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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/202101">202101</a></dd>
<dt>Author</dt> <dd>keith_miller@apple.com</dd>
<dt>Date</dt> <dd>2016-06-15 12:40:43 -0700 (Wed, 15 Jun 2016)</dd>
</dl>
<h3>Log Message</h3>
<pre>DFGByteCodeParser should be able to infer the value of unset properties in MultiGetByOffset
https://bugs.webkit.org/show_bug.cgi?id=158802
Reviewed by Filip Pizlo.
This patch adds support for unset properties in MultiGetByOffset. Since MultiGetByOffset
already supports constant values this patch just adds a constant case where the fetched
value is undefined. Fortunately (or unfortunately) we don't support object allocation
sinking for constant cases of MultiGetByOffset, which means we don't need to adjust any
in that phase.
* dfg/DFGByteCodeParser.cpp:
(JSC::DFG::ByteCodeParser::planLoad):
(JSC::DFG::ByteCodeParser::handleGetById):
* dfg/DFGMultiGetByOffsetData.h:
* tests/stress/multi-get-by-offset-proto-or-unset.js: Added.
(foo):
* tests/stress/multi-get-by-offset-proto-self-or-unset.js: Added.
(foo):
* tests/stress/multi-get-by-offset-self-or-unset.js: Added.
(foo):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGByteCodeParsercpp">trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp</a></li>
<li><a href="#trunkSourceJavaScriptCoredfgDFGMultiGetByOffsetDatah">trunk/Source/JavaScriptCore/dfg/DFGMultiGetByOffsetData.h</a></li>
</ul>
<h3>Added Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoretestsstressmultigetbyoffsetprotoorunsetjs">trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-proto-or-unset.js</a></li>
<li><a href="#trunkSourceJavaScriptCoretestsstressmultigetbyoffsetprotoselforunsetjs">trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-proto-self-or-unset.js</a></li>
<li><a href="#trunkSourceJavaScriptCoretestsstressmultigetbyoffsetselforunsetjs">trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-self-or-unset.js</a></li>
</ul>
</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (202100 => 202101)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2016-06-15 19:32:50 UTC (rev 202100)
+++ trunk/Source/JavaScriptCore/ChangeLog 2016-06-15 19:40:43 UTC (rev 202101)
</span><span class="lines">@@ -1,3 +1,27 @@
</span><ins>+2016-06-15 Keith Miller <keith_miller@apple.com>
+
+ DFGByteCodeParser should be able to infer the value of unset properties in MultiGetByOffset
+ https://bugs.webkit.org/show_bug.cgi?id=158802
+
+ Reviewed by Filip Pizlo.
+
+ This patch adds support for unset properties in MultiGetByOffset. Since MultiGetByOffset
+ already supports constant values this patch just adds a constant case where the fetched
+ value is undefined. Fortunately (or unfortunately) we don't support object allocation
+ sinking for constant cases of MultiGetByOffset, which means we don't need to adjust any
+ in that phase.
+
+ * dfg/DFGByteCodeParser.cpp:
+ (JSC::DFG::ByteCodeParser::planLoad):
+ (JSC::DFG::ByteCodeParser::handleGetById):
+ * dfg/DFGMultiGetByOffsetData.h:
+ * tests/stress/multi-get-by-offset-proto-or-unset.js: Added.
+ (foo):
+ * tests/stress/multi-get-by-offset-proto-self-or-unset.js: Added.
+ (foo):
+ * tests/stress/multi-get-by-offset-self-or-unset.js: Added.
+ (foo):
+
</ins><span class="cx"> 2016-06-15 Chris Dumez <cdumez@apple.com>
</span><span class="cx">
</span><span class="cx"> Unreviewed GCC build fix after r202098.
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGByteCodeParsercpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp (202100 => 202101)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp 2016-06-15 19:32:50 UTC (rev 202100)
+++ trunk/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp 2016-06-15 19:40:43 UTC (rev 202101)
</span><span class="lines">@@ -2942,7 +2942,11 @@
</span><span class="cx"> break;
</span><span class="cx"> }
</span><span class="cx"> }
</span><del>- RELEASE_ASSERT(!!result);
</del><ins>+ if (!result) {
+ // We have a unset property.
+ ASSERT(!conditionSet.numberOfConditionsWithKind(PropertyCondition::Presence));
+ return GetByOffsetMethod::constant(m_constantUndefined);
+ }
</ins><span class="cx"> return result;
</span><span class="cx"> }
</span><span class="cx">
</span><span class="lines">@@ -3150,7 +3154,7 @@
</span><span class="cx"> // optimal, if there is some rarely executed case in the chain that requires a lot
</span><span class="cx"> // of checks and those checks are not watchpointable.
</span><span class="cx"> for (const GetByIdVariant& variant : getByIdStatus.variants()) {
</span><del>- if (variant.intrinsic() != NoIntrinsic || variant.isPropertyUnset()) {
</del><ins>+ if (variant.intrinsic() != NoIntrinsic) {
</ins><span class="cx"> set(VirtualRegister(destinationOperand),
</span><span class="cx"> addToGraph(getById, OpInfo(identifierNumber), OpInfo(prediction), base));
</span><span class="cx"> return;
</span><span class="lines">@@ -3163,7 +3167,7 @@
</span><span class="cx"> GetByOffsetMethod::load(variant.offset())));
</span><span class="cx"> continue;
</span><span class="cx"> }
</span><del>-
</del><ins>+
</ins><span class="cx"> GetByOffsetMethod method = planLoad(variant.conditionSet());
</span><span class="cx"> if (!method) {
</span><span class="cx"> set(VirtualRegister(destinationOperand),
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoredfgDFGMultiGetByOffsetDatah"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/dfg/DFGMultiGetByOffsetData.h (202100 => 202101)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/dfg/DFGMultiGetByOffsetData.h 2016-06-15 19:32:50 UTC (rev 202100)
+++ trunk/Source/JavaScriptCore/dfg/DFGMultiGetByOffsetData.h 2016-06-15 19:40:43 UTC (rev 202101)
</span><span class="lines">@@ -40,6 +40,9 @@
</span><span class="cx"> public:
</span><span class="cx"> enum Kind {
</span><span class="cx"> Invalid,
</span><ins>+ // Constant might mean either that we have some fixed property or that the
+ // property is unset and we know the result is undefined. We don't distingish
+ // between these cases because no one cares about this distintion yet.
</ins><span class="cx"> Constant,
</span><span class="cx"> Load,
</span><span class="cx"> LoadFromPrototype
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoretestsstressmultigetbyoffsetprotoorunsetjs"></a>
<div class="addfile"><h4>Added: trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-proto-or-unset.js (0 => 202101)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-proto-or-unset.js (rev 0)
+++ trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-proto-or-unset.js 2016-06-15 19:40:43 UTC (rev 202101)
</span><span class="lines">@@ -0,0 +1,41 @@
</span><ins>+function foo(o, start) {
+ var result = 0;
+ for (var i = 0; i < 100; ++i)
+ result += o.f;
+ return result;
+}
+
+noInline(foo);
+
+
+var p = {};
+p.f = 42;
+var o = Object.create(p);
+
+var q = {}
+q.f = 42;
+
+var f = {};
+
+for (var i = 0; i < 10000; ++i)
+ o.f = i;
+o.f = 42;
+
+for (var i = 0; i < 10000; ++i) {
+ if (i % 100 === 0) {
+ if (foo(q) !== 42000)
+ throw new Error("bad result: " + result);
+ }
+
+ if (foo(o) !== 4200)
+ throw new Error("bad result: " + result);
+ var result = foo(f);
+ if (!Number.isNaN(result))
+ throw "Error: bad result: " + result;
+}
+
+var q = {};
+q.f = 43;
+var result = foo(q);
+if (result != 100 * 43)
+ throw "Error: bad result at end: " + result;
</ins></span></pre></div>
<a id="trunkSourceJavaScriptCoretestsstressmultigetbyoffsetprotoselforunsetjs"></a>
<div class="addfile"><h4>Added: trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-proto-self-or-unset.js (0 => 202101)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-proto-self-or-unset.js (rev 0)
+++ trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-proto-self-or-unset.js 2016-06-15 19:40:43 UTC (rev 202101)
</span><span class="lines">@@ -0,0 +1,30 @@
</span><ins>+function foo(o, start) {
+ var result = 0;
+ for (var i = 0; i < 100; ++i)
+ result += o.f;
+ return result;
+}
+
+noInline(foo);
+
+var o = {};
+o.f = 42;
+var f = {};
+
+for (var i = 0; i < 10000; ++i)
+ o.f = i;
+o.f = 42;
+
+for (var i = 0; i < 10000; ++i) {
+ if (foo(o) !== 4200)
+ throw new Error("bad result: " + result);
+ var result = foo(f);
+ if (!Number.isNaN(result))
+ throw "Error: bad result: " + result;
+}
+
+var q = {};
+q.f = 43;
+var result = foo(q);
+if (result != 100 * 43)
+ throw "Error: bad result at end: " + result;
</ins></span></pre></div>
<a id="trunkSourceJavaScriptCoretestsstressmultigetbyoffsetselforunsetjs"></a>
<div class="addfile"><h4>Added: trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-self-or-unset.js (0 => 202101)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-self-or-unset.js (rev 0)
+++ trunk/Source/JavaScriptCore/tests/stress/multi-get-by-offset-self-or-unset.js 2016-06-15 19:40:43 UTC (rev 202101)
</span><span class="lines">@@ -0,0 +1,30 @@
</span><ins>+function foo(o, start) {
+ var result = 0;
+ for (var i = 0; i < 100; ++i)
+ result += o.f;
+ return result;
+}
+
+noInline(foo);
+
+var o = {};
+o.f = 42;
+var f = {};
+
+for (var i = 0; i < 10000; ++i)
+ o.f = i;
+o.f = 42;
+
+for (var i = 0; i < 10000; ++i) {
+ if (foo(o) !== 4200)
+ throw new Error("bad result: " + result);
+ var result = foo(f);
+ if (!Number.isNaN(result))
+ throw "Error: bad result: " + result;
+}
+
+var q = {};
+q.f = 43;
+var result = foo(q);
+if (result != 100 * 43)
+ throw "Error: bad result at end: " + result;
</ins></span></pre>
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