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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/183897">183897</a></dd>
<dt>Author</dt> <dd>fpizlo@apple.com</dd>
<dt>Date</dt> <dd>2015-05-06 16:14:14 -0700 (Wed, 06 May 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>Sane chain and string watchpoints should be set in FixupPhase or the backend rather than WatchpointCollectionPhase
https://bugs.webkit.org/show_bug.cgi?id=144665
Reviewed by Michael Saboff.
This is a step towards getting rid of WatchpointCollectionPhase. It's also a step towards
extending SaneChain to all indexing shapes.
* dfg/DFGFixupPhase.cpp:
(JSC::DFG::FixupPhase::fixupNode): Set the watchpoints here so that we don't need a case in WatchpointCollectionPhase.
(JSC::DFG::FixupPhase::checkArray): Clarify the need for checking the structure. We often forget why we do this instead of always using CheckArray.
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compileGetByValOnString): Set the watchpoints here so that we don't need a case in WatchpointCollectionPhase.
* dfg/DFGWatchpointCollectionPhase.cpp:
(JSC::DFG::WatchpointCollectionPhase::handle): Remove some code.
(JSC::DFG::WatchpointCollectionPhase::handleStringGetByVal): Deleted.
* ftl/FTLLowerDFGToLLVM.cpp:
(JSC::FTL::LowerDFGToLLVM::compileStringCharAt): Set the watchpoints here so that we don't need a case in WatchpointCollectionPhase.</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="#trunkSourceJavaScriptCoredfgDFGSpeculativeJITcpp">trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGWatchpointCollectionPhasecpp">trunk/Source/JavaScriptCore/dfg/DFGWatchpointCollectionPhase.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoreftlFTLLowerDFGToLLVMcpp">trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToLLVM.cpp</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (183896 => 183897)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-05-06 23:05:38 UTC (rev 183896)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-05-06 23:14:14 UTC (rev 183897)
</span><span class="lines">@@ -1,3 +1,24 @@
</span><ins>+2015-05-05 Filip Pizlo <fpizlo@apple.com>
+
+ Sane chain and string watchpoints should be set in FixupPhase or the backend rather than WatchpointCollectionPhase
+ https://bugs.webkit.org/show_bug.cgi?id=144665
+
+ Reviewed by Michael Saboff.
+
+ This is a step towards getting rid of WatchpointCollectionPhase. It's also a step towards
+ extending SaneChain to all indexing shapes.
+
+ * dfg/DFGFixupPhase.cpp:
+ (JSC::DFG::FixupPhase::fixupNode): Set the watchpoints here so that we don't need a case in WatchpointCollectionPhase.
+ (JSC::DFG::FixupPhase::checkArray): Clarify the need for checking the structure. We often forget why we do this instead of always using CheckArray.
+ * dfg/DFGSpeculativeJIT.cpp:
+ (JSC::DFG::SpeculativeJIT::compileGetByValOnString): Set the watchpoints here so that we don't need a case in WatchpointCollectionPhase.
+ * dfg/DFGWatchpointCollectionPhase.cpp:
+ (JSC::DFG::WatchpointCollectionPhase::handle): Remove some code.
+ (JSC::DFG::WatchpointCollectionPhase::handleStringGetByVal): Deleted.
+ * ftl/FTLLowerDFGToLLVM.cpp:
+ (JSC::FTL::LowerDFGToLLVM::compileStringCharAt): Set the watchpoints here so that we don't need a case in WatchpointCollectionPhase.
+
</ins><span class="cx"> 2015-04-02 Myles C. Maxfield <mmaxfield@apple.com>
</span><span class="cx">
</span><span class="cx"> Introducing the Platform Abstraction Layer (PAL)
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGFixupPhasecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp (183896 => 183897)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp 2015-05-06 23:05:38 UTC (rev 183896)
+++ trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp 2015-05-06 23:14:14 UTC (rev 183897)
</span><span class="lines">@@ -28,6 +28,7 @@
</span><span class="cx">
</span><span class="cx"> #if ENABLE(DFG_JIT)
</span><span class="cx">
</span><ins>+#include "ArrayPrototype.h"
</ins><span class="cx"> #include "DFGGraph.h"
</span><span class="cx"> #include "DFGInsertionSet.h"
</span><span class="cx"> #include "DFGPhase.h"
</span><span class="lines">@@ -517,10 +518,17 @@
</span><span class="cx"> switch (arrayMode.type()) {
</span><span class="cx"> case Array::Double:
</span><span class="cx"> if (arrayMode.arrayClass() == Array::OriginalArray
</span><del>- && arrayMode.speculation() == Array::InBounds
- && m_graph.globalObjectFor(node->origin.semantic)->arrayPrototypeChainIsSane()
- && !(node->flags() & NodeBytecodeUsesAsOther))
- node->setArrayMode(arrayMode.withSpeculation(Array::SaneChain));
</del><ins>+ && arrayMode.speculation() == Array::InBounds) {
+ JSGlobalObject* globalObject = m_graph.globalObjectFor(node->origin.semantic);
+ if (globalObject->arrayPrototypeChainIsSane()
+ && !(node->flags() & NodeBytecodeUsesAsOther)) {
+ m_graph.watchpoints().addLazily(
+ globalObject->arrayPrototype()->structure()->transitionWatchpointSet());
+ m_graph.watchpoints().addLazily(
+ globalObject->objectPrototype()->structure()->transitionWatchpointSet());
+ node->setArrayMode(arrayMode.withSpeculation(Array::SaneChain));
+ }
+ }
</ins><span class="cx"> break;
</span><span class="cx">
</span><span class="cx"> case Array::String:
</span><span class="lines">@@ -1542,10 +1550,12 @@
</span><span class="cx"> m_insertionSet.insertNode(
</span><span class="cx"> m_indexInBlock, SpecNone, Check, origin, Edge(array, StringUse));
</span><span class="cx"> } else {
</span><ins>+ // Note that we only need to be using a structure check if we opt for SaneChain, since
+ // that needs to protect against JSArray's __proto__ being changed.
</ins><span class="cx"> Structure* structure = arrayMode.originalArrayStructure(m_graph, origin.semantic);
</span><span class="cx">
</span><span class="cx"> Edge indexEdge = index ? Edge(index, Int32Use) : Edge();
</span><del>-
</del><ins>+
</ins><span class="cx"> if (arrayMode.doesConversion()) {
</span><span class="cx"> if (structure) {
</span><span class="cx"> m_insertionSet.insertNode(
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGSpeculativeJITcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp (183896 => 183897)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp 2015-05-06 23:05:38 UTC (rev 183896)
+++ trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp 2015-05-06 23:14:14 UTC (rev 183897)
</span><span class="lines">@@ -1756,6 +1756,15 @@
</span><span class="cx">
</span><span class="cx"> JSGlobalObject* globalObject = m_jit.globalObjectFor(node->origin.semantic);
</span><span class="cx"> if (globalObject->stringPrototypeChainIsSane()) {
</span><ins>+ // FIXME: This could be captured using a Speculation mode that means "out-of-bounds
+ // loads return a trivial value". Something like SaneChainOutOfBounds. This should
+ // speculate that we don't take negative out-of-bounds, or better yet, it should rely
+ // on a stringPrototypeChainIsSane() guaranteeing that the prototypes have no negative
+ // indexed properties either.
+ // https://bugs.webkit.org/show_bug.cgi?id=144668
+ m_jit.graph().watchpoints().addLazily(globalObject->stringPrototype()->structure()->transitionWatchpointSet());
+ m_jit.graph().watchpoints().addLazily(globalObject->objectPrototype()->structure()->transitionWatchpointSet());
+
</ins><span class="cx"> #if USE(JSVALUE64)
</span><span class="cx"> addSlowPathGenerator(std::make_unique<SaneStringGetByValSlowPathGenerator>(
</span><span class="cx"> outOfBounds, this, JSValueRegs(scratchReg), baseReg, propertyReg));
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGWatchpointCollectionPhasecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGWatchpointCollectionPhase.cpp (183896 => 183897)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGWatchpointCollectionPhase.cpp 2015-05-06 23:05:38 UTC (rev 183896)
+++ trunk/Source/JavaScriptCore/dfg/DFGWatchpointCollectionPhase.cpp 2015-05-06 23:14:14 UTC (rev 183897)
</span><span class="lines">@@ -34,6 +34,14 @@
</span><span class="cx"> #include "DFGPhase.h"
</span><span class="cx"> #include "JSCInlines.h"
</span><span class="cx">
</span><ins>+// FIXME: Remove this phase entirely by moving the addLazily() calls into either the backend or
+// into the phase that performs the optimization. Moving the calls into the backend makes the most
+// sense when the intermediate phases don't need to know that the watchpoint was set. Moving the
+// calls earlier usually only makes sense if the node's only purpose was to convey the need for
+// the watchpoint (like VarInjectionWatchpoint). But, it can also make sense if the fact that the
+// watchpoint was set enables other optimizations.
+// https://bugs.webkit.org/show_bug.cgi?id=144669
+
</ins><span class="cx"> namespace JSC { namespace DFG {
</span><span class="cx">
</span><span class="cx"> class WatchpointCollectionPhase : public Phase {
</span><span class="lines">@@ -83,21 +91,6 @@
</span><span class="cx"> handleMasqueradesAsUndefined();
</span><span class="cx"> break;
</span><span class="cx">
</span><del>- case GetByVal:
- if (m_node->arrayMode().type() == Array::Double
- && m_node->arrayMode().isSaneChain()) {
- addLazily(globalObject()->arrayPrototype()->structure()->transitionWatchpointSet());
- addLazily(globalObject()->objectPrototype()->structure()->transitionWatchpointSet());
- }
-
- if (m_node->arrayMode().type() == Array::String)
- handleStringGetByVal();
- break;
-
- case StringCharAt:
- handleStringGetByVal();
- break;
-
</del><span class="cx"> case NewArray:
</span><span class="cx"> case NewArrayWithSize:
</span><span class="cx"> case NewArrayBuffer:
</span><span class="lines">@@ -120,16 +113,6 @@
</span><span class="cx"> addLazily(globalObject()->masqueradesAsUndefinedWatchpoint());
</span><span class="cx"> }
</span><span class="cx">
</span><del>- void handleStringGetByVal()
- {
- if (!m_node->arrayMode().isOutOfBounds())
- return;
- if (!globalObject()->stringPrototypeChainIsSane())
- return;
- addLazily(globalObject()->stringPrototype()->structure()->transitionWatchpointSet());
- addLazily(globalObject()->objectPrototype()->structure()->transitionWatchpointSet());
- }
-
</del><span class="cx"> void addLazily(WatchpointSet* set)
</span><span class="cx"> {
</span><span class="cx"> m_graph.watchpoints().addLazily(set);
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreftlFTLLowerDFGToLLVMcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToLLVM.cpp (183896 => 183897)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToLLVM.cpp 2015-05-06 23:05:38 UTC (rev 183896)
+++ trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToLLVM.cpp 2015-05-06 23:14:14 UTC (rev 183897)
</span><span class="lines">@@ -3615,6 +3615,14 @@
</span><span class="cx"> JSGlobalObject* globalObject = m_graph.globalObjectFor(m_node->origin.semantic);
</span><span class="cx">
</span><span class="cx"> if (globalObject->stringPrototypeChainIsSane()) {
</span><ins>+ // FIXME: This could be captured using a Speculation mode that means
+ // "out-of-bounds loads return a trivial value", something like
+ // SaneChainOutOfBounds.
+ // https://bugs.webkit.org/show_bug.cgi?id=144668
+
+ m_graph.watchpoints().addLazily(globalObject->stringPrototype()->structure()->transitionWatchpointSet());
+ m_graph.watchpoints().addLazily(globalObject->objectPrototype()->structure()->transitionWatchpointSet());
+
</ins><span class="cx"> LBasicBlock negativeIndex = FTL_NEW_BLOCK(m_out, ("GetByVal String negative index"));
</span><span class="cx">
</span><span class="cx"> results.append(m_out.anchor(m_out.constInt64(JSValue::encode(jsUndefined()))));
</span></span></pre>
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