Bug 1317397: Only set lastIndex for global or sticky RegExps in RegExpBuiltinExec per ES2017

3 files changed, 75 insertions, 29 deletions

diff --git a/js/src/builtin/RegExp.js b/js/src/builtin/RegExp.js
index f71ce4f75..0b849292c 100644
--- a/js/src/builtin/RegExp.js
+++ b/js/src/builtin/RegExp.js
@@ -609,7 +609,8 @@ function RegExpGlobalReplaceShortOpt(rx, S, lengthS, replaceValue, fullUnicode)
 #undef SUBSTITUTION
 #undef FUNC_NAME
 
-// ES 2017 draft 6859bb9ccaea9c6ede81d71e5320e3833b92cb3e 21.2.5.9.
+// ES2017 draft rev 6390c2f1b34b309895d31d8c0512eac8660a0210
+// 21.2.5.9 RegExp.prototype [ @@search ] ( string )
 function RegExpSearch(string) {
     // Step 1.
     var rx = this;
@@ -621,41 +622,69 @@ function RegExpSearch(string) {
     // Step 3.
     var S = ToString(string);
 
+    // Step 4.
+    var previousLastIndex = rx.lastIndex;
+
+    // Step 5.
+    var lastIndexIsZero = SameValue(previousLastIndex, 0);
+    if (!lastIndexIsZero)
+        rx.lastIndex = 0;
+
     if (IsRegExpMethodOptimizable(rx) && S.length < 0x7fff) {
         // Step 6.
         var result = RegExpSearcher(rx, S, 0);
 
-        // Step 8.
+        // We need to consider two cases:
+        //
+        // 1. Neither global nor sticky is set:
+        // RegExpBuiltinExec doesn't modify lastIndex for local RegExps, that
+        // means |SameValue(rx.lastIndex, 0)| is true after calling exec. The
+        // comparison in steps 7-8 |SameValue(rx.lastIndex, previousLastIndex)|
+        // is therefore equal to the already computed |lastIndexIsZero| value.
+        //
+        // 2. Global or sticky flag is set.
+        // RegExpBuiltinExec will always update lastIndex and we need to
+        // restore the property to its original value.
+
+        // Steps 7-8.
+        if (!lastIndexIsZero) {
+            rx.lastIndex = previousLastIndex;
+        } else {
+            var flags = UnsafeGetInt32FromReservedSlot(rx, REGEXP_FLAGS_SLOT);
+            if (flags & (REGEXP_GLOBAL_FLAG | REGEXP_STICKY_FLAG))
+                rx.lastIndex = previousLastIndex;
+        }
+
+        // Step 9.
         if (result === -1)
             return -1;
 
-        // Step 9.
+        // Step 10.
         return result & 0x7fff;
     }
 
-    return RegExpSearchSlowPath(rx, S);
+    return RegExpSearchSlowPath(rx, S, previousLastIndex);
 }
 
-// ES 2017 draft 6859bb9ccaea9c6ede81d71e5320e3833b92cb3e 21.2.5.9
-// steps 4-9.
-function RegExpSearchSlowPath(rx, S) {
-    // Step 4.
-    var previousLastIndex = rx.lastIndex;
-
-    // Step 5.
-    rx.lastIndex = 0;
-
+// ES2017 draft rev 6390c2f1b34b309895d31d8c0512eac8660a0210
+// 21.2.5.9 RegExp.prototype [ @@search ] ( string )
+// Steps 6-10.
+function RegExpSearchSlowPath(rx, S, previousLastIndex) {
     // Step 6.
     var result = RegExpExec(rx, S, false);
 
     // Step 7.
-    rx.lastIndex = previousLastIndex;
+    var currentLastIndex = rx.lastIndex;
 
     // Step 8.
+    if (!SameValue(currentLastIndex, previousLastIndex))
+        rx.lastIndex = previousLastIndex;
+
+    // Step 9.
     if (result === null)
         return -1;
 
-    // Step 9.
+    // Step 10.
     return result.index;
 }
 
@@ -904,15 +933,16 @@ function RegExpExec(R, S, forTest) {
     return forTest ? result !== null : result;
 }
 
-// ES 2017 draft rev 6a13789aa9e7c6de4e96b7d3e24d9e6eba6584ad 21.2.5.2.2.
+// ES2017 draft rev 6390c2f1b34b309895d31d8c0512eac8660a0210
+// 21.2.5.2.2 Runtime Semantics: RegExpBuiltinExec ( R, S )
 function RegExpBuiltinExec(R, S, forTest) {
-    // ES6 21.2.5.2.1 step 6.
+    // 21.2.5.2.1 Runtime Semantics: RegExpExec, step 5.
     // This check is here for RegExpTest.  RegExp_prototype_Exec does same
     // thing already.
     if (!IsRegExpObject(R))
         return UnwrapAndCallRegExpBuiltinExec(R, S, forTest);
 
-    // Steps 1-2 (skipped).
+    // Steps 1-3 (skipped).
 
     // Step 4.
     var lastIndex = ToLength(R.lastIndex);
@@ -927,9 +957,11 @@ function RegExpBuiltinExec(R, S, forTest) {
     if (!globalOrSticky) {
         lastIndex = 0;
     } else {
+        // Step 12.a.
         if (lastIndex > S.length) {
-            // Steps 12.a.i-ii, 12.c.i.1-2.
-            R.lastIndex = 0;
+            // Steps 12.a.i-ii.
+            if (globalOrSticky)
+                R.lastIndex = 0;
             return forTest ? false : null;
         }
     }
@@ -939,7 +971,8 @@ function RegExpBuiltinExec(R, S, forTest) {
         var endIndex = RegExpTester(R, S, lastIndex);
         if (endIndex == -1) {
             // Steps 12.a.i-ii, 12.c.i.1-2.
-            R.lastIndex = 0;
+            if (globalOrSticky)
+                R.lastIndex = 0;
             return false;
         }
 
@@ -953,8 +986,9 @@ function RegExpBuiltinExec(R, S, forTest) {
     // Steps 3, 9-25, except 12.a.i-ii, 12.c.i.1-2, 15.
     var result = RegExpMatcher(R, S, lastIndex);
     if (result === null) {
-        // Steps 12.a.i-ii, 12.c.i.1-2.
-        R.lastIndex = 0;
+        // Steps 12.a.i, 12.c.i.
+        if (globalOrSticky)
+            R.lastIndex = 0;
     } else {
         // Step 15.
         if (globalOrSticky)
diff --git a/js/src/builtin/RegExpLocalReplaceOpt.h.js b/js/src/builtin/RegExpLocalReplaceOpt.h.js
index 96451d8a0..1acd6a73a 100644
--- a/js/src/builtin/RegExpLocalReplaceOpt.h.js
+++ b/js/src/builtin/RegExpLocalReplaceOpt.h.js
@@ -11,7 +11,7 @@
 //   * FUNCTIONAL       -- replaceValue is a function
 //   * neither of above -- replaceValue is a string without "$"
 
-// ES 2017 draft 03bfda119d060aca4099d2b77cf43f6d4f11cfa2 21.2.5.8
+// ES 2017 draft 6390c2f1b34b309895d31d8c0512eac8660a0210 21.2.5.8
 // steps 11.a-16.
 // Optimized path for @@replace with the following conditions:
 //   * global flag is false
@@ -36,8 +36,10 @@ function FUNC_NAME(rx, S, lengthS, replaceValue
     if (globalOrSticky) {
         // 21.2.5.2.2 RegExpBuiltinExec, step 12.a.
         if (lastIndex > lengthS) {
-            // FIXME: Implement changes for bug 1317397.
-            rx.lastIndex = 0;
+            if (globalOrSticky)
+                rx.lastIndex = 0;
+
+            // Steps 12-16.
             return S;
         }
     } else {
@@ -51,8 +53,8 @@ function FUNC_NAME(rx, S, lengthS, replaceValue
     // 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;
+        if (globalOrSticky)
+            rx.lastIndex = 0;
 
         // Steps 12-16.
         return S;
diff --git a/js/src/builtin/Utilities.js b/js/src/builtin/Utilities.js
index 2dece3801..3145b4d51 100644
--- a/js/src/builtin/Utilities.js
+++ b/js/src/builtin/Utilities.js
@@ -106,7 +106,17 @@ function ToLength(v) {
     return std_Math_min(v, 0x1fffffffffffff);
 }
 
-/* Spec: ECMAScript Draft, 6th edition Oct 14, 2014, 7.2.4 */
+// ES2017 draft rev aebf014403a3e641fb1622aec47c40f051943527
+// 7.2.9 SameValue ( x, y )
+function SameValue(x, y) {
+    if (x === y) {
+        return (x !== 0) || (1 / x === 1 / y);
+    }
+    return (x !== x && y !== y);
+}
+
+// ES2017 draft rev aebf014403a3e641fb1622aec47c40f051943527
+// 7.2.10 SameValueZero ( x, y )
 function SameValueZero(x, y) {
     return x === y || (x !== x && y !== y);
 }