1 files changed, 23 insertions, 5 deletions
diff --git a/js/src/builtin/RegExpLocalReplaceOpt.h.js b/js/src/builtin/RegExpLocalReplaceOpt.h.js
index edc2e2056..96451d8a0 100644
--- a/js/src/builtin/RegExpLocalReplaceOpt.h.js
+++ b/js/src/builtin/RegExpLocalReplaceOpt.h.js
@@ -15,20 +15,33 @@
 // steps 11.a-16.
 // Optimized path for @@replace with the following conditions:
 //   * global flag is false
-function FUNC_NAME(rx, S, lengthS, replaceValue, sticky
+function FUNC_NAME(rx, S, lengthS, replaceValue
 #ifdef SUBSTITUTION
                    , firstDollarIndex
 #endif
                   )
 {
-    var lastIndex;
-    if (sticky) {
-        lastIndex = ToLength(rx.lastIndex);
+    // 21.2.5.2.2 RegExpBuiltinExec, step 4.
+    var lastIndex = ToLength(rx.lastIndex);
+
+    // 21.2.5.2.2 RegExpBuiltinExec, step 5.
+    // Side-effects in step 4 can recompile the RegExp, so we need to read the
+    // flags again and handle the case when global was enabled even though this
+    // function is optimized for non-global RegExps.
+    var flags = UnsafeGetInt32FromReservedSlot(rx, REGEXP_FLAGS_SLOT);
+
+    // 21.2.5.2.2 RegExpBuiltinExec, steps 6-7.
+    var globalOrSticky = !!(flags & (REGEXP_GLOBAL_FLAG | REGEXP_STICKY_FLAG));
+
+    if (globalOrSticky) {
+        // 21.2.5.2.2 RegExpBuiltinExec, step 12.a.
         if (lastIndex > lengthS) {
+            // FIXME: Implement changes for bug 1317397.
             rx.lastIndex = 0;
             return S;
         }
     } else {
+        // 21.2.5.2.2 RegExpBuiltinExec, step 8.
         lastIndex = 0;
     }
 
@@ -37,7 +50,11 @@ function FUNC_NAME(rx, S, lengthS, replaceValue, sticky
 
     // Step 11.b.
     if (result === null) {
+        // 21.2.5.2.2 RegExpBuiltinExec, steps 12.a.i, 12.c.i.
+        // FIXME: Implement changes for bug 1317397.
         rx.lastIndex = 0;
+
+        // Steps 12-16.
         return S;
     }
 
@@ -61,7 +78,8 @@ function FUNC_NAME(rx, S, lengthS, replaceValue, sticky
     // To set rx.lastIndex before RegExpGetComplexReplacement.
     var nextSourcePosition = position + matchLength;
 
-    if (sticky)
+    // 21.2.5.2.2 RegExpBuiltinExec, step 15.
+    if (globalOrSticky)
        rx.lastIndex = nextSourcePosition;
 
     var replacement;