.twoPtrValue.ptr1)
 
 /*
  *----------------------------------------------------------------------
@@ -245,14 +254,18 @@ DisassembleByteCodeObj(
     Tcl_Interp *interp,
     Tcl_Obj *objPtr)		/* The bytecode object to disassemble. */
 {
-    ByteCode *codePtr = BYTECODE(objPtr);
+    ByteCode *codePtr;
     unsigned char *codeStart, *codeLimit, *pc;
     unsigned char *codeDeltaNext, *codeLengthNext;
     unsigned char *srcDeltaNext, *srcLengthNext;
     int codeOffset, codeLen, srcOffset, srcLen, numCmds, delta, i, line;
-    Interp *iPtr = (Interp *) *codePtr->interpHandle;
+    Interp *iPtr;
     Tcl_Obj *bufferObj, *fileObj;
 
+    ByteCodeGetIntRep(objPtr, &tclByteCodeType, codePtr);
+
+    iPtr = (Interp *) *codePtr->interpHandle;
+
     TclNewObj(bufferObj);
     if (!codePtr->refCount) {
 	return bufferObj;	/* Already freed. */
@@ -796,9 +809,8 @@ TclNewInstNameObj(
 {
     Tcl_Obj *objPtr = Tcl_NewObj();
 
-    objPtr->typePtr = &tclInstNameType;
-    objPtr->internalRep.wideValue = (long) inst;
-    objPtr->bytes = NULL;
+    TclInvalidateStringRep(objPtr);
+    InstNameSetIntRep(objPtr, (long) inst);
 
     return objPtr;
 }
@@ -817,20 +829,22 @@ static void
 UpdateStringOfInstName(
     Tcl_Obj *objPtr)
 {
-    size_t len, inst = (size_t)objPtr->internalRep.wideValue;
-    char *s, buf[TCL_INTEGER_SPACE + 5];
+    size_t inst;	/* NOTE: We know this is really an unsigned char */
+    char *dst;
+
+    InstNameGetIntRep(objPtr, inst);
 
     if (inst > LAST_INST_OPCODE) {
-        sprintf(buf, "inst_%" TCL_Z_MODIFIER "d", inst);
-        s = buf;
+	dst = Tcl_InitStringRep(objPtr, NULL, TCL_INTEGER_SPACE + 5);
+	TclOOM(dst, TCL_INTEGER_SPACE + 5);
+        sprintf(dst, "inst_%" TCL_Z_MODIFIER "d", inst);
+	(void) Tcl_InitStringRep(objPtr, NULL, strlen(dst));
     } else {
-        s = (char *) tclInstructionTable[inst].name;
+	const char *s = tclInstructionTable[inst].name;
+	unsigned int len = strlen(s);
+	dst = Tcl_InitStringRep(objPtr, s, len);
+	TclOOM(dst, len);
     }
-    len = strlen(s);
-    /* assert (len < UINT_MAX) */
-    objPtr->bytes = ckalloc(len + 1);
-    memcpy(objPtr->bytes, s, len + 1);
-    objPtr->length = len;
 }
 
 /*
@@ -942,13 +956,15 @@ DisassembleByteCodeAsDicts(
 				 * procedure, if one exists. */
     Tcl_Obj *objPtr)		/* The bytecode-holding value to take apart */
 {
-    ByteCode *codePtr = BYTECODE(objPtr);
+    ByteCode *codePtr;
     Tcl_Obj *description, *literals, *variables, *instructions, *inst;
     Tcl_Obj *aux, *exn, *commands, *file;
     unsigned char *pc, *opnd, *codeOffPtr, *codeLenPtr, *srcOffPtr, *srcLenPtr;
     int codeOffset, codeLength, sourceOffset, sourceLength;
     int i, val, line;
 
+    ByteCodeGetIntRep(objPtr, &tclByteCodeType, codePtr);
+
     /*
      * Get the literals from the bytecode.
      */
@@ -1286,6 +1302,7 @@ Tcl_DisassembleObjCmd(
     Proc *procPtr = NULL;
     Tcl_HashEntry *hPtr;
     Object *oPtr;
+    ByteCode *codePtr;
     Method *methodPtr;
 
     if (objc < 2) {
@@ -1304,27 +1321,19 @@ Tcl_DisassembleObjCmd(
 
 	/*
 	 * Compile (if uncompiled) and disassemble a lambda term.
-	 *
-	 * WARNING! Pokes inside the lambda objtype.
 	 */
 
 	if (objc != 3) {
 	    Tcl_WrongNumArgs(interp, 2, objv, "lambdaTerm");
 	    return TCL_ERROR;
 	}
-	if (objv[2]->typePtr == &tclLambdaType) {
-	    procPtr = objv[2]->internalRep.twoPtrValue.ptr1;
-	}
-	if (procPtr == NULL || procPtr->iPtr != (Interp *) interp) {
-	    result = tclLambdaType.setFromAnyProc(interp, objv[2]);
-	    if (result != TCL_OK) {
-		return result;
-	    }
-	    procPtr = objv[2]->internalRep.twoPtrValue.ptr1;
+
+	procPtr = TclGetLambdaFromObj(interp, objv[2], &nsObjPtr);
+	if (procPtr == NULL) {
+	    return TCL_ERROR;
 	}
 
 	memset(&cmd, 0, sizeof(Command));
-	nsObjPtr = objv[2]->internalRep.twoPtrValue.ptr2;
 	result = TclGetNamespaceFromObj(interp, nsObjPtr, &nsPtr);
 	if (result != TCL_OK) {
 	    return result;
@@ -1374,8 +1383,9 @@ Tcl_DisassembleObjCmd(
 	    Tcl_WrongNumArgs(interp, 2, objv, "script");
 	    return TCL_ERROR;
 	}
-	if ((objv[2]->typePtr != &tclByteCodeType)
-		&& (TclSetByteCodeFromAny(interp, objv[2], NULL, NULL) != TCL_OK)) {
+
+	if ((NULL == Tcl_FetchIntRep(objv[2], &tclByteCodeType)) && (TCL_OK
+		!= TclSetByteCodeFromAny(interp, objv[2], NULL, NULL))) {
 	    return TCL_ERROR;
 	}
 	codeObjPtr = objv[2];
@@ -1575,7 +1585,7 @@ Tcl_DisassembleObjCmd(
 		    "METHODTYPE", NULL);
 	    return TCL_ERROR;
 	}
-	if (procPtr->bodyPtr->typePtr != &tclByteCodeType) {
+	if (NULL == Tcl_FetchIntRep(procPtr->bodyPtr, &tclByteCodeType)) {
 	    Command cmd;
 
 	    /*
@@ -1603,7 +1613,9 @@ Tcl_DisassembleObjCmd(
      * Do the actual disassembly.
      */
 
-    if (BYTECODE(codeObjPtr)->flags & TCL_BYTECODE_PRECOMPILED) {
+    ByteCodeGetIntRep(codeObjPtr, &tclByteCodeType, codePtr);
+
+    if (codePtr->flags & TCL_BYTECODE_PRECOMPILED) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
 		"may not disassemble prebuilt bytecode", -1));
 	Tcl_SetErrorCode(interp, "TCL", "OPERATION", "DISASSEMBLE",
diff --git a/generic/tclEncoding.c b/generic/tclEncoding.c
index d5e8c9a..6d32676 100644
--- a/generic/tclEncoding.c
+++ b/generic/tclEncoding.c
@@ -279,6 +279,21 @@ static int		Iso88591ToUtfProc(ClientData clientData,
 static const Tcl_ObjType encodingType = {
     "encoding", FreeEncodingIntRep, DupEncodingIntRep, NULL, NULL
 };
+#define EncodingSetIntRep(objPtr, encoding)				\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	ir.twoPtrValue.ptr1 = (encoding);				\
+	ir.twoPtrValue.ptr2 = NULL;					\
+	Tcl_StoreIntRep((objPtr), &encodingType, &ir);			\
+    } while (0)
+
+#define EncodingGetIntRep(objPtr, encoding)				\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep ((objPtr), &encodingType);		\
+	(encoding) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+    } while (0)
+
 
 /*
  *----------------------------------------------------------------------
@@ -305,17 +320,16 @@ Tcl_GetEncodingFromObj(
     Tcl_Obj *objPtr,
     Tcl_Encoding *encodingPtr)
 {
+    Tcl_Encoding encoding;
     const char *name = TclGetString(objPtr);
 
-    if (objPtr->typePtr != &encodingType) {
-	Tcl_Encoding encoding = Tcl_GetEncoding(interp, name);
-
+    EncodingGetIntRep(objPtr, encoding);
+    if (encoding == NULL) {
+	encoding = Tcl_GetEncoding(interp, name);
 	if (encoding == NULL) {
 	    return TCL_ERROR;
 	}
-	TclFreeIntRep(objPtr);
-	objPtr->internalRep.twoPtrValue.ptr1 = encoding;
-	objPtr->typePtr = &encodingType;
+	EncodingSetIntRep(objPtr, encoding);
     }
     *encodingPtr = Tcl_GetEncoding(NULL, name);
     return TCL_OK;
@@ -335,8 +349,10 @@ static void
 FreeEncodingIntRep(
     Tcl_Obj *objPtr)
 {
-    Tcl_FreeEncoding(objPtr->internalRep.twoPtrValue.ptr1);
-    objPtr->typePtr = NULL;
+    Tcl_Encoding encoding;
+
+    EncodingGetIntRep(objPtr, encoding);
+    Tcl_FreeEncoding(encoding);
 }
 
 /*
@@ -354,8 +370,8 @@ DupEncodingIntRep(
     Tcl_Obj *srcPtr,
     Tcl_Obj *dupPtr)
 {
-    dupPtr->internalRep.twoPtrValue.ptr1 = Tcl_GetEncoding(NULL, srcPtr->bytes);
-    dupPtr->typePtr = &encodingType;
+    Tcl_Encoding encoding = Tcl_GetEncoding(NULL, TclGetString(srcPtr));
+    EncodingSetIntRep(dupPtr, encoding);
 }
 
 /*
diff --git a/generic/tclEnsemble.c b/generic/tclEnsemble.c
index 84ed9e3..b710399 100644
--- a/generic/tclEnsemble.c
+++ b/generic/tclEnsemble.c
@@ -84,6 +84,21 @@ static const Tcl_ObjType ensembleCmdType = {
     NULL			/* setFromAnyProc */
 };
 
+#define ECRSetIntRep(objPtr, ecRepPtr)					\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	ir.twoPtrValue.ptr1 = (ecRepPtr);				\
+	ir.twoPtrValue.ptr2 = NULL;					\
+	Tcl_StoreIntRep((objPtr), &ensembleCmdType, &ir);		\
+    } while (0)
+
+#define ECRGetIntRep(objPtr, ecRepPtr)					\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep((objPtr), &ensembleCmdType);		\
+	(ecRepPtr) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+    } while (0)
+
 /*
  * The internal rep for caching ensemble subcommand lookups and spelling
  * corrections.
@@ -1742,10 +1757,10 @@ NsEnsembleImplementationCmdNR(
 	 * check here, and if we're still valid, we can jump straight to the
 	 * part where we do the invocation of the subcommand.
 	 */
+	EnsembleCmdRep *ensembleCmd;
 
-	if (subObj->typePtr==&ensembleCmdType){
-	    EnsembleCmdRep *ensembleCmd = subObj->internalRep.twoPtrValue.ptr1;
-
+	ECRGetIntRep(subObj, ensembleCmd);
+	if (ensembleCmd) {
 	    if (ensembleCmd->epoch == ensemblePtr->epoch &&
 		    ensembleCmd->token == (Command *)ensemblePtr->token) {
 		prefixObj = Tcl_GetHashValue(ensembleCmd->hPtr);
@@ -2378,8 +2393,8 @@ MakeCachedEnsembleCommand(
 {
     register EnsembleCmdRep *ensembleCmd;
 
-    if (objPtr->typePtr == &ensembleCmdType) {
-	ensembleCmd = objPtr->internalRep.twoPtrValue.ptr1;
+    ECRGetIntRep(objPtr, ensembleCmd);
+    if (ensembleCmd) {
 	TclCleanupCommandMacro(ensembleCmd->token);
 	if (ensembleCmd->fix) {
 	    Tcl_DecrRefCount(ensembleCmd->fix);
@@ -2390,10 +2405,8 @@ MakeCachedEnsembleCommand(
 	 * our own.
 	 */
 
-	TclFreeIntRep(objPtr);
 	ensembleCmd = ckalloc(sizeof(EnsembleCmdRep));
-	objPtr->internalRep.twoPtrValue.ptr1 = ensembleCmd;
-	objPtr->typePtr = &ensembleCmdType;
+	ECRSetIntRep(objPtr, ensembleCmd);
     }
 
     /*
@@ -2797,14 +2810,14 @@ static void
 FreeEnsembleCmdRep(
     Tcl_Obj *objPtr)
 {
-    EnsembleCmdRep *ensembleCmd = objPtr->internalRep.twoPtrValue.ptr1;
+    EnsembleCmdRep *ensembleCmd;
 
+    ECRGetIntRep(objPtr, ensembleCmd);
     TclCleanupCommandMacro(ensembleCmd->token);
     if (ensembleCmd->fix) {
 	Tcl_DecrRefCount(ensembleCmd->fix);
     }
     ckfree(ensembleCmd);
-    objPtr->typePtr = NULL;
 }
 
 /*
@@ -2830,11 +2843,12 @@ DupEnsembleCmdRep(
     Tcl_Obj *objPtr,
     Tcl_Obj *copyPtr)
 {
-    EnsembleCmdRep *ensembleCmd = objPtr->internalRep.twoPtrValue.ptr1;
+    EnsembleCmdRep *ensembleCmd;
     EnsembleCmdRep *ensembleCopy = ckalloc(sizeof(EnsembleCmdRep));
 
-    copyPtr->typePtr = &ensembleCmdType;
-    copyPtr->internalRep.twoPtrValue.ptr1 = ensembleCopy;
+    ECRGetIntRep(objPtr, ensembleCmd);
+    ECRSetIntRep(copyPtr, ensembleCopy);
+
     ensembleCopy->epoch = ensembleCmd->epoch;
     ensembleCopy->token = ensembleCmd->token;
     ensembleCopy->token->refCount++;
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index 7355bc1..f38f7cd 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -748,20 +748,22 @@ ReleaseDictIterator(
 {
     Tcl_DictSearch *searchPtr;
     Tcl_Obj *dictPtr;
+    const Tcl_ObjIntRep *irPtr;
+
+    irPtr = Tcl_FetchIntRep(objPtr, &dictIteratorType);
+    assert(irPtr != NULL);
 
     /*
      * First kill the search, and then release the reference to the dictionary
      * that we were holding.
      */
 
-    searchPtr = objPtr->internalRep.twoPtrValue.ptr1;
+    searchPtr = irPtr->twoPtrValue.ptr1;
     Tcl_DictObjDone(searchPtr);
     ckfree(searchPtr);
 
-    dictPtr = objPtr->internalRep.twoPtrValue.ptr2;
+    dictPtr = irPtr->twoPtrValue.ptr2;
     TclDecrRefCount(dictPtr);
-
-    objPtr->typePtr = NULL;
 }
 
 /*
@@ -1450,19 +1452,23 @@ CompileExprObj(
      * Get the expression ByteCode from the object. If it exists, make sure it
      * is valid in the current context.
      */
-    if (objPtr->typePtr == &exprCodeType) {
+
+    ByteCodeGetIntRep(objPtr, &exprCodeType, codePtr);
+    
+    if (codePtr != NULL) {
 	Namespace *namespacePtr = iPtr->varFramePtr->nsPtr;
 
-	codePtr = objPtr->internalRep.twoPtrValue.ptr1;
 	if (((Interp *) *codePtr->interpHandle != iPtr)
 		|| (codePtr->compileEpoch != iPtr->compileEpoch)
 		|| (codePtr->nsPtr != namespacePtr)
 		|| (codePtr->nsEpoch != namespacePtr->resolverEpoch)
 		|| (codePtr->localCachePtr != iPtr->varFramePtr->localCachePtr)) {
-	    TclFreeIntRep(objPtr);
+	    Tcl_StoreIntRep(objPtr, &exprCodeType, NULL);
+	    codePtr = NULL;
 	}
     }
-    if (objPtr->typePtr != &exprCodeType) {
+
+    if (codePtr == NULL) {
 	/*
 	 * TIP #280: No invoker (yet) - Expression compilation.
 	 */
@@ -1562,7 +1568,9 @@ static void
 FreeExprCodeInternalRep(
     Tcl_Obj *objPtr)
 {
-    ByteCode *codePtr = objPtr->internalRep.twoPtrValue.ptr1;
+    ByteCode *codePtr;
+    ByteCodeGetIntRep(objPtr, &exprCodeType, codePtr);
+    assert(codePtr != NULL);
 
     TclReleaseByteCode(codePtr);
 }
@@ -1600,7 +1608,8 @@ TclCompileObj(
      * compilation). Otherwise, check that it is "fresh" enough.
      */
 
-    if (objPtr->typePtr == &tclByteCodeType) {
+    ByteCodeGetIntRep(objPtr, &tclByteCodeType, codePtr);
+    if (codePtr != NULL) {
 	/*
 	 * Make sure the Bytecode hasn't been invalidated by, e.g., someone
 	 * redefining a command with a compile procedure (this might make the
@@ -1618,7 +1627,6 @@ TclCompileObj(
 	 * here.
 	 */
 
-	codePtr = objPtr->internalRep.twoPtrValue.ptr1;
 	if (((Interp *) *codePtr->interpHandle != iPtr)
 		|| (codePtr->compileEpoch != iPtr->compileEpoch)
 		|| (codePtr->nsPtr != namespacePtr)
@@ -1746,7 +1754,7 @@ TclCompileObj(
     iPtr->invokeWord = word;
     TclSetByteCodeFromAny(interp, objPtr, NULL, NULL);
     iPtr->invokeCmdFramePtr = NULL;
-    codePtr = objPtr->internalRep.twoPtrValue.ptr1;
+    ByteCodeGetIntRep(objPtr, &tclByteCodeType, codePtr);
     if (iPtr->varFramePtr->localCachePtr) {
 	codePtr->localCachePtr = iPtr->varFramePtr->localCachePtr;
 	codePtr->localCachePtr->refCount++;
@@ -4760,7 +4768,7 @@ TEBCresume(
 	 */
 
 	if ((TclListObjGetElements(interp, valuePtr, &objc, &objv) == TCL_OK)
-		&& (value2Ptr->typePtr != &tclListType)
+		&& (NULL == Tcl_FetchIntRep(value2Ptr, &tclListType))
 		&& (TclGetIntForIndexM(NULL, value2Ptr, objc-1,
 			&index) == TCL_OK)) {
 	    TclDecrRefCount(value2Ptr);
@@ -7104,13 +7112,16 @@ TEBCresume(
 	    TRACE_ERROR(interp);
 	    goto gotError;
 	}
-	TclNewObj(statePtr);
-	statePtr->typePtr = &dictIteratorType;
-	statePtr->internalRep.twoPtrValue.ptr1 = searchPtr;
-	statePtr->internalRep.twoPtrValue.ptr2 = dictPtr;
+	{
+	    Tcl_ObjIntRep ir;
+	    TclNewObj(statePtr);
+	    ir.twoPtrValue.ptr1 = searchPtr;
+	    ir.twoPtrValue.ptr2 = dictPtr;
+	    Tcl_StoreIntRep(statePtr, &dictIteratorType, &ir);
+	}
 	varPtr = LOCAL(opnd);
 	if (varPtr->value.objPtr) {
-	    if (varPtr->value.objPtr->typePtr == &dictIteratorType) {
+	    if (Tcl_FetchIntRep(varPtr->value.objPtr, &dictIteratorType)) {
 		Tcl_Panic("mis-issued dictFirst!");
 	    }
 	    TclDecrRefCount(varPtr->value.objPtr);
@@ -7123,11 +7134,17 @@ TEBCresume(
 	opnd = TclGetUInt4AtPtr(pc+1);
 	TRACE(("%u => ", opnd));
 	statePtr = (*LOCAL(opnd)).value.objPtr;
-	if (statePtr == NULL || statePtr->typePtr != &dictIteratorType) {
-	    Tcl_Panic("mis-issued dictNext!");
+	{
+	    const Tcl_ObjIntRep *irPtr;
+
+	    if (statePtr &&
+		    (irPtr = Tcl_FetchIntRep(statePtr, &dictIteratorType))) {
+		searchPtr = irPtr->twoPtrValue.ptr1;
+		Tcl_DictObjNext(searchPtr, &keyPtr, &valuePtr, &done);
+	    } else {
+		Tcl_Panic("mis-issued dictNext!");
+	    }
 	}
-	searchPtr = statePtr->internalRep.twoPtrValue.ptr1;
-	Tcl_DictObjNext(searchPtr, &keyPtr, &valuePtr, &done);
     pushDictIteratorResult:
 	if (done) {
 	    TclNewObj(emptyPtr);
@@ -9758,7 +9775,7 @@ EvalStatsCmd(
     for (i = 0;  i < globalTablePtr->numBuckets;  i++) {
 	for (entryPtr = globalTablePtr->buckets[i];  entryPtr != NULL;
 		entryPtr = entryPtr->nextPtr) {
-	    if (entryPtr->objPtr->typePtr == &tclByteCodeType) {
+	    if (NULL != Tcl_FetchIntRep(entryPtr->objPtr, &tclByteCodeType)) {
 		numByteCodeLits++;
 	    }
 	    (void) TclGetStringFromObj(entryPtr->objPtr, &length);
diff --git a/generic/tclIO.c b/generic/tclIO.c
index 10362d4..d144cbc 100644
--- a/generic/tclIO.c
+++ b/generic/tclIO.c
@@ -337,6 +337,22 @@ static const Tcl_ObjType chanObjType = {
     NULL			/* setFromAnyProc */
 };
 
+#define ChanSetIntRep(objPtr, resPtr)					\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	(resPtr)->refCount++;						\
+	ir.twoPtrValue.ptr1 = (resPtr);					\
+	ir.twoPtrValue.ptr2 = NULL;					\
+	Tcl_StoreIntRep((objPtr), &chanObjType, &ir);			\
+    } while (0)
+
+#define ChanGetIntRep(objPtr, resPtr)					\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep((objPtr), &chanObjType);		\
+	(resPtr) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+    } while (0)
+
 #define BUSY_STATE(st, fl) \
      ((((st)->csPtrR) && ((fl) & TCL_READABLE)) || \
       (((st)->csPtrW) && ((fl) & TCL_WRITABLE)))
@@ -1515,12 +1531,12 @@ TclGetChannelFromObj(
 	return TCL_ERROR;
     }
 
-    if (objPtr->typePtr == &chanObjType) {
+    ChanGetIntRep(objPtr, resPtr);
+    if (resPtr) {
 	/*
  	 * Confirm validity of saved lookup results.
  	 */
 
-	resPtr = (ResolvedChanName *) objPtr->internalRep.twoPtrValue.ptr1;
 	statePtr = resPtr->statePtr;
 	if ((resPtr->interp == interp)		/* Same interp context */
 			/* No epoch change in channel since lookup */
@@ -1537,7 +1553,7 @@ TclGetChannelFromObj(
 
     if (chan == NULL) {
 	if (resPtr) {
-	    FreeChannelIntRep(objPtr);
+	    Tcl_StoreIntRep(objPtr, &chanObjType, NULL);
 	}
 	return TCL_ERROR;
     }
@@ -1548,14 +1564,10 @@ TclGetChannelFromObj(
          */
 
 	Tcl_Release((ClientData) resPtr->statePtr);
-
     } else {
-	TclFreeIntRep(objPtr);
-
 	resPtr = (ResolvedChanName *) ckalloc(sizeof(ResolvedChanName));
-	resPtr->refCount = 1;
-	objPtr->internalRep.twoPtrValue.ptr1 = (ClientData) resPtr;
-	objPtr->typePtr = &chanObjType;
+	resPtr->refCount = 0;
+	ChanSetIntRep(objPtr, resPtr);		/* Overwrites, if needed */
     }
     statePtr = ((Channel *)chan)->state;
     resPtr->statePtr = statePtr;
@@ -11198,11 +11210,11 @@ DupChannelIntRep(
     register Tcl_Obj *copyPtr)	/* Object with internal rep to set. Must not
 				 * currently have an internal rep.*/
 {
-    ResolvedChanName *resPtr = srcPtr->internalRep.twoPtrValue.ptr1;
+    ResolvedChanName *resPtr;
 
-    resPtr->refCount++;
-    copyPtr->internalRep.twoPtrValue.ptr1 = resPtr;
-    copyPtr->typePtr = srcPtr->typePtr;
+    ChanGetIntRep(srcPtr, resPtr);
+    assert(resPtr);
+    ChanSetIntRep(copyPtr, resPtr);
 }
 
 /*
@@ -11225,9 +11237,10 @@ static void
 FreeChannelIntRep(
     Tcl_Obj *objPtr)		/* Object with internal rep to free. */
 {
-    ResolvedChanName *resPtr = objPtr->internalRep.twoPtrValue.ptr1;
+    ResolvedChanName *resPtr;
 
-    objPtr->typePtr = NULL;
+    ChanGetIntRep(objPtr, resPtr);
+    assert(resPtr);
     if (resPtr->refCount-- > 1) {
 	return;
     }
diff --git a/generic/tclIndexObj.c b/generic/tclIndexObj.c
index eeed0e5..c39c0dc 100644
--- a/generic/tclIndexObj.c
+++ b/generic/tclIndexObj.c
@@ -115,14 +115,18 @@ Tcl_GetIndexFromObj(
     int flags,			/* 0 or TCL_EXACT */
     int *indexPtr)		/* Place to store resulting integer index. */
 {
+    if (!(flags & INDEX_TEMP_TABLE)) {
+
     /*
      * See if there is a valid cached result from a previous lookup (doing the
      * check here saves the overhead of calling Tcl_GetIndexFromObjStruct in
      * the common case where the result is cached).
      */
 
-    if (!(flags & INDEX_TEMP_TABLE) && objPtr->typePtr == &indexType) {
-	IndexRep *indexRep = objPtr->internalRep.twoPtrValue.ptr1;
+    const Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(objPtr, &indexType);
+
+    if (irPtr) {
+	IndexRep *indexRep = irPtr->twoPtrValue.ptr1;
 
 	/*
 	 * Here's hoping we don't get hit by unfortunate packing constraints
@@ -135,6 +139,7 @@ Tcl_GetIndexFromObj(
 	    return TCL_OK;
 	}
     }
+    }
     return Tcl_GetIndexFromObjStruct(interp, objPtr, tablePtr, sizeof(char *),
 	    msg, flags, indexPtr);
 }
@@ -266,6 +271,7 @@ Tcl_GetIndexFromObjStruct(
     const char *const *entryPtr;
     Tcl_Obj *resultPtr;
     IndexRep *indexRep;
+    const Tcl_ObjIntRep *irPtr;
 
     /* Protect against invalid values, like -1 or 0. */
     if (offset < (int)sizeof(char *)) {
@@ -275,13 +281,16 @@ Tcl_GetIndexFromObjStruct(
      * See if there is a valid cached result from a previous lookup.
      */
 
-    if (!(flags & INDEX_TEMP_TABLE) && objPtr->typePtr == &indexType) {
-	indexRep = objPtr->internalRep.twoPtrValue.ptr1;
+    if (!(flags & INDEX_TEMP_TABLE)) {
+    irPtr = Tcl_FetchIntRep(objPtr, &indexType);
+    if (irPtr) {
+	indexRep = irPtr->twoPtrValue.ptr1;
 	if (indexRep->tablePtr==tablePtr && indexRep->offset==offset) {
 	    *indexPtr = indexRep->index;
 	    return TCL_OK;
 	}
     }
+    }
 
     /*
      * Lookup the value of the object in the table. Accept unique
@@ -337,17 +346,19 @@ Tcl_GetIndexFromObjStruct(
      */
 
     if (!(flags & INDEX_TEMP_TABLE)) {
-	if (objPtr->typePtr == &indexType) {
-	    indexRep = objPtr->internalRep.twoPtrValue.ptr1;
-	} else {
-	    TclFreeIntRep(objPtr);
-	    indexRep = ckalloc(sizeof(IndexRep));
-	    objPtr->internalRep.twoPtrValue.ptr1 = indexRep;
-	    objPtr->typePtr = &indexType;
-	}
-	indexRep->tablePtr = (void *) tablePtr;
-	indexRep->offset = offset;
-	indexRep->index = index;
+    irPtr = Tcl_FetchIntRep(objPtr, &indexType);
+    if (irPtr) {
+	indexRep = irPtr->twoPtrValue.ptr1;
+    } else {
+	Tcl_ObjIntRep ir;
+
+	indexRep = ckalloc(sizeof(IndexRep));
+	ir.twoPtrValue.ptr1 = indexRep;
+	Tcl_StoreIntRep(objPtr, &indexType, &ir);
+    }
+    indexRep->tablePtr = (void *) tablePtr;
+    indexRep->offset = offset;
+    indexRep->index = index;
     }
 
     *indexPtr = index;
@@ -446,16 +457,10 @@ static void
 UpdateStringOfIndex(
     Tcl_Obj *objPtr)
 {
-    IndexRep *indexRep = objPtr->internalRep.twoPtrValue.ptr1;
-    register char *buf;
-    register unsigned len;
+    IndexRep *indexRep = Tcl_FetchIntRep(objPtr, &indexType)->twoPtrValue.ptr1;
     register const char *indexStr = EXPAND_OF(indexRep);
 
-    len = strlen(indexStr);
-    buf = ckalloc(len + 1);
-    memcpy(buf, indexStr, len+1);
-    objPtr->bytes = buf;
-    objPtr->length = len;
+    Tcl_InitStringRep(objPtr, indexStr, strlen(indexStr));
 }
 
 /*
@@ -481,12 +486,14 @@ DupIndex(
     Tcl_Obj *srcPtr,
     Tcl_Obj *dupPtr)
 {
-    IndexRep *srcIndexRep = srcPtr->internalRep.twoPtrValue.ptr1;
+    Tcl_ObjIntRep ir;
     IndexRep *dupIndexRep = ckalloc(sizeof(IndexRep));
 
-    memcpy(dupIndexRep, srcIndexRep, sizeof(IndexRep));
-    dupPtr->internalRep.twoPtrValue.ptr1 = dupIndexRep;
-    dupPtr->typePtr = &indexType;
+    memcpy(dupIndexRep, Tcl_FetchIntRep(srcPtr, &indexType)->twoPtrValue.ptr1,
+	    sizeof(IndexRep));
+
+    ir.twoPtrValue.ptr1 = dupIndexRep;
+    Tcl_StoreIntRep(dupPtr, &indexType, &ir);
 }
 
 /*
@@ -510,7 +517,7 @@ static void
 FreeIndex(
     Tcl_Obj *objPtr)
 {
-    ckfree(objPtr->internalRep.twoPtrValue.ptr1);
+    ckfree(Tcl_FetchIntRep(objPtr, &indexType)->twoPtrValue.ptr1);
     objPtr->typePtr = NULL;
 }
 
@@ -957,10 +964,10 @@ Tcl_WrongNumArgs(
 	    /*
 	     * Add the element, quoting it if necessary.
 	     */
+	    const Tcl_ObjIntRep *irPtr;
 
-	    if (origObjv[i]->typePtr == &indexType) {
-		register IndexRep *indexRep =
-			origObjv[i]->internalRep.twoPtrValue.ptr1;
+	    if ((irPtr = Tcl_FetchIntRep(origObjv[i], &indexType))) {
+		register IndexRep *indexRep = irPtr->twoPtrValue.ptr1;
 
 		elementStr = EXPAND_OF(indexRep);
 		elemLen = strlen(elementStr);
@@ -1007,9 +1014,10 @@ Tcl_WrongNumArgs(
 	 * the correct error message even if the subcommand was abbreviated.
 	 * Otherwise, just use the string rep.
 	 */
+	const Tcl_ObjIntRep *irPtr;
 
-	if (objv[i]->typePtr == &indexType) {
-	    register IndexRep *indexRep = objv[i]->internalRep.twoPtrValue.ptr1;
+	if ((irPtr = Tcl_FetchIntRep(objv[i], &indexType))) {
+	    register IndexRep *indexRep = irPtr->twoPtrValue.ptr1;
 
 	    Tcl_AppendStringsToObj(objPtr, EXPAND_OF(indexRep), NULL);
 	} else {
diff --git a/generic/tclInt.h b/generic/tclInt.h
index abf6c83..453c10f 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -2364,6 +2364,13 @@ typedef struct Interp {
 #define TCL_ALIGN(x) (((int)(x) + 7) & ~7)
 
 /*
+ * A common panic alert when memory allocation fails.
+ */
+
+#define TclOOM(ptr, size) \
+	((size) && ((ptr)||(Tcl_Panic("unable to alloc %u bytes", (size)),1)))
+
+/*
  * The following enum values are used to specify the runtime platform setting
  * of the tclPlatform variable.
  */
@@ -2437,12 +2444,6 @@ typedef struct List {
 #define ListRepPtr(listPtr) \
     ((List *) (listPtr)->internalRep.twoPtrValue.ptr1)
 
-#define ListSetIntRep(objPtr, listRepPtr) \
-    (objPtr)->internalRep.twoPtrValue.ptr1 = (void *)(listRepPtr), \
-    (objPtr)->internalRep.twoPtrValue.ptr2 = NULL, \
-    (listRepPtr)->refCount++, \
-    (objPtr)->typePtr = &tclListType
-
 #define ListObjGetElements(listPtr, objc, objv) \
     ((objv) = &(ListRepPtr(listPtr)->elements), \
      (objc) = ListRepPtr(listPtr)->elemCount)
@@ -2750,7 +2751,6 @@ MODULE_SCOPE const Tcl_ObjType tclBooleanType;
 MODULE_SCOPE const Tcl_ObjType tclByteArrayType;
 MODULE_SCOPE const Tcl_ObjType tclByteCodeType;
 MODULE_SCOPE const Tcl_ObjType tclDoubleType;
-MODULE_SCOPE const Tcl_ObjType tclEndOffsetType;
 MODULE_SCOPE const Tcl_ObjType tclIntType;
 MODULE_SCOPE const Tcl_ObjType tclListType;
 MODULE_SCOPE const Tcl_ObjType tclDictType;
@@ -3030,6 +3030,8 @@ MODULE_SCOPE int	TclGetChannelFromObj(Tcl_Interp *interp,
 MODULE_SCOPE CmdFrame *	TclGetCmdFrameForProcedure(Proc *procPtr);
 MODULE_SCOPE int	TclGetCompletionCodeFromObj(Tcl_Interp *interp,
 			    Tcl_Obj *value, int *code);
+MODULE_SCOPE Proc *	TclGetLambdaFromObj(Tcl_Interp *interp,
+			    Tcl_Obj *objPtr, Tcl_Obj **nsObjPtrPtr);
 MODULE_SCOPE int	TclGetNumberFromObj(Tcl_Interp *interp,
 			    Tcl_Obj *objPtr, ClientData *clientDataPtr,
 			    int *typePtr);
@@ -4421,7 +4423,7 @@ MODULE_SCOPE void	TclDbInitNewObj(Tcl_Obj *objPtr, const char *file,
 	(objPtr)->length = 0; \
     } else { \
 	(objPtr)->bytes = (char *) ckalloc((unsigned) ((len) + 1)); \
-	memcpy((objPtr)->bytes, (bytePtr), (unsigned) (len)); \
+	memcpy((objPtr)->bytes, (bytePtr) ? (bytePtr) : &tclEmptyString, (unsigned) (len)); \
 	(objPtr)->bytes[len] = '\0'; \
 	(objPtr)->length = (len); \
     }
@@ -4483,6 +4485,18 @@ MODULE_SCOPE void	TclDbInitNewObj(Tcl_Obj *objPtr, const char *file,
 
 /*
  *----------------------------------------------------------------
+ * Macro used by the Tcl core to test whether an object has a
+ * string representation (or is a 'pure' internal value).
+ * The ANSI C "prototype" for this macro is:
+ *
+ * MODULE_SCOPE int	TclHasStringRep(Tcl_Obj *objPtr);
+ *----------------------------------------------------------------
+ */
+
+#define TclHasStringRep(objPtr) ((objPtr)->bytes != NULL)
+
+/*
+ *----------------------------------------------------------------
  * Macros used by the Tcl core to grow Tcl_Token arrays. They use the same
  * growth algorithm as used in tclStringObj.c for growing strings. The ANSI C
  * "prototype" for this macro is:
@@ -4700,18 +4714,18 @@ MODULE_SCOPE Tcl_PackageInitProc Procbodytest_SafeInit;
 
 #define TclSetIntObj(objPtr, i) \
     do {						\
+	Tcl_ObjIntRep ir;				\
+	ir.wideValue = (Tcl_WideInt) i;			\
 	TclInvalidateStringRep(objPtr);			\
-	TclFreeIntRep(objPtr);				\
-	(objPtr)->internalRep.wideValue = (Tcl_WideInt)(i);	\
-	(objPtr)->typePtr = &tclIntType;		\
+	Tcl_StoreIntRep(objPtr, &tclIntType, &ir);	\
     } while (0)
 
 #define TclSetDoubleObj(objPtr, d) \
-    do {							\
-	TclInvalidateStringRep(objPtr);				\
-	TclFreeIntRep(objPtr);					\
-	(objPtr)->internalRep.doubleValue = (double)(d);	\
-	(objPtr)->typePtr = &tclDoubleType;			\
+    do {						\
+	Tcl_ObjIntRep ir;				\
+	ir.doubleValue = (double) d;			\
+	TclInvalidateStringRep(objPtr);			\
+	Tcl_StoreIntRep(objPtr, &tclDoubleType, &ir);	\
     } while (0)
 
 /*
diff --git a/generic/tclInterp.c b/generic/tclInterp.c
index 1e75298..b1cc0c8 100644
--- a/generic/tclInterp.c
+++ b/generic/tclInterp.c
@@ -1826,7 +1826,7 @@ AliasNRCmd(
     cmdc = prefc + objc - 1;
 
     listPtr = Tcl_NewListObj(cmdc, NULL);
-    listRep = listPtr->internalRep.twoPtrValue.ptr1;
+    listRep = ListRepPtr(listPtr);
     listRep->elemCount = cmdc;
     cmdv = &listRep->elements;
 
diff --git a/generic/tclLink.c b/generic/tclLink.c
index 53187d7..952df4e 100644
--- a/generic/tclLink.c
+++ b/generic/tclLink.c
@@ -416,7 +416,8 @@ LinkTraceProc(
     case TCL_LINK_DOUBLE:
 	if (Tcl_GetDoubleFromObj(NULL, valueObj, &linkPtr->lastValue.d) != TCL_OK) {
 #ifdef ACCEPT_NAN
-	    if (valueObj->typePtr != &tclDoubleType) {
+	    Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(valueObj, &tclDoubleType);
+	    if (irPtr == NULL) {
 #endif
 		if (GetInvalidDoubleFromObj(valueObj, &linkPtr->lastValue.d) != TCL_OK) {
 		    Tcl_ObjSetVar2(interp, linkPtr->varName, NULL, ObjValue(linkPtr),
@@ -425,7 +426,7 @@ LinkTraceProc(
 		}
 #ifdef ACCEPT_NAN
 	    }
-	    linkPtr->lastValue.d = valueObj->internalRep.doubleValue;
+	    linkPtr->lastValue.d = irPtr->doubleValue;
 #endif
 	}
 	LinkedVar(double) = linkPtr->lastValue.d;
diff --git a/generic/tclListObj.c b/generic/tclListObj.c
index 8314306..2078989 100644
--- a/generic/tclListObj.c
+++ b/generic/tclListObj.c
@@ -12,6 +12,7 @@
  */
 
 #include "tclInt.h"
+#include <assert.h>
 
 /*
  * Prototypes for functions defined later in this file:
@@ -46,6 +47,27 @@ const Tcl_ObjType tclListType = {
     SetListFromAny		/* setFromAnyProc */
 };
 
+/* Macros to manipulate the List internal rep */
+
+#define ListSetIntRep(objPtr, listRepPtr)				\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	ir.twoPtrValue.ptr1 = (listRepPtr);				\
+	ir.twoPtrValue.ptr2 = NULL;					\
+	(listRepPtr)->refCount++;					\
+	Tcl_StoreIntRep((objPtr), &tclListType, &ir);			\
+    } while (0)
+
+#define ListGetIntRep(objPtr, listRepPtr)				\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep((objPtr), &tclListType);		\
+	(listRepPtr) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+    } while (0)
+
+#define ListResetIntRep(objPtr, listRepPtr) \
+    Tcl_FetchIntRep((objPtr), &tclListType)->twoPtrValue.ptr1 = (listRepPtr)
+
 #ifndef TCL_MIN_ELEMENT_GROWTH
 #define TCL_MIN_ELEMENT_GROWTH TCL_MIN_GROWTH/sizeof(Tcl_Obj *)
 #endif
@@ -374,8 +396,7 @@ Tcl_SetListObj(
 	listRepPtr = NewListIntRep(objc, objv, 1);
 	ListSetIntRep(objPtr, listRepPtr);
     } else {
-	objPtr->bytes = &tclEmptyString;
-	objPtr->length = 0;
+	Tcl_InitStringRep(objPtr, NULL, 0);
     }
 }
 
@@ -407,8 +428,10 @@ TclListObjCopy(
 				 * to be returned. */
 {
     Tcl_Obj *copyPtr;
+    List *listRepPtr;
 
-    if (listPtr->typePtr != &tclListType) {
+    ListGetIntRep(listPtr, listRepPtr);
+    if (NULL == listRepPtr) {
 	if (SetListFromAny(interp, listPtr) != TCL_OK) {
 	    return NULL;
 	}
@@ -543,10 +566,13 @@ Tcl_ListObjGetElements(
 {
     register List *listRepPtr;
 
-    if (listPtr->typePtr != &tclListType) {
-	int result;
+    ListGetIntRep(listPtr, listRepPtr);
+
+    if (listRepPtr == NULL) {
+	int result, length;
 
-	if (listPtr->bytes == &tclEmptyString) {
+	(void) Tcl_GetStringFromObj(listPtr, &length);
+	if (length == 0) {
 	    *objcPtr = 0;
 	    *objvPtr = NULL;
 	    return TCL_OK;
@@ -555,8 +581,8 @@ Tcl_ListObjGetElements(
 	if (result != TCL_OK) {
 	    return result;
 	}
+	ListGetIntRep(listPtr, listRepPtr);
     }
-    listRepPtr = ListRepPtr(listPtr);
     *objcPtr = listRepPtr->elemCount;
     *objvPtr = &listRepPtr->elements;
     return TCL_OK;
@@ -653,10 +679,13 @@ Tcl_ListObjAppendElement(
     if (Tcl_IsShared(listPtr)) {
 	Tcl_Panic("%s called with shared object", "Tcl_ListObjAppendElement");
     }
-    if (listPtr->typePtr != &tclListType) {
-	int result;
 
-	if (listPtr->bytes == &tclEmptyString) {
+    ListGetIntRep(listPtr, listRepPtr);
+    if (listRepPtr == NULL) {
+	int result, length;
+
+	(void) Tcl_GetStringFromObj(listPtr, &length);
+	if (length == 0) {
 	    Tcl_SetListObj(listPtr, 1, &objPtr);
 	    return TCL_OK;
 	}
@@ -664,9 +693,9 @@ Tcl_ListObjAppendElement(
 	if (result != TCL_OK) {
 	    return result;
 	}
+	ListGetIntRep(listPtr, listRepPtr);
     }
 
-    listRepPtr = ListRepPtr(listPtr);
     numElems = listRepPtr->elemCount;
     numRequired = numElems + 1 ;
     needGrow = (numRequired > listRepPtr->maxElemCount);
@@ -762,7 +791,11 @@ Tcl_ListObjAppendElement(
 	}
 	listRepPtr = newPtr;
     }
-    listPtr->internalRep.twoPtrValue.ptr1 = listRepPtr;
+    ListResetIntRep(listPtr, listRepPtr);
+    listRepPtr->refCount++;
+    TclFreeIntRep(listPtr);
+    ListSetIntRep(listPtr, listRepPtr);
+    listRepPtr->refCount--;
 
     /*
      * Add objPtr to the end of listPtr's array of element pointers. Increment
@@ -817,10 +850,12 @@ Tcl_ListObjIndex(
 {
     register List *listRepPtr;
 
-    if (listPtr->typePtr != &tclListType) {
-	int result;
+    ListGetIntRep(listPtr, listRepPtr);
+    if (listRepPtr == NULL) {
+	int result, length;
 
-	if (listPtr->bytes == &tclEmptyString) {
+	(void) Tcl_GetStringFromObj(listPtr, &length);
+	if (length == 0) {
 	    *objPtrPtr = NULL;
 	    return TCL_OK;
 	}
@@ -828,9 +863,9 @@ Tcl_ListObjIndex(
 	if (result != TCL_OK) {
 	    return result;
 	}
+	ListGetIntRep(listPtr, listRepPtr);
     }
 
-    listRepPtr = ListRepPtr(listPtr);
     if ((index < 0) || (index >= listRepPtr->elemCount)) {
 	*objPtrPtr = NULL;
     } else {
@@ -870,10 +905,12 @@ Tcl_ListObjLength(
 {
     register List *listRepPtr;
 
-    if (listPtr->typePtr != &tclListType) {
-	int result;
+    ListGetIntRep(listPtr, listRepPtr);
+    if (listRepPtr == NULL) {
+	int result, length;
 
-	if (listPtr->bytes == &tclEmptyString) {
+	(void) Tcl_GetStringFromObj(listPtr, &length);
+	if (length == 0) {
 	    *intPtr = 0;
 	    return TCL_OK;
 	}
@@ -881,9 +918,9 @@ Tcl_ListObjLength(
 	if (result != TCL_OK) {
 	    return result;
 	}
+	ListGetIntRep(listPtr, listRepPtr);
     }
 
-    listRepPtr = ListRepPtr(listPtr);
     *intPtr = listRepPtr->elemCount;
     return TCL_OK;
 }
@@ -943,9 +980,14 @@ Tcl_ListObjReplace(
     if (Tcl_IsShared(listPtr)) {
 	Tcl_Panic("%s called with shared object", "Tcl_ListObjReplace");
     }
-    if (listPtr->typePtr != &tclListType) {
-	if (listPtr->bytes == &tclEmptyString) {
-	    if (!objc) {
+
+    ListGetIntRep(listPtr, listRepPtr);
+    if (listRepPtr == NULL) {
+	int length;
+
+	(void) Tcl_GetStringFromObj(listPtr, &length);
+	if (length == 0) {
+	    if (objc == 0) {
 		return TCL_OK;
 	    }
 	    Tcl_SetListObj(listPtr, objc, NULL);
@@ -956,6 +998,7 @@ Tcl_ListObjReplace(
 		return result;
 	    }
 	}
+	ListGetIntRep(listPtr, listRepPtr);
     }
 
     /*
@@ -966,7 +1009,6 @@ Tcl_ListObjReplace(
      * Resist any temptation to optimize this case.
      */
 
-    listRepPtr = ListRepPtr(listPtr);
     elemPtrs = &listRepPtr->elements;
     numElems = listRepPtr->elemCount;
 
@@ -1020,7 +1062,7 @@ Tcl_ListObjReplace(
 	}
 	if (newPtr) {
 	    listRepPtr = newPtr;
-	    listPtr->internalRep.twoPtrValue.ptr1 = listRepPtr;
+	    ListResetIntRep(listPtr, listRepPtr);
 	    elemPtrs = &listRepPtr->elements;
 	    listRepPtr->maxElemCount = attempt;
 	    needGrow = numRequired > listRepPtr->maxElemCount;
@@ -1093,7 +1135,7 @@ Tcl_ListObjReplace(
 	    }
 	}
 
-	listPtr->internalRep.twoPtrValue.ptr1 = listRepPtr;
+	ListResetIntRep(listPtr, listRepPtr);
 	listRepPtr->refCount++;
 
 	elemPtrs = &listRepPtr->elements;
@@ -1166,10 +1208,15 @@ Tcl_ListObjReplace(
     listRepPtr->elemCount = numRequired;
 
     /*
-     * Invalidate and free any old string representation since it no longer
-     * reflects the list's internal representation.
+     * Invalidate and free any old representations that may not agree
+     * with the revised list's internal representation.
      */
 
+    listRepPtr->refCount++;
+    TclFreeIntRep(listPtr);
+    ListSetIntRep(listPtr, listRepPtr);
+    listRepPtr->refCount--;
+
     TclInvalidateStringRep(listPtr);
     return TCL_OK;
 }
@@ -1208,6 +1255,7 @@ TclLindexList(
 
     int index;			/* Index into the list. */
     Tcl_Obj *indexListCopy;
+    List *listRepPtr;
 
     /*
      * Determine whether argPtr designates a list or a single index. We have
@@ -1215,7 +1263,8 @@ TclLindexList(
      * shimmering; see TIP#22 and TIP#33 for the details.
      */
 
-    if (argPtr->typePtr != &tclListType
+    ListGetIntRep(argPtr, listRepPtr);
+    if ((listRepPtr == NULL)
 	    && TclGetIntForIndexM(NULL , argPtr, 0, &index) == TCL_OK) {
 	/*
 	 * argPtr designates a single index.
@@ -1246,13 +1295,12 @@ TclLindexList(
 	return TclLindexFlat(interp, listPtr, 1, &argPtr);
     }
 
-    {
-	int indexCount = -1;		/* Size of the array of list indices. */
-	Tcl_Obj **indices = NULL; 	/* Array of list indices. */
+    ListGetIntRep(indexListCopy, listRepPtr);
 
-	TclListObjGetElements(NULL, indexListCopy, &indexCount, &indices);
-	listPtr = TclLindexFlat(interp, listPtr, indexCount, indices);
-    }
+    assert(listRepPtr != NULL);
+
+    listPtr = TclLindexFlat(interp, listPtr, listRepPtr->elemCount,
+		&listRepPtr->elements);
     Tcl_DecrRefCount(indexListCopy);
     return listPtr;
 }
@@ -1387,6 +1435,7 @@ TclLsetList(
     Tcl_Obj *retValuePtr;	/* Pointer to the list to be returned. */
     int index;			/* Current index in the list - discarded. */
     Tcl_Obj *indexListCopy;
+    List *listRepPtr;
 
     /*
      * Determine whether the index arg designates a list or a single index.
@@ -1394,7 +1443,8 @@ TclLsetList(
      * shimmering; see TIP #22 and #23 for details.
      */
 
-    if (indexArgPtr->typePtr != &tclListType
+    ListGetIntRep(indexArgPtr, listRepPtr);
+    if (listRepPtr == NULL
 	    && TclGetIntForIndexM(NULL, indexArgPtr, 0, &index) == TCL_OK) {
 	/*
 	 * indexArgPtr designates a single index.
@@ -1479,6 +1529,7 @@ TclLsetFlat(
 {
     int index, result, len;
     Tcl_Obj *subListPtr, *retValuePtr, *chainPtr;
+    Tcl_ObjIntRep *irPtr;
 
     /*
      * If there are no indices, simply return the new value.  (Without
@@ -1609,7 +1660,8 @@ TclLsetFlat(
 	     * them at that time.
 	     */
 
-	    parentList->internalRep.twoPtrValue.ptr2 = chainPtr;
+	    irPtr = Tcl_FetchIntRep(parentList, &tclListType);
+	    irPtr->twoPtrValue.ptr2 = chainPtr;
 	    chainPtr = parentList;
 	}
     } while (indexCount > 0);
@@ -1623,22 +1675,32 @@ TclLsetFlat(
 
     while (chainPtr) {
 	Tcl_Obj *objPtr = chainPtr;
+	List *listRepPtr;
+
+	/*
+	 * Clear away our intrep surgery mess.
+	 */
 
+	irPtr = Tcl_FetchIntRep(objPtr, &tclListType);
+	listRepPtr = irPtr->twoPtrValue.ptr1;
+	chainPtr = irPtr->twoPtrValue.ptr2;
+	
 	if (result == TCL_OK) {
+
 	    /*
 	     * We're going to store valuePtr, so spoil string reps of all
 	     * containing lists.
 	     */
 
+	    listRepPtr->refCount++;
+	    TclFreeIntRep(objPtr);
+	    ListSetIntRep(objPtr, listRepPtr);
+	    listRepPtr->refCount--;
+
 	    TclInvalidateStringRep(objPtr);
+	} else {
+	    irPtr->twoPtrValue.ptr2 = NULL;
 	}
-
-	/*
-	 * Clear away our intrep surgery mess.
-	 */
-
-	chainPtr = objPtr->internalRep.twoPtrValue.ptr2;
-	objPtr->internalRep.twoPtrValue.ptr2 = NULL;
     }
 
     if (result != TCL_OK) {
@@ -1665,8 +1727,8 @@ TclLsetFlat(
 	Tcl_ListObjAppendElement(NULL, subListPtr, valuePtr);
     } else {
 	TclListObjSetElement(NULL, subListPtr, index, valuePtr);
+	TclInvalidateStringRep(subListPtr);
     }
-    TclInvalidateStringRep(subListPtr);
     Tcl_IncrRefCount(retValuePtr);
     return retValuePtr;
 }
@@ -1722,10 +1784,13 @@ TclListObjSetElement(
     if (Tcl_IsShared(listPtr)) {
 	Tcl_Panic("%s called with shared object", "TclListObjSetElement");
     }
-    if (listPtr->typePtr != &tclListType) {
-	int result;
 
-	if (listPtr->bytes == &tclEmptyString) {
+    ListGetIntRep(listPtr, listRepPtr);
+    if (listRepPtr == NULL) {
+	int result, length;
+
+	(void) Tcl_GetStringFromObj(listPtr, &length);
+	if (length == 0) {
 	    if (interp != NULL) {
 		Tcl_SetObjResult(interp,
 			Tcl_NewStringObj("list index out of range", -1));
@@ -1738,9 +1803,9 @@ TclListObjSetElement(
 	if (result != TCL_OK) {
 	    return result;
 	}
+	ListGetIntRep(listPtr, listRepPtr);
     }
 
-    listRepPtr = ListRepPtr(listPtr);
     elemCount = listRepPtr->elemCount;
 
     /*
@@ -1783,7 +1848,8 @@ TclListObjSetElement(
 
 	listRepPtr->refCount--;
 
-	listPtr->internalRep.twoPtrValue.ptr1 = listRepPtr = newPtr;
+	listRepPtr = newPtr;
+	ListResetIntRep(listPtr, listRepPtr);
     }
     elemPtrs = &listRepPtr->elements;
 
@@ -1805,6 +1871,18 @@ TclListObjSetElement(
 
     elemPtrs[index] = valuePtr;
 
+    /*
+     * Invalidate outdated intreps.
+     */
+
+    ListGetIntRep(listPtr, listRepPtr);
+    listRepPtr->refCount++;
+    TclFreeIntRep(listPtr);
+    ListSetIntRep(listPtr, listRepPtr);
+    listRepPtr->refCount--;
+
+    TclInvalidateStringRep(listPtr);
+
     return TCL_OK;
 }
 
@@ -1820,9 +1898,8 @@ TclListObjSetElement(
  *	None.
  *
  * Side effects:
- *	Frees listPtr's List* internal representation and sets listPtr's
- *	internalRep.twoPtrValue.ptr1 to NULL. Decrements the ref counts of all
- *	element objects, which may free them.
+ *	Frees listPtr's List* internal representation, if no longer shared.
+ *	May decrement the ref counts of element objects, which may free them.
  *
  *----------------------------------------------------------------------
  */
@@ -1831,7 +1908,10 @@ static void
 FreeListInternalRep(
     Tcl_Obj *listPtr)		/* List object with internal rep to free. */
 {
-    List *listRepPtr = ListRepPtr(listPtr);
+    List *listRepPtr;
+
+    ListGetIntRep(listPtr, listRepPtr);
+    assert(listRepPtr != NULL);
 
     if (listRepPtr->refCount-- <= 1) {
 	Tcl_Obj **elemPtrs = &listRepPtr->elements;
@@ -1842,8 +1922,6 @@ FreeListInternalRep(
 	}
 	ckfree(listRepPtr);
     }
-
-    listPtr->typePtr = NULL;
 }
 
 /*
@@ -1868,8 +1946,10 @@ DupListInternalRep(
     Tcl_Obj *srcPtr,		/* Object with internal rep to copy. */
     Tcl_Obj *copyPtr)		/* Object with internal rep to set. */
 {
-    List *listRepPtr = ListRepPtr(srcPtr);
+    List *listRepPtr;
 
+    ListGetIntRep(srcPtr, listRepPtr);
+    assert(listRepPtr != NULL);
     ListSetIntRep(copyPtr, listRepPtr);
 }
 
@@ -1908,7 +1988,7 @@ SetListFromAny(
      * describe duplicate keys).
      */
 
-    if (objPtr->typePtr == &tclDictType && !objPtr->bytes) {
+    if (!TclHasStringRep(objPtr) && Tcl_FetchIntRep(objPtr, &tclDictType)) {
 	Tcl_Obj *keyPtr, *valuePtr;
 	Tcl_DictSearch search;
 	int done, size;
@@ -1966,10 +2046,12 @@ SetListFromAny(
 
 	while (nextElem < limit) {
 	    const char *elemStart;
+	    char *check;
 	    int elemSize, literal;
 
 	    if (TCL_OK != TclFindElement(interp, nextElem, limit - nextElem,
 		    &elemStart, &nextElem, &elemSize, &literal)) {
+	    fail:
 		while (--elemPtrs >= &listRepPtr->elements) {
 		    Tcl_DecrRefCount(*elemPtrs);
 		}
@@ -1980,14 +2062,21 @@ SetListFromAny(
 		break;
 	    }
 
-	    /* TODO: replace panic with error on alloc failure? */
-	    if (literal) {
-		TclNewStringObj(*elemPtrs, elemStart, elemSize);
-	    } else {
-		TclNewObj(*elemPtrs);
-		(*elemPtrs)->bytes = ckalloc((unsigned) elemSize + 1);
-		(*elemPtrs)->length = TclCopyAndCollapse(elemSize, elemStart,
-			(*elemPtrs)->bytes);
+	    TclNewObj(*elemPtrs);
+	    TclInvalidateStringRep(*elemPtrs);
+	    check = Tcl_InitStringRep(*elemPtrs, literal ? elemStart : NULL,
+		    elemSize);
+	    if (elemSize && check == NULL) {
+		if (interp) {
+		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
+			    "cannot construct list, out of memory", -1));
+		    Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
+		}
+		goto fail;
+	    }
+	    if (!literal) {
+		Tcl_InitStringRep(*elemPtrs, NULL,
+			TclCopyAndCollapse(elemSize, elemStart, check));
 	    }
 
 	    Tcl_IncrRefCount(*elemPtrs++);/* Since list now holds ref to it. */
@@ -1997,12 +2086,11 @@ SetListFromAny(
     }
 
     /*
-     * Free the old internalRep before setting the new one. We do this as late
+     * Store the new internalRep. We do this as late
      * as possible to allow the conversion code, in particular
-     * Tcl_GetStringFromObj, to use that old internalRep.
+     * Tcl_GetStringFromObj, to use the old internalRep.
      */
 
-    TclFreeIntRep(objPtr);
     ListSetIntRep(objPtr, listRepPtr);
     return TCL_OK;
 }
@@ -2034,12 +2122,17 @@ UpdateStringOfList(
 {
 #   define LOCAL_SIZE 64
     char localFlags[LOCAL_SIZE], *flagPtr = NULL;
-    List *listRepPtr = ListRepPtr(listPtr);
-    int numElems = listRepPtr->elemCount;
-    int i, length, bytesNeeded = 0;
+    int numElems, i, length, bytesNeeded = 0;
     const char *elem;
     char *dst;
     Tcl_Obj **elemPtrs;
+    List *listRepPtr;
+
+    ListGetIntRep(listPtr, listRepPtr);
+
+    assert(listRepPtr != NULL);
+
+    numElems = listRepPtr->elemCount;
 
     /*
      * Mark the list as being canonical; although it will now have a string
@@ -2054,8 +2147,7 @@ UpdateStringOfList(
      */
 
     if (numElems == 0) {
-	listPtr->bytes = &tclEmptyString;
-	listPtr->length = 0;
+	Tcl_InitStringRep(listPtr, NULL, 0);
 	return;
     }
 
@@ -2084,22 +2176,21 @@ UpdateStringOfList(
     if (bytesNeeded > INT_MAX - numElems + 1) {
 	Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
     }
-    bytesNeeded += numElems;
+    bytesNeeded += numElems - 1;
 
     /*
      * Pass 2: copy into string rep buffer.
      */
 
-    listPtr->length = bytesNeeded - 1;
-    listPtr->bytes = ckalloc(bytesNeeded);
-    dst = listPtr->bytes;
+    dst = Tcl_InitStringRep(listPtr, NULL, bytesNeeded);
+    TclOOM(dst, bytesNeeded);
     for (i = 0; i < numElems; i++) {
 	flagPtr[i] |= (i ? TCL_DONT_QUOTE_HASH : 0);
 	elem = TclGetStringFromObj(elemPtrs[i], &length);
 	dst += TclConvertElement(elem, length, dst, flagPtr[i]);
 	*dst++ = ' ';
     }
-    listPtr->bytes[listPtr->length] = '\0';
+    (void) Tcl_InitStringRep(listPtr, NULL, bytesNeeded);
 
     if (flagPtr != localFlags) {
 	ckfree(flagPtr);
diff --git a/generic/tclNamesp.c b/generic/tclNamesp.c
index 2b8dd51..27aafc3 100644
--- a/generic/tclNamesp.c
+++ b/generic/tclNamesp.c
@@ -25,6 +25,7 @@
 
 #include "tclInt.h"
 #include "tclCompile.h" /* for TclLogCommandInfo visibility */
+#include <assert.h>
 
 /*
  * Thread-local storage used to avoid having a global lock on data that is not
@@ -152,6 +153,22 @@ static const Tcl_ObjType nsNameType = {
     SetNsNameFromAny		/* setFromAnyProc */
 };
 
+#define NsNameSetIntRep(objPtr, nnPtr)					\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	(nnPtr)->refCount++;						\
+	ir.twoPtrValue.ptr1 = (nnPtr);					\
+	ir.twoPtrValue.ptr2 = NULL;					\
+	Tcl_StoreIntRep((objPtr), &nsNameType, &ir);			\
+    } while (0)
+
+#define NsNameGetIntRep(objPtr, nnPtr)					\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep((objPtr), &nsNameType);			\
+	(nnPtr) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+    } while (0)
+
 /*
  * Array of values describing how to implement each standard subcommand of the
  * "namespace" command.
@@ -2898,15 +2915,16 @@ GetNamespaceFromObj(
     Tcl_Namespace **nsPtrPtr)	/* Result namespace pointer goes here. */
 {
     ResolvedNsName *resNamePtr;
-    Namespace *nsPtr, *refNsPtr;
 
-    if (objPtr->typePtr == &nsNameType) {
+    NsNameGetIntRep(objPtr, resNamePtr);
+    if (resNamePtr) {
+	Namespace *nsPtr, *refNsPtr;
+
 	/*
 	 * Check that the ResolvedNsName is still valid; avoid letting the ref
 	 * cross interps.
 	 */
 
-	resNamePtr = objPtr->internalRep.twoPtrValue.ptr1;
 	nsPtr = resNamePtr->nsPtr;
 	refNsPtr = resNamePtr->refNsPtr;
 	if (!(nsPtr->flags & NS_DYING) && (interp == nsPtr->interp)
@@ -2915,9 +2933,11 @@ GetNamespaceFromObj(
 	    *nsPtrPtr = (Tcl_Namespace *) nsPtr;
 	    return TCL_OK;
 	}
+	Tcl_StoreIntRep(objPtr, &nsNameType, NULL);
     }
     if (SetNsNameFromAny(interp, objPtr) == TCL_OK) {
-	resNamePtr = objPtr->internalRep.twoPtrValue.ptr1;
+	NsNameGetIntRep(objPtr, resNamePtr);
+	assert(resNamePtr != NULL);
 	*nsPtrPtr = (Tcl_Namespace *) resNamePtr->nsPtr;
 	return TCL_OK;
     }
@@ -4687,8 +4707,11 @@ FreeNsNameInternalRep(
     register Tcl_Obj *objPtr)	/* nsName object with internal representation
 				 * to free. */
 {
-    ResolvedNsName *resNamePtr = objPtr->internalRep.twoPtrValue.ptr1;
+    ResolvedNsName *resNamePtr;
 
+    NsNameGetIntRep(objPtr, resNamePtr);
+    assert(resNamePtr != NULL);
+	
     /*
      * Decrement the reference count of the namespace. If there are no more
      * references, free it up.
@@ -4704,7 +4727,6 @@ FreeNsNameInternalRep(
 	TclNsDecrRefCount(resNamePtr->nsPtr);
 	ckfree(resNamePtr);
     }
-    objPtr->typePtr = NULL;
 }
 
 /*
@@ -4731,11 +4753,11 @@ DupNsNameInternalRep(
     Tcl_Obj *srcPtr,		/* Object with internal rep to copy. */
     register Tcl_Obj *copyPtr)	/* Object with internal rep to set. */
 {
-    ResolvedNsName *resNamePtr = srcPtr->internalRep.twoPtrValue.ptr1;
+    ResolvedNsName *resNamePtr;
 
-    copyPtr->internalRep.twoPtrValue.ptr1 = resNamePtr;
-    resNamePtr->refCount++;
-    copyPtr->typePtr = &nsNameType;
+    NsNameGetIntRep(srcPtr, resNamePtr);
+    assert(resNamePtr != NULL);
+    NsNameSetIntRep(copyPtr, resNamePtr);
 }
 
 /*
@@ -4780,24 +4802,15 @@ SetNsNameFromAny(
     TclGetNamespaceForQualName(interp, name, NULL, TCL_FIND_ONLY_NS,
 	     &nsPtr, &dummy1Ptr, &dummy2Ptr, &dummy);
 
+    if ((nsPtr == NULL) || (nsPtr->flags & NS_DYING)) {
+	return TCL_ERROR;
+    }
+
     /*
      * If we found a namespace, then create a new ResolvedNsName structure
      * that holds a reference to it.
      */
 
-    if ((nsPtr == NULL) || (nsPtr->flags & NS_DYING)) {
-	/*
-	 * Our failed lookup proves any previously cached nsName intrep is no
-	 * longer valid. Get rid of it so we no longer waste memory storing
-	 * it, nor time determining its invalidity again and again.
-	 */
-
-	if (objPtr->typePtr == &nsNameType) {
-	    TclFreeIntRep(objPtr);
-	}
-	return TCL_ERROR;
-    }
-
     nsPtr->refCount++;
     resNamePtr = ckalloc(sizeof(ResolvedNsName));
     resNamePtr->nsPtr = nsPtr;
@@ -4806,10 +4819,8 @@ SetNsNameFromAny(
     } else {
 	resNamePtr->refNsPtr = (Namespace *) TclGetCurrentNamespace(interp);
     }
-    resNamePtr->refCount = 1;
-    TclFreeIntRep(objPtr);
-    objPtr->internalRep.twoPtrValue.ptr1 = resNamePtr;
-    objPtr->typePtr = &nsNameType;
+    resNamePtr->refCount = 0;
+    NsNameSetIntRep(objPtr, resNamePtr);
     return TCL_OK;
 }
 
diff --git a/generic/tclOOCall.c b/generic/tclOOCall.c
index 9d5312c..50a9c80 100644
--- a/generic/tclOOCall.c
+++ b/generic/tclOOCall.c
@@ -15,6 +15,7 @@
 #endif
 #include "tclInt.h"
 #include "tclOOInt.h"
+#include <assert.h>
 
 /*
  * Structure containing a CallContext and any other values needed only during
@@ -128,6 +129,7 @@ static const Tcl_ObjType methodNameType = {
     NULL,
     NULL
 };
+
 
 /*
  * ----------------------------------------------------------------------
@@ -222,11 +224,12 @@ StashCallChain(
     Tcl_Obj *objPtr,
     CallChain *callPtr)
 {
+    Tcl_ObjIntRep ir;
+
     callPtr->refCount++;
     TclGetString(objPtr);
-    TclFreeIntRep(objPtr);
-    objPtr->typePtr = &methodNameType;
-    objPtr->internalRep.twoPtrValue.ptr1 = callPtr;
+    ir.twoPtrValue.ptr1 = callPtr;
+    Tcl_StoreIntRep(objPtr, &methodNameType, &ir);
 }
 
 void
@@ -253,21 +256,16 @@ DupMethodNameRep(
     Tcl_Obj *srcPtr,
     Tcl_Obj *dstPtr)
 {
-    register CallChain *callPtr = srcPtr->internalRep.twoPtrValue.ptr1;
-
-    dstPtr->typePtr = &methodNameType;
-    dstPtr->internalRep.twoPtrValue.ptr1 = callPtr;
-    callPtr->refCount++;
+    StashCallChain(dstPtr,
+	    Tcl_FetchIntRep(srcPtr, &methodNameType)->twoPtrValue.ptr1);
 }
 
 static void
 FreeMethodNameRep(
     Tcl_Obj *objPtr)
 {
-    register CallChain *callPtr = objPtr->internalRep.twoPtrValue.ptr1;
-
-    TclOODeleteChain(callPtr);
-    objPtr->typePtr = NULL;
+    TclOODeleteChain(
+	    Tcl_FetchIntRep(objPtr, &methodNameType)->twoPtrValue.ptr1);
 }
 
 /*
@@ -1165,15 +1163,16 @@ TclOOGetCallContext(
 	 * the object, and in the class).
 	 */
 
+	const Tcl_ObjIntRep *irPtr;
 	const int reuseMask = (WANT_PUBLIC(flags) ? ~0 : ~PUBLIC_METHOD);
 
-	if (cacheInThisObj->typePtr == &methodNameType) {
-	    callPtr = cacheInThisObj->internalRep.twoPtrValue.ptr1;
+	if ((irPtr = Tcl_FetchIntRep(cacheInThisObj, &methodNameType))) {
+	    callPtr = irPtr->twoPtrValue.ptr1;
 	    if (IsStillValid(callPtr, oPtr, flags, reuseMask)) {
 		callPtr->refCount++;
 		goto returnContext;
 	    }
-	    FreeMethodNameRep(cacheInThisObj);
+	    Tcl_StoreIntRep(cacheInThisObj, &methodNameType, NULL);
 	}
 
 	if (oPtr->flags & USE_CLASS_CACHE) {
diff --git a/generic/tclOOMethod.c b/generic/tclOOMethod.c
index ad14a1a..545cb47 100644
--- a/generic/tclOOMethod.c
+++ b/generic/tclOOMethod.c
@@ -799,6 +799,7 @@ PushMethodCallFrame(
     register int result;
     const char *namePtr;
     CallFrame **framePtrPtr = &fdPtr->framePtr;
+    ByteCode *codePtr;
 
     /*
      * Compute basic information on the basis of the type of method it is.
@@ -864,10 +865,8 @@ PushMethodCallFrame(
      * alternative is *so* slow...
      */
 
-    if (pmPtr->procPtr->bodyPtr->typePtr == &tclByteCodeType) {
-	ByteCode *codePtr =
-		pmPtr->procPtr->bodyPtr->internalRep.twoPtrValue.ptr1;
-
+    ByteCodeGetIntRep(pmPtr->procPtr->bodyPtr, &tclByteCodeType, codePtr);
+    if (codePtr) {
 	codePtr->nsPtr = nsPtr;
     }
     result = TclProcCompileProc(interp, pmPtr->procPtr,
@@ -1341,7 +1340,7 @@ CloneProcedureMethod(
 
     bodyObj = Tcl_DuplicateObj(pmPtr->procPtr->bodyPtr);
     Tcl_GetString(bodyObj);
-    TclFreeIntRep(bodyObj);
+    Tcl_StoreIntRep(pmPtr->procPtr->bodyPtr, &tclByteCodeType, NULL);
 
     /*
      * Create the actual copy of the method record, manufacturing a new proc
@@ -1570,9 +1569,7 @@ TclOOGetMethodBody(
     if (mPtr->typePtr == &procMethodType) {
 	ProcedureMethod *pmPtr = mPtr->clientData;
 
-	if (pmPtr->procPtr->bodyPtr->bytes == NULL) {
-	    (void) Tcl_GetString(pmPtr->procPtr->bodyPtr);
-	}
+	(void) TclGetString(pmPtr->procPtr->bodyPtr);
 	return pmPtr->procPtr->bodyPtr;
     }
     return NULL;
diff --git a/generic/tclObj.c b/generic/tclObj.c
index 5a8ce3b..6a4d161 100644
--- a/generic/tclObj.c
+++ b/generic/tclObj.c
@@ -17,6 +17,7 @@
 #include "tclInt.h"
 #include "tommath.h"
 #include <math.h>
+#include <assert.h>
 
 /*
  * Table of all object types.
@@ -1065,9 +1066,8 @@ TclDbInitNewObj(
 				 * debugging. */
 {
     objPtr->refCount = 0;
-    objPtr->bytes = &tclEmptyString;
-    objPtr->length = 0;
     objPtr->typePtr = NULL;
+    TclInitStringRep(objPtr, NULL, 0);
 
 #if TCL_THREADS
     /*
@@ -1725,6 +1725,91 @@ Tcl_GetStringFromObj(
 /*
  *----------------------------------------------------------------------
  *
+ * Tcl_InitStringRep --
+ *
+ *	This function is called in several configurations to provide all
+ *	the tools needed to set an object's string representation. The
+ *	function is determined by the arguments.
+ *	
+ *	(objPtr->bytes != NULL && bytes != NULL) || (numBytes < 0)
+ *	    Invalid call -- panic!
+ *	
+ *	objPtr->bytes == NULL && bytes == NULL && numBytes >= 0
+ *	    Allocation only - allocate space for (numBytes+1) chars.
+ *	    store in objPtr->bytes and return. Also sets
+ *	    objPtr->length to 0 and objPtr->bytes[0] to NUL.
+ *	
+ *	objPtr->bytes == NULL && bytes != NULL && numBytes >= 0
+ *	    Allocate and copy. bytes is assumed to point to chars to
+ *	    copy into the string rep. objPtr->length = numBytes. Allocate
+ *	    array of (numBytes + 1) chars. store in objPtr->bytes. Copy
+ *	    numBytes chars from bytes to objPtr->bytes; Set
+ *	    objPtr->bytes[numBytes] to NUL and return objPtr->bytes.
+ *	    Caller must guarantee there are numBytes chars at bytes to
+ *	    be copied.
+ *
+ *	objPtr->bytes != NULL && bytes == NULL && numBytes >= 0
+ *	    Truncate.  Set objPtr->length to numBytes and
+ *	    objPr->bytes[numBytes] to NUL.  Caller has to guarantee
+ *	    that a prior allocating call allocated enough bytes for
+ *	    this to be valid. Return objPtr->bytes.
+ *
+ *	Caller is expected to ascertain that the bytes copied into
+ *	the string rep make up complete valid UTF-8 characters.
+ *
+ * Results:
+ *	A pointer to the string rep of objPtr.
+ *
+ * Side effects:
+ *	As described above.
+ *
+ *----------------------------------------------------------------------
+ */
+
+char *
+Tcl_InitStringRep(
+    Tcl_Obj *objPtr,	/* Object whose string rep is to be set */
+    const char *bytes,
+    unsigned int numBytes)
+{
+    assert(objPtr->bytes == NULL || bytes == NULL);
+
+    if (numBytes > INT_MAX) {
+	Tcl_Panic("max size for a Tcl value (%d bytes) exceeded", INT_MAX);
+    }
+
+    /* Allocate */
+    if (objPtr->bytes == NULL) {
+	/* Allocate only as empty - extend later if bytes copied */
+	objPtr->length = 0;
+	if (numBytes) {
+	    objPtr->bytes = attemptckalloc(numBytes + 1);
+	    if (objPtr->bytes == NULL) {
+		return NULL;
+	    }
+	    if (bytes) {
+		/* Copy */
+		memcpy(objPtr->bytes, bytes, numBytes);
+		objPtr->length = (int) numBytes;
+	    }
+	} else {
+	    TclInitStringRep(objPtr, NULL, 0);
+	}
+    } else {
+	/* objPtr->bytes != NULL bytes == NULL - Truncate */
+	objPtr->bytes = ckrealloc(objPtr->bytes, numBytes + 1);
+	objPtr->length = (int)numBytes;
+    }
+
+    /* Terminate */
+    objPtr->bytes[objPtr->length] = '\0';
+
+    return objPtr->bytes;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * Tcl_InvalidateStringRep --
  *
  *	This function is called to invalidate an object's string
@@ -1751,6 +1836,123 @@ Tcl_InvalidateStringRep(
 /*
  *----------------------------------------------------------------------
  *
+ * Tcl_HasStringRep --
+ *
+ *	This function reports whether object has a string representation.
+ *
+ * Results:
+ *	Boolean.
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_HasStringRep(
+    Tcl_Obj *objPtr)	/* Object to test */
+{
+    return TclHasStringRep(objPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_StoreIntRep --
+ *
+ *	This function is called to set the object's internal
+ *	representation to match a particular type.
+ *
+ *	It is the caller's responsibility to guarantee that
+ *	the value of the submitted IntRep is in agreement with
+ *	the value of any existing string rep.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Calls the freeIntRepProc of the current Tcl_ObjType, if any.
+ *	Sets the internalRep and typePtr fields to the submitted values.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_StoreIntRep(
+    Tcl_Obj *objPtr,		/* Object whose internal rep should be set. */
+    const Tcl_ObjType *typePtr,	/* New type for the object */
+    const Tcl_ObjIntRep *irPtr)	/* New IntRep for the object */
+{
+    /* Clear out any existing IntRep ( "shimmer" ) */
+    TclFreeIntRep(objPtr);
+
+    /* When irPtr == NULL, just leave objPtr with no IntRep for typePtr */
+    if (irPtr) {
+	/* Copy the new IntRep into place */
+	objPtr->internalRep = *irPtr;
+
+	/* Set the type to match */
+	objPtr->typePtr = typePtr;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_FetchIntRep --
+ *
+ *	This function is called to retrieve the object's internal
+ *	representation matching a requested type, if any.
+ *
+ * Results:
+ *	A read-only pointer to the associated Tcl_ObjIntRep, or
+ *	NULL if no such internal representation exists.
+ *
+ * Side effects:
+ *	Calls the freeIntRepProc of the current Tcl_ObjType, if any.
+ *	Sets the internalRep and typePtr fields to the submitted values.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_ObjIntRep *
+Tcl_FetchIntRep(
+    Tcl_Obj *objPtr,		/* Object to fetch from. */
+    const Tcl_ObjType *typePtr)	/* Requested type */
+{
+    /* If objPtr type doesn't match request, nothing can be fetched */
+    if (objPtr->typePtr != typePtr) {
+	return NULL;
+    }
+
+    /* Type match! objPtr IntRep is the one sought. */
+    return &(objPtr->internalRep);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_FreeIntRep --
+ *
+ *	This function is called to free an object's internal representation.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Calls the freeIntRepProc of the current Tcl_ObjType, if any.
+ *	Sets typePtr field to NULL.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tcl_FreeIntRep(
+    Tcl_Obj *objPtr)	/* Object whose internal rep should be freed. */
+{
+    TclFreeIntRep(objPtr);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * Tcl_NewBooleanObj --
  *
  *	This function is normally called when not debugging: i.e., when
@@ -1835,6 +2037,7 @@ Tcl_DbNewBooleanObj(
     register Tcl_Obj *objPtr;
 
     TclDbNewObj(objPtr, file, line);
+    /* Optimized TclInvalidateStringRep() */
     objPtr->bytes = NULL;
 
     objPtr->internalRep.wideValue = (boolValue != 0);
@@ -2221,6 +2424,7 @@ Tcl_DbNewDoubleObj(
     register Tcl_Obj *objPtr;
 
     TclDbNewObj(objPtr, file, line);
+    /* Optimized TclInvalidateStringRep() */
     objPtr->bytes = NULL;
 
     objPtr->internalRep.doubleValue = dblValue;
@@ -2381,15 +2585,12 @@ static void
 UpdateStringOfDouble(
     register Tcl_Obj *objPtr)	/* Double obj with string rep to update. */
 {
-    char buffer[TCL_DOUBLE_SPACE];
-    register int len;
+    char *dst = Tcl_InitStringRep(objPtr, NULL, TCL_DOUBLE_SPACE);
 
-    Tcl_PrintDouble(NULL, objPtr->internalRep.doubleValue, buffer);
-    len = strlen(buffer);
+    TclOOM(dst, TCL_DOUBLE_SPACE + 1);
 
-    objPtr->bytes = ckalloc(len + 1);
-    memcpy(objPtr->bytes, buffer, (unsigned) len + 1);
-    objPtr->length = len;
+    Tcl_PrintDouble(NULL, objPtr->internalRep.doubleValue, dst);
+    (void) Tcl_InitStringRep(objPtr, NULL, strlen(dst));
 }
 
 /*
@@ -2578,14 +2779,11 @@ static void
 UpdateStringOfInt(
     register Tcl_Obj *objPtr)	/* Int object whose string rep to update. */
 {
-    char buffer[TCL_INTEGER_SPACE];
-    register int len;
-
-    len = TclFormatInt(buffer, objPtr->internalRep.wideValue);
+    char *dst = Tcl_InitStringRep( objPtr, NULL, TCL_INTEGER_SPACE);
 
-    objPtr->bytes = ckalloc(len + 1);
-    memcpy(objPtr->bytes, buffer, (unsigned) len + 1);
-    objPtr->length = len;
+    TclOOM(dst, TCL_INTEGER_SPACE + 1);
+    (void) Tcl_InitStringRep(objPtr, NULL,
+	    TclFormatInt(dst, objPtr->internalRep.wideValue));
 }
 
 #if !defined(TCL_NO_DEPRECATED) && TCL_MAJOR_VERSION < 9 && !defined(TCL_WIDE_INT_IS_LONG)
@@ -2593,14 +2791,11 @@ static void
 UpdateStringOfOldInt(
     register Tcl_Obj *objPtr)	/* Int object whose string rep to update. */
 {
-    char buffer[TCL_INTEGER_SPACE];
-    register int len;
+    char *dst = Tcl_InitStringRep( objPtr, NULL, TCL_INTEGER_SPACE);
 
-    len = TclFormatInt(buffer, objPtr->internalRep.longValue);
-
-    objPtr->bytes = ckalloc(len + 1);
-    memcpy(objPtr->bytes, buffer, (unsigned) len + 1);
-    objPtr->length = len;
+    TclOOM(dst, TCL_INTEGER_SPACE + 1);
+    (void) Tcl_InitStringRep(objPtr, NULL,
+	    TclFormatInt(dst, objPtr->internalRep.longValue));
 }
 #endif
 
@@ -2706,6 +2901,7 @@ Tcl_DbNewLongObj(
     register Tcl_Obj *objPtr;
 
     TclDbNewObj(objPtr, file, line);
+    /* Optimized TclInvalidateStringRep */
     objPtr->bytes = NULL;
 
     objPtr->internalRep.wideValue = longValue;
@@ -3262,12 +3458,10 @@ UpdateStringOfBignum(
 {
     mp_int bignumVal;
     int size;
-    int status;
     char *stringVal;
 
     UNPACK_BIGNUM(objPtr, bignumVal);
-    status = mp_radix_size(&bignumVal, 10, &size);
-    if (status != MP_OKAY) {
+    if (MP_OKAY != mp_radix_size(&bignumVal, 10, &size)) {
 	Tcl_Panic("radix size failure in UpdateStringOfBignum");
     }
     if (size < 2) {
@@ -3282,13 +3476,14 @@ UpdateStringOfBignum(
 
 	Tcl_Panic("UpdateStringOfBignum: string length limit exceeded");
     }
-    stringVal = ckalloc(size);
-    status = mp_toradix_n(&bignumVal, stringVal, 10, size);
-    if (status != MP_OKAY) {
+
+    stringVal = Tcl_InitStringRep(objPtr, NULL, size - 1);
+
+    TclOOM(stringVal, size);
+    if (MP_OKAY != mp_toradix_n(&bignumVal, stringVal, 10, size)) {
 	Tcl_Panic("conversion failure in UpdateStringOfBignum");
     }
-    objPtr->bytes = stringVal;
-    objPtr->length = size - 1;	/* size includes a trailing NUL byte. */
+    (void) Tcl_InitStringRep(objPtr, NULL, size - 1);
 }
 
 /*
@@ -3408,11 +3603,17 @@ GetBignumFromObj(
 		mp_init_copy(bignumValue, &temp);
 	    } else {
 		UNPACK_BIGNUM(objPtr, *bignumValue);
+		/* Optimized TclFreeIntRep */
 		objPtr->internalRep.twoPtrValue.ptr1 = NULL;
 		objPtr->internalRep.twoPtrValue.ptr2 = NULL;
 		objPtr->typePtr = NULL;
+		/*
+		 * TODO: If objPtr has a string rep, this leaves
+		 * it undisturbed.  Not clear that's proper. Pure
+		 * bignum values are converted to empty string.
+		 */
 		if (objPtr->bytes == NULL) {
-		    TclInitStringRep(objPtr, &tclEmptyString, 0);
+		    TclInitStringRep(objPtr, NULL, 0);
 		}
 	    }
 	    return TCL_OK;
diff --git a/generic/tclPathObj.c b/generic/tclPathObj.c
index 2453c46..c072fe0 100644
--- a/generic/tclPathObj.c
+++ b/generic/tclPathObj.c
@@ -36,7 +36,7 @@ static int		MakePathFromNormalized(Tcl_Interp *interp,
  * internally.
  */
 
-static const Tcl_ObjType tclFsPathType = {
+static const Tcl_ObjType fsPathType = {
     "path",				/* name */
     FreeFsPathInternalRep,		/* freeIntRepProc */
     DupFsPathInternalRep,		/* dupIntRepProc */
@@ -51,19 +51,14 @@ static const Tcl_ObjType tclFsPathType = {
  * represent relative or absolute paths, and has certain optimisations when
  * used to represent paths which are already normalized and absolute.
  *
- * Note that both 'translatedPathPtr' and 'normPathPtr' can be a circular
- * reference to the container Tcl_Obj of this FsPath.
- *
  * There are two cases, with the first being the most common:
  *
  * (i) flags == 0, => Ordinary path.
  *
- * translatedPathPtr contains the translated path (which may be a circular
- * reference to the object itself). If it is NULL then the path is pure
- * normalized (and the normPathPtr will be a circular reference). cwdPtr is
- * null for an absolute path, and non-null for a relative path (unless the cwd
- * has never been set, in which case the cwdPtr may also be null for a
- * relative path).
+ * translatedPathPtr contains the translated path. If it is NULL then the path
+ * is pure normalized. cwdPtr is null for an absolute path, and non-null for a
+ * relative path (unless the cwd has never been set, in which case the cwdPtr
+ * may also be null for a relative path).
  *
  * (ii) flags != 0, => Special path, see TclNewFSPathObj
  *
@@ -79,11 +74,7 @@ typedef struct FsPath {
 				 * Tcl_Obj's string rep is already both
 				 * translated and normalized. */
     Tcl_Obj *normPathPtr;	/* Normalized absolute path, without ., .. or
-				 * ~user sequences. If the Tcl_Obj containing
-				 * this FsPath is already normalized, this may
-				 * be a circular reference back to the
-				 * container. If that is NOT the case, we have
-				 * a refCount on the object. */
+				 * ~user sequences. */
     Tcl_Obj *cwdPtr;		/* If null, path is absolute, else this points
 				 * to the cwd object used for this path. We
 				 * have a refCount on the object. */
@@ -110,9 +101,14 @@ typedef struct FsPath {
  * fields.
  */
 
-#define PATHOBJ(pathPtr) ((FsPath *) (pathPtr)->internalRep.twoPtrValue.ptr1)
+#define PATHOBJ(pathPtr) ((FsPath *) (Tcl_FetchIntRep((pathPtr), &fsPathType)->twoPtrValue.ptr1))
 #define SETPATHOBJ(pathPtr,fsPathPtr) \
-	((pathPtr)->internalRep.twoPtrValue.ptr1 = (void *) (fsPathPtr))
+	do {							\
+		Tcl_ObjIntRep ir;				\
+		ir.twoPtrValue.ptr1 = (void *) (fsPathPtr);	\
+		ir.twoPtrValue.ptr2 = NULL;			\
+		Tcl_StoreIntRep((pathPtr), &fsPathType, &ir);	\
+	} while (0)
 #define PATHFLAGS(pathPtr) (PATHOBJ(pathPtr)->flags)
 
 /*
@@ -564,7 +560,9 @@ TclPathPart(
     Tcl_Obj *pathPtr,		/* Path to take dirname of */
     Tcl_PathPart portion)	/* Requested portion of name */
 {
-    if (pathPtr->typePtr == &tclFsPathType) {
+    Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(pathPtr, &fsPathType);
+
+    if (irPtr) {
 	FsPath *fsPathPtr = PATHOBJ(pathPtr);
 
 	if (PATHFLAGS(pathPtr) != 0) {
@@ -864,6 +862,7 @@ TclJoinPath(
 
     if (elements == 2) {
 	Tcl_Obj *elt = objv[0];
+	Tcl_ObjIntRep *eltIr = Tcl_FetchIntRep(elt, &fsPathType);
 
 	/*
 	 * This is a special case where we can be much more efficient, where
@@ -877,7 +876,7 @@ TclJoinPath(
 	 * to be an absolute path. Added a check for that elt is absolute.
 	 */
 
-	if ((elt->typePtr == &tclFsPathType)
+	if ((eltIr)
 		&& !((elt->bytes != NULL) && (elt->bytes[0] == '\0'))
                 && TclGetPathType(elt, NULL, NULL, NULL) == TCL_PATH_ABSOLUTE) {
             Tcl_Obj *tailObj = objv[1];
@@ -1154,6 +1153,8 @@ Tcl_FSConvertToPathType(
     Tcl_Obj *pathPtr)		/* Object to convert to a valid, current path
 				 * type. */
 {
+    Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(pathPtr, &fsPathType);
+
     /*
      * While it is bad practice to examine an object's type directly, this is
      * actually the best thing to do here. The reason is that if we are
@@ -1164,39 +1165,16 @@ Tcl_FSConvertToPathType(
      * path.
      */
 
-    if (pathPtr->typePtr == &tclFsPathType) {
+    if (irPtr) {
 	if (TclFSEpochOk(PATHOBJ(pathPtr)->filesystemEpoch)) {
 	    return TCL_OK;
 	}
 
-	if (pathPtr->bytes == NULL) {
-	    UpdateStringOfFsPath(pathPtr);
-	}
-	FreeFsPathInternalRep(pathPtr);
+	TclGetString(pathPtr);
+	Tcl_StoreIntRep(pathPtr, &fsPathType, NULL);
     }
 
     return SetFsPathFromAny(interp, pathPtr);
-
-    /*
-     * We used to have more complex code here:
-     *
-     * FsPath *fsPathPtr = PATHOBJ(pathPtr);
-     * if (fsPathPtr->cwdPtr == NULL || PATHFLAGS(pathPtr) != 0) {
-     *     return TCL_OK;
-     * } else {
-     *     if (TclFSCwdPointerEquals(&fsPathPtr->cwdPtr)) {
-     *         return TCL_OK;
-     *     } else {
-     *         if (pathPtr->bytes == NULL) {
-     *             UpdateStringOfFsPath(pathPtr);
-     *         }
-     *         FreeFsPathInternalRep(pathPtr);
-     *         return Tcl_ConvertToType(interp, pathPtr, &tclFsPathType);
-     *     }
-     * }
-     *
-     * But we no longer believe this is necessary.
-     */
 }
 
 /*
@@ -1328,9 +1306,7 @@ TclNewFSPathObj(
 
     SETPATHOBJ(pathPtr, fsPathPtr);
     PATHFLAGS(pathPtr) = TCLPATH_APPENDED;
-    pathPtr->typePtr = &tclFsPathType;
-    pathPtr->bytes = NULL;
-    pathPtr->length = 0;
+    TclInvalidateStringRep(pathPtr);
 
     /*
      * Look for path components made up of only "."
@@ -1430,8 +1406,9 @@ TclFSMakePathRelative(
 {
     int cwdLen, len;
     const char *tempStr;
+    Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(pathPtr, &fsPathType);
 
-    if (pathPtr->typePtr == &tclFsPathType) {
+    if (irPtr) {
 	FsPath *fsPathPtr = PATHOBJ(pathPtr);
 
 	if (PATHFLAGS(pathPtr) != 0 && fsPathPtr->cwdPtr == cwdPtr) {
@@ -1498,31 +1475,12 @@ MakePathFromNormalized(
     Tcl_Obj *pathPtr)		/* The object to convert. */
 {
     FsPath *fsPathPtr;
+    Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(pathPtr, &fsPathType);
 
-    if (pathPtr->typePtr == &tclFsPathType) {
+    if (irPtr) {
 	return TCL_OK;
     }
 
-    /*
-     * Free old representation
-     */
-
-    if (pathPtr->typePtr != NULL) {
-	if (pathPtr->bytes == NULL) {
-	    if (pathPtr->typePtr->updateStringProc == NULL) {
-		if (interp != NULL) {
-		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
-			    "can't find object string representation", -1));
-		    Tcl_SetErrorCode(interp, "TCL", "VALUE", "PATH", "WTF",
-			    NULL);
-		}
-		return TCL_ERROR;
-	    }
-	    pathPtr->typePtr->updateStringProc(pathPtr);
-	}
-	TclFreeIntRep(pathPtr);
-    }
-
     fsPathPtr = ckalloc(sizeof(FsPath));
 
     /*
@@ -1531,11 +1489,7 @@ MakePathFromNormalized(
 
     fsPathPtr->translatedPathPtr = NULL;
 
-    /*
-     * Circular reference by design.
-     */
-
-    fsPathPtr->normPathPtr = pathPtr;
+    Tcl_IncrRefCount(fsPathPtr->normPathPtr = Tcl_DuplicateObj(pathPtr));
     fsPathPtr->cwdPtr = NULL;
     fsPathPtr->nativePathPtr = NULL;
     fsPathPtr->fsPtr = NULL;
@@ -1544,7 +1498,6 @@ MakePathFromNormalized(
 
     SETPATHOBJ(pathPtr, fsPathPtr);
     PATHFLAGS(pathPtr) = 0;
-    pathPtr->typePtr = &tclFsPathType;
 
     return TCL_OK;
 }
@@ -1595,25 +1548,12 @@ Tcl_FSNewNativePath(
      * safe.
      */
 
-    if (pathPtr->typePtr != NULL) {
-	if (pathPtr->bytes == NULL) {
-	    if (pathPtr->typePtr->updateStringProc == NULL) {
-		return NULL;
-	    }
-	    pathPtr->typePtr->updateStringProc(pathPtr);
-	}
-	TclFreeIntRep(pathPtr);
-    }
-
+    Tcl_StoreIntRep(pathPtr, &fsPathType, NULL);
     fsPathPtr = ckalloc(sizeof(FsPath));
 
     fsPathPtr->translatedPathPtr = NULL;
 
-    /*
-     * Circular reference, by design.
-     */
-
-    fsPathPtr->normPathPtr = pathPtr;
+    Tcl_IncrRefCount(fsPathPtr->normPathPtr = Tcl_DuplicateObj(pathPtr));
     fsPathPtr->cwdPtr = NULL;
     fsPathPtr->nativePathPtr = clientData;
     fsPathPtr->fsPtr = fromFilesystem;
@@ -1621,7 +1561,6 @@ Tcl_FSNewNativePath(
 
     SETPATHOBJ(pathPtr, fsPathPtr);
     PATHFLAGS(pathPtr) = 0;
-    pathPtr->typePtr = &tclFsPathType;
 
     return pathPtr;
 }
@@ -1668,20 +1607,22 @@ Tcl_FSGetTranslatedPath(
 
 	    Tcl_Obj *translatedCwdPtr = Tcl_FSGetTranslatedPath(interp,
 		    srcFsPathPtr->cwdPtr);
+	    Tcl_ObjIntRep *translatedCwdIrPtr;
+
 	    if (translatedCwdPtr == NULL) {
 		return NULL;
 	    }
 
 	    retObj = Tcl_FSJoinToPath(translatedCwdPtr, 1,
 		    &srcFsPathPtr->normPathPtr);
-	    srcFsPathPtr->translatedPathPtr = retObj;
-	    if (translatedCwdPtr->typePtr == &tclFsPathType) {
+	    Tcl_IncrRefCount(srcFsPathPtr->translatedPathPtr = retObj);
+	    translatedCwdIrPtr = Tcl_FetchIntRep(translatedCwdPtr, &fsPathType);
+	    if (translatedCwdIrPtr) {
 		srcFsPathPtr->filesystemEpoch
 			= PATHOBJ(translatedCwdPtr)->filesystemEpoch;
 	    } else {
 		srcFsPathPtr->filesystemEpoch = 0;
 	    }
-	    Tcl_IncrRefCount(retObj);
 	    Tcl_DecrRefCount(translatedCwdPtr);
 	} else {
 	    /*
@@ -1791,9 +1732,7 @@ Tcl_FSGetNormalizedPath(
 	    return NULL;
 	}
 	/* TODO: Figure out why this is needed. */
-	if (pathPtr->bytes == NULL) {
-	    UpdateStringOfFsPath(pathPtr);
-	}
+	TclGetString(pathPtr);
 
 	TclGetStringFromObj(fsPathPtr->normPathPtr, &tailLen);
 	if (tailLen) {
@@ -1845,7 +1784,7 @@ Tcl_FSGetNormalizedPath(
 
 	    /*
 	     * NOTE: here we are (dangerously?) assuming that origDir points
-	     * to a Tcl_Obj with Tcl_ObjType == &tclFsPathType. The
+	     * to a Tcl_Obj with Tcl_ObjType == &fsPathType. The
 	     *     pathType = Tcl_FSGetPathType(fsPathPtr->cwdPtr);
 	     * above that set the pathType value should have established that,
 	     * but it's far less clear on what basis we know there's been no
@@ -1863,6 +1802,7 @@ Tcl_FSGetNormalizedPath(
 	    /*
 	     * That's our reference to copy used.
 	     */
+	    copy = NULL;
 
 	    TclDecrRefCount(dir);
 	    TclDecrRefCount(origDir);
@@ -1875,7 +1815,7 @@ Tcl_FSGetNormalizedPath(
 	    /*
 	     * That's our reference to copy used.
 	     */
-
+	    copy = NULL;
 	    TclDecrRefCount(dir);
 	}
 	PATHFLAGS(pathPtr) = 0;
@@ -1887,10 +1827,8 @@ Tcl_FSGetNormalizedPath(
 
     if (fsPathPtr->cwdPtr != NULL) {
 	if (!TclFSCwdPointerEquals(&fsPathPtr->cwdPtr)) {
-	    if (pathPtr->bytes == NULL) {
-		UpdateStringOfFsPath(pathPtr);
-	    }
-	    FreeFsPathInternalRep(pathPtr);
+	    TclGetString(pathPtr);
+	    Tcl_StoreIntRep(pathPtr, &fsPathType, NULL);
 	    if (SetFsPathFromAny(interp, pathPtr) != TCL_OK) {
 		return NULL;
 	    }
@@ -1916,7 +1854,6 @@ Tcl_FSGetNormalizedPath(
     }
     if (fsPathPtr->normPathPtr == NULL) {
 	Tcl_Obj *useThisCwd = NULL;
-	int pureNormalized = 1;
 
 	/*
 	 * Since normPathPtr is NULL, but this is a valid path object, we know
@@ -1966,7 +1903,6 @@ Tcl_FSGetNormalizedPath(
 		    return NULL;
 		}
 
-		pureNormalized = 0;
 		Tcl_DecrRefCount(absolutePath);
 		absolutePath = Tcl_FSJoinToPath(useThisCwd, 1, &absolutePath);
 		Tcl_IncrRefCount(absolutePath);
@@ -1986,7 +1922,6 @@ Tcl_FSGetNormalizedPath(
 		if (absolutePath == NULL) {
 		    return NULL;
 		}
-		pureNormalized = 0;
 #endif /* _WIN32 */
 	    }
 	}
@@ -1995,35 +1930,12 @@ Tcl_FSGetNormalizedPath(
 	 * Already has refCount incremented.
 	 */
 
+	if (fsPathPtr->normPathPtr) {
+	    Tcl_DecrRefCount(fsPathPtr->normPathPtr);
+	}
 	fsPathPtr->normPathPtr = TclFSNormalizeAbsolutePath(interp,
 		absolutePath);
 
-	/*
-	 * Check if path is pure normalized (this can only be the case if it
-	 * is an absolute path).
-	 */
-
-	if (pureNormalized) {
-	    int normPathLen, pathLen;
-	    const char *normPath;
-
-	    path = TclGetStringFromObj(pathPtr, &pathLen);
-	    normPath = TclGetStringFromObj(fsPathPtr->normPathPtr, &normPathLen);
-	    if ((pathLen == normPathLen) && !memcmp(path, normPath, pathLen)) {
-		/*
-		 * The path was already normalized. Get rid of the duplicate.
-		 */
-
-		TclDecrRefCount(fsPathPtr->normPathPtr);
-
-		/*
-		 * We do *not* increment the refCount for this circular
-		 * reference.
-		 */
-
-		fsPathPtr->normPathPtr = pathPtr;
-	    }
-	}
 	if (useThisCwd != NULL) {
 	    /*
 	     * We just need to free an object we allocated above for relative
@@ -2169,8 +2081,9 @@ TclFSEnsureEpochOk(
     const Tcl_Filesystem **fsPtrPtr)
 {
     FsPath *srcFsPathPtr;
+    Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(pathPtr, &fsPathType);
 
-    if (pathPtr->typePtr != &tclFsPathType) {
+    if (irPtr == NULL) {
 	return TCL_OK;
     }
 
@@ -2186,10 +2099,8 @@ TclFSEnsureEpochOk(
 	 * We have to discard the stale representation and recalculate it.
 	 */
 
-	if (pathPtr->bytes == NULL) {
-	    UpdateStringOfFsPath(pathPtr);
-	}
-	FreeFsPathInternalRep(pathPtr);
+	TclGetString(pathPtr);
+	Tcl_StoreIntRep(pathPtr, &fsPathType, NULL);
 	if (SetFsPathFromAny(NULL, pathPtr) != TCL_OK) {
 	    return TCL_ERROR;
 	}
@@ -2229,12 +2140,13 @@ TclFSSetPathDetails(
     ClientData clientData)
 {
     FsPath *srcFsPathPtr;
+    Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(pathPtr, &fsPathType);;
 
     /*
      * Make sure pathPtr is of the correct type.
      */
 
-    if (pathPtr->typePtr != &tclFsPathType) {
+    if (irPtr == NULL) {
 	if (SetFsPathFromAny(NULL, pathPtr) != TCL_OK) {
 	    return;
 	}
@@ -2332,8 +2244,9 @@ SetFsPathFromAny(
     FsPath *fsPathPtr;
     Tcl_Obj *transPtr;
     char *name;
+    Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(pathPtr, &fsPathType);
 
-    if (pathPtr->typePtr == &tclFsPathType) {
+    if (irPtr) {
 	return TCL_OK;
     }
 
@@ -2475,27 +2388,21 @@ SetFsPathFromAny(
 
     fsPathPtr = ckalloc(sizeof(FsPath));
 
-    fsPathPtr->translatedPathPtr = transPtr;
-    if (transPtr != pathPtr) {
-	Tcl_IncrRefCount(fsPathPtr->translatedPathPtr);
-	/* Redo translation when $env(HOME) changes */
-	fsPathPtr->filesystemEpoch = TclFSEpoch();
+    if (transPtr == pathPtr) {
+        transPtr = Tcl_DuplicateObj(pathPtr);
+        fsPathPtr->filesystemEpoch = 0;
     } else {
-	fsPathPtr->filesystemEpoch = 0;
+        fsPathPtr->filesystemEpoch = TclFSEpoch();
     }
+    Tcl_IncrRefCount(transPtr);
+    fsPathPtr->translatedPathPtr = transPtr;
     fsPathPtr->normPathPtr = NULL;
     fsPathPtr->cwdPtr = NULL;
     fsPathPtr->nativePathPtr = NULL;
     fsPathPtr->fsPtr = NULL;
 
-    /*
-     * Free old representation before installing our new one.
-     */
-
-    TclFreeIntRep(pathPtr);
     SETPATHOBJ(pathPtr, fsPathPtr);
     PATHFLAGS(pathPtr) = 0;
-    pathPtr->typePtr = &tclFsPathType;
     return TCL_OK;
 }
 
@@ -2518,6 +2425,7 @@ FreeFsPathInternalRep(
     }
     if (fsPathPtr->cwdPtr != NULL) {
 	TclDecrRefCount(fsPathPtr->cwdPtr);
+	fsPathPtr->cwdPtr = NULL;
     }
     if (fsPathPtr->nativePathPtr != NULL && fsPathPtr->fsPtr != NULL) {
 	Tcl_FSFreeInternalRepProc *freeProc =
@@ -2530,7 +2438,6 @@ FreeFsPathInternalRep(
     }
 
     ckfree(fsPathPtr);
-    pathPtr->typePtr = NULL;
 }
 
 static void
@@ -2543,24 +2450,14 @@ DupFsPathInternalRep(
 
     SETPATHOBJ(copyPtr, copyFsPathPtr);
 
-    if (srcFsPathPtr->translatedPathPtr == srcPtr) {
-	/* Cycle in src -> make cycle in copy. */
-	copyFsPathPtr->translatedPathPtr = copyPtr;
-    } else {
-	copyFsPathPtr->translatedPathPtr = srcFsPathPtr->translatedPathPtr;
-	if (copyFsPathPtr->translatedPathPtr != NULL) {
-	    Tcl_IncrRefCount(copyFsPathPtr->translatedPathPtr);
-	}
+    copyFsPathPtr->translatedPathPtr = srcFsPathPtr->translatedPathPtr;
+    if (copyFsPathPtr->translatedPathPtr != NULL) {
+	Tcl_IncrRefCount(copyFsPathPtr->translatedPathPtr);
     }
 
-    if (srcFsPathPtr->normPathPtr == srcPtr) {
-	/* Cycle in src -> make cycle in copy. */
-	copyFsPathPtr->normPathPtr = copyPtr;
-    } else {
-	copyFsPathPtr->normPathPtr = srcFsPathPtr->normPathPtr;
-	if (copyFsPathPtr->normPathPtr != NULL) {
-	    Tcl_IncrRefCount(copyFsPathPtr->normPathPtr);
-	}
+    copyFsPathPtr->normPathPtr = srcFsPathPtr->normPathPtr;
+    if (copyFsPathPtr->normPathPtr != NULL) {
+	Tcl_IncrRefCount(copyFsPathPtr->normPathPtr);
     }
 
     copyFsPathPtr->cwdPtr = srcFsPathPtr->cwdPtr;
@@ -2586,8 +2483,6 @@ DupFsPathInternalRep(
     }
     copyFsPathPtr->fsPtr = srcFsPathPtr->fsPtr;
     copyFsPathPtr->filesystemEpoch = srcFsPathPtr->filesystemEpoch;
-
-    copyPtr->typePtr = &tclFsPathType;
 }
 
 /*
@@ -2619,11 +2514,15 @@ UpdateStringOfFsPath(
     }
 
     copy = AppendPath(fsPathPtr->cwdPtr, fsPathPtr->normPathPtr);
+    if (Tcl_IsShared(copy)) {
+	copy = Tcl_DuplicateObj(copy);
+    }
 
+    Tcl_IncrRefCount(copy);
+    /* Steal copy's string rep */
     pathPtr->bytes = TclGetStringFromObj(copy, &cwdLen);
     pathPtr->length = cwdLen;
-    copy->bytes = &tclEmptyString;
-    copy->length = 0;
+    TclInitStringRep(copy, NULL, 0);
     TclDecrRefCount(copy);
 }
 
@@ -2653,6 +2552,8 @@ TclNativePathInFilesystem(
     Tcl_Obj *pathPtr,
     ClientData *clientDataPtr)
 {
+    Tcl_ObjIntRep *irPtr = Tcl_FetchIntRep(pathPtr, &fsPathType);
+
     /*
      * A special case is required to handle the empty path "". This is a valid
      * path (i.e. the user should be able to do 'file exists ""' without
@@ -2660,7 +2561,7 @@ TclNativePathInFilesystem(
      * semantics of Tcl (at present anyway), so we have to abide by them here.
      */
 
-    if (pathPtr->typePtr == &tclFsPathType) {
+    if (irPtr) {
 	if (pathPtr->bytes != NULL && pathPtr->bytes[0] == '\0') {
 	    /*
 	     * We reject the empty path "".
@@ -2675,7 +2576,7 @@ TclNativePathInFilesystem(
     } else {
 	/*
 	 * It is somewhat unusual to reach this code path without the object
-	 * being of tclFsPathType. However, we do our best to deal with the
+	 * being of fsPathType. However, we do our best to deal with the
 	 * situation.
 	 */
 
diff --git a/generic/tclProc.c b/generic/tclProc.c
index 32c3b2e..f1822a2 100644
--- a/generic/tclProc.c
+++ b/generic/tclProc.c
@@ -15,6 +15,7 @@
 
 #include "tclInt.h"
 #include "tclCompile.h"
+#include <assert.h>
 
 /*
  * Variables that are part of the [apply] command implementation and which
@@ -67,6 +68,22 @@ const Tcl_ObjType tclProcBodyType = {
 				 * should panic instead. */
 };
 
+#define ProcSetIntRep(objPtr, procPtr)					\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	(procPtr)->refCount++;						\
+	ir.twoPtrValue.ptr1 = (procPtr);				\
+	ir.twoPtrValue.ptr2 = NULL;					\
+	Tcl_StoreIntRep((objPtr), &tclProcBodyType, &ir);		\
+    } while (0)
+
+#define ProcGetIntRep(objPtr, procPtr)					\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep((objPtr), &tclProcBodyType);		\
+	(procPtr) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+    } while (0)
+
 /*
  * The [upvar]/[uplevel] level reference type. Uses the longValue field
  * to remember the integer value of a parsed #<integer> format.
@@ -89,13 +106,31 @@ static const Tcl_ObjType levelReferenceType = {
  * will execute within. IF YOU CHANGE THIS, CHECK IN tclDisassemble.c TOO.
  */
 
-const Tcl_ObjType tclLambdaType = {
+static const Tcl_ObjType lambdaType = {
     "lambdaExpr",		/* name */
     FreeLambdaInternalRep,	/* freeIntRepProc */
     DupLambdaInternalRep,	/* dupIntRepProc */
     NULL,			/* updateStringProc */
     SetLambdaFromAny		/* setFromAnyProc */
 };
+
+#define LambdaSetIntRep(objPtr, procPtr, nsObjPtr)			\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	ir.twoPtrValue.ptr1 = (procPtr);				\
+	ir.twoPtrValue.ptr2 = (nsObjPtr);				\
+	Tcl_IncrRefCount((nsObjPtr));					\
+	Tcl_StoreIntRep((objPtr), &lambdaType, &ir);			\
+    } while (0)
+
+#define LambdaGetIntRep(objPtr, procPtr, nsObjPtr)			\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep((objPtr), &lambdaType);			\
+	(procPtr) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+	(nsObjPtr) = irPtr ? irPtr->twoPtrValue.ptr2 : NULL;		\
+    } while (0)
+
 
 /*
  *----------------------------------------------------------------------
@@ -294,7 +329,7 @@ Tcl_ProcObjCmd(
      *	   of all procs whose argument list is just _args_
      */
 
-    if (objv[3]->typePtr == &tclProcBodyType) {
+    if (Tcl_FetchIntRep(objv[3], &tclProcBodyType)) {
 	goto done;
     }
 
@@ -370,7 +405,7 @@ TclCreateProc(
 {
     Interp *iPtr = (Interp *) interp;
 
-    register Proc *procPtr;
+    register Proc *procPtr = NULL;
     int i, result, numArgs, plen;
     const char *bytes, *argname, *argnamei;
     char argnamelast;
@@ -378,7 +413,8 @@ TclCreateProc(
     Tcl_Obj *defPtr, *errorObj, **argArray;
     int precompiled = 0;
 
-    if (bodyPtr->typePtr == &tclProcBodyType) {
+    ProcGetIntRep(bodyPtr, procPtr);
+    if (procPtr != NULL) {
 	/*
 	 * Because the body is a TclProProcBody, the actual body is already
 	 * compiled, and it is not shared with anyone else, so it's OK not to
@@ -391,7 +427,6 @@ TclCreateProc(
 	 * will be holding a reference to it.
 	 */
 
-	procPtr = bodyPtr->internalRep.twoPtrValue.ptr1;
 	procPtr->iPtr = iPtr;
 	procPtr->refCount++;
 	precompiled = 1;
@@ -733,6 +768,7 @@ TclObjGetFrame(
 {
     register Interp *iPtr = (Interp *) interp;
     int curLevel, level, result;
+    const Tcl_ObjIntRep *irPtr;
     const char *name = NULL;
     Tcl_WideInt w;
 
@@ -758,8 +794,8 @@ TclObjGetFrame(
 	    level = curLevel - level;
 	    result = 1;
 	}
-    } else if (objPtr->typePtr == &levelReferenceType) {
-	level = (int) objPtr->internalRep.wideValue;
+    } else if ((irPtr = Tcl_FetchIntRep(objPtr, &levelReferenceType))) {
+	level = irPtr->wideValue;
 	result = 1;
     } else {
 	name = TclGetString(objPtr);
@@ -768,9 +804,10 @@ TclObjGetFrame(
 		if (level < 0 || (level > 0 && name[1] == '-')) {
 		    result = -1;
 		} else {
-		    TclFreeIntRep(objPtr);
-		    objPtr->typePtr = &levelReferenceType;
-		    objPtr->internalRep.wideValue = level;
+		    Tcl_ObjIntRep ir;
+
+		    ir.wideValue = level;
+		    Tcl_StoreIntRep(objPtr, &levelReferenceType, &ir);
 		    result = 1;
 		}
 	    } else {
@@ -1094,10 +1131,10 @@ TclInitCompiledLocals(
     ByteCode *codePtr;
 
     bodyPtr = framePtr->procPtr->bodyPtr;
-    if (bodyPtr->typePtr != &tclByteCodeType) {
+    ByteCodeGetIntRep(bodyPtr, &tclByteCodeType, codePtr);
+    if (codePtr == NULL) {
 	Tcl_Panic("body object for proc attached to frame is not a byte code type");
     }
-    codePtr = bodyPtr->internalRep.twoPtrValue.ptr1;
 
     if (framePtr->numCompiledLocals) {
 	if (!codePtr->localCachePtr) {
@@ -1260,7 +1297,7 @@ InitLocalCache(
     Proc *procPtr)
 {
     Interp *iPtr = procPtr->iPtr;
-    ByteCode *codePtr = procPtr->bodyPtr->internalRep.twoPtrValue.ptr1;
+    ByteCode *codePtr;
     int localCt = procPtr->numCompiledLocals;
     int numArgs = procPtr->numArgs, i = 0;
 
@@ -1270,6 +1307,8 @@ InitLocalCache(
     CompiledLocal *localPtr;
     int new;
 
+    ByteCodeGetIntRep(procPtr->bodyPtr, &tclByteCodeType, codePtr);
+
     /*
      * Cache the names and initial values of local variables; store the
      * cache in both the framePtr for this execution and in the codePtr
@@ -1337,11 +1376,13 @@ InitArgsAndLocals(
 {
     CallFrame *framePtr = ((Interp *)interp)->varFramePtr;
     register Proc *procPtr = framePtr->procPtr;
-    ByteCode *codePtr = procPtr->bodyPtr->internalRep.twoPtrValue.ptr1;
+    ByteCode *codePtr;
     register Var *varPtr, *defPtr;
     int localCt = procPtr->numCompiledLocals, numArgs, argCt, i, imax;
     Tcl_Obj *const *argObjs;
 
+    ByteCodeGetIntRep(procPtr->bodyPtr, &tclByteCodeType, codePtr);
+
     /*
      * Make sure that the local cache of variable names and initial values has
      * been initialised properly .
@@ -1516,7 +1557,8 @@ TclPushProcCallFrame(
      * local variables are found while compiling.
      */
 
-    if (procPtr->bodyPtr->typePtr == &tclByteCodeType) {
+    ByteCodeGetIntRep(procPtr->bodyPtr, &tclByteCodeType, codePtr);
+    if (codePtr != NULL) {
 	Interp *iPtr = (Interp *) interp;
 
 	/*
@@ -1528,7 +1570,6 @@ TclPushProcCallFrame(
 	 * commands and/or resolver changes are considered).
 	 */
 
-	codePtr = procPtr->bodyPtr->internalRep.twoPtrValue.ptr1;
 	if (((Interp *) *codePtr->interpHandle != iPtr)
 		|| (codePtr->compileEpoch != iPtr->compileEpoch)
 		|| (codePtr->nsPtr != nsPtr)
@@ -1726,7 +1767,7 @@ TclNRInterpProcCore(
      */
 
     procPtr->refCount++;
-    codePtr = procPtr->bodyPtr->internalRep.twoPtrValue.ptr1;
+    ByteCodeGetIntRep(procPtr->bodyPtr, &tclByteCodeType, codePtr);
 
     TclNRAddCallback(interp, InterpProcNR2, procNameObj, errorProc,
 	    NULL, NULL);
@@ -1860,7 +1901,9 @@ TclProcCompileProc(
 {
     Interp *iPtr = (Interp *) interp;
     Tcl_CallFrame *framePtr;
-    ByteCode *codePtr = bodyPtr->internalRep.twoPtrValue.ptr1;
+    ByteCode *codePtr;
+
+    ByteCodeGetIntRep(bodyPtr, &tclByteCodeType, codePtr);
 
     /*
      * If necessary, compile the procedure's body. The compiler will allocate
@@ -1876,7 +1919,7 @@ TclProcCompileProc(
      * are not recompiled, even if things have changed.
      */
 
-    if (bodyPtr->typePtr == &tclByteCodeType) {
+    if (codePtr != NULL) {
 	if (((Interp *) *codePtr->interpHandle == iPtr)
 		&& (codePtr->compileEpoch == iPtr->compileEpoch)
 		&& (codePtr->nsPtr == nsPtr)
@@ -1895,11 +1938,12 @@ TclProcCompileProc(
 	    codePtr->compileEpoch = iPtr->compileEpoch;
 	    codePtr->nsPtr = nsPtr;
 	} else {
-	    TclFreeIntRep(bodyPtr);
+	    Tcl_StoreIntRep(bodyPtr, &tclByteCodeType, NULL);
+	    codePtr = NULL;
 	}
     }
 
-    if (bodyPtr->typePtr != &tclByteCodeType) {
+    if (codePtr == NULL) {
 	Tcl_HashEntry *hePtr;
 
 #ifdef TCL_COMPILE_DEBUG
@@ -2248,10 +2292,7 @@ TclNewProcBodyObj(
 
     TclNewObj(objPtr);
     if (objPtr) {
-	objPtr->typePtr = &tclProcBodyType;
-	objPtr->internalRep.twoPtrValue.ptr1 = procPtr;
-
-	procPtr->refCount++;
+	ProcSetIntRep(objPtr, procPtr);
     }
 
     return objPtr;
@@ -2279,11 +2320,10 @@ ProcBodyDup(
     Tcl_Obj *srcPtr,		/* Object to copy. */
     Tcl_Obj *dupPtr)		/* Target object for the duplication. */
 {
-    Proc *procPtr = srcPtr->internalRep.twoPtrValue.ptr1;
+    Proc *procPtr;
+    ProcGetIntRep(srcPtr, procPtr);
 
-    dupPtr->typePtr = &tclProcBodyType;
-    dupPtr->internalRep.twoPtrValue.ptr1 = procPtr;
-    procPtr->refCount++;
+    ProcSetIntRep(dupPtr, procPtr);
 }
 
 /*
@@ -2309,7 +2349,9 @@ static void
 ProcBodyFree(
     Tcl_Obj *objPtr)		/* The object to clean up. */
 {
-    Proc *procPtr = objPtr->internalRep.twoPtrValue.ptr1;
+    Proc *procPtr;
+
+    ProcGetIntRep(objPtr, procPtr);
 
     if (procPtr->refCount-- <= 1) {
 	TclProcCleanupProc(procPtr);
@@ -2335,15 +2377,15 @@ DupLambdaInternalRep(
     Tcl_Obj *srcPtr,		/* Object with internal rep to copy. */
     register Tcl_Obj *copyPtr)	/* Object with internal rep to set. */
 {
-    Proc *procPtr = srcPtr->internalRep.twoPtrValue.ptr1;
-    Tcl_Obj *nsObjPtr = srcPtr->internalRep.twoPtrValue.ptr2;
+    Proc *procPtr;
+    Tcl_Obj *nsObjPtr;
 
-    copyPtr->internalRep.twoPtrValue.ptr1 = procPtr;
-    copyPtr->internalRep.twoPtrValue.ptr2 = nsObjPtr;
+    LambdaGetIntRep(srcPtr, procPtr, nsObjPtr);
+    assert(procPtr != NULL);
 
     procPtr->refCount++;
-    Tcl_IncrRefCount(nsObjPtr);
-    copyPtr->typePtr = &tclLambdaType;
+
+    LambdaSetIntRep(copyPtr, procPtr, nsObjPtr);
 }
 
 static void
@@ -2351,14 +2393,16 @@ FreeLambdaInternalRep(
     register Tcl_Obj *objPtr)	/* CmdName object with internal representation
 				 * to free. */
 {
-    Proc *procPtr = objPtr->internalRep.twoPtrValue.ptr1;
-    Tcl_Obj *nsObjPtr = objPtr->internalRep.twoPtrValue.ptr2;
+    Proc *procPtr;
+    Tcl_Obj *nsObjPtr;
+
+    LambdaGetIntRep(objPtr, procPtr, nsObjPtr);
+    assert(procPtr != NULL);
 
     if (procPtr->refCount-- <= 1) {
 	TclProcCleanupProc(procPtr);
     }
     TclDecrRefCount(nsObjPtr);
-    objPtr->typePtr = NULL;
 }
 
 static int
@@ -2379,7 +2423,7 @@ SetLambdaFromAny(
 
     /*
      * Convert objPtr to list type first; if it cannot be converted, or if its
-     * length is not 2, then it cannot be converted to tclLambdaType.
+     * length is not 2, then it cannot be converted to lambdaType.
      */
 
     result = TclListObjGetElements(NULL, objPtr, &objc, &objv);
@@ -2520,21 +2564,42 @@ SetLambdaFromAny(
 	}
     }
 
-    Tcl_IncrRefCount(nsObjPtr);
-
     /*
      * Free the list internalrep of objPtr - this will free argsPtr, but
      * bodyPtr retains a reference from the Proc structure. Then finish the
-     * conversion to tclLambdaType.
+     * conversion to lambdaType.
      */
 
-    TclFreeIntRep(objPtr);
-
-    objPtr->internalRep.twoPtrValue.ptr1 = procPtr;
-    objPtr->internalRep.twoPtrValue.ptr2 = nsObjPtr;
-    objPtr->typePtr = &tclLambdaType;
+    LambdaSetIntRep(objPtr, procPtr, nsObjPtr);
     return TCL_OK;
 }
+
+Proc *
+TclGetLambdaFromObj(
+    Tcl_Interp *interp,
+    Tcl_Obj *objPtr,
+    Tcl_Obj **nsObjPtrPtr)
+{
+    Proc *procPtr;
+    Tcl_Obj *nsObjPtr;
+
+    LambdaGetIntRep(objPtr, procPtr, nsObjPtr);
+
+    if (procPtr == NULL) {
+	if (SetLambdaFromAny(interp, objPtr) != TCL_OK) {
+	    return NULL;
+	}
+	LambdaGetIntRep(objPtr, procPtr, nsObjPtr);
+    }
+
+    assert(procPtr != NULL);
+    if (procPtr->iPtr != (Interp *)interp) {
+	return NULL;
+    }
+
+    *nsObjPtrPtr = nsObjPtr;
+    return procPtr;
+}
 
 /*
  *----------------------------------------------------------------------
@@ -2570,7 +2635,6 @@ TclNRApplyObjCmd(
     int objc,			/* Number of arguments. */
     Tcl_Obj *const objv[])	/* Argument objects. */
 {
-    Interp *iPtr = (Interp *) interp;
     Proc *procPtr = NULL;
     Tcl_Obj *lambdaPtr, *nsObjPtr;
     int result;
@@ -2588,24 +2652,17 @@ TclNRApplyObjCmd(
      */
 
     lambdaPtr = objv[1];
-    if (lambdaPtr->typePtr == &tclLambdaType) {
-	procPtr = lambdaPtr->internalRep.twoPtrValue.ptr1;
-    }
+    procPtr = TclGetLambdaFromObj(interp, lambdaPtr, &nsObjPtr);
 
-    if ((procPtr == NULL) || (procPtr->iPtr != iPtr)) {
-	result = SetLambdaFromAny(interp, lambdaPtr);
-	if (result != TCL_OK) {
-	    return result;
-	}
-	procPtr = lambdaPtr->internalRep.twoPtrValue.ptr1;
+    if (procPtr == NULL) {
+	return TCL_ERROR;
     }
 
     /*
-     * Find the namespace where this lambda should run, and push a call frame
-     * for that namespace. Note that TclObjInterpProc() will pop it.
+     * Push a call frame for the lambda namespace.
+     * Note that TclObjInterpProc() will pop it.
      */
 
-    nsObjPtr = lambdaPtr->internalRep.twoPtrValue.ptr2;
     result = TclGetNamespaceFromObj(interp, nsObjPtr, &nsPtr);
     if (result != TCL_OK) {
 	return TCL_ERROR;
diff --git a/generic/tclRegexp.c b/generic/tclRegexp.c
index 5f8dc20..a01ace3 100644
--- a/generic/tclRegexp.c
+++ b/generic/tclRegexp.c
@@ -13,6 +13,7 @@
 
 #include "tclInt.h"
 #include "tclRegexp.h"
+#include <assert.h>
 
 /*
  *----------------------------------------------------------------------
@@ -107,6 +108,23 @@ const Tcl_ObjType tclRegexpType = {
     NULL,				/* updateStringProc */
     SetRegexpFromAny			/* setFromAnyProc */
 };
+
+#define RegexpSetIntRep(objPtr, rePtr)					\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	(rePtr)->refCount++;						\
+	ir.twoPtrValue.ptr1 = (rePtr);					\
+	ir.twoPtrValue.ptr2 = NULL;					\
+	Tcl_StoreIntRep((objPtr), &tclRegexpType, &ir);			\
+    } while (0)
+
+#define RegexpGetIntRep(objPtr, rePtr)					\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep((objPtr), &tclRegexpType);		\
+	(rePtr) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+    } while (0)
+
 
 /*
  *----------------------------------------------------------------------
@@ -580,14 +598,9 @@ Tcl_GetRegExpFromObj(
     TclRegexp *regexpPtr;
     const char *pattern;
 
-    /*
-     * This is OK because we only actually interpret this value properly as a
-     * TclRegexp* when the type is tclRegexpType.
-     */
-
-    regexpPtr = objPtr->internalRep.twoPtrValue.ptr1;
+    RegexpGetIntRep(objPtr, regexpPtr);
 
-    if ((objPtr->typePtr != &tclRegexpType) || (regexpPtr->flags != flags)) {
+    if ((regexpPtr == NULL) || (regexpPtr->flags != flags)) {
 	pattern = TclGetStringFromObj(objPtr, &length);
 
 	regexpPtr = CompileRegexp(interp, pattern, length, flags);
@@ -595,21 +608,7 @@ Tcl_GetRegExpFromObj(
 	    return NULL;
 	}
 
-	/*
-	 * Add a reference to the regexp so it will persist even if it is
-	 * pushed out of the current thread's regexp cache. This reference
-	 * will be removed when the object's internal rep is freed.
-	 */
-
-	regexpPtr->refCount++;
-
-	/*
-	 * Free the old representation and set our type.
-	 */
-
-	TclFreeIntRep(objPtr);
-	objPtr->internalRep.twoPtrValue.ptr1 = regexpPtr;
-	objPtr->typePtr = &tclRegexpType;
+	RegexpSetIntRep(objPtr, regexpPtr);
     }
     return (Tcl_RegExp) regexpPtr;
 }
@@ -756,7 +755,11 @@ static void
 FreeRegexpInternalRep(
     Tcl_Obj *objPtr)		/* Regexp object with internal rep to free. */
 {
-    TclRegexp *regexpRepPtr = objPtr->internalRep.twoPtrValue.ptr1;
+    TclRegexp *regexpRepPtr;
+
+    RegexpGetIntRep(objPtr, regexpRepPtr);
+
+    assert(regexpRepPtr != NULL);
 
     /*
      * If this is the last reference to the regexp, free it.
@@ -765,7 +768,6 @@ FreeRegexpInternalRep(
     if (regexpRepPtr->refCount-- <= 1) {
 	FreeRegexp(regexpRepPtr);
     }
-    objPtr->typePtr = NULL;
 }
 
 /*
@@ -790,11 +792,13 @@ DupRegexpInternalRep(
     Tcl_Obj *srcPtr,		/* Object with internal rep to copy. */
     Tcl_Obj *copyPtr)		/* Object with internal rep to set. */
 {
-    TclRegexp *regexpPtr = srcPtr->internalRep.twoPtrValue.ptr1;
+    TclRegexp *regexpPtr;
+
+    RegexpGetIntRep(srcPtr, regexpPtr);
+
+    assert(regexpPtr != NULL);
 
-    regexpPtr->refCount++;
-    copyPtr->internalRep.twoPtrValue.ptr1 = srcPtr->internalRep.twoPtrValue.ptr1;
-    copyPtr->typePtr = &tclRegexpType;
+    RegexpSetIntRep(copyPtr, regexpPtr);
 }
 
 /*
diff --git a/generic/tclScan.c b/generic/tclScan.c
index 6a1311f..745f05b 100644
--- a/generic/tclScan.c
+++ b/generic/tclScan.c
@@ -1009,8 +1009,10 @@ Tcl_ScanObjCmd(
 		double dvalue;
 		if (Tcl_GetDoubleFromObj(NULL, objPtr, &dvalue) != TCL_OK) {
 #ifdef ACCEPT_NAN
-		    if (objPtr->typePtr == &tclDoubleType) {
-			dvalue = objPtr->internalRep.doubleValue;
+		    const Tcl_ObjIntRep *irPtr
+			    = Tcl_FetchIntRep(objPtr, &tclDoubleType);
+		    if (irPtr) {
+			dvalue = irPtr->doubleValue;
 		    } else
 #endif
 		    {
diff --git a/generic/tclStrToD.c b/generic/tclStrToD.c
index a46b29a..a46b29a 100644..100755
--- a/generic/tclStrToD.c
+++ b/generic/tclStrToD.c
diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c
index fa55bb0..7be74ca 100644
--- a/generic/tclStringObj.c
+++ b/generic/tclStringObj.c
@@ -4211,7 +4211,7 @@ UpdateStringOfString(
     stringPtr->allocated = 0;
 
     if (stringPtr->numChars == 0) {
-	TclInitStringRep(objPtr, &tclEmptyString, 0);
+	TclInitStringRep(objPtr, NULL, 0);
     } else {
 	(void) ExtendStringRepWithUnicode(objPtr, stringPtr->unicode,
 		stringPtr->numChars);
diff --git a/generic/tclStubInit.c b/generic/tclStubInit.c
index 6a4eabc..4c9d3e8 100644
--- a/generic/tclStubInit.c
+++ b/generic/tclStubInit.c
@@ -1581,6 +1581,11 @@ const TclStubs tclStubs = {
     TclZipfs_Unmount, /* 633 */
     TclZipfs_TclLibrary, /* 634 */
     TclZipfs_MountBuffer, /* 635 */
+    Tcl_FreeIntRep, /* 636 */
+    Tcl_InitStringRep, /* 637 */
+    Tcl_FetchIntRep, /* 638 */
+    Tcl_StoreIntRep, /* 639 */
+    Tcl_HasStringRep, /* 640 */
 };
 
 /* !END!: Do not edit above this line. */
diff --git a/generic/tclTest.c b/generic/tclTest.c
index 2cdd356..fb8857c 100644
--- a/generic/tclTest.c
+++ b/generic/tclTest.c
@@ -7082,17 +7082,11 @@ TestconcatobjCmd(
 
     list1Ptr = Tcl_NewStringObj("foo bar sum", -1);
     Tcl_ListObjLength(NULL, list1Ptr, &len);
-    if (list1Ptr->bytes != NULL) {
-	ckfree(list1Ptr->bytes);
-	list1Ptr->bytes = NULL;
-    }
+    Tcl_InvalidateStringRep(list1Ptr);
 
     list2Ptr = Tcl_NewStringObj("eeny meeny", -1);
     Tcl_ListObjLength(NULL, list2Ptr, &len);
-    if (list2Ptr->bytes != NULL) {
-	ckfree(list2Ptr->bytes);
-	list2Ptr->bytes = NULL;
-    }
+    Tcl_InvalidateStringRep(list2Ptr);
 
     /*
      * Verify that concat'ing a list obj with one or more empty strings does
diff --git a/generic/tclTimer.c b/generic/tclTimer.c
index 54854d0..ccfd179 100644
--- a/generic/tclTimer.c
+++ b/generic/tclTimer.c
@@ -789,7 +789,7 @@ Tcl_AfterObjCmd(
     AfterInfo *afterPtr;
     AfterAssocData *assocPtr;
     int length;
-    int index;
+    int index = -1;
     static const char *const afterSubCmds[] = {
 	"cancel", "idle", "info", NULL
     };
@@ -818,12 +818,9 @@ Tcl_AfterObjCmd(
      * First lets see if the command was passed a number as the first argument.
      */
 
-    if (objv[1]->typePtr == &tclIntType
-	    || objv[1]->typePtr == &tclBignumType
-	    || (Tcl_GetIndexFromObj(NULL, objv[1], afterSubCmds, "", 0,
-		    &index) != TCL_OK)) {
-	index = -1;
-	if (Tcl_GetWideIntFromObj(NULL, objv[1], &ms) != TCL_OK) {
+    if (Tcl_GetWideIntFromObj(NULL, objv[1], &ms) != TCL_OK) {
+	if (Tcl_GetIndexFromObj(NULL, objv[1], afterSubCmds, "", 0, &index)
+		!= TCL_OK) {
             const char *arg = Tcl_GetString(objv[1]);
 
 	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
diff --git a/generic/tclUtil.c b/generic/tclUtil.c
index 76a3890..ef3c3dc 100644
--- a/generic/tclUtil.c
+++ b/generic/tclUtil.c
@@ -1390,9 +1390,9 @@ TclConvertElement(
      */
 
     if ((src == NULL) || (length == 0) || (*src == '\0' && length == -1)) {
-	src = &tclEmptyString;
-	length = 0;
-	conversion = CONVERT_BRACE;
+	p[0] = '{';
+	p[1] = '}';
+	return 2;
     }
 
     /*
@@ -2089,7 +2089,7 @@ Tcl_ConcatObj(
 	resPtr = NULL;
 	for (i = 0;  i < objc;  i++) {
 	    objPtr = objv[i];
-	    if (objPtr->bytes && objPtr->length == 0) {
+	    if (!TclListObjIsCanonical(objPtr)) {
 		continue;
 	    }
 	    if (resPtr) {
@@ -3903,20 +3903,19 @@ TclGetIntForIndex(
     }
     return TCL_OK;
 }
-
 /*
  *----------------------------------------------------------------------
  *
  * GetEndOffsetFromObj --
  *
- *      Look for a string of the form "end[+-]offset" and convert it to an
- *      internal representation holding the offset.
+ *	Look for a string of the form "end[+-]offset" and convert it to an
+ *	internal representation holding the offset.
  *
  * Results:
- *      Tcl return code.
+ *	Tcl return code.
  *
  * Side effects:
- *      May store a Tcl_ObjType.
+ *	May store a Tcl_ObjType.
  *
  *----------------------------------------------------------------------
  */
@@ -3929,9 +3928,11 @@ GetEndOffsetFromObj(
     Tcl_WideInt *widePtr)       /* Location filled in with an integer
                                  * representing an index. */
 {
+    Tcl_ObjIntRep *irPtr;
     Tcl_WideInt offset = 0;	/* Offset in the "end-offset" expression */
 
-    if (objPtr->typePtr != &endOffsetType) {
+    while ((irPtr = Tcl_FetchIntRep(objPtr, &endOffsetType)) == NULL) {
+	Tcl_ObjIntRep ir;
 	int length;
 	const char *bytes = TclGetStringFromObj(objPtr, &length);
 
@@ -3985,13 +3986,12 @@ GetEndOffsetFromObj(
 	    }
 	}
 
-	/* Success. Free the old internal rep and set the new one. */
-	TclFreeIntRep(objPtr);
-	objPtr->internalRep.wideValue = offset;
-	objPtr->typePtr = &endOffsetType;
+	/* Success. Store the new internal rep. */
+	ir.wideValue = offset;
+	Tcl_StoreIntRep(objPtr, &endOffsetType, &ir);
     }
 
-    offset = objPtr->internalRep.wideValue;
+    offset = irPtr->wideValue;
 
     if ((endValue ^ offset) < 0) {
         /* Different signs, sum cannot overflow */
diff --git a/generic/tclVar.c b/generic/tclVar.c
index cafa6a3..dfe883f 100644
--- a/generic/tclVar.c
+++ b/generic/tclVar.c
@@ -254,10 +254,49 @@ static const Tcl_ObjType localVarNameType = {
     FreeLocalVarName, DupLocalVarName, NULL, NULL
 };
 
-static const Tcl_ObjType tclParsedVarNameType = {
+#define LocalSetIntRep(objPtr, index, namePtr)				\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	Tcl_Obj *ptr = (namePtr);					\
+	if (ptr) {Tcl_IncrRefCount(ptr);}				\
+	ir.twoPtrValue.ptr1 = ptr;					\
+	ir.twoPtrValue.ptr2 = INT2PTR(index);				\
+	Tcl_StoreIntRep((objPtr), &localVarNameType, &ir);		\
+    } while (0)
+
+#define LocalGetIntRep(objPtr, index, name)				\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep((objPtr), &localVarNameType);		\
+	(name) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+	(index) = irPtr ? PTR2INT(irPtr->twoPtrValue.ptr2) : -1;	\
+    } while (0)
+
+static const Tcl_ObjType parsedVarNameType = {
     "parsedVarName",
     FreeParsedVarName, DupParsedVarName, NULL, NULL
 };
+
+#define ParsedSetIntRep(objPtr, arrayPtr, elem)				\
+    do {								\
+	Tcl_ObjIntRep ir;						\
+	Tcl_Obj *ptr1 = (arrayPtr);					\
+	Tcl_Obj *ptr2 = (elem);						\
+	if (ptr1) {Tcl_IncrRefCount(ptr1);}				\
+	if (ptr2) {Tcl_IncrRefCount(ptr2);}				\
+	ir.twoPtrValue.ptr1 = ptr1;					\
+	ir.twoPtrValue.ptr2 = ptr2;					\
+	Tcl_StoreIntRep((objPtr), &parsedVarNameType, &ir);		\
+    } while (0)
+
+#define ParsedGetIntRep(objPtr, parsed, array, elem)			\
+    do {								\
+	const Tcl_ObjIntRep *irPtr;					\
+	irPtr = Tcl_FetchIntRep((objPtr), &parsedVarNameType);		\
+	(parsed) = (irPtr != NULL);					\
+	(array) = irPtr ? irPtr->twoPtrValue.ptr1 : NULL;		\
+	(elem) = irPtr ? irPtr->twoPtrValue.ptr2 : NULL;		\
+    } while (0)
 
 Var *
 TclVarHashCreateVar(
@@ -482,9 +521,8 @@ TclLookupVar(
  *
  * Side effects:
  *	New hashtable entries may be created if createPart1 or createPart2
- *	are 1. The object part1Ptr is converted to one of localVarNameType,
- *	tclNsVarNameType or tclParsedVarNameType and caches as much of the
- *	lookup as it can.
+ *	are 1. The object part1Ptr is converted to one of localVarNameType
+ *	or parsedVarNameType and caches as much of the lookup as it can.
  *	When createPart1 is 1, callers must IncrRefCount part1Ptr if they
  *	plan to DecrRefCount it.
  *
@@ -571,15 +609,15 @@ TclObjLookupVarEx(
 				 * structure. */
     const char *errMsg = NULL;
     int index, parsed = 0;
-    const Tcl_ObjType *typePtr = part1Ptr->typePtr;
 
-    *arrayPtrPtr = NULL;
+    int localIndex;
+    Tcl_Obj *namePtr, *arrayPtr, *elem;
 
-    if (typePtr == &localVarNameType) {
-	int localIndex;
+    *arrayPtrPtr = NULL;
 
-    localVarNameTypeHandling:
-	localIndex = PTR2INT(part1Ptr->internalRep.twoPtrValue.ptr2);
+  restart:
+    LocalGetIntRep(part1Ptr, localIndex, namePtr);
+    if (localIndex >= 0) {
 	if (HasLocalVars(varFramePtr)
 		&& !(flags & (TCL_GLOBAL_ONLY | TCL_NAMESPACE_ONLY))
 		&& (localIndex < varFramePtr->numCompiledLocals)) {
@@ -587,7 +625,6 @@ TclObjLookupVarEx(
 	     * Use the cached index if the names coincide.
 	     */
 
-	    Tcl_Obj *namePtr = part1Ptr->internalRep.twoPtrValue.ptr1;
 	    Tcl_Obj *checkNamePtr = localName(varFramePtr, localIndex);
 
 	    if ((!namePtr && (checkNamePtr == part1Ptr)) ||
@@ -600,12 +637,11 @@ TclObjLookupVarEx(
     }
 
     /*
-     * If part1Ptr is a tclParsedVarNameType, separate it into the pre-parsed
-     * parts.
+     * If part1Ptr is a parsedVarNameType, retrieve the pre-parsed parts.
      */
 
-    if (typePtr == &tclParsedVarNameType) {
-	if (part1Ptr->internalRep.twoPtrValue.ptr1 != NULL) {
+    ParsedGetIntRep(part1Ptr, parsed, arrayPtr, elem);
+    if (parsed && arrayPtr) {
 	    if (part2Ptr != NULL) {
 		/*
 		 * ERROR: part1Ptr is already an array element, cannot specify
@@ -619,14 +655,9 @@ TclObjLookupVarEx(
 		}
 		return NULL;
 	    }
-	    part2Ptr = part1Ptr->internalRep.twoPtrValue.ptr2;
-	    part1Ptr = part1Ptr->internalRep.twoPtrValue.ptr1;
-	    typePtr = part1Ptr->typePtr;
-	    if (typePtr == &localVarNameType) {
-		goto localVarNameTypeHandling;
-	    }
-	}
-	parsed = 1;
+	    part2Ptr = elem;
+	    part1Ptr = arrayPtr;
+	    goto restart;
     }
 
     if (!parsed) {
@@ -641,8 +672,6 @@ TclObjLookupVarEx(
 	    const char *part2 = strchr(part1, '(');
 
 	    if (part2) {
-		Tcl_Obj *arrayPtr;
-
 		if (part2Ptr != NULL) {
 		    if (flags & TCL_LEAVE_ERR_MSG) {
 			TclObjVarErrMsg(interp, part1Ptr, part2Ptr, msg,
@@ -657,13 +686,7 @@ TclObjLookupVarEx(
 		part2Ptr = Tcl_NewStringObj(part2 + 1,
 			len - (part2 - part1) - 2);
 
-		TclFreeIntRep(part1Ptr);
-
-		Tcl_IncrRefCount(arrayPtr);
-		part1Ptr->internalRep.twoPtrValue.ptr1 = arrayPtr;
-		Tcl_IncrRefCount(part2Ptr);
-		part1Ptr->internalRep.twoPtrValue.ptr2 = part2Ptr;
-		part1Ptr->typePtr = &tclParsedVarNameType;
+		ParsedSetIntRep(part1Ptr, arrayPtr, part2Ptr);
 
 		part1Ptr = arrayPtr;
 	    }
@@ -691,7 +714,6 @@ TclObjLookupVarEx(
      * Cache the newly found variable if possible.
      */
 
-    TclFreeIntRep(part1Ptr);
     if (index >= 0) {
 	/*
 	 * An indexed local variable.
@@ -699,26 +721,36 @@ TclObjLookupVarEx(
 
 	Tcl_Obj *cachedNamePtr = localName(varFramePtr, index);
 
-	part1Ptr->typePtr = &localVarNameType;
-	if (part1Ptr != cachedNamePtr) {
-	    part1Ptr->internalRep.twoPtrValue.ptr1 = cachedNamePtr;
-	    Tcl_IncrRefCount(cachedNamePtr);
-	    if (cachedNamePtr->typePtr != &localVarNameType
-		    || cachedNamePtr->internalRep.twoPtrValue.ptr1 != NULL) {
-		TclFreeIntRep(cachedNamePtr);
-	    }
+	if (part1Ptr == cachedNamePtr) {
+	    cachedNamePtr = NULL;
 	} else {
-	    part1Ptr->internalRep.twoPtrValue.ptr1 = NULL;
+	    /*
+	     * [80304238ac] Trickiness here.  We will store and incr the
+	     * refcount on cachedNamePtr.  Trouble is that it's possible
+	     * (see test var-22.1) for cachedNamePtr to have an intrep
+	     * that contains a stored and refcounted part1Ptr.  This
+	     * would be a reference cycle which leads to a memory leak.
+	     *
+	     * The solution here is to wipe away all intrep(s) in
+	     * cachedNamePtr and leave it as string only.  This is
+	     * radical and destructive, so a better idea would be welcome.
+	     */
+	    TclFreeIntRep(cachedNamePtr);
+
+	    /*
+	     * Now go ahead and convert it the the "localVarName" type,
+	     * since we suspect at least some use of the value as a
+	     * varname and we want to resolve it quickly.
+	     */
+	    LocalSetIntRep(cachedNamePtr, index, NULL);
 	}
-	part1Ptr->internalRep.twoPtrValue.ptr2 = INT2PTR(index);
+	LocalSetIntRep(part1Ptr, index, cachedNamePtr);
     } else {
 	/*
 	 * At least mark part1Ptr as already parsed.
 	 */
 
-	part1Ptr->typePtr = &tclParsedVarNameType;
-	part1Ptr->internalRep.twoPtrValue.ptr1 = NULL;
-	part1Ptr->internalRep.twoPtrValue.ptr2 = NULL;
+	ParsedSetIntRep(part1Ptr, NULL, NULL);
     }
 
   donePart1:
@@ -5764,12 +5796,15 @@ static void
 FreeLocalVarName(
     Tcl_Obj *objPtr)
 {
-    Tcl_Obj *namePtr = objPtr->internalRep.twoPtrValue.ptr1;
+    int index;
+    Tcl_Obj *namePtr;
+
+    LocalGetIntRep(objPtr, index, namePtr);
 
+    index++;	/* Compiler warning bait. */
     if (namePtr) {
 	Tcl_DecrRefCount(namePtr);
     }
-    objPtr->typePtr = NULL;
 }
 
 static void
@@ -5777,17 +5812,14 @@ DupLocalVarName(
     Tcl_Obj *srcPtr,
     Tcl_Obj *dupPtr)
 {
-    Tcl_Obj *namePtr = srcPtr->internalRep.twoPtrValue.ptr1;
+    int index;
+    Tcl_Obj *namePtr;
 
+    LocalGetIntRep(srcPtr, index, namePtr);
     if (!namePtr) {
 	namePtr = srcPtr;
     }
-    dupPtr->internalRep.twoPtrValue.ptr1 = namePtr;
-    Tcl_IncrRefCount(namePtr);
-
-    dupPtr->internalRep.twoPtrValue.ptr2 =
-	    srcPtr->internalRep.twoPtrValue.ptr2;
-    dupPtr->typePtr = &localVarNameType;
+    LocalSetIntRep(dupPtr, index, namePtr);
 }
 
 /*
@@ -5803,14 +5835,16 @@ static void
 FreeParsedVarName(
     Tcl_Obj *objPtr)
 {
-    register Tcl_Obj *arrayPtr = objPtr->internalRep.twoPtrValue.ptr1;
-    register Tcl_Obj *elem = objPtr->internalRep.twoPtrValue.ptr2;
+    register Tcl_Obj *arrayPtr, *elem;
+    int parsed;
+
+    ParsedGetIntRep(objPtr, parsed, arrayPtr, elem);
 
+    parsed++;				/* Silence compiler. */
     if (arrayPtr != NULL) {
 	TclDecrRefCount(arrayPtr);
 	TclDecrRefCount(elem);
     }
-    objPtr->typePtr = NULL;
 }
 
 static void
@@ -5818,17 +5852,13 @@ DupParsedVarName(
     Tcl_Obj *srcPtr,
     Tcl_Obj *dupPtr)
 {
-    register Tcl_Obj *arrayPtr = srcPtr->internalRep.twoPtrValue.ptr1;
-    register Tcl_Obj *elem = srcPtr->internalRep.twoPtrValue.ptr2;
+    register Tcl_Obj *arrayPtr, *elem;
+    int parsed;
 
-    if (arrayPtr != NULL) {
-	Tcl_IncrRefCount(arrayPtr);
-	Tcl_IncrRefCount(elem);
-    }
+    ParsedGetIntRep(srcPtr, parsed, arrayPtr, elem);
 
-    dupPtr->internalRep.twoPtrValue.ptr1 = arrayPtr;
-    dupPtr->internalRep.twoPtrValue.ptr2 = elem;
-    dupPtr->typePtr = &tclParsedVarNameType;
+    parsed++;				/* Silence compiler. */
+    ParsedSetIntRep(dupPtr, arrayPtr, elem);
 }
 
 /*
diff --git a/library/clock.tcl b/library/clock.tcl
index 8e4b657..8e4b657 100644..100755
--- a/library/clock.tcl
+++ b/library/clock.tcl
diff --git a/library/encoding/tis-620.enc b/library/encoding/tis-620.enc
index c233be5..c233be5 100644..100755
--- a/library/encoding/tis-620.enc
+++ b/library/encoding/tis-620.enc
diff --git a/library/msgs/af.msg b/library/msgs/af.msg
index 0892615..0892615 100644..100755
--- a/library/msgs/af.msg
+++ b/library/msgs/af.msg
diff --git a/library/msgs/af_za.msg b/library/msgs/af_za.msg
index fef48ad..fef48ad 100644..100755
--- a/library/msgs/af_za.msg
+++ b/library/msgs/af_za.msg
diff --git a/library/msgs/ar.msg b/library/msgs/ar.msg
index 2d403ec..2d403ec 100644..100755
--- a/library/msgs/ar.msg
+++ b/library/msgs/ar.msg
diff --git a/library/msgs/ar_in.msg b/library/msgs/ar_in.msg
index 185e49c..185e49c 100644..100755
--- a/library/msgs/ar_in.msg
+++ b/library/msgs/ar_in.msg
diff --git a/library/msgs/ar_jo.msg b/library/msgs/ar_jo.msg
index 9a9dda0..9a9dda0 100644..100755
--- a/library/msgs/ar_jo.msg
+++ b/library/msgs/ar_jo.msg
diff --git a/library/msgs/ar_lb.msg b/library/msgs/ar_lb.msg
index c23aa2c..c23aa2c 100644..100755
--- a/library/msgs/ar_lb.msg
+++ b/library/msgs/ar_lb.msg
diff --git a/library/msgs/ar_sy.msg b/library/msgs/ar_sy.msg
index f0daec0..f0daec0 100644..100755
--- a/library/msgs/ar_sy.msg
+++ b/library/msgs/ar_sy.msg
diff --git a/library/msgs/be.msg b/library/msgs/be.msg
index a0aceed..a0aceed 100644..100755
--- a/library/msgs/be.msg
+++ b/library/msgs/be.msg
diff --git a/library/msgs/bg.msg b/library/msgs/bg.msg
index 2e7730d..2e7730d 100644..100755
--- a/library/msgs/bg.msg
+++ b/library/msgs/bg.msg
diff --git a/library/msgs/bn.msg b/library/msgs/bn.msg
index a0aef13..a0aef13 100644..100755
--- a/library/msgs/bn.msg
+++ b/library/msgs/bn.msg
diff --git a/library/msgs/bn_in.msg b/library/msgs/bn_in.msg
index 28c000f..28c000f 100644..100755
--- a/library/msgs/bn_in.msg
+++ b/library/msgs/bn_in.msg
diff --git a/library/msgs/ca.msg b/library/msgs/ca.msg
index 272f682..272f682 100644..100755
--- a/library/msgs/ca.msg
+++ b/library/msgs/ca.msg
diff --git a/library/msgs/cs.msg b/library/msgs/cs.msg
index 4673cd4..4673cd4 100644..100755
--- a/library/msgs/cs.msg
+++ b/library/msgs/cs.msg
diff --git a/library/msgs/da.msg b/library/msgs/da.msg
index abed3c5..abed3c5 100644..100755
--- a/library/msgs/da.msg
+++ b/library/msgs/da.msg
diff --git a/library/msgs/de.msg b/library/msgs/de.msg
index 0bb7399..0bb7399 100644..100755
--- a/library/msgs/de.msg
+++ b/library/msgs/de.msg
diff --git a/library/msgs/de_at.msg b/library/msgs/de_at.msg
index 1a0a0f5..1a0a0f5 100644..100755
--- a/library/msgs/de_at.msg
+++ b/library/msgs/de_at.msg
diff --git a/library/msgs/de_be.msg b/library/msgs/de_be.msg
index 04cf88c..04cf88c 100644..100755
--- a/library/msgs/de_be.msg
+++ b/library/msgs/de_be.msg
diff --git a/library/msgs/el.msg b/library/msgs/el.msg
index 26bdfe9..26bdfe9 100644..100755
--- a/library/msgs/el.msg
+++ b/library/msgs/el.msg
diff --git a/library/msgs/en_au.msg b/library/msgs/en_au.msg
index 7f9870c..7f9870c 100644..100755
--- a/library/msgs/en_au.msg
+++ b/library/msgs/en_au.msg
diff --git a/library/msgs/en_be.msg b/library/msgs/en_be.msg
index 5072986..5072986 100644..100755
--- a/library/msgs/en_be.msg
+++ b/library/msgs/en_be.msg
diff --git a/library/msgs/en_bw.msg b/library/msgs/en_bw.msg
index 8fd20c7..8fd20c7 100644..100755
--- a/library/msgs/en_bw.msg
+++ b/library/msgs/en_bw.msg
diff --git a/library/msgs/en_ca.msg b/library/msgs/en_ca.msg
index 278efe7..278efe7 100644..100755
--- a/library/msgs/en_ca.msg
+++ b/library/msgs/en_ca.msg
diff --git a/library/msgs/en_gb.msg b/library/msgs/en_gb.msg
index 5c61c43..5c61c43 100644..100755
--- a/library/msgs/en_gb.msg
+++ b/library/msgs/en_gb.msg
diff --git a/library/msgs/en_hk.msg b/library/msgs/en_hk.msg
index 8b33bc0..8b33bc0 100644..100755
--- a/library/msgs/en_hk.msg
+++ b/library/msgs/en_hk.msg
diff --git a/library/msgs/en_ie.msg b/library/msgs/en_ie.msg
index ba621cf..ba621cf 100644..100755
--- a/library/msgs/en_ie.msg
+++ b/library/msgs/en_ie.msg
diff --git a/library/msgs/en_in.msg b/library/msgs/en_in.msg
index a1f155d..a1f155d 100644..100755
--- a/library/msgs/en_in.msg
+++ b/library/msgs/en_in.msg
diff --git a/library/msgs/en_nz.msg b/library/msgs/en_nz.msg
index b419017..b419017 100644..100755
--- a/library/msgs/en_nz.msg
+++ b/library/msgs/en_nz.msg
diff --git a/library/msgs/en_ph.msg b/library/msgs/en_ph.msg
index 682666d..682666d 100644..100755
--- a/library/msgs/en_ph.msg
+++ b/library/msgs/en_ph.msg
diff --git a/library/msgs/en_sg.msg b/library/msgs/en_sg.msg
index 4dc5b1d..4dc5b1d 100644..100755
--- a/library/msgs/en_sg.msg
+++ b/library/msgs/en_sg.msg
diff --git a/library/msgs/en_za.msg b/library/msgs/en_za.msg
index fe43797..fe43797 100644..100755
--- a/library/msgs/en_za.msg
+++ b/library/msgs/en_za.msg
diff --git a/library/msgs/en_zw.msg b/library/msgs/en_zw.msg
index 2a5804f..2a5804f 100644..100755
--- a/library/msgs/en_zw.msg
+++ b/library/msgs/en_zw.msg
diff --git a/library/msgs/eo.msg b/library/msgs/eo.msg
index b9b1500..b9b1500 100644..100755
--- a/library/msgs/eo.msg
+++ b/library/msgs/eo.msg
diff --git a/library/msgs/es.msg b/library/msgs/es.msg
index 6090eab..6090eab 100644..100755
--- a/library/msgs/es.msg
+++ b/library/msgs/es.msg
diff --git a/library/msgs/es_ar.msg b/library/msgs/es_ar.msg
index 7d35027..7d35027 100644..100755
--- a/library/msgs/es_ar.msg
+++ b/library/msgs/es_ar.msg
diff --git a/library/msgs/es_bo.msg b/library/msgs/es_bo.msg
index 498ad0d..498ad0d 100644..100755
--- a/library/msgs/es_bo.msg
+++ b/library/msgs/es_bo.msg
diff --git a/library/msgs/es_cl.msg b/library/msgs/es_cl.msg
index 31d465c..31d465c 100644..100755
--- a/library/msgs/es_cl.msg
+++ b/library/msgs/es_cl.msg
diff --git a/library/msgs/es_co.msg b/library/msgs/es_co.msg
index 77e57f0..77e57f0 100644..100755
--- a/library/msgs/es_co.msg
+++ b/library/msgs/es_co.msg
diff --git a/library/msgs/es_cr.msg b/library/msgs/es_cr.msg
index 7a652fa..7a652fa 100644..100755
--- a/library/msgs/es_cr.msg
+++ b/library/msgs/es_cr.msg
diff --git a/library/msgs/es_do.msg b/library/msgs/es_do.msg
index 0e283da..0e283da 100644..100755
--- a/library/msgs/es_do.msg
+++ b/library/msgs/es_do.msg
diff --git a/library/msgs/es_ec.msg b/library/msgs/es_ec.msg
index 9e921e0..9e921e0 100644..100755
--- a/library/msgs/es_ec.msg
+++ b/library/msgs/es_ec.msg
diff --git a/library/msgs/es_gt.msg b/library/msgs/es_gt.msg
index ecd6faf..ecd6faf 100644..100755
--- a/library/msgs/es_gt.msg
+++ b/library/msgs/es_gt.msg
diff --git a/library/msgs/es_hn.msg b/library/msgs/es_hn.msg
index a758ca2..a758ca2 100644..100755
--- a/library/msgs/es_hn.msg
+++ b/library/msgs/es_hn.msg
diff --git a/library/msgs/es_mx.msg b/library/msgs/es_mx.msg
index 7cfb545..7cfb545 100644..100755
--- a/library/msgs/es_mx.msg
+++ b/library/msgs/es_mx.msg
diff --git a/library/msgs/es_ni.msg b/library/msgs/es_ni.msg
index 7c39495..7c39495 100644..100755
--- a/library/msgs/es_ni.msg
+++ b/library/msgs/es_ni.msg
diff --git a/library/msgs/es_pa.msg b/library/msgs/es_pa.msg
index cecacdc..cecacdc 100644..100755
--- a/library/msgs/es_pa.msg
+++ b/library/msgs/es_pa.msg
diff --git a/library/msgs/es_pe.msg b/library/msgs/es_pe.msg
index 9f90595..9f90595 100644..100755
--- a/library/msgs/es_pe.msg
+++ b/library/msgs/es_pe.msg
diff --git a/library/msgs/es_pr.msg b/library/msgs/es_pr.msg
index 8511b12..8511b12 100644..100755
--- a/library/msgs/es_pr.msg
+++ b/library/msgs/es_pr.msg
diff --git a/library/msgs/es_py.msg b/library/msgs/es_py.msg
index aa93d36..aa93d36 100644..100755
--- a/library/msgs/es_py.msg
+++ b/library/msgs/es_py.msg
diff --git a/library/msgs/es_sv.msg b/library/msgs/es_sv.msg
index fc7954d..fc7954d 100644..100755
--- a/library/msgs/es_sv.msg
+++ b/library/msgs/es_sv.msg
diff --git a/library/msgs/es_uy.msg b/library/msgs/es_uy.msg
index b33525c..b33525c 100644..100755
--- a/library/msgs/es_uy.msg
+++ b/library/msgs/es_uy.msg
diff --git a/library/msgs/es_ve.msg b/library/msgs/es_ve.msg
index 7c2a7b0..7c2a7b0 100644..100755
--- a/library/msgs/es_ve.msg
+++ b/library/msgs/es_ve.msg
diff --git a/library/msgs/et.msg b/library/msgs/et.msg
index a782f9b..a782f9b 100644..100755
--- a/library/msgs/et.msg
+++ b/library/msgs/et.msg
diff --git a/library/msgs/eu.msg b/library/msgs/eu.msg
index cf708b6..cf708b6 100644..100755
--- a/library/msgs/eu.msg
+++ b/library/msgs/eu.msg
diff --git a/library/msgs/eu_es.msg b/library/msgs/eu_es.msg
index 2694418..2694418 100644..100755
--- a/library/msgs/eu_es.msg
+++ b/library/msgs/eu_es.msg
diff --git a/library/msgs/fa.msg b/library/msgs/fa.msg
index 6166e28..6166e28 100644..100755
--- a/library/msgs/fa.msg
+++ b/library/msgs/fa.msg
diff --git a/library/msgs/fa_in.msg b/library/msgs/fa_in.msg
index ce32f99..ce32f99 100644..100755
--- a/library/msgs/fa_in.msg
+++ b/library/msgs/fa_in.msg
diff --git a/library/msgs/fa_ir.msg b/library/msgs/fa_ir.msg
index 9ce9284..9ce9284 100644..100755
--- a/library/msgs/fa_ir.msg
+++ b/library/msgs/fa_ir.msg
diff --git a/library/msgs/fi.msg b/library/msgs/fi.msg
index 69be367..69be367 100644..100755
--- a/library/msgs/fi.msg
+++ b/library/msgs/fi.msg
diff --git a/library/msgs/fo.msg b/library/msgs/fo.msg
index 1f1794d..1f1794d 100644..100755
--- a/library/msgs/fo.msg
+++ b/library/msgs/fo.msg
diff --git a/library/msgs/fo_fo.msg b/library/msgs/fo_fo.msg
index 2392b8e..2392b8e 100644..100755
--- a/library/msgs/fo_fo.msg
+++ b/library/msgs/fo_fo.msg
diff --git a/library/msgs/fr.msg b/library/msgs/fr.msg
index a274468..a274468 100644..100755
--- a/library/msgs/fr.msg
+++ b/library/msgs/fr.msg
diff --git a/library/msgs/fr_be.msg b/library/msgs/fr_be.msg
index cdb13bd..cdb13bd 100644..100755
--- a/library/msgs/fr_be.msg
+++ b/library/msgs/fr_be.msg
diff --git a/library/msgs/fr_ca.msg b/library/msgs/fr_ca.msg
index 00ccfff..00ccfff 100644..100755
--- a/library/msgs/fr_ca.msg
+++ b/library/msgs/fr_ca.msg
diff --git a/library/msgs/fr_ch.msg b/library/msgs/fr_ch.msg
index 7e2bac7..7e2bac7 100644..100755
--- a/library/msgs/fr_ch.msg
+++ b/library/msgs/fr_ch.msg
diff --git a/library/msgs/ga.msg b/library/msgs/ga.msg
index 056c9a0..056c9a0 100644..100755
--- a/library/msgs/ga.msg
+++ b/library/msgs/ga.msg
diff --git a/library/msgs/ga_ie.msg b/library/msgs/ga_ie.msg
index b6acbbc..b6acbbc 100644..100755
--- a/library/msgs/ga_ie.msg
+++ b/library/msgs/ga_ie.msg
diff --git a/library/msgs/gl.msg b/library/msgs/gl.msg
index c2fefc9..c2fefc9 100644..100755
--- a/library/msgs/gl.msg
+++ b/library/msgs/gl.msg
diff --git a/library/msgs/gl_es.msg b/library/msgs/gl_es.msg
index d4ed270..d4ed270 100644..100755
--- a/library/msgs/gl_es.msg
+++ b/library/msgs/gl_es.msg
diff --git a/library/msgs/gv.msg b/library/msgs/gv.msg
index 7d332ad..7d332ad 100644..100755
--- a/library/msgs/gv.msg
+++ b/library/msgs/gv.msg
diff --git a/library/msgs/gv_gb.msg b/library/msgs/gv_gb.msg
index 5e96e6f..5e96e6f 100644..100755
--- a/library/msgs/gv_gb.msg
+++ b/library/msgs/gv_gb.msg
diff --git a/library/msgs/he.msg b/library/msgs/he.msg
index 13a81b7..13a81b7 100644..100755
--- a/library/msgs/he.msg
+++ b/library/msgs/he.msg
diff --git a/library/msgs/hi.msg b/library/msgs/hi.msg
index 18c8bf0..18c8bf0 100644..100755
--- a/library/msgs/hi.msg
+++ b/library/msgs/hi.msg
diff --git a/library/msgs/hi_in.msg b/library/msgs/hi_in.msg
index 239793f..239793f 100644..100755
--- a/library/msgs/hi_in.msg
+++ b/library/msgs/hi_in.msg
diff --git a/library/msgs/hr.msg b/library/msgs/hr.msg
index 30491e1..30491e1 100644..100755
--- a/library/msgs/hr.msg
+++ b/library/msgs/hr.msg
diff --git a/library/msgs/hu.msg b/library/msgs/hu.msg
index 46776dd..46776dd 100644..100755
--- a/library/msgs/hu.msg
+++ b/library/msgs/hu.msg
diff --git a/library/msgs/id.msg b/library/msgs/id.msg
index 17c6bb5..17c6bb5 100644..100755
--- a/library/msgs/id.msg
+++ b/library/msgs/id.msg
diff --git a/library/msgs/id_id.msg b/library/msgs/id_id.msg
index bb672c1..bb672c1 100644..100755
--- a/library/msgs/id_id.msg
+++ b/library/msgs/id_id.msg
diff --git a/library/msgs/is.msg b/library/msgs/is.msg
index a369b89..a369b89 100644..100755
--- a/library/msgs/is.msg
+++ b/library/msgs/is.msg
diff --git a/library/msgs/it.msg b/library/msgs/it.msg
index e51aee2..e51aee2 100644..100755
--- a/library/msgs/it.msg
+++ b/library/msgs/it.msg
diff --git a/library/msgs/it_ch.msg b/library/msgs/it_ch.msg
index b36ed36..b36ed36 100644..100755
--- a/library/msgs/it_ch.msg
+++ b/library/msgs/it_ch.msg
diff --git a/library/msgs/ja.msg b/library/msgs/ja.msg
index 76b5fa4..76b5fa4 100644..100755
--- a/library/msgs/ja.msg
+++ b/library/msgs/ja.msg
diff --git a/library/msgs/kl.msg b/library/msgs/kl.msg
index d877bfe..d877bfe 100644..100755
--- a/library/msgs/kl.msg
+++ b/library/msgs/kl.msg
diff --git a/library/msgs/kl_gl.msg b/library/msgs/kl_gl.msg
index 403aa10..403aa10 100644..100755
--- a/library/msgs/kl_gl.msg
+++ b/library/msgs/kl_gl.msg
diff --git a/library/msgs/ko.msg b/library/msgs/ko.msg
index 817c2e7..817c2e7 100644..100755
--- a/library/msgs/ko.msg
+++ b/library/msgs/ko.msg
diff --git a/library/msgs/ko_kr.msg b/library/msgs/ko_kr.msg
index f23bd6b..f23bd6b 100644..100755
--- a/library/msgs/ko_kr.msg
+++ b/library/msgs/ko_kr.msg
diff --git a/library/msgs/kok.msg b/library/msgs/kok.msg
index 231853b..231853b 100644..100755
--- a/library/msgs/kok.msg
+++ b/library/msgs/kok.msg
diff --git a/library/msgs/kok_in.msg b/library/msgs/kok_in.msg
index abcb1ff..abcb1ff 100644..100755
--- a/library/msgs/kok_in.msg
+++ b/library/msgs/kok_in.msg
diff --git a/library/msgs/kw.msg b/library/msgs/kw.msg
index aaf79b3..aaf79b3 100644..100755
--- a/library/msgs/kw.msg
+++ b/library/msgs/kw.msg
diff --git a/library/msgs/kw_gb.msg b/library/msgs/kw_gb.msg
index 2967680..2967680 100644..100755
--- a/library/msgs/kw_gb.msg
+++ b/library/msgs/kw_gb.msg
diff --git a/library/msgs/lt.msg b/library/msgs/lt.msg
index 15829a9..15829a9 100644..100755
--- a/library/msgs/lt.msg
+++ b/library/msgs/lt.msg
diff --git a/library/msgs/lv.msg b/library/msgs/lv.msg
index 730fd33..730fd33 100644..100755
--- a/library/msgs/lv.msg
+++ b/library/msgs/lv.msg
diff --git a/library/msgs/mk.msg b/library/msgs/mk.msg
index 9b7bd9d..9b7bd9d 100644..100755
--- a/library/msgs/mk.msg
+++ b/library/msgs/mk.msg
diff --git a/library/msgs/mr.msg b/library/msgs/mr.msg
index e475615..e475615 100644..100755
--- a/library/msgs/mr.msg
+++ b/library/msgs/mr.msg
diff --git a/library/msgs/mr_in.msg b/library/msgs/mr_in.msg
index 1889da5..1889da5 100644..100755
--- a/library/msgs/mr_in.msg
+++ b/library/msgs/mr_in.msg
diff --git a/library/msgs/ms.msg b/library/msgs/ms.msg
index e954431..e954431 100644..100755
--- a/library/msgs/ms.msg
+++ b/library/msgs/ms.msg
diff --git a/library/msgs/ms_my.msg b/library/msgs/ms_my.msg
index c1f93d4..c1f93d4 100644..100755
--- a/library/msgs/ms_my.msg
+++ b/library/msgs/ms_my.msg
diff --git a/library/msgs/mt.msg b/library/msgs/mt.msg
index c479e47..c479e47 100644..100755
--- a/library/msgs/mt.msg
+++ b/library/msgs/mt.msg
diff --git a/library/msgs/nb.msg b/library/msgs/nb.msg
index 4dd76c7..4dd76c7 100644..100755
--- a/library/msgs/nb.msg
+++ b/library/msgs/nb.msg
diff --git a/library/msgs/nl.msg b/library/msgs/nl.msg
index 4c5c675..4c5c675 100644..100755
--- a/library/msgs/nl.msg
+++ b/library/msgs/nl.msg
diff --git a/library/msgs/nl_be.msg b/library/msgs/nl_be.msg
index 4b19670..4b19670 100644..100755
--- a/library/msgs/nl_be.msg
+++ b/library/msgs/nl_be.msg
diff --git a/library/msgs/nn.msg b/library/msgs/nn.msg
index b61a2dd..b61a2dd 100644..100755
--- a/library/msgs/nn.msg
+++ b/library/msgs/nn.msg
diff --git a/library/msgs/pl.msg b/library/msgs/pl.msg
index 821eea7..821eea7 100644..100755
--- a/library/msgs/pl.msg
+++ b/library/msgs/pl.msg
diff --git a/library/msgs/pt.msg b/library/msgs/pt.msg
index 425c1f6..425c1f6 100644..100755
--- a/library/msgs/pt.msg
+++ b/library/msgs/pt.msg
diff --git a/library/msgs/pt_br.msg b/library/msgs/pt_br.msg
index 8684327..8684327 100644..100755
--- a/library/msgs/pt_br.msg
+++ b/library/msgs/pt_br.msg
diff --git a/library/msgs/ro.msg b/library/msgs/ro.msg
index f4452ba..f4452ba 100644..100755
--- a/library/msgs/ro.msg
+++ b/library/msgs/ro.msg
diff --git a/library/msgs/ru.msg b/library/msgs/ru.msg
index 983a253..983a253 100644..100755
--- a/library/msgs/ru.msg
+++ b/library/msgs/ru.msg
diff --git a/library/msgs/ru_ua.msg b/library/msgs/ru_ua.msg
index 6e1f8a8..6e1f8a8 100644..100755
--- a/library/msgs/ru_ua.msg
+++ b/library/msgs/ru_ua.msg
diff --git a/library/msgs/sh.msg b/library/msgs/sh.msg
index 2e4143d..2e4143d 100644..100755
--- a/library/msgs/sh.msg
+++ b/library/msgs/sh.msg
diff --git a/library/msgs/sk.msg b/library/msgs/sk.msg
index dc6f6b6..dc6f6b6 100644..100755
--- a/library/msgs/sk.msg
+++ b/library/msgs/sk.msg
diff --git a/library/msgs/sl.msg b/library/msgs/sl.msg
index 2ee0a03..2ee0a03 100644..100755
--- a/library/msgs/sl.msg
+++ b/library/msgs/sl.msg
diff --git a/library/msgs/sq.msg b/library/msgs/sq.msg
index 65da407..65da407 100644..100755
--- a/library/msgs/sq.msg
+++ b/library/msgs/sq.msg
diff --git a/library/msgs/sr.msg b/library/msgs/sr.msg
index 3d84d6c..3d84d6c 100644..100755
--- a/library/msgs/sr.msg
+++ b/library/msgs/sr.msg
diff --git a/library/msgs/sv.msg b/library/msgs/sv.msg
index 5716092..5716092 100644..100755
--- a/library/msgs/sv.msg
+++ b/library/msgs/sv.msg
diff --git a/library/msgs/sw.msg b/library/msgs/sw.msg
index b888b43..b888b43 100644..100755
--- a/library/msgs/sw.msg
+++ b/library/msgs/sw.msg
diff --git a/library/msgs/ta.msg b/library/msgs/ta.msg
index ea62552..ea62552 100644..100755
--- a/library/msgs/ta.msg
+++ b/library/msgs/ta.msg
diff --git a/library/msgs/ta_in.msg b/library/msgs/ta_in.msg
index 24590ac..24590ac 100644..100755
--- a/library/msgs/ta_in.msg
+++ b/library/msgs/ta_in.msg
diff --git a/library/msgs/te.msg b/library/msgs/te.msg
index f35ece4..f35ece4 100644..100755
--- a/library/msgs/te.msg
+++ b/library/msgs/te.msg
diff --git a/library/msgs/te_in.msg b/library/msgs/te_in.msg
index 84dd2b3..84dd2b3 100644..100755
--- a/library/msgs/te_in.msg
+++ b/library/msgs/te_in.msg
diff --git a/library/msgs/th.msg b/library/msgs/th.msg
index edaa149..edaa149 100644..100755
--- a/library/msgs/th.msg
+++ b/library/msgs/th.msg
diff --git a/library/msgs/tr.msg b/library/msgs/tr.msg
index 12869ee..12869ee 100644..100755
--- a/library/msgs/tr.msg
+++ b/library/msgs/tr.msg
diff --git a/library/msgs/uk.msg b/library/msgs/uk.msg
index 42eb095..42eb095 100644..100755
--- a/library/msgs/uk.msg
+++ b/library/msgs/uk.msg
diff --git a/library/msgs/vi.msg b/library/msgs/vi.msg
index 3437ebf..3437ebf 100644..100755
--- a/library/msgs/vi.msg
+++ b/library/msgs/vi.msg
diff --git a/library/msgs/zh.msg b/library/msgs/zh.msg
index 9c1d08b..9c1d08b 100644..100755
--- a/library/msgs/zh.msg
+++ b/library/msgs/zh.msg
diff --git a/library/msgs/zh_cn.msg b/library/msgs/zh_cn.msg
index da2869a..da2869a 100644..100755
--- a/library/msgs/zh_cn.msg
+++ b/library/msgs/zh_cn.msg
diff --git a/library/msgs/zh_hk.msg b/library/msgs/zh_hk.msg
index 7f1b181..7f1b181 100644..100755
--- a/library/msgs/zh_hk.msg
+++ b/library/msgs/zh_hk.msg
diff --git a/library/msgs/zh_sg.msg b/library/msgs/zh_sg.msg
index 690edf7..690edf7 100644..100755
--- a/library/msgs/zh_sg.msg
+++ b/library/msgs/zh_sg.msg
diff --git a/library/msgs/zh_tw.msg b/library/msgs/zh_tw.msg
index 17a6dd7..17a6dd7 100644..100755
--- a/library/msgs/zh_tw.msg
+++ b/library/msgs/zh_tw.msg
diff --git a/library/tzdata/Africa/Asmara b/library/tzdata/Africa/Asmara
index 3d33c94..3d33c94 100644..100755
--- a/library/tzdata/Africa/Asmara
+++ b/library/tzdata/Africa/Asmara
diff --git a/library/tzdata/America/Atikokan b/library/tzdata/America/Atikokan
index e72b04f..e72b04f 100644..100755
--- a/library/tzdata/America/Atikokan
+++ b/library/tzdata/America/Atikokan
diff --git a/library/tzdata/America/Blanc-Sablon b/library/tzdata/America/Blanc-Sablon
index d5485e8..d5485e8 100644..100755
--- a/library/tzdata/America/Blanc-Sablon
+++ b/library/tzdata/America/Blanc-Sablon
diff --git a/library/tzdata/America/Indiana/Petersburg b/library/tzdata/America/Indiana/Petersburg
index 6992bfc..6992bfc 100644..100755
--- a/library/tzdata/America/Indiana/Petersburg
+++ b/library/tzdata/America/Indiana/Petersburg
diff --git a/library/tzdata/America/Indiana/Tell_City b/library/tzdata/America/Indiana/Tell_City
index 9eebcf7..9eebcf7 100644..100755
--- a/library/tzdata/America/Indiana/Tell_City
+++ b/library/tzdata/America/Indiana/Tell_City
diff --git a/library/tzdata/America/Indiana/Vincennes b/library/tzdata/America/Indiana/Vincennes
index 1af7fc9..1af7fc9 100644..100755
--- a/library/tzdata/America/Indiana/Vincennes
+++ b/library/tzdata/America/Indiana/Vincennes
diff --git a/library/tzdata/America/Indiana/Winamac b/library/tzdata/America/Indiana/Winamac
index fb6cd37..fb6cd37 100644..100755
--- a/library/tzdata/America/Indiana/Winamac
+++ b/library/tzdata/America/Indiana/Winamac
diff --git a/library/tzdata/America/Moncton b/library/tzdata/America/Moncton
index d286c88..d286c88 100644..100755
--- a/library/tzdata/America/Moncton
+++ b/library/tzdata/America/Moncton
diff --git a/library/tzdata/America/North_Dakota/New_Salem b/library/tzdata/America/North_Dakota/New_Salem
index 5a9d229..5a9d229 100644..100755
--- a/library/tzdata/America/North_Dakota/New_Salem
+++ b/library/tzdata/America/North_Dakota/New_Salem
diff --git a/library/tzdata/America/Resolute b/library/tzdata/America/Resolute
index a9881b4..a9881b4 100644..100755
--- a/library/tzdata/America/Resolute
+++ b/library/tzdata/America/Resolute
diff --git a/library/tzdata/Atlantic/Faroe b/library/tzdata/Atlantic/Faroe
index d2c314a..d2c314a 100644..100755
--- a/library/tzdata/Atlantic/Faroe
+++ b/library/tzdata/Atlantic/Faroe
diff --git a/library/tzdata/Australia/Eucla b/library/tzdata/Australia/Eucla
index 8008980..8008980 100644..100755
--- a/library/tzdata/Australia/Eucla
+++ b/library/tzdata/Australia/Eucla
diff --git a/library/tzdata/Europe/Guernsey b/library/tzdata/Europe/Guernsey
index 4372c64..4372c64 100644..100755
--- a/library/tzdata/Europe/Guernsey
+++ b/library/tzdata/Europe/Guernsey
diff --git a/library/tzdata/Europe/Isle_of_Man b/library/tzdata/Europe/Isle_of_Man
index 870ac45..870ac45 100644..100755
--- a/library/tzdata/Europe/Isle_of_Man
+++ b/library/tzdata/Europe/Isle_of_Man
diff --git a/library/tzdata/Europe/Jersey b/library/tzdata/Europe/Jersey
index e4da512..e4da512 100644..100755
--- a/library/tzdata/Europe/Jersey
+++ b/library/tzdata/Europe/Jersey
diff --git a/library/tzdata/Europe/Podgorica b/library/tzdata/Europe/Podgorica
index f4f9066..f4f9066 100644..100755
--- a/library/tzdata/Europe/Podgorica
+++ b/library/tzdata/Europe/Podgorica
diff --git a/library/tzdata/Europe/Volgograd b/library/tzdata/Europe/Volgograd
index 3938683..3938683 100644..100755
--- a/library/tzdata/Europe/Volgograd
+++ b/library/tzdata/Europe/Volgograd
diff --git a/macosx/tclMacOSXFCmd.c b/macosx/tclMacOSXFCmd.c
index 3adc808..f09a441 100644
--- a/macosx/tclMacOSXFCmd.c
+++ b/macosx/tclMacOSXFCmd.c
@@ -692,24 +692,28 @@ UpdateStringOfOSType(
     register Tcl_Obj *objPtr)	/* OSType object whose string rep to
 				 * update. */
 {
-    char string[5];
+    const int size = TCL_UTF_MAX * 4;
+    char *dst = Tcl_InitStringRep(objPtr, NULL, size);
     OSType osType = (OSType) objPtr->internalRep.longValue;
-    Tcl_DString ds;
-    Tcl_Encoding encoding = Tcl_GetEncoding(NULL, "macRoman");
-    unsigned len;
-
-    string[0] = (char) (osType >> 24);
-    string[1] = (char) (osType >> 16);
-    string[2] = (char) (osType >>  8);
-    string[3] = (char) (osType);
-    string[4] = '\0';
-    Tcl_ExternalToUtfDString(encoding, string, -1, &ds);
-    len = (unsigned) Tcl_DStringLength(&ds) + 1;
-    objPtr->bytes = ckalloc(len);
-    memcpy(objPtr->bytes, Tcl_DStringValue(&ds), len);
-    objPtr->length = Tcl_DStringLength(&ds);
-    Tcl_DStringFree(&ds);
+    int written = 0;
+    Tcl_Encoding encoding;
+    char src[5];
+
+    TclOOM(dst, size);
+
+    src[0] = (char) (osType >> 24);
+    src[1] = (char) (osType >> 16);
+    src[2] = (char) (osType >>  8);
+    src[3] = (char) (osType);
+    src[4] = '\0';
+
+    encoding = Tcl_GetEncoding(NULL, "macRoman");
+    Tcl_ExternalToUtf(NULL, encoding, src, -1, /* flags */ 0,
+	    /* statePtr */ NULL, dst, size, /* srcReadPtr */ NULL,
+	    /* dstWrotePtr */ &written, /* dstCharsPtr */ NULL);
     Tcl_FreeEncoding(encoding);
+
+    (void)Tcl_InitStringRep(objPtr, NULL, written);
 }
 
 /*
diff --git a/tests/lsetComp.test b/tests/lsetComp.test
index 6330de4..6330de4 100644..100755
--- a/tests/lsetComp.test
+++ b/tests/lsetComp.test
diff --git a/tests/notify.test b/tests/notify.test
index d2b9123..d2b9123 100644..100755
--- a/tests/notify.test
+++ b/tests/notify.test
diff --git a/tests/obj.test b/tests/obj.test
index cd33eaa..87c8d08 100644
--- a/tests/obj.test
+++ b/tests/obj.test
@@ -540,7 +540,6 @@ test obj-30.1 {Ref counting and object deletion, simple types} testobj {
     lappend result [testobj refcount 2]
 } {{} 1024 1024 int 4 4 0 int 3 2}
 
-
 test obj-32.1 {freeing very large object trees} {
     set x {}
     for {set i 0} {$i<100000} {incr i} {
diff --git a/tools/encoding/ebcdic.txt b/tools/encoding/ebcdic.txt
index d9fa42e..d9fa42e 100644..100755
--- a/tools/encoding/ebcdic.txt
+++ b/tools/encoding/ebcdic.txt
diff --git a/tools/encoding/tis-620.txt b/tools/encoding/tis-620.txt
index d3656c5..d3656c5 100644..100755
--- a/tools/encoding/tis-620.txt
+++ b/tools/encoding/tis-620.txt
diff --git a/unix/tclUnixSock.c b/unix/tclUnixSock.c
index 2793d3b..bd54a2e 100644
--- a/unix/tclUnixSock.c
+++ b/unix/tclUnixSock.c
@@ -253,9 +253,6 @@ InitializeHostName(
 	    native = u.nodename;
         }
     }
-    if (native == NULL) {
-	native = &tclEmptyString;
-    }
 #else /* !NO_UNAME */
     /*
      * Uname doesn't exist; try gethostname instead.
@@ -284,9 +281,15 @@ InitializeHostName(
 #endif /* NO_UNAME */
 
     *encodingPtr = Tcl_GetEncoding(NULL, NULL);
-    *lengthPtr = strlen(native);
-    *valuePtr = ckalloc(*lengthPtr + 1);
-    memcpy(*valuePtr, native, *lengthPtr + 1);
+    if (native) {
+	*lengthPtr = strlen(native);
+	*valuePtr = ckalloc(*lengthPtr + 1);
+	memcpy(*valuePtr, native, *lengthPtr + 1);
+    } else {
+	*lengthPtr = 0;
+	*valuePtr = ckalloc(1);
+	*valuePtr[0] = '\0';
+    }
 }
 
 /*
diff --git a/win/buildall.vc.bat b/win/buildall.vc.bat
index cb136be..cb136be 100644..100755
--- a/win/buildall.vc.bat
+++ b/win/buildall.vc.bat
diff --git a/win/tclWinFile.c b/win/tclWinFile.c
index 6582ee1..6582ee1 100644..100755
--- a/win/tclWinFile.c
+++ b/win/tclWinFile.c