More efficient issuing of INST_START_CMD instructions. See ChangeLog for discussion

3 files changed, 42 insertions, 22 deletions

diff --git a/ChangeLog b/ChangeLog
index dd5e1a7..8dc700f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2007-01-19  Donal K. Fellows  <donal.k.fellows@man.ac.uk>
+
+	* generic/tclCompile.c (TclCompileScript): Reduce the frequency with
+	which we issue INST_START_CMD, making bytecode both more compact and
+	somewhat faster. The optimized case is where we would otherwise be
+	issuing a sequence of those instructions; in those cases, it is only
+	ever the first one encountered that could possibly trigger.
+
 2007-01-19  Joe Mistachkin  <joe@mistachkin.com>
 
 	* tools/man2tcl.c: Include stdlib.h for exit() and improve comment
@@ -13,22 +21,22 @@
 
 	* macosx/tclMacOSXNotify.c: accommodate changes to prototypes of
 	OSSpinLock(Un)Lock API.
-	
+
 	* macosx/Tcl.xcodeproj/project.pbxproj: ensure HOME and USER env vars
 	* macosx/Tcl.xcodeproj/default.pbxuser: are defined when running
 	                                        testsuite from Xcode.
-	
+
 	* tests/env.test: add extra system env vars that need to be preserved
 	on some Mac OS X versions for testsuite to work.
 
-	* unix/Makefile.in:  move libtommath defines into configure.in to avoid
-	* unix/configure.in: replicating them across multiple buildsystems.
-	* macosx/Tcl.xcodeproj/project.pbxproj:
+	* unix/Makefile.in:  Move libtommath defines into configure.in to
+	* unix/configure.in: avoid replicating them across multiple
+	* macosx/Tcl.xcodeproj/project.pbxproj: buildsystems.
 
 	* unix/tcl.m4: ensure CPPFLAGS env var is used when set. [Bug 1586861]
-	(Darwin): add -isysroot and -mmacosx-version-min flags to CPPFLAGS when
-	present in CFLAGS to avoid discrepancies between what headers configure
-	sees during preprocessing tests and compiling tests.
+	(Darwin): add -isysroot and -mmacosx-version-min flags to CPPFLAGS
+	when present in CFLAGS to avoid discrepancies between what headers
+	configure sees during preprocessing tests and compiling tests.
 
 	* unix/configure: autoconf-2.59
 	* unix/tclConfig.h.in: autoheader-2.59
@@ -48,15 +56,15 @@
 
 2007-01-11  Joe English  <jenglish@users.sourceforge.net>
 
-	* win/tcl.m4(CFLAGS_WARNING): Remove "-Wconversion".
-	This was removed from unix/tcl.m4 2004-07-16 but not from here.
+	* win/tcl.m4(CFLAGS_WARNING): Remove "-Wconversion". This was removed
+	from unix/tcl.m4 2004-07-16 but not from here.
 	* win/configure: Regenerated.
 
 2007-01-11  Pat Thoyts  <patthoyts@users.sourceforge.net>
 
-	* win/makefile.vc: Fixes to work better on Win98. Read version
-	* win/nmakehlp.c:  numbers from package index file to avoid
-	* win/rules.vc:    keeping numbers in the makefile.
+	* win/makefile.vc: Fixes to work better on Win98. Read version numbers
+	* win/nmakehlp.c:  from package index file to avoid keeping numbers in
+	* win/rules.vc:    the makefile where they may become de-synchronized.
 
 2007-01-10  Donal K. Fellows  <donal.k.fellows@manchester.ac.uk>
 
diff --git a/generic/tclCompile.c b/generic/tclCompile.c
index 0dcfb32..2964e46 100644
--- a/generic/tclCompile.c
+++ b/generic/tclCompile.c
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclCompile.c,v 1.105 2007/01/18 23:17:07 dkf Exp $
+ * RCS: @(#) $Id: tclCompile.c,v 1.106 2007/01/19 14:06:09 dkf Exp $
  */
 
 #include "tclInt.h"
@@ -854,6 +854,7 @@ TclInitCompileEnv(
     envPtr->cmdMapPtr = envPtr->staticCmdMapSpace;
     envPtr->cmdMapEnd = COMPILEENV_INIT_CMD_MAP_SIZE;
     envPtr->mallocedCmdMap = 0;
+    envPtr->atCmdStart = 0;
 
     /*
      * TIP #280: Set up the extended command location information, based on
@@ -1124,7 +1125,7 @@ TclCompileScript(
     Command *cmdPtr;
     Tcl_Token *tokenPtr;
     int bytesLeft, isFirstCmd, gotParse, wordIdx, currCmdIndex;
-    int commandLength, objIndex, code;
+    int commandLength, objIndex;
     Tcl_DString ds;
     /* TIP #280 */
     ExtCmdLoc *eclPtr = envPtr->extCmdMapPtr;
@@ -1468,6 +1469,7 @@ TclCompileScript(
 			int savedNumCmds = envPtr->numCommands;
 			unsigned int savedCodeNext =
 				envPtr->codeNext - envPtr->codeStart;
+			int update = 0, code;
 
 			/*
 			 * Mark the start of the command; the proper bytecode
@@ -1479,14 +1481,15 @@ TclCompileScript(
 			 * (savedCodeNext == 0)
 			 */
 
-			if (savedCodeNext != 0) {
+			if (savedCodeNext != 0 && !envPtr->atCmdStart) {
 			    TclEmitInstInt4(INST_START_CMD, 0, envPtr);
+			    update = 1;
 			}
 
 			code = (cmdPtr->compileProc)(interp, &parse, envPtr);
 
 			if (code == TCL_OK) {
-			    if (savedCodeNext != 0) {
+			    if (update) {
 				/*
 				 * Fix the bytecode length.
 				 */
diff --git a/generic/tclCompile.h b/generic/tclCompile.h
index a99f501..cba0888 100644
--- a/generic/tclCompile.h
+++ b/generic/tclCompile.h
@@ -8,7 +8,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclCompile.h,v 1.67 2006/12/13 16:28:06 dkf Exp $
+ * RCS: @(#) $Id: tclCompile.h,v 1.68 2007/01/19 14:06:10 dkf Exp $
  */
 
 #ifndef _TCLCOMPILATION
@@ -281,11 +281,15 @@ typedef struct CompileEnv {
     AuxData staticAuxDataArraySpace[COMPILEENV_INIT_AUX_DATA_SIZE];
 				/* Initial storage for aux data array. */
     /* TIP #280 */
-    ExtCmdLoc* extCmdMapPtr;    /* Extended command location information
+    ExtCmdLoc *extCmdMapPtr;	/* Extended command location information
 				 * for 'info frame'. */
-    int        line;            /* First line of the script, based on the
+    int line;			/* First line of the script, based on the
 				 * invoking context, then the line of the
 				 * command currently compiled. */
+    int atCmdStart;		/* Flag to say whether an INST_START_CMD
+				 * should be issued; they should never be
+				 * issued repeatedly, as that is significantly
+				 * inefficient. */
 } CompileEnv;
 
 /*
@@ -957,9 +961,11 @@ MODULE_SCOPE int	TclWordSimpleExpansion(Tcl_Token *tokenPtr);
  */
 
 #define TclEmitOpcode(op, envPtr) \
-    if ((envPtr)->codeNext == (envPtr)->codeEnd) \
+    if ((envPtr)->codeNext == (envPtr)->codeEnd) { \
 	TclExpandCodeArray(envPtr); \
+    } \
     *(envPtr)->codeNext++ = (unsigned char) (op);\
+    (envPtr)->atCmdStart = ((op) == INST_START_CMD); \
     TclUpdateStackReqs(op, 0, envPtr)
 
 /*
@@ -971,8 +977,9 @@ MODULE_SCOPE int	TclWordSimpleExpansion(Tcl_Token *tokenPtr);
  */
 
 #define TclEmitInt1(i, envPtr) \
-    if ((envPtr)->codeNext == (envPtr)->codeEnd) \
+    if ((envPtr)->codeNext == (envPtr)->codeEnd) { \
 	TclExpandCodeArray(envPtr); \
+    } \
     *(envPtr)->codeNext++ = (unsigned char) ((unsigned int) (i))
 
 #define TclEmitInt4(i, envPtr) \
@@ -1004,6 +1011,7 @@ MODULE_SCOPE int	TclWordSimpleExpansion(Tcl_Token *tokenPtr);
     } \
     *(envPtr)->codeNext++ = (unsigned char) (op); \
     *(envPtr)->codeNext++ = (unsigned char) ((unsigned int) (i));\
+    (envPtr)->atCmdStart = ((op) == INST_START_CMD); \
     TclUpdateStackReqs(op, i, envPtr)
 
 #define TclEmitInstInt4(op, i, envPtr) \
@@ -1019,6 +1027,7 @@ MODULE_SCOPE int	TclWordSimpleExpansion(Tcl_Token *tokenPtr);
 	(unsigned char) ((unsigned int) (i) >>  8); \
     *(envPtr)->codeNext++ = \
 	(unsigned char) ((unsigned int) (i)      );\
+    (envPtr)->atCmdStart = ((op) == INST_START_CMD); \
     TclUpdateStackReqs(op, i, envPtr)
 
 /*