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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/189492">189492</a></dd>
<dt>Author</dt> <dd>fpizlo@apple.com</dd>
<dt>Date</dt> <dd>2015-09-08 10:00:05 -0700 (Tue, 08 Sep 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>The put_by_id IC store barrier contract should benefit transition over replace
https://bugs.webkit.org/show_bug.cgi?id=148943
Reviewed by Mark Lam.
Previously, we would only emit a barrier if the value being stored was possibly a cell, so
the transition stub code generator would have to emit a barrier for the store of the
structure, just in case the structure was newer than the base object.
This changes the contract so that the put_by_id callsite would always have a barrier on the
base (except if it proved that the base was brand new). That way, the transition doesn't have
to have a barrier unless it allocates.
This is meant to be a perf-neutral change that I need for the IC refactoring in
https://bugs.webkit.org/show_bug.cgi?id=148717.
* dfg/DFGFixupPhase.cpp:
(JSC::DFG::FixupPhase::fixupNode):
* dfg/DFGStoreBarrierInsertionPhase.cpp:
* jit/Repatch.cpp:
(JSC::emitPutTransitionStub):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGFixupPhasecpp">trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGStoreBarrierInsertionPhasecpp">trunk/Source/JavaScriptCore/dfg/DFGStoreBarrierInsertionPhase.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCorejitRepatchcpp">trunk/Source/JavaScriptCore/jit/Repatch.cpp</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (189491 => 189492)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-09-08 16:54:58 UTC (rev 189491)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-09-08 17:00:05 UTC (rev 189492)
</span><span class="lines">@@ -1,3 +1,27 @@
</span><ins>+2015-09-07 Filip Pizlo <fpizlo@apple.com>
+
+ The put_by_id IC store barrier contract should benefit transition over replace
+ https://bugs.webkit.org/show_bug.cgi?id=148943
+
+ Reviewed by Mark Lam.
+
+ Previously, we would only emit a barrier if the value being stored was possibly a cell, so
+ the transition stub code generator would have to emit a barrier for the store of the
+ structure, just in case the structure was newer than the base object.
+
+ This changes the contract so that the put_by_id callsite would always have a barrier on the
+ base (except if it proved that the base was brand new). That way, the transition doesn't have
+ to have a barrier unless it allocates.
+
+ This is meant to be a perf-neutral change that I need for the IC refactoring in
+ https://bugs.webkit.org/show_bug.cgi?id=148717.
+
+ * dfg/DFGFixupPhase.cpp:
+ (JSC::DFG::FixupPhase::fixupNode):
+ * dfg/DFGStoreBarrierInsertionPhase.cpp:
+ * jit/Repatch.cpp:
+ (JSC::emitPutTransitionStub):
+
</ins><span class="cx"> 2015-09-07 Alex Christensen <achristensen@webkit.org>
</span><span class="cx">
</span><span class="cx"> Windows non-cygwin build fix after r189333.
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGFixupPhasecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp (189491 => 189492)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp 2015-09-08 16:54:58 UTC (rev 189491)
+++ trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp 2015-09-08 17:00:05 UTC (rev 189492)
</span><span class="lines">@@ -1041,7 +1041,6 @@
</span><span class="cx"> case PutByIdFlush:
</span><span class="cx"> case PutByIdDirect: {
</span><span class="cx"> fixEdge<CellUse>(node->child1());
</span><del>- speculateForBarrier(node->child2());
</del><span class="cx"> break;
</span><span class="cx"> }
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGStoreBarrierInsertionPhasecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGStoreBarrierInsertionPhase.cpp (189491 => 189492)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGStoreBarrierInsertionPhase.cpp 2015-09-08 16:54:58 UTC (rev 189491)
+++ trunk/Source/JavaScriptCore/dfg/DFGStoreBarrierInsertionPhase.cpp 2015-09-08 17:00:05 UTC (rev 189492)
</span><span class="lines">@@ -260,14 +260,18 @@
</span><span class="cx">
</span><span class="cx"> case PutClosureVar:
</span><span class="cx"> case PutToArguments:
</span><del>- case PutById:
- case PutByIdFlush:
- case PutByIdDirect:
</del><span class="cx"> case MultiPutByOffset: {
</span><span class="cx"> considerBarrier(m_node->child1(), m_node->child2());
</span><span class="cx"> break;
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ case PutById:
+ case PutByIdFlush:
+ case PutByIdDirect: {
+ considerBarrier(m_node->child1());
+ break;
+ }
+
</ins><span class="cx"> case PutByOffset: {
</span><span class="cx"> considerBarrier(m_node->child2(), m_node->child3());
</span><span class="cx"> break;
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorejitRepatchcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/jit/Repatch.cpp (189491 => 189492)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/jit/Repatch.cpp 2015-09-08 16:54:58 UTC (rev 189491)
+++ trunk/Source/JavaScriptCore/jit/Repatch.cpp 2015-09-08 17:00:05 UTC (rev 189492)
</span><span class="lines">@@ -1133,8 +1133,8 @@
</span><span class="cx">
</span><span class="cx"> #if ENABLE(GGC)
</span><span class="cx"> MacroAssembler::Call callFlushWriteBarrierBuffer;
</span><del>- MacroAssembler::Jump ownerIsRememberedOrInEden = stubJit.jumpIfIsRememberedOrInEden(baseGPR);
- {
</del><ins>+ if (structure->outOfLineCapacity() != oldStructure->outOfLineCapacity()) {
+ MacroAssembler::Jump ownerIsRememberedOrInEden = stubJit.jumpIfIsRememberedOrInEden(baseGPR);
</ins><span class="cx"> WriteBarrierBuffer& writeBarrierBuffer = stubJit.vm()->heap.writeBarrierBuffer();
</span><span class="cx"> stubJit.load32(writeBarrierBuffer.currentIndexAddress(), scratchGPR2);
</span><span class="cx"> MacroAssembler::Jump needToFlush =
</span><span class="lines">@@ -1157,8 +1157,8 @@
</span><span class="cx"> allocator.restoreUsedRegistersFromScratchBufferForCall(stubJit, scratchBuffer, scratchGPR2);
</span><span class="cx">
</span><span class="cx"> doneWithBarrier.link(&stubJit);
</span><ins>+ ownerIsRememberedOrInEden.link(&stubJit);
</ins><span class="cx"> }
</span><del>- ownerIsRememberedOrInEden.link(&stubJit);
</del><span class="cx"> #endif
</span><span class="cx">
</span><span class="cx"> MacroAssembler::Jump success;
</span><span class="lines">@@ -1203,12 +1203,12 @@
</span><span class="cx"> patchBuffer.link(failure, failureLabel);
</span><span class="cx"> else
</span><span class="cx"> patchBuffer.link(failureCases, failureLabel);
</span><del>-#if ENABLE(GGC)
- patchBuffer.link(callFlushWriteBarrierBuffer, operationFlushWriteBarrierBuffer);
-#endif
</del><span class="cx"> if (structure->outOfLineCapacity() != oldStructure->outOfLineCapacity()) {
</span><span class="cx"> patchBuffer.link(operationCall, operationReallocateStorageAndFinishPut);
</span><span class="cx"> patchBuffer.link(successInSlowPath, stubInfo.callReturnLocation.labelAtOffset(stubInfo.patch.deltaCallToDone));
</span><ins>+#if ENABLE(GGC)
+ patchBuffer.link(callFlushWriteBarrierBuffer, operationFlushWriteBarrierBuffer);
+#endif
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> stubRoutine =
</span></span></pre>
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