From efe36a3e290e2f47f8bed9ca19569cf46d0079ce Mon Sep 17 00:00:00 2001
From: dgp <dgp@users.sourceforge.net>
Date: Mon, 30 Nov 2015 18:24:03 +0000
Subject: [32c5740a4d] Have Tcl_ListObjReplace() try to use realloc() for
 growing when it can do so.

---
 generic/tclListObj.c | 33 ++++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/generic/tclListObj.c b/generic/tclListObj.c
index 0dfa845..14b8a14 100644
--- a/generic/tclListObj.c
+++ b/generic/tclListObj.c
@@ -857,7 +857,7 @@ Tcl_ListObjReplace(
 {
     List *listRepPtr;
     register Tcl_Obj **elemPtrs;
-    int numElems, numRequired, numAfterLast, start, i, j, isShared;
+    int needGrow, numElems, numRequired, numAfterLast, start, i, j, isShared;
 
     if (Tcl_IsShared(listPtr)) {
 	Tcl_Panic("%s called with shared object", "Tcl_ListObjReplace");
@@ -913,12 +913,39 @@ Tcl_ListObjReplace(
     }
     isShared = (listRepPtr->refCount > 1);
     numRequired = numElems - count + objc; /* Known <= LIST_MAX */
+    needGrow = numRequired > listRepPtr->maxElemCount;
 
     for (i = 0;  i < objc;  i++) {
 	Tcl_IncrRefCount(objv[i]);
     }
 
-    if ((numRequired <= listRepPtr->maxElemCount) && !isShared) {
+    if (needGrow && !isShared) {
+	/* Try to use realloc */
+	List *newPtr = NULL;
+	int attempt = 2 * numRequired;
+	if (attempt <= LIST_MAX) {
+	    newPtr = attemptckrealloc(listRepPtr, LIST_SIZE(attempt));
+	}
+	if (newPtr == NULL) {
+	    attempt = numRequired + 1 + TCL_MIN_ELEMENT_GROWTH;
+	    if (attempt > LIST_MAX) {
+		attempt = LIST_MAX;
+	    }
+	    newPtr = attemptckrealloc(listRepPtr, LIST_SIZE(attempt));
+	}
+	if (newPtr == NULL) {
+	    attempt = numRequired;
+	    newPtr = attemptckrealloc(listRepPtr, LIST_SIZE(attempt));
+	}
+	if (newPtr) {
+	    listRepPtr = newPtr;
+	    listPtr->internalRep.twoPtrValue.ptr1 = listRepPtr;
+	    elemPtrs = &listRepPtr->elements;
+	    listRepPtr->maxElemCount = attempt;
+	    needGrow = numRequired > listRepPtr->maxElemCount;
+	}
+    }
+    if (!needGrow && !isShared) {
 	int shift;
 
 	/*
@@ -955,7 +982,7 @@ Tcl_ListObjReplace(
 	Tcl_Obj **oldPtrs = elemPtrs;
 	int newMax;
 
-	if (numRequired > listRepPtr->maxElemCount){
+	if (needGrow){
 	    newMax = 2 * numRequired;
 	} else {
 	    newMax = listRepPtr->maxElemCount;
-- 
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