[webkit-changes] [91041] trunk/Source/JavaScriptCore

Thu, 14 Jul 2011 19:06:17 -0700

Title: [91041] trunk/Source/_javascript_Core
Revision
91041
Author
[email protected]
Date
2011-07-14 19:06:10 -0700 (Thu, 14 Jul 2011)

Log Message

DFG JIT does not optimize Branch as well as it could.
https://bugs.webkit.org/show_bug.cgi?id=64574

Patch by Filip Pizlo <[email protected]> on 2011-07-14
Reviewed by Gavin Barraclough.

This creates a common code path for emitting unfused branches, which does
no speculation, and only performs a slow call if absolutely necessary.

* dfg/DFGJITCodeGenerator.cpp:
(JSC::DFG::JITCodeGenerator::emitBranch):
* dfg/DFGJITCodeGenerator.h:
* dfg/DFGNonSpeculativeJIT.cpp:
(JSC::DFG::NonSpeculativeJIT::compile):
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compile):

Modified Paths

Diff

Modified: trunk/Source/_javascript_Core/ChangeLog (91040 => 91041)


--- trunk/Source/_javascript_Core/ChangeLog	2011-07-15 01:51:45 UTC (rev 91040)
+++ trunk/Source/_javascript_Core/ChangeLog	2011-07-15 02:06:10 UTC (rev 91041)
@@ -1,5 +1,23 @@
 2011-07-14  Filip Pizlo  <[email protected]>
 
+        DFG JIT does not optimize Branch as well as it could.
+        https://bugs.webkit.org/show_bug.cgi?id=64574
+
+        Reviewed by Gavin Barraclough.
+        
+        This creates a common code path for emitting unfused branches, which does
+        no speculation, and only performs a slow call if absolutely necessary.
+
+        * dfg/DFGJITCodeGenerator.cpp:
+        (JSC::DFG::JITCodeGenerator::emitBranch):
+        * dfg/DFGJITCodeGenerator.h:
+        * dfg/DFGNonSpeculativeJIT.cpp:
+        (JSC::DFG::NonSpeculativeJIT::compile):
+        * dfg/DFGSpeculativeJIT.cpp:
+        (JSC::DFG::SpeculativeJIT::compile):
+
+2011-07-14  Filip Pizlo  <[email protected]>
+
         GC allocation fast path has too many operations.
         https://bugs.webkit.org/show_bug.cgi?id=64493

Modified: trunk/Source/_javascript_Core/dfg/DFGJITCodeGenerator.cpp (91040 => 91041)


--- trunk/Source/_javascript_Core/dfg/DFGJITCodeGenerator.cpp	2011-07-15 01:51:45 UTC (rev 91040)
+++ trunk/Source/_javascript_Core/dfg/DFGJITCodeGenerator.cpp	2011-07-15 02:06:10 UTC (rev 91041)
@@ -468,6 +468,36 @@
     m_jit.addMethodGet(slowCall, structToCompare, protoObj, protoStructToCompare, putFunction);
 }
 
+void JITCodeGenerator::emitBranch(Node& node)
+{
+    JSValueOperand value(this, node.child1());
+    GPRReg valueGPR = value.gpr();
+    
+    GPRTemporary result(this);
+    GPRReg resultGPR = result.gpr();
+    
+    BlockIndex taken = m_jit.graph().blockIndexForBytecodeOffset(node.takenBytecodeOffset());
+    BlockIndex notTaken = m_jit.graph().blockIndexForBytecodeOffset(node.notTakenBytecodeOffset());
+
+    addBranch(m_jit.branchPtr(MacroAssembler::Equal, valueGPR, MacroAssembler::ImmPtr(JSValue::encode(jsNumber(0)))), notTaken);
+    addBranch(m_jit.branchPtr(MacroAssembler::AboveOrEqual, valueGPR, GPRInfo::tagTypeNumberRegister), taken);
+    addBranch(m_jit.branchPtr(MacroAssembler::Equal, valueGPR, MacroAssembler::ImmPtr(JSValue::encode(jsBoolean(false)))), notTaken);
+    addBranch(m_jit.branchPtr(MacroAssembler::Equal, valueGPR, MacroAssembler::ImmPtr(JSValue::encode(jsBoolean(true)))), taken);
+    
+    silentSpillAllRegisters(resultGPR);
+    m_jit.move(valueGPR, GPRInfo::argumentGPR1);
+    m_jit.move(GPRInfo::callFrameRegister, GPRInfo::argumentGPR0);
+    appendCallWithExceptionCheck(dfgConvertJSValueToBoolean);
+    m_jit.move(GPRInfo::returnValueGPR, resultGPR);
+    silentFillAllRegisters(resultGPR);
+    
+    addBranch(m_jit.branchTest8(MacroAssembler::NonZero, resultGPR), taken);
+    if (notTaken != (m_block + 1))
+        addBranch(m_jit.jump(), notTaken);
+    
+    noResult(m_compileIndex);
+}
+
 void JITCodeGenerator::emitCall(Node& node)
 {
     P_DFGOperation_E slowCallFunction;

Modified: trunk/Source/_javascript_Core/dfg/DFGJITCodeGenerator.h (91040 => 91041)


--- trunk/Source/_javascript_Core/dfg/DFGJITCodeGenerator.h	2011-07-15 01:51:45 UTC (rev 91040)
+++ trunk/Source/_javascript_Core/dfg/DFGJITCodeGenerator.h	2011-07-15 02:06:10 UTC (rev 91041)
@@ -535,6 +535,8 @@
     void cachedPutById(GPRReg baseGPR, GPRReg valueGPR, GPRReg scratchGPR, unsigned identifierNumber, PutKind, JITCompiler::Jump slowPathTarget = JITCompiler::Jump());
     void cachedGetMethod(GPRReg baseGPR, GPRReg resultGPR, unsigned identifierNumber, JITCompiler::Jump slowPathTarget = JITCompiler::Jump());
     
+    void emitBranch(Node&);
+    
     MacroAssembler::Address addressOfCallData(int idx)
     {
         return MacroAssembler::Address(GPRInfo::callFrameRegister, (m_jit.codeBlock()->m_numCalleeRegisters + idx) * static_cast<int>(sizeof(Register)));

Modified: trunk/Source/_javascript_Core/dfg/DFGNonSpeculativeJIT.cpp (91040 => 91041)


--- trunk/Source/_javascript_Core/dfg/DFGNonSpeculativeJIT.cpp	2011-07-15 01:51:45 UTC (rev 91040)
+++ trunk/Source/_javascript_Core/dfg/DFGNonSpeculativeJIT.cpp	2011-07-15 02:06:10 UTC (rev 91041)
@@ -920,24 +920,9 @@
         break;
     }
 
-    case Branch: {
-        JSValueOperand value(this, node.child1());
-        GPRReg valueGPR = value.gpr();
-        flushRegisters();
-
-        GPRResult result(this);
-        callOperation(dfgConvertJSValueToBoolean, result.gpr(), valueGPR);
-
-        BlockIndex taken = m_jit.graph().blockIndexForBytecodeOffset(node.takenBytecodeOffset());
-        BlockIndex notTaken = m_jit.graph().blockIndexForBytecodeOffset(node.notTakenBytecodeOffset());
-
-        addBranch(m_jit.branchTest8(MacroAssembler::NonZero, result.gpr()), taken);
-        if (notTaken != (m_block + 1))
-            addBranch(m_jit.jump(), notTaken);
-
-        noResult(m_compileIndex);
+    case Branch:
+        emitBranch(node);
         break;
-    }
 
     case Return: {
         ASSERT(GPRInfo::callFrameRegister != GPRInfo::regT1);

Modified: trunk/Source/_javascript_Core/dfg/DFGSpeculativeJIT.cpp (91040 => 91041)


--- trunk/Source/_javascript_Core/dfg/DFGSpeculativeJIT.cpp	2011-07-15 01:51:45 UTC (rev 91040)
+++ trunk/Source/_javascript_Core/dfg/DFGSpeculativeJIT.cpp	2011-07-15 02:06:10 UTC (rev 91041)
@@ -943,31 +943,9 @@
         break;
     }
 
-    case Branch: {
-        JSValueOperand value(this, node.child1());
-        GPRReg valueReg = value.gpr();
-
-        BlockIndex taken = m_jit.graph().blockIndexForBytecodeOffset(node.takenBytecodeOffset());
-        BlockIndex notTaken = m_jit.graph().blockIndexForBytecodeOffset(node.notTakenBytecodeOffset());
-
-        // Integers
-        addBranch(m_jit.branchPtr(MacroAssembler::Equal, valueReg, MacroAssembler::ImmPtr(JSValue::encode(jsNumber(0)))), notTaken);
-        MacroAssembler::Jump isNonZeroInteger = m_jit.branchPtr(MacroAssembler::AboveOrEqual, valueReg, GPRInfo::tagTypeNumberRegister);
-
-        // Booleans
-        addBranch(m_jit.branchPtr(MacroAssembler::Equal, valueReg, MacroAssembler::ImmPtr(JSValue::encode(jsBoolean(false)))), notTaken);
-        speculationCheck(m_jit.branchPtr(MacroAssembler::NotEqual, valueReg, MacroAssembler::ImmPtr(JSValue::encode(jsBoolean(true)))));
-
-        if (taken == (m_block + 1))
-            isNonZeroInteger.link(&m_jit);
-        else {
-            addBranch(isNonZeroInteger, taken);
-            addBranch(m_jit.jump(), taken);
-        }
-
-        noResult(m_compileIndex);
+    case Branch:
+        emitBranch(node);
         break;
-    }
 
     case Return: {
         ASSERT(GPRInfo::callFrameRegister != GPRInfo::regT1);

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