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<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/170766">170766</a></dd>
<dt>Author</dt> <dd>fpizlo@apple.com</dd>
<dt>Date</dt> <dd>2014-07-03 13:22:23 -0700 (Thu, 03 Jul 2014)</dd>
</dl>
<h3>Log Message</h3>
<pre>JSActivation::symbolTablePut() should invalidate variable watchpoints
https://bugs.webkit.org/show_bug.cgi?id=134602
Reviewed by Oliver Hunt.
Usually stores to captured variables cause us to invalidate the variable watchpoint because CodeBlock does so
during linking - we essentially assume that if it's at all possible for an inner function to store to a
variable we declare then this variable cannot be a constant. But this misses the dynamic store case, i.e.
JSActivation::symbolTablePut(). Part of the problem here is that JSActivation duplicates
JSSymbolTableObject's symbolTablePut() logic, which did have the invalidation. This patch keeps that code
duplicated, but fixes JSActivation::symbolTablePut() to do the right thing.
* runtime/JSActivation.cpp:
(JSC::JSActivation::symbolTablePut):
* runtime/JSSymbolTableObject.h:
(JSC::symbolTablePut):
* tests/stress/constant-closure-var-with-dynamic-invalidation.js: Added.
(.):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreruntimeJSActivationcpp">trunk/Source/JavaScriptCore/runtime/JSActivation.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoreruntimeJSSymbolTableObjecth">trunk/Source/JavaScriptCore/runtime/JSSymbolTableObject.h</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoretestsstressconstantclosurevarwithdynamicinvalidationjs">trunk/Source/JavaScriptCore/tests/stress/constant-closure-var-with-dynamic-invalidation.js</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (170765 => 170766)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2014-07-03 20:10:33 UTC (rev 170765)
+++ trunk/Source/JavaScriptCore/ChangeLog 2014-07-03 20:22:23 UTC (rev 170766)
</span><span class="lines">@@ -1,3 +1,24 @@
</span><ins>+2014-07-03 Filip Pizlo <fpizlo@apple.com>
+
+ JSActivation::symbolTablePut() should invalidate variable watchpoints
+ https://bugs.webkit.org/show_bug.cgi?id=134602
+
+ Reviewed by Oliver Hunt.
+
+ Usually stores to captured variables cause us to invalidate the variable watchpoint because CodeBlock does so
+ during linking - we essentially assume that if it's at all possible for an inner function to store to a
+ variable we declare then this variable cannot be a constant. But this misses the dynamic store case, i.e.
+ JSActivation::symbolTablePut(). Part of the problem here is that JSActivation duplicates
+ JSSymbolTableObject's symbolTablePut() logic, which did have the invalidation. This patch keeps that code
+ duplicated, but fixes JSActivation::symbolTablePut() to do the right thing.
+
+ * runtime/JSActivation.cpp:
+ (JSC::JSActivation::symbolTablePut):
+ * runtime/JSSymbolTableObject.h:
+ (JSC::symbolTablePut):
+ * tests/stress/constant-closure-var-with-dynamic-invalidation.js: Added.
+ (.):
+
</ins><span class="cx"> 2014-07-01 Mark Lam <mark.lam@apple.com>
</span><span class="cx">
</span><span class="cx"> Debugger's breakpoint list should not be a Vector.
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreruntimeJSActivationcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/runtime/JSActivation.cpp (170765 => 170766)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/runtime/JSActivation.cpp 2014-07-03 20:10:33 UTC (rev 170765)
+++ trunk/Source/JavaScriptCore/runtime/JSActivation.cpp 2014-07-03 20:22:23 UTC (rev 170766)
</span><span class="lines">@@ -89,20 +89,26 @@
</span><span class="cx"> VM& vm = exec->vm();
</span><span class="cx"> ASSERT(!Heap::heap(value) || Heap::heap(value) == Heap::heap(this));
</span><span class="cx">
</span><del>- SymbolTableEntry entry = symbolTable()->inlineGet(propertyName.uid());
- if (entry.isNull())
- return false;
- if (entry.isReadOnly()) {
- if (shouldThrow)
- throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
- return true;
</del><ins>+ WriteBarrierBase<Unknown>* reg;
+ {
+ GCSafeConcurrentJITLocker locker(symbolTable()->m_lock, exec->vm().heap);
+ SymbolTable::Map::iterator iter = symbolTable()->find(locker, propertyName.uid());
+ if (iter == symbolTable()->end(locker))
+ return false;
+ ASSERT(!iter->value.isNull());
+ if (iter->value.isReadOnly()) {
+ if (shouldThrow)
+ throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
+ return true;
+ }
+ // Defend against the inspector asking for a var after it has been optimized out.
+ if (isTornOff() && !isValid(iter->value))
+ return false;
+ if (VariableWatchpointSet* set = iter->value.watchpointSet())
+ set->invalidate(); // Don't mess around - if we had found this statically, we would have invcalidated it.
+ reg = &registerAt(iter->value.getIndex());
</ins><span class="cx"> }
</span><del>-
- // Defend against the inspector asking for a var after it has been optimized out.
- if (isTornOff() && !isValid(entry))
- return false;
-
- registerAt(entry.getIndex()).set(vm, this, value);
</del><ins>+ reg->set(vm, this, value);
</ins><span class="cx"> return true;
</span><span class="cx"> }
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreruntimeJSSymbolTableObjecth"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/runtime/JSSymbolTableObject.h (170765 => 170766)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/runtime/JSSymbolTableObject.h 2014-07-03 20:10:33 UTC (rev 170765)
+++ trunk/Source/JavaScriptCore/runtime/JSSymbolTableObject.h 2014-07-03 20:22:23 UTC (rev 170766)
</span><span class="lines">@@ -126,6 +126,8 @@
</span><span class="cx"> WriteBarrierBase<Unknown>* reg;
</span><span class="cx"> {
</span><span class="cx"> SymbolTable& symbolTable = *object->symbolTable();
</span><ins>+ // FIXME: This is very suspicious. We shouldn't need a GC-safe lock here.
+ // https://bugs.webkit.org/show_bug.cgi?id=134601
</ins><span class="cx"> GCSafeConcurrentJITLocker locker(symbolTable.m_lock, exec->vm().heap);
</span><span class="cx"> SymbolTable::Map::iterator iter = symbolTable.find(locker, propertyName.uid());
</span><span class="cx"> if (iter == symbolTable.end(locker))
</span><span class="lines">@@ -138,8 +140,11 @@
</span><span class="cx"> throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
</span><span class="cx"> return true;
</span><span class="cx"> }
</span><del>- if (VariableWatchpointSet* set = iter->value.watchpointSet())
</del><ins>+ if (VariableWatchpointSet* set = iter->value.watchpointSet()) {
+ // FIXME: It's strange that we're doing this while holding the symbol table's lock.
+ // https://bugs.webkit.org/show_bug.cgi?id=134601
</ins><span class="cx"> set->notifyWrite(vm, value);
</span><ins>+ }
</ins><span class="cx"> reg = &object->registerAt(fastEntry.getIndex());
</span><span class="cx"> }
</span><span class="cx"> // I'd prefer we not hold lock while executing barriers, since I prefer to reserve
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoretestsstressconstantclosurevarwithdynamicinvalidationjs"></a>
<div class="addfile"><h4>Added: trunk/Source/JavaScriptCore/tests/stress/constant-closure-var-with-dynamic-invalidation.js (0 => 170766)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/tests/stress/constant-closure-var-with-dynamic-invalidation.js (rev 0)
+++ trunk/Source/JavaScriptCore/tests/stress/constant-closure-var-with-dynamic-invalidation.js 2014-07-03 20:22:23 UTC (rev 170766)
</span><span class="lines">@@ -0,0 +1,17 @@
</span><ins>+(function() {
+ var x = 42;
+ var result = 0;
+ var n = 100000;
+ var m = 100;
+ for (var i = 0; i < n; ++i) {
+ result += x;
+ (function() {
+ with ({}) {
+ if (i == n - m - 1)
+ x = 53;
+ }
+ })();
+ }
+ if (result != 42 * (n - m) + 53 * m)
+ throw "Error: bad result: " + result;
+})();
</ins></span></pre>
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