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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/191978">191978</a></dd>
<dt>Author</dt> <dd>mark.lam@apple.com</dd>
<dt>Date</dt> <dd>2015-11-03 14:13:52 -0800 (Tue, 03 Nov 2015)</dd>
</dl>
<h3>Log Message</h3>
<pre>Fix some inefficiencies in the baseline usage of JITAddGenerator.
https://bugs.webkit.org/show_bug.cgi?id=150850
Reviewed by Michael Saboff.
1. emit_op_add() was loading the operands twice. Removed the redundant load.
2. The snippet may decide that it wants to go the slow path route all the time.
In that case, emit_op_add will end up emitting a branch to an out of line
slow path followed by some dead code to store the result of the fast path
on to the stack.
We now check if the snippet determined that there's no fast path, and just
emit the slow path inline, and skip the dead store of the fast path result.
* jit/JITArithmetic.cpp:
(JSC::JIT::emit_op_add):</pre>
<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCorejitJITArithmeticcpp">trunk/Source/JavaScriptCore/jit/JITArithmetic.cpp</a></li>
</ul>
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<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (191977 => 191978)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog 2015-11-03 22:03:48 UTC (rev 191977)
+++ trunk/Source/JavaScriptCore/ChangeLog 2015-11-03 22:13:52 UTC (rev 191978)
</span><span class="lines">@@ -1,3 +1,21 @@
</span><ins>+2015-11-03 Mark Lam <mark.lam@apple.com>
+
+ Fix some inefficiencies in the baseline usage of JITAddGenerator.
+ https://bugs.webkit.org/show_bug.cgi?id=150850
+
+ Reviewed by Michael Saboff.
+
+ 1. emit_op_add() was loading the operands twice. Removed the redundant load.
+ 2. The snippet may decide that it wants to go the slow path route all the time.
+ In that case, emit_op_add will end up emitting a branch to an out of line
+ slow path followed by some dead code to store the result of the fast path
+ on to the stack.
+ We now check if the snippet determined that there's no fast path, and just
+ emit the slow path inline, and skip the dead store of the fast path result.
+
+ * jit/JITArithmetic.cpp:
+ (JSC::JIT::emit_op_add):
+
</ins><span class="cx"> 2015-11-03 Filip Pizlo <fpizlo@apple.com>
</span><span class="cx">
</span><span class="cx"> B3::LowerToAir should do copy propagation
</span></span></pre></div>
<a id="trunkSourceJavaScriptCorejitJITArithmeticcpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/jit/JITArithmetic.cpp (191977 => 191978)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/jit/JITArithmetic.cpp 2015-11-03 22:03:48 UTC (rev 191977)
+++ trunk/Source/JavaScriptCore/jit/JITArithmetic.cpp 2015-11-03 22:13:52 UTC (rev 191978)
</span><span class="lines">@@ -932,9 +932,6 @@
</span><span class="cx"> FPRReg scratchFPR = fpRegT2;
</span><span class="cx"> #endif
</span><span class="cx">
</span><del>- emitGetVirtualRegister(op1, leftRegs);
- emitGetVirtualRegister(op2, rightRegs);
-
</del><span class="cx"> bool leftIsConstInt32 = isOperandConstantInt(op1);
</span><span class="cx"> bool rightIsConstInt32 = isOperandConstantInt(op2);
</span><span class="cx"> JITAddGenerator::OperandsConstness operandsConstness;
</span><span class="lines">@@ -968,10 +965,17 @@
</span><span class="cx"> fpRegT0, fpRegT1, scratchGPR, scratchFPR);
</span><span class="cx">
</span><span class="cx"> gen.generateFastPath(*this);
</span><del>- gen.endJumpList().link(this);
- emitPutVirtualRegister(result, resultRegs);
</del><span class="cx">
</span><del>- addSlowCase(gen.slowPathJumpList());
</del><ins>+ if (!gen.endJumpList().empty()) {
+ gen.endJumpList().link(this);
+ emitPutVirtualRegister(result, resultRegs);
+
+ addSlowCase(gen.slowPathJumpList());
+ } else {
+ gen.slowPathJumpList().link(this);
+ JITSlowPathCall slowPathCall(this, currentInstruction, slow_path_add);
+ slowPathCall.call();
+ }
</ins><span class="cx"> }
</span><span class="cx">
</span><span class="cx"> void JIT::emitSlow_op_add(Instruction* currentInstruction, Vector<SlowCaseEntry>::iterator& iter)
</span></span></pre>
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