New TEBC opcode, INST_JUMP_TABLE, for compiling the simple (and common) case of

[switch] into a jump-table. Much faster for long switches.
Also compiler support for generating the new instruction where appropriate.

1 files changed, 41 insertions, 17 deletions

diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index 38a7a6e..31870b5 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -12,7 +12,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclExecute.c,v 1.221 2005/11/27 02:33:49 das Exp $
+ * RCS: @(#) $Id: tclExecute.c,v 1.222 2005/11/30 14:59:40 dkf Exp $
  */
 
 #include "tclInt.h"
@@ -2601,25 +2601,23 @@ TclExecuteByteCode(
      * ---------------------------------------------------------
      */
 
-    case INST_JUMP1:
-	{
-	    int opnd;
+    case INST_JUMP1: {
+	int opnd;
 
-	    opnd = TclGetInt1AtPtr(pc+1);
-	    TRACE(("%d => new pc %u\n", opnd,
-			  (unsigned int)(pc + opnd - codePtr->codeStart)));
-	    NEXT_INST_F(opnd, 0, 0);
-	}
+	opnd = TclGetInt1AtPtr(pc+1);
+	TRACE(("%d => new pc %u\n", opnd,
+		(unsigned int)(pc + opnd - codePtr->codeStart)));
+	NEXT_INST_F(opnd, 0, 0);
+    }
 
-    case INST_JUMP4:
-	{
-	   int opnd;
+    case INST_JUMP4: {
+	int opnd;
 
-	   opnd = TclGetInt4AtPtr(pc+1);
-	   TRACE(("%d => new pc %u\n", opnd,
-			 (unsigned int)(pc + opnd - codePtr->codeStart)));
-	   NEXT_INST_F(opnd, 0, 0);
-	}
+	opnd = TclGetInt4AtPtr(pc+1);
+	TRACE(("%d => new pc %u\n", opnd,
+		(unsigned int)(pc + opnd - codePtr->codeStart)));
+	NEXT_INST_F(opnd, 0, 0);
+    }
 
     {
 	int jmpOffset[2];
@@ -2680,6 +2678,32 @@ TclExecuteByteCode(
 	NEXT_INST_F(jmpOffset[b], 1, 0);
     }
 
+    case INST_JUMP_TABLE: {
+	Tcl_HashEntry *hPtr;
+	JumptableInfo *jtPtr;
+	int opnd;
+
+	/*
+	 * Jump to location looked up in a hashtable; fall through to next
+	 * instr if lookup fails.
+	 */
+
+	opnd = TclGetInt4AtPtr(pc+1);
+	jtPtr = (JumptableInfo *) codePtr->auxDataArrayPtr[opnd].clientData;
+	TRACE(("%d => %.20s ", opnd, O2S(*tosPtr)));
+	hPtr = Tcl_FindHashEntry(&jtPtr->hashTable, Tcl_GetString(*tosPtr));
+	if (hPtr != NULL) {
+	    int jumpOffset = (int) Tcl_GetHashValue(hPtr);
+
+	    TRACE_APPEND(("found in table, new pc %u\n",
+		    (unsigned int)(pc - codePtr->codeStart + jumpOffset)));
+	    NEXT_INST_F(jumpOffset, 1, 0);
+	} else {
+	    TRACE_APPEND(("not found in table\n"));
+	    NEXT_INST_F(5, 1, 0);
+	}
+    }
+
     /*
      * These two instructions are now redundant: the complete logic of the LOR
      * and LAND is now handled by the expression compiler.