From 4cc4d69fe462a3661da5df84b1897b9959f6d5fd Mon Sep 17 00:00:00 2001
From: mig <mig>
Date: Wed, 18 Dec 2013 15:34:39 +0000
Subject: Making the optimizer pluggable by extensions; please review for
 committing to trunk

---
 generic/tclBasic.c    | 3 +++
 generic/tclCompile.c  | 4 +++-
 generic/tclCompile.h  | 2 +-
 generic/tclInt.h      | 9 ++++++++-
 generic/tclOptimize.c | 2 +-
 5 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index a41351e..8ec94ca 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -526,6 +526,9 @@ Tcl_CreateInterp(void)
     iPtr->hiddenCmdTablePtr = NULL;
     iPtr->interpInfo = NULL;
 
+    TCL_CT_ASSERT(sizeof(iPtr->extra) <= sizeof(Tcl_HashTable));
+    iPtr->extra.optimizer = TclOptimizeBytecode;
+
     iPtr->numLevels = 0;
     iPtr->maxNestingDepth = MAX_NESTING_DEPTH;
     iPtr->framePtr = NULL;	/* Initialise as soon as :: is available */
diff --git a/generic/tclCompile.c b/generic/tclCompile.c
index 6c2e2b6..525571d 100644
--- a/generic/tclCompile.c
+++ b/generic/tclCompile.c
@@ -765,7 +765,9 @@ TclSetByteCodeFromAny(
      * instruction generator boundaries.
      */
 
-    TclOptimizeBytecode(&compEnv);
+    if (iPtr->extra.optimizer) {
+	(iPtr->extra.optimizer)(&compEnv);
+    }
 
     /*
      * Invoke the compilation hook procedure if one exists.
diff --git a/generic/tclCompile.h b/generic/tclCompile.h
index 7f62849..55dd37a 100644
--- a/generic/tclCompile.h
+++ b/generic/tclCompile.h
@@ -1064,7 +1064,7 @@ MODULE_SCOPE void	TclFinalizeLoopExceptionRange(CompileEnv *envPtr,
 MODULE_SCOPE char *	TclLiteralStats(LiteralTable *tablePtr);
 MODULE_SCOPE int	TclLog2(int value);
 #endif
-MODULE_SCOPE void	TclOptimizeBytecode(CompileEnv *envPtr);
+MODULE_SCOPE void	TclOptimizeBytecode(void *envPtr);
 #ifdef TCL_COMPILE_DEBUG
 MODULE_SCOPE void	TclPrintByteCodeObj(Tcl_Interp *interp,
 			    Tcl_Obj *objPtr);
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 5c8dbfd..8ccfadb 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -1809,7 +1809,14 @@ typedef struct Interp {
     ClientData interpInfo;	/* Information used by tclInterp.c to keep
 				 * track of master/slave interps on a
 				 * per-interp basis. */
-    Tcl_HashTable unused2;	/* No longer used (was mathFuncTable) */
+    union {
+	void (*optimizer)(void *envPtr);
+	Tcl_HashTable unused2;	/* No longer used (was mathFuncTable). The
+				 * unused space in interp was repurposed for
+				 * pluggable bytecode optimizers. The core
+				 * contains one optimizer, which can be
+				 * selectively overriden by extensions. */
+    } extra;
 
     /*
      * Information related to procedures and variables. See tclProc.c and
diff --git a/generic/tclOptimize.c b/generic/tclOptimize.c
index 3b16e6e..74de7a3 100644
--- a/generic/tclOptimize.c
+++ b/generic/tclOptimize.c
@@ -427,7 +427,7 @@ AdvanceJumps(
 
 void
 TclOptimizeBytecode(
-    CompileEnv *envPtr)
+    void *envPtr)
 {
     ConvertZeroEffectToNOP(envPtr);
     AdvanceJumps(envPtr);
-- 
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