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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/171400">171400</a></dd>
<dt>Author</dt> <dd>dburkart@apple.com</dd>
<dt>Date</dt> <dd>2014-07-22 22:11:48 -0700 (Tue, 22 Jul 2014)</dd>
</dl>
<h3>Log Message</h3>
<pre>Merge <a href="http://trac.webkit.org/projects/webkit/changeset/171190">r171190</a></pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#branchessafari6001branchSourceJavaScriptCoreChangeLog">branches/safari-600.1-branch/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#branchessafari6001branchSourceJavaScriptCoredfgDFGCSEPhasecpp">branches/safari-600.1-branch/Source/JavaScriptCore/dfg/DFGCSEPhase.cpp</a></li>
<li><a href="#branchessafari6001branchSourceJavaScriptCoredfgDFGNodeTypeh">branches/safari-600.1-branch/Source/JavaScriptCore/dfg/DFGNodeType.h</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#branchessafari6001branchSourceJavaScriptCoretestsstresscaptureescapeandthrowjs">branches/safari-600.1-branch/Source/JavaScriptCore/tests/stress/capture-escape-and-throw.js</a></li>
<li><a href="#branchessafari6001branchSourceJavaScriptCoretestsstressnewarraywithsizethrowexceptionandtearoffargumentsjs">branches/safari-600.1-branch/Source/JavaScriptCore/tests/stress/new-array-with-size-throw-exception-and-tear-off-arguments.js</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="branchessafari6001branchSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: branches/safari-600.1-branch/Source/JavaScriptCore/ChangeLog (171399 => 171400)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-600.1-branch/Source/JavaScriptCore/ChangeLog 2014-07-23 05:09:52 UTC (rev 171399)
+++ branches/safari-600.1-branch/Source/JavaScriptCore/ChangeLog 2014-07-23 05:11:48 UTC (rev 171400)
</span><span class="lines">@@ -1,3 +1,48 @@
</span><ins>+2014-07-22 Dana Burkart <dburkart@apple.com>
+
+ Merge r171190.
+
+ 2014-07-16 Filip Pizlo <fpizlo@apple.com>
+
+ DFG Flush(SetLocal) store elimination is overzealous for captured variables in the presence of nodes that have no effects but may throw
+ https://bugs.webkit.org/show_bug.cgi?id=134988
+ <rdar://problem/17706349>
+
+ Reviewed by Oliver Hunt.
+
+ Luckily, we also don't need this optimization to be super powerful: the only place
+ where it really matters is for getting rid of the redundancy between op_enter and
+ op_init_lazy_reg, and in that case, there is a small set of possible nodes between the
+ two things. This change updates the store eliminator to know about only that small,
+ obviously safe, set of nodes over which we can store-eliminate.
+
+ This shouldn't have any performance impact in the DFG because this optimization kicks
+ in relatively rarely already. And once we tier up into the FTL, we get a much better
+ store elimination over LLVM IR, so this really shouldn't matter at all.
+
+ The tricky part of this patch is that there is a close relative of this optimization,
+ for uncaptured variables that got flushed. This happens for arguments to inlined calls.
+ I make this work by splitting it into two different store eliminators.
+
+ Note that in the process of crafting the tests, I realized that we were incorrectly
+ DCEing NewArrayWithSize. That's not cool, since that can throw an exception for
+ negative array sizes. If we ever did want to DCE this node, we'd need to lower the node
+ to a check node followed by the actual allocation.
+
+ * dfg/DFGCSEPhase.cpp:
+ (JSC::DFG::CSEPhase::uncapturedSetLocalStoreElimination):
+ (JSC::DFG::CSEPhase::capturedSetLocalStoreElimination):
+ (JSC::DFG::CSEPhase::setLocalStoreElimination):
+ (JSC::DFG::CSEPhase::performNodeCSE):
+ (JSC::DFG::CSEPhase::SetLocalStoreEliminationResult::SetLocalStoreEliminationResult): Deleted.
+ * dfg/DFGNodeType.h:
+ * tests/stress/capture-escape-and-throw.js: Added.
+ (foo.f):
+ (foo):
+ * tests/stress/new-array-with-size-throw-exception-and-tear-off-arguments.js: Added.
+ (foo):
+ (bar):
+
</ins><span class="cx"> 2014-07-17 Dean Jackson <dino@apple.com>
</span><span class="cx">
</span><span class="cx"> <rdar://problem/17675068> Disable some features on this branch.
</span></span></pre></div>
<a id="branchessafari6001branchSourceJavaScriptCoredfgDFGCSEPhasecpp"></a>
<div class="modfile"><h4>Modified: branches/safari-600.1-branch/Source/JavaScriptCore/dfg/DFGCSEPhase.cpp (171399 => 171400)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-600.1-branch/Source/JavaScriptCore/dfg/DFGCSEPhase.cpp 2014-07-23 05:09:52 UTC (rev 171399)
+++ branches/safari-600.1-branch/Source/JavaScriptCore/dfg/DFGCSEPhase.cpp 2014-07-23 05:11:48 UTC (rev 171400)
</span><span class="lines">@@ -928,48 +928,34 @@
</span><span class="cx"> return 0;
</span><span class="cx"> }
</span><span class="cx">
</span><del>- struct SetLocalStoreEliminationResult {
- SetLocalStoreEliminationResult()
- : mayBeAccessed(false)
- , mayExit(false)
- , mayClobberWorld(false)
- {
- }
-
- bool mayBeAccessed;
- bool mayExit;
- bool mayClobberWorld;
- };
- SetLocalStoreEliminationResult setLocalStoreElimination(
- VirtualRegister local, Node* expectedNode)
</del><ins>+ bool uncapturedSetLocalStoreElimination(VirtualRegister local, Node* expectedNode)
</ins><span class="cx"> {
</span><del>- SetLocalStoreEliminationResult result;
</del><span class="cx"> for (unsigned i = m_indexInBlock; i--;) {
</span><span class="cx"> Node* node = m_currentBlock->at(i);
</span><span class="cx"> switch (node->op()) {
</span><span class="cx"> case GetLocal:
</span><span class="cx"> case Flush:
</span><span class="cx"> if (node->local() == local)
</span><del>- result.mayBeAccessed = true;
</del><ins>+ return false;
</ins><span class="cx"> break;
</span><span class="cx">
</span><span class="cx"> case GetLocalUnlinked:
</span><span class="cx"> if (node->unlinkedLocal() == local)
</span><del>- result.mayBeAccessed = true;
</del><ins>+ return false;
</ins><span class="cx"> break;
</span><span class="cx">
</span><span class="cx"> case SetLocal: {
</span><span class="cx"> if (node->local() != local)
</span><span class="cx"> break;
</span><span class="cx"> if (node != expectedNode)
</span><del>- result.mayBeAccessed = true;
- return result;
</del><ins>+ return false;
+ return true;
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> case GetClosureVar:
</span><span class="cx"> case PutClosureVar:
</span><span class="cx"> if (static_cast<VirtualRegister>(node->varNumber()) == local)
</span><del>- result.mayBeAccessed = true;
</del><ins>+ return false;
</ins><span class="cx"> break;
</span><span class="cx">
</span><span class="cx"> case GetMyScope:
</span><span class="lines">@@ -977,25 +963,24 @@
</span><span class="cx"> if (node->origin.semantic.inlineCallFrame)
</span><span class="cx"> break;
</span><span class="cx"> if (m_graph.uncheckedActivationRegister() == local)
</span><del>- result.mayBeAccessed = true;
</del><ins>+ return false;
</ins><span class="cx"> break;
</span><span class="cx">
</span><span class="cx"> case CheckArgumentsNotCreated:
</span><span class="cx"> case GetMyArgumentsLength:
</span><span class="cx"> case GetMyArgumentsLengthSafe:
</span><span class="cx"> if (m_graph.uncheckedArgumentsRegisterFor(node->origin.semantic) == local)
</span><del>- result.mayBeAccessed = true;
</del><ins>+ return false;
</ins><span class="cx"> break;
</span><span class="cx">
</span><span class="cx"> case GetMyArgumentByVal:
</span><span class="cx"> case GetMyArgumentByValSafe:
</span><del>- result.mayBeAccessed = true;
- break;
</del><ins>+ return false;
</ins><span class="cx">
</span><span class="cx"> case GetByVal:
</span><span class="cx"> // If this is accessing arguments then it's potentially accessing locals.
</span><span class="cx"> if (node->arrayMode().type() == Array::Arguments)
</span><del>- result.mayBeAccessed = true;
</del><ins>+ return false;
</ins><span class="cx"> break;
</span><span class="cx">
</span><span class="cx"> case CreateArguments:
</span><span class="lines">@@ -1005,21 +990,66 @@
</span><span class="cx"> // are live. We could be clever here and check if the local qualifies as an
</span><span class="cx"> // argument register. But that seems like it would buy us very little since
</span><span class="cx"> // any kind of tear offs are rare to begin with.
</span><del>- result.mayBeAccessed = true;
- break;
</del><ins>+ return false;
</ins><span class="cx">
</span><span class="cx"> default:
</span><span class="cx"> break;
</span><span class="cx"> }
</span><del>- result.mayExit |= node->canExit();
- result.mayClobberWorld |= m_graph.clobbersWorld(node);
</del><ins>+ if (m_graph.clobbersWorld(node))
+ return false;
</ins><span class="cx"> }
</span><span class="cx"> RELEASE_ASSERT_NOT_REACHED();
</span><del>- // Be safe in release mode.
- result.mayBeAccessed = true;
- return result;
</del><ins>+ return false;
</ins><span class="cx"> }
</span><ins>+
+ bool capturedSetLocalStoreElimination(VirtualRegister local, Node* expectedNode)
+ {
+ for (unsigned i = m_indexInBlock; i--;) {
+ Node* node = m_currentBlock->at(i);
+ switch (node->op()) {
+ case GetLocal:
+ case Flush:
+ if (node->local() == local)
+ return false;
+ break;
+
+ case GetLocalUnlinked:
+ if (node->unlinkedLocal() == local)
+ return false;
+ break;
+
+ case SetLocal: {
+ if (node->local() != local)
+ break;
+ if (node != expectedNode)
+ return false;
+ return true;
+ }
+
+ case Phantom:
+ case Check:
+ case HardPhantom:
+ case MovHint:
+ case JSConstant:
+ case DoubleConstant:
+ case Int52Constant:
+ break;
+
+ default:
+ return false;
+ }
+ }
+ RELEASE_ASSERT_NOT_REACHED();
+ return false;
+ }
</ins><span class="cx">
</span><ins>+ bool setLocalStoreElimination(VariableAccessData* variableAccessData, Node* expectedNode)
+ {
+ if (variableAccessData->isCaptured())
+ return capturedSetLocalStoreElimination(variableAccessData->local(), expectedNode);
+ return uncapturedSetLocalStoreElimination(variableAccessData->local(), expectedNode);
+ }
+
</ins><span class="cx"> bool invalidationPointElimination()
</span><span class="cx"> {
</span><span class="cx"> for (unsigned i = m_indexInBlock; i--;) {
</span><span class="lines">@@ -1215,7 +1245,6 @@
</span><span class="cx"> case Flush: {
</span><span class="cx"> ASSERT(m_graph.m_form != SSA);
</span><span class="cx"> VariableAccessData* variableAccessData = node->variableAccessData();
</span><del>- VirtualRegister local = variableAccessData->local();
</del><span class="cx"> if (!node->child1()) {
</span><span class="cx"> // FIXME: It's silly that we punt on flush-eliminating here. We don't really
</span><span class="cx"> // need child1 to figure out what's going on.
</span><span class="lines">@@ -1239,12 +1268,9 @@
</span><span class="cx"> if (replacement->canExit())
</span><span class="cx"> break;
</span><span class="cx"> }
</span><del>- SetLocalStoreEliminationResult result =
- setLocalStoreElimination(local, replacement);
- if (result.mayBeAccessed || result.mayClobberWorld)
</del><ins>+ if (!setLocalStoreElimination(variableAccessData, replacement))
</ins><span class="cx"> break;
</span><span class="cx"> ASSERT(replacement->op() == SetLocal);
</span><del>- // FIXME: Investigate using mayExit as a further optimization.
</del><span class="cx"> node->convertToPhantom();
</span><span class="cx"> Node* dataNode = replacement->child1().node();
</span><span class="cx"> ASSERT(dataNode->hasResult());
</span></span></pre></div>
<a id="branchessafari6001branchSourceJavaScriptCoredfgDFGNodeTypeh"></a>
<div class="modfile"><h4>Modified: branches/safari-600.1-branch/Source/JavaScriptCore/dfg/DFGNodeType.h (171399 => 171400)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-600.1-branch/Source/JavaScriptCore/dfg/DFGNodeType.h 2014-07-23 05:09:52 UTC (rev 171399)
+++ branches/safari-600.1-branch/Source/JavaScriptCore/dfg/DFGNodeType.h 2014-07-23 05:11:48 UTC (rev 171400)
</span><span class="lines">@@ -233,7 +233,7 @@
</span><span class="cx"> /* Allocations. */\
</span><span class="cx"> macro(NewObject, NodeResultJS) \
</span><span class="cx"> macro(NewArray, NodeResultJS | NodeHasVarArgs) \
</span><del>- macro(NewArrayWithSize, NodeResultJS) \
</del><ins>+ macro(NewArrayWithSize, NodeResultJS | NodeMustGenerate) \
</ins><span class="cx"> macro(NewArrayBuffer, NodeResultJS) \
</span><span class="cx"> macro(NewTypedArray, NodeResultJS | NodeClobbersWorld | NodeMustGenerate) \
</span><span class="cx"> macro(NewRegexp, NodeResultJS) \
</span></span></pre></div>
<a id="branchessafari6001branchSourceJavaScriptCoretestsstresscaptureescapeandthrowjsfromrev171190trunkSourceJavaScriptCoretestsstresscaptureescapeandthrowjs"></a>
<div class="copfile"><h4>Copied: branches/safari-600.1-branch/Source/JavaScriptCore/tests/stress/capture-escape-and-throw.js (from rev 171190, trunk/Source/JavaScriptCore/tests/stress/capture-escape-and-throw.js) (0 => 171400)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-600.1-branch/Source/JavaScriptCore/tests/stress/capture-escape-and-throw.js (rev 0)
+++ branches/safari-600.1-branch/Source/JavaScriptCore/tests/stress/capture-escape-and-throw.js 2014-07-23 05:11:48 UTC (rev 171400)
</span><span class="lines">@@ -0,0 +1,28 @@
</span><ins>+var f;
+
+function foo(s) {
+ var x = 1;
+ f = function() { return x; };
+ x = 2;
+ new Array(s);
+ x = 3;
+}
+
+noInline(foo);
+
+for (var i = 0; i < 10000; ++i)
+ foo(1);
+
+var didThrow = false;
+try {
+ foo(-1);
+} catch (e) {
+ didThrow = e;
+}
+
+if (("" + didThrow).indexOf("RangeError") != 0)
+ throw "Error: did not throw right exception: " + didThrow;
+
+var result = f();
+if (result != 2)
+ throw "Error: bad result from f(): " + result;
</ins></span></pre></div>
<a id="branchessafari6001branchSourceJavaScriptCoretestsstressnewarraywithsizethrowexceptionandtearoffargumentsjsfromrev171190trunkSourceJavaScriptCoretestsstressnewarraywithsizethrowexceptionandtearoffargumentsjs"></a>
<div class="copfile"><h4>Copied: branches/safari-600.1-branch/Source/JavaScriptCore/tests/stress/new-array-with-size-throw-exception-and-tear-off-arguments.js (from rev 171190, trunk/Source/JavaScriptCore/tests/stress/new-array-with-size-throw-exception-and-tear-off-arguments.js) (0 => 171400)</h4>
<pre class="diff"><span>
<span class="info">--- branches/safari-600.1-branch/Source/JavaScriptCore/tests/stress/new-array-with-size-throw-exception-and-tear-off-arguments.js (rev 0)
+++ branches/safari-600.1-branch/Source/JavaScriptCore/tests/stress/new-array-with-size-throw-exception-and-tear-off-arguments.js 2014-07-23 05:11:48 UTC (rev 171400)
</span><span class="lines">@@ -0,0 +1,26 @@
</span><ins>+function foo() {
+ var a = arguments;
+ return new Array(a[0]);
+}
+
+function bar(x) {
+ return foo(x);
+}
+
+noInline(bar);
+
+for (var i = 0; i < 10000; ++i) {
+ var result = bar(42);
+ if (result.length != 42)
+ throw "Error: bad result length: " + result;
+}
+
+var didThrow = false;
+try {
+ bar(-1);
+} catch (e) {
+ didThrow = e;
+}
+
+if (("" + didThrow).indexOf("RangeError") != 0)
+ throw "Error: did not throw right exception: " + didThrow;
</ins></span></pre>
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