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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/183495">183495</a></dd>
<dt>Author</dt> <dd>akling@apple.com</dd>
<dt>Date</dt> <dd>2015-04-28 11:54:12 -0700 (Tue, 28 Apr 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>Source/JavaScriptCore:
DFG+FTL should generate efficient code for branching on a string's boolean value.
<https://webkit.org/b/144317>
Reviewed by Geoff Garen & Filip Pizlo
Teach Branch nodes about StringUse and have them generate an efficient zero-length string check
instead of dropping out to C++ whenever we branch on a string.
The FTL JIT already handled Branch nodes with StringUse through its use of boolify(), so only
the DFG JIT gets some new codegen logic in this patch.
Test: js/regress/branch-on-string-as-boolean.js (~4.5x speedup)
* dfg/DFGFixupPhase.cpp:
(JSC::DFG::FixupPhase::fixupNode):
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::emitStringBranch):
* dfg/DFGSpeculativeJIT.h:
* dfg/DFGSpeculativeJIT32_64.cpp:
(JSC::DFG::SpeculativeJIT::emitBranch):
* dfg/DFGSpeculativeJIT64.cpp:
(JSC::DFG::SpeculativeJIT::emitBranch):
LayoutTests:
DFG should generate efficient code for branching on a string's boolean value.
<https://webkit.org/b/144317>
Reviewed by Geoff Garen & Filip Pizlo.
* js/regress/branch-on-string-as-boolean-expected.txt: Added.
* js/regress/branch-on-string-as-boolean.html: Added.
* js/regress/script-tests/branch-on-string-as-boolean.js: Added.</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkLayoutTestsChangeLog">trunk/LayoutTests/ChangeLog</a></li>
<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="#trunkSourceJavaScriptCoredfgDFGSpeculativeJITh">trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.h</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGSpeculativeJIT32_64cpp">trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT32_64.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGSpeculativeJIT64cpp">trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT64.cpp</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#trunkLayoutTestsjsregressbranchonstringasbooleanexpectedtxt">trunk/LayoutTests/js/regress/branch-on-string-as-boolean-expected.txt</a></li>
<li><a href="#trunkLayoutTestsjsregressbranchonstringasbooleanhtml">trunk/LayoutTests/js/regress/branch-on-string-as-boolean.html</a></li>
<li><a href="#trunkLayoutTestsjsregressscripttestsbranchonstringasbooleanjs">trunk/LayoutTests/js/regress/script-tests/branch-on-string-as-boolean.js</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkLayoutTestsChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/LayoutTests/ChangeLog (183494 => 183495)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/ChangeLog 2015-04-28 18:36:59 UTC (rev 183494)
+++ trunk/LayoutTests/ChangeLog 2015-04-28 18:54:12 UTC (rev 183495)
</span><span class="lines">@@ -1,3 +1,14 @@
</span><ins>+2015-04-28 Andreas Kling <akling@apple.com>
+
+ DFG should generate efficient code for branching on a string's boolean value.
+ <https://webkit.org/b/144317>
+
+ Reviewed by Geoff Garen & Filip Pizlo.
+
+ * js/regress/branch-on-string-as-boolean-expected.txt: Added.
+ * js/regress/branch-on-string-as-boolean.html: Added.
+ * js/regress/script-tests/branch-on-string-as-boolean.js: Added.
+
</ins><span class="cx"> 2015-04-27 Myles C. Maxfield <mmaxfield@apple.com>
</span><span class="cx">
</span><span class="cx"> Implement font-synthesis CSS property
</span></span></pre></div>
<a id="trunkLayoutTestsjsregressbranchonstringasbooleanexpectedtxt"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/js/regress/branch-on-string-as-boolean-expected.txt (0 => 183495)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/js/regress/branch-on-string-as-boolean-expected.txt (rev 0)
+++ trunk/LayoutTests/js/regress/branch-on-string-as-boolean-expected.txt 2015-04-28 18:54:12 UTC (rev 183495)
</span><span class="lines">@@ -0,0 +1,10 @@
</span><ins>+JSRegress/branch-on-string-as-boolean
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS no exception thrown
+PASS successfullyParsed is true
+
+TEST COMPLETE
+
</ins></span></pre></div>
<a id="trunkLayoutTestsjsregressbranchonstringasbooleanhtml"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/js/regress/branch-on-string-as-boolean.html (0 => 183495)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/js/regress/branch-on-string-as-boolean.html (rev 0)
+++ trunk/LayoutTests/js/regress/branch-on-string-as-boolean.html 2015-04-28 18:54:12 UTC (rev 183495)
</span><span class="lines">@@ -0,0 +1,12 @@
</span><ins>+<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
+<html>
+<head>
+<script src="../../resources/js-test-pre.js"></script>
+</head>
+<body>
+<script src="../../resources/regress-pre.js"></script>
+<script src="script-tests/branch-on-string-as-boolean.js"></script>
+<script src="../../resources/regress-post.js"></script>
+<script src="../../resources/js-test-post.js"></script>
+</body>
+</html>
</ins></span></pre></div>
<a id="trunkLayoutTestsjsregressscripttestsbranchonstringasbooleanjs"></a>
<div class="addfile"><h4>Added: trunk/LayoutTests/js/regress/script-tests/branch-on-string-as-boolean.js (0 => 183495)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/LayoutTests/js/regress/script-tests/branch-on-string-as-boolean.js (rev 0)
+++ trunk/LayoutTests/js/regress/script-tests/branch-on-string-as-boolean.js 2015-04-28 18:54:12 UTC (rev 183495)
</span><span class="lines">@@ -0,0 +1,12 @@
</span><ins>+// This test branches on the boolean value of a string, which should be fast in the DFG.
+
+function foo(string) {
+ var bar;
+ for (var i = 0; i < 10000000; ++i) {
+ if (string)
+ bar++;
+ }
+ return bar;
+}
+
+result = foo('hurr im a string');
</ins></span></pre></div>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (183494 => 183495)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-04-28 18:36:59 UTC (rev 183494)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-04-28 18:54:12 UTC (rev 183495)
</span><span class="lines">@@ -1,3 +1,28 @@
</span><ins>+2015-04-28 Andreas Kling <akling@apple.com>
+
+ DFG+FTL should generate efficient code for branching on a string's boolean value.
+ <https://webkit.org/b/144317>
+
+ Reviewed by Geoff Garen & Filip Pizlo
+
+ Teach Branch nodes about StringUse and have them generate an efficient zero-length string check
+ instead of dropping out to C++ whenever we branch on a string.
+
+ The FTL JIT already handled Branch nodes with StringUse through its use of boolify(), so only
+ the DFG JIT gets some new codegen logic in this patch.
+
+ Test: js/regress/branch-on-string-as-boolean.js (~4.5x speedup)
+
+ * dfg/DFGFixupPhase.cpp:
+ (JSC::DFG::FixupPhase::fixupNode):
+ * dfg/DFGSpeculativeJIT.cpp:
+ (JSC::DFG::SpeculativeJIT::emitStringBranch):
+ * dfg/DFGSpeculativeJIT.h:
+ * dfg/DFGSpeculativeJIT32_64.cpp:
+ (JSC::DFG::SpeculativeJIT::emitBranch):
+ * dfg/DFGSpeculativeJIT64.cpp:
+ (JSC::DFG::SpeculativeJIT::emitBranch):
+
</ins><span class="cx"> 2015-04-28 Filip Pizlo <fpizlo@apple.com>
</span><span class="cx">
</span><span class="cx"> VarargsForwardingPhase should only consider MovHints that have the candidate as a child
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGFixupPhasecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp (183494 => 183495)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp 2015-04-28 18:36:59 UTC (rev 183494)
+++ trunk/Source/JavaScriptCore/dfg/DFGFixupPhase.cpp 2015-04-28 18:54:12 UTC (rev 183495)
</span><span class="lines">@@ -737,6 +737,8 @@
</span><span class="cx"> fixEdge<Int32Use>(node->child1());
</span><span class="cx"> else if (node->child1()->shouldSpeculateNumber())
</span><span class="cx"> fixEdge<DoubleRepUse>(node->child1());
</span><ins>+ else if (node->child1()->shouldSpeculateString())
+ fixEdge<StringUse>(node->child1());
</ins><span class="cx"> break;
</span><span class="cx"> }
</span><span class="cx">
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGSpeculativeJITcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp (183494 => 183495)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp 2015-04-28 18:36:59 UTC (rev 183494)
+++ trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.cpp 2015-04-28 18:54:12 UTC (rev 183495)
</span><span class="lines">@@ -4040,6 +4040,15 @@
</span><span class="cx"> unblessedBooleanResult(eqGPR, node);
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+void SpeculativeJIT::emitStringBranch(Edge nodeUse, BasicBlock* taken, BasicBlock* notTaken)
+{
+ SpeculateCellOperand str(this, nodeUse);
+ speculateString(nodeUse, str.gpr());
+ branchTest32(JITCompiler::NonZero, MacroAssembler::Address(str.gpr(), JSString::offsetOfLength()), taken);
+ jump(notTaken);
+ noResult(m_currentNode);
+}
+
</ins><span class="cx"> void SpeculativeJIT::compileConstantStoragePointer(Node* node)
</span><span class="cx"> {
</span><span class="cx"> GPRTemporary storage(this);
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGSpeculativeJITh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.h (183494 => 183495)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.h 2015-04-28 18:36:59 UTC (rev 183494)
+++ trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT.h 2015-04-28 18:54:12 UTC (rev 183495)
</span><span class="lines">@@ -2103,6 +2103,7 @@
</span><span class="cx"> void compileMiscStrictEq(Node*);
</span><span class="cx">
</span><span class="cx"> void emitObjectOrOtherBranch(Edge value, BasicBlock* taken, BasicBlock* notTaken);
</span><ins>+ void emitStringBranch(Edge value, BasicBlock* taken, BasicBlock* notTaken);
</ins><span class="cx"> void emitBranch(Node*);
</span><span class="cx">
</span><span class="cx"> struct StringSwitchCase {
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGSpeculativeJIT32_64cpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT32_64.cpp (183494 => 183495)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT32_64.cpp 2015-04-28 18:36:59 UTC (rev 183494)
+++ trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT32_64.cpp 2015-04-28 18:54:12 UTC (rev 183495)
</span><span class="lines">@@ -1573,7 +1573,12 @@
</span><span class="cx"> emitObjectOrOtherBranch(node->child1(), taken, notTaken);
</span><span class="cx"> return;
</span><span class="cx"> }
</span><del>-
</del><ins>+
+ case StringUse: {
+ emitStringBranch(node->child1(), taken, notTaken);
+ return;
+ }
+
</ins><span class="cx"> case DoubleRepUse:
</span><span class="cx"> case Int32Use: {
</span><span class="cx"> if (node->child1().useKind() == Int32Use) {
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGSpeculativeJIT64cpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT64.cpp (183494 => 183495)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT64.cpp 2015-04-28 18:36:59 UTC (rev 183494)
+++ trunk/Source/JavaScriptCore/dfg/DFGSpeculativeJIT64.cpp 2015-04-28 18:54:12 UTC (rev 183495)
</span><span class="lines">@@ -1742,6 +1742,11 @@
</span><span class="cx"> return;
</span><span class="cx"> }
</span><span class="cx">
</span><ins>+ case StringUse: {
+ emitStringBranch(node->child1(), taken, notTaken);
+ return;
+ }
+
</ins><span class="cx"> case UntypedUse:
</span><span class="cx"> case BooleanUse: {
</span><span class="cx"> JSValueOperand value(this, node->child1(), ManualOperandSpeculation);
</span></span></pre>
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