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<dl class="meta">
<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/205830">205830</a></dd>
<dt>Author</dt> <dd>commit-queue@webkit.org</dd>
<dt>Date</dt> <dd>2016-09-12 15:13:37 -0700 (Mon, 12 Sep 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>[JSC] Use GetArrayLength for JSArray.length even when the array type is undecided
https://bugs.webkit.org/show_bug.cgi?id=161671
Patch by Benjamin Poulain <bpoulain@apple.com> on 2016-09-12
Reviewed by Geoffrey Garen.
JSTests:
* stress/get-array-length-on-undecided.js: Added.
Source/JavaScriptCore:
UndecidedShape is a type with storage. When we allocate an uninitialized JSArray,
it gets a butterfly with its length.
When we were querying that length, we were generating a generic GetById with inline cache.
This patch adds the missing bits to treat Undecided like the other types with storage.
* dfg/DFGArrayMode.cpp:
(JSC::DFG::canBecomeGetArrayLength):
(JSC::DFG::ArrayMode::refine):
* dfg/DFGArrayMode.h:
(JSC::DFG::ArrayMode::usesButterfly):
(JSC::DFG::ArrayMode::lengthNeedsStorage):
* dfg/DFGClobberize.h:
(JSC::DFG::clobberize):
* dfg/DFGFixupPhase.cpp:
(JSC::DFG::FixupPhase::checkArray):
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compileGetArrayLength):
* ftl/FTLCapabilities.cpp:
(JSC::FTL::canCompile):
* ftl/FTLLowerDFGToB3.cpp:
(JSC::FTL::DFG::LowerDFGToB3::compileGetArrayLength):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkJSTestsChangeLog">trunk/JSTests/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGArrayModecpp">trunk/Source/JavaScriptCore/dfg/DFGArrayMode.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGArrayModeh">trunk/Source/JavaScriptCore/dfg/DFGArrayMode.h</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGClobberizeh">trunk/Source/JavaScriptCore/dfg/DFGClobberize.h</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="#trunkSourceJavaScriptCoreftlFTLCapabilitiescpp">trunk/Source/JavaScriptCore/ftl/FTLCapabilities.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoreftlFTLLowerDFGToB3cpp">trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#trunkJSTestsstressgetarraylengthonundecidedjs">trunk/JSTests/stress/get-array-length-on-undecided.js</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkJSTestsChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/JSTests/ChangeLog (205829 => 205830)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/JSTests/ChangeLog 2016-09-12 22:05:54 UTC (rev 205829)
+++ trunk/JSTests/ChangeLog 2016-09-12 22:13:37 UTC (rev 205830)
</span><span class="lines">@@ -1,3 +1,12 @@
</span><ins>+2016-09-12 Benjamin Poulain <bpoulain@apple.com>
+
+ [JSC] Use GetArrayLength for JSArray.length even when the array type is undecided
+ https://bugs.webkit.org/show_bug.cgi?id=161671
+
+ Reviewed by Geoffrey Garen.
+
+ * stress/get-array-length-on-undecided.js: Added.
+
</ins><span class="cx"> 2016-09-12 Yusuke Suzuki <utatane.tea@gmail.com>
</span><span class="cx">
</span><span class="cx"> [DFG][FTL] Add ArithTan
</span></span></pre></div>
<a id="trunkJSTestsstressgetarraylengthonundecidedjs"></a>
<div class="addfile"><h4>Added: trunk/JSTests/stress/get-array-length-on-undecided.js (0 => 205830)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/JSTests/stress/get-array-length-on-undecided.js (rev 0)
+++ trunk/JSTests/stress/get-array-length-on-undecided.js 2016-09-12 22:13:37 UTC (rev 205830)
</span><span class="lines">@@ -0,0 +1,76 @@
</span><ins>+function forceTransition() {
+ // We want to test the StructureCheck in testSparseArray(), not this watchpoint.
+ // We start with the transition so that it's nothing new.
+ let array = new Array();
+ array[100001] = "WebKit!";
+}
+forceTransition();
+
+function opaqueGetArrayLength(array)
+{
+ return array.length;
+}
+noInline(opaqueGetArrayLength);
+
+function testEmptyArray()
+{
+ let array = [];
+ for (let i = 0; i < 1e6; ++i) {
+ if (opaqueGetArrayLength(array) !== 0) {
+ throw "Failed testEmptyArray";
+ }
+ }
+
+ array = new Array();
+ for (let i = 0; i < 1e6; ++i) {
+ if (opaqueGetArrayLength(array) !== 0) {
+ throw "Failed testEmptyArray";
+ }
+ }
+}
+testEmptyArray();
+
+
+function testUnitializedArray()
+{
+ let array = new Array(32);
+ for (let i = 0; i < 1e6; ++i) {
+ if (opaqueGetArrayLength(array) !== 32) {
+ throw "Failed testUnitializedArray";
+ }
+ }
+
+ array = new Array();
+ array.length = 64
+ for (let i = 0; i < 1e6; ++i) {
+ if (opaqueGetArrayLength(array) !== 64) {
+ throw "Failed testUnitializedArray";
+ }
+ }
+}
+testUnitializedArray();
+
+function testOversizedArray()
+{
+ let array = new Array(100001);
+ for (let i = 0; i < 1e6; ++i) {
+ if (opaqueGetArrayLength(array) !== 100001) {
+ throw "Failed testOversizedArray";
+ }
+ }
+}
+testOversizedArray();
+
+// This should OSR Exit and fallback to GetById to get the length.
+function testSparseArray()
+{
+ let array = new Array();
+ array[100001] = "WebKit!";
+ for (let i = 0; i < 1e6; ++i) {
+ if (opaqueGetArrayLength(array) !== 100002) {
+ throw "Failed testOversizedArray";
+ }
+ }
+}
+testSparseArray();
+
</ins></span></pre></div>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (205829 => 205830)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2016-09-12 22:05:54 UTC (rev 205829)
+++ trunk/Source/JavaScriptCore/ChangeLog 2016-09-12 22:13:37 UTC (rev 205830)
</span><span class="lines">@@ -1,3 +1,33 @@
</span><ins>+2016-09-12 Benjamin Poulain <bpoulain@apple.com>
+
+ [JSC] Use GetArrayLength for JSArray.length even when the array type is undecided
+ https://bugs.webkit.org/show_bug.cgi?id=161671
+
+ Reviewed by Geoffrey Garen.
+
+ UndecidedShape is a type with storage. When we allocate an uninitialized JSArray,
+ it gets a butterfly with its length.
+ When we were querying that length, we were generating a generic GetById with inline cache.
+
+ This patch adds the missing bits to treat Undecided like the other types with storage.
+
+ * dfg/DFGArrayMode.cpp:
+ (JSC::DFG::canBecomeGetArrayLength):
+ (JSC::DFG::ArrayMode::refine):
+ * dfg/DFGArrayMode.h:
+ (JSC::DFG::ArrayMode::usesButterfly):
+ (JSC::DFG::ArrayMode::lengthNeedsStorage):
+ * dfg/DFGClobberize.h:
+ (JSC::DFG::clobberize):
+ * dfg/DFGFixupPhase.cpp:
+ (JSC::DFG::FixupPhase::checkArray):
+ * dfg/DFGSpeculativeJIT.cpp:
+ (JSC::DFG::SpeculativeJIT::compileGetArrayLength):
+ * ftl/FTLCapabilities.cpp:
+ (JSC::FTL::canCompile):
+ * ftl/FTLLowerDFGToB3.cpp:
+ (JSC::FTL::DFG::LowerDFGToB3::compileGetArrayLength):
+
</ins><span class="cx"> 2016-09-12 Yusuke Suzuki <utatane.tea@gmail.com>
</span><span class="cx">
</span><span class="cx"> [DFG][FTL] Add ArithTan
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGArrayModecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGArrayMode.cpp (205829 => 205830)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGArrayMode.cpp 2016-09-12 22:05:54 UTC (rev 205829)
+++ trunk/Source/JavaScriptCore/dfg/DFGArrayMode.cpp 2016-09-12 22:13:37 UTC (rev 205830)
</span><span class="lines">@@ -150,6 +150,14 @@
</span><span class="cx"> }
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+static bool canBecomeGetArrayLength(Graph& graph, Node* node)
+{
+ if (node->op() != GetById)
+ return false;
+ auto uid = graph.identifiers()[node->identifierNumber()];
+ return uid == graph.m_vm.propertyNames->length.impl();
+}
+
</ins><span class="cx"> ArrayMode ArrayMode::refine(
</span><span class="cx"> Graph& graph, Node* node,
</span><span class="cx"> SpeculatedType base, SpeculatedType index, SpeculatedType value) const
</span><span class="lines">@@ -192,7 +200,7 @@
</span><span class="cx"> // If we have an OriginalArray and the JSArray prototype chain is sane,
</span><span class="cx"> // any indexed access always return undefined. We have a fast path for that.
</span><span class="cx"> JSGlobalObject* globalObject = graph.globalObjectFor(node->origin.semantic);
</span><del>- if (node->op() == GetByVal
</del><ins>+ if ((node->op() == GetByVal || canBecomeGetArrayLength(graph, node))
</ins><span class="cx"> && arrayClass() == Array::OriginalArray
</span><span class="cx"> && globalObject->arrayPrototypeChainIsSane()
</span><span class="cx"> && !graph.hasExitSite(node->origin.semantic, OutOfBounds)) {
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGArrayModeh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGArrayMode.h (205829 => 205830)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGArrayMode.h 2016-09-12 22:05:54 UTC (rev 205829)
+++ trunk/Source/JavaScriptCore/dfg/DFGArrayMode.h 2016-09-12 22:13:37 UTC (rev 205830)
</span><span class="lines">@@ -234,6 +234,7 @@
</span><span class="cx"> bool usesButterfly() const
</span><span class="cx"> {
</span><span class="cx"> switch (type()) {
</span><ins>+ case Array::Undecided:
</ins><span class="cx"> case Array::Int32:
</span><span class="cx"> case Array::Double:
</span><span class="cx"> case Array::Contiguous:
</span><span class="lines">@@ -312,6 +313,7 @@
</span><span class="cx"> bool lengthNeedsStorage() const
</span><span class="cx"> {
</span><span class="cx"> switch (type()) {
</span><ins>+ case Array::Undecided:
</ins><span class="cx"> case Array::Int32:
</span><span class="cx"> case Array::Double:
</span><span class="cx"> case Array::Contiguous:
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGClobberizeh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGClobberize.h (205829 => 205830)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGClobberize.h 2016-09-12 22:05:54 UTC (rev 205829)
+++ trunk/Source/JavaScriptCore/dfg/DFGClobberize.h 2016-09-12 22:13:37 UTC (rev 205830)
</span><span class="lines">@@ -942,6 +942,7 @@
</span><span class="cx"> case GetArrayLength: {
</span><span class="cx"> ArrayMode mode = node->arrayMode();
</span><span class="cx"> switch (mode.type()) {
</span><ins>+ case Array::Undecided:
</ins><span class="cx"> case Array::Int32:
</span><span class="cx"> case Array::Double:
</span><span class="cx"> case Array::Contiguous:
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGFixupPhasecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp (205829 => 205830)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp 2016-09-12 22:05:54 UTC (rev 205829)
+++ trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp 2016-09-12 22:13:37 UTC (rev 205830)
</span><span class="lines">@@ -2102,7 +2102,7 @@
</span><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> if (!storageCheck(arrayMode))
</span><del>- return 0;
</del><ins>+ return nullptr;
</ins><span class="cx">
</span><span class="cx"> if (arrayMode.usesButterfly()) {
</span><span class="cx"> return m_insertionSet.insertNode(
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGSpeculativeJITcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp (205829 => 205830)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp 2016-09-12 22:05:54 UTC (rev 205829)
+++ trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp 2016-09-12 22:13:37 UTC (rev 205830)
</span><span class="lines">@@ -6051,6 +6051,7 @@
</span><span class="cx"> void SpeculativeJIT::compileGetArrayLength(Node* node)
</span><span class="cx"> {
</span><span class="cx"> switch (node->arrayMode().type()) {
</span><ins>+ case Array::Undecided:
</ins><span class="cx"> case Array::Int32:
</span><span class="cx"> case Array::Double:
</span><span class="cx"> case Array::Contiguous: {
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreftlFTLCapabilitiescpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ftl/FTLCapabilities.cpp (205829 => 205830)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ftl/FTLCapabilities.cpp 2016-09-12 22:05:54 UTC (rev 205829)
+++ trunk/Source/JavaScriptCore/ftl/FTLCapabilities.cpp 2016-09-12 22:13:37 UTC (rev 205830)
</span><span class="lines">@@ -288,6 +288,7 @@
</span><span class="cx"> break;
</span><span class="cx"> case GetArrayLength:
</span><span class="cx"> switch (node->arrayMode().type()) {
</span><ins>+ case Array::Undecided:
</ins><span class="cx"> case Array::Int32:
</span><span class="cx"> case Array::Double:
</span><span class="cx"> case Array::Contiguous:
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreftlFTLLowerDFGToB3cpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp (205829 => 205830)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp 2016-09-12 22:05:54 UTC (rev 205829)
+++ trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp 2016-09-12 22:13:37 UTC (rev 205830)
</span><span class="lines">@@ -2900,6 +2900,7 @@
</span><span class="cx"> void compileGetArrayLength()
</span><span class="cx"> {
</span><span class="cx"> switch (m_node->arrayMode().type()) {
</span><ins>+ case Array::Undecided:
</ins><span class="cx"> case Array::Int32:
</span><span class="cx"> case Array::Double:
</span><span class="cx"> case Array::Contiguous: {
</span></span></pre>
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