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<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/196323">196323</a></dd>
<dt>Author</dt> <dd>fpizlo@apple.com</dd>
<dt>Date</dt> <dd>2016-02-09 12:18:31 -0800 (Tue, 09 Feb 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>Spread expressions are not fair game for direct binding
https://bugs.webkit.org/show_bug.cgi?id=154042
rdar://problem/24291413
Reviewed by Saam Barati.
Prior to this change we crashed on this:
var [x] = [...y];
Because NodesCodegen thinks that this is a direct binding. It's not, because we cannot
directly generate bytecode for "...y". This is a unique property of spread expressions, so
its sufficient to just bail out of direct binding if we see a spread expression. That's what
this patch does.
* bytecompiler/NodesCodegen.cpp:
(JSC::ArrayPatternNode::emitDirectBinding):
* tests/stress/spread-in-tail.js: Added.
(foo):
(catch):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCorebytecompilerNodesCodegencpp">trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoretestsstressspreadintailjs">trunk/Source/JavaScriptCore/tests/stress/spread-in-tail.js</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (196322 => 196323)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2016-02-09 19:50:05 UTC (rev 196322)
+++ trunk/Source/JavaScriptCore/ChangeLog 2016-02-09 20:18:31 UTC (rev 196323)
</span><span class="lines">@@ -1,3 +1,26 @@
</span><ins>+2016-02-09 Filip Pizlo <fpizlo@apple.com>
+
+ Spread expressions are not fair game for direct binding
+ https://bugs.webkit.org/show_bug.cgi?id=154042
+ rdar://problem/24291413
+
+ Reviewed by Saam Barati.
+
+ Prior to this change we crashed on this:
+
+ var [x] = [...y];
+
+ Because NodesCodegen thinks that this is a direct binding. It's not, because we cannot
+ directly generate bytecode for "...y". This is a unique property of spread expressions, so
+ its sufficient to just bail out of direct binding if we see a spread expression. That's what
+ this patch does.
+
+ * bytecompiler/NodesCodegen.cpp:
+ (JSC::ArrayPatternNode::emitDirectBinding):
+ * tests/stress/spread-in-tail.js: Added.
+ (foo):
+ (catch):
+
</ins><span class="cx"> 2016-02-09 Commit Queue <commit-queue@webkit.org>
</span><span class="cx">
</span><span class="cx"> Unreviewed, rolling out r196286.
</span><span class="lines">@@ -38,6 +61,7 @@
</span><span class="cx">
</span><span class="cx"> runtimeTypeForValue should protect against seeing TDZ value
</span><span class="cx"> https://bugs.webkit.org/show_bug.cgi?id=154023
</span><ins>+ rdar://problem/24291413
</ins><span class="cx">
</span><span class="cx"> Reviewed by Michael Saboff.
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorebytecompilerNodesCodegencpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp (196322 => 196323)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp 2016-02-09 19:50:05 UTC (rev 196322)
+++ trunk/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp 2016-02-09 20:18:31 UTC (rev 196323)
</span><span class="lines">@@ -3431,17 +3431,22 @@
</span><span class="cx"> RegisterID* ArrayPatternNode::emitDirectBinding(BytecodeGenerator& generator, RegisterID* dst, ExpressionNode* rhs)
</span><span class="cx"> {
</span><span class="cx"> if (!rhs->isSimpleArray())
</span><del>- return 0;
</del><ins>+ return nullptr;
</ins><span class="cx">
</span><ins>+ ElementNode* elementNodes = static_cast<ArrayNode*>(rhs)->elements();
+ Vector<ExpressionNode*> elements;
+ for (; elementNodes; elementNodes = elementNodes->next()) {
+ ExpressionNode* value = elementNodes->value();
+ if (value->isSpreadExpression())
+ return nullptr;
+ elements.append(value);
+ }
+
</ins><span class="cx"> RefPtr<RegisterID> resultRegister;
</span><span class="cx"> if (dst && dst != generator.ignoredResult())
</span><span class="cx"> resultRegister = generator.emitNewArray(generator.newTemporary(), 0, 0);
</span><del>- ElementNode* elementNodes = static_cast<ArrayNode*>(rhs)->elements();
- Vector<ExpressionNode*> elements;
- for (; elementNodes; elementNodes = elementNodes->next())
- elements.append(elementNodes->value());
</del><span class="cx"> if (m_targetPatterns.size() != elements.size())
</span><del>- return 0;
</del><ins>+ return nullptr;
</ins><span class="cx"> Vector<RefPtr<RegisterID>> registers;
</span><span class="cx"> registers.reserveCapacity(m_targetPatterns.size());
</span><span class="cx"> for (size_t i = 0; i < m_targetPatterns.size(); i++) {
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoretestsstressspreadintailjs"></a>
<div class="addfile"><h4>Added: trunk/Source/JavaScriptCore/tests/stress/spread-in-tail.js (0 => 196323)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/tests/stress/spread-in-tail.js (rev 0)
+++ trunk/Source/JavaScriptCore/tests/stress/spread-in-tail.js 2016-02-09 20:18:31 UTC (rev 196323)
</span><span class="lines">@@ -0,0 +1,18 @@
</span><ins>+function foo(b, y, d) {
+ // Note that when we fixed this, this simpler thing would also crash:
+ // var [x] = [...y];
+
+ var [a, x, c] = [b, ...y, d];
+ return [a, x, c];
+}
+
+function test(args, expected) {
+ var actual = foo.apply(this, args);
+ if ("" + actual != "" + expected)
+ throw "Error: bad result: " + actual;
+}
+
+test([1, [], 2], [1, 2, void 0]);
+test([1, [2], 3], [1, 2, 3]);
+test([1, [2, 3], 4], [1, 2, 3]);
+
</ins></span></pre>
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