DFG JIT Construct opcode takes a this argument even though it's

not passed
https://bugs.webkit.org/show_bug.cgi?id=68782

Reviewed by Oliver Hunt.

This is performance-neutral, mostly. It's a slight speed-up on
v8-splay.

* dfg/DFGByteCodeParser.cpp:
(JSC::DFG::ByteCodeParser::addCall):
* dfg/DFGJITCodeGenerator.cpp:
(JSC::DFG::JITCodeGenerator::emitCall):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@95927 268f45cc-cd09-0410-ab3c-d52691b4dbfc

diff --git a/Source/JavaScriptCore/ChangeLog b/Source/JavaScriptCore/ChangeLog
index 0b953d3..156cd7a 100644 (file)
--- a/Source/JavaScriptCore/ChangeLog
+++ b/Source/JavaScriptCore/ChangeLog
@@ -1,5 +1,21 @@
 2011-09-25  Filip Pizlo  <fpizlo@apple.com>
 
+        DFG JIT Construct opcode takes a this argument even though it's
+        not passed
+        https://bugs.webkit.org/show_bug.cgi?id=68782
+
+        Reviewed by Oliver Hunt.
+        
+        This is performance-neutral, mostly. It's a slight speed-up on
+        v8-splay.
+        
+        * dfg/DFGByteCodeParser.cpp:
+        (JSC::DFG::ByteCodeParser::addCall):
+        * dfg/DFGJITCodeGenerator.cpp:
+        (JSC::DFG::JITCodeGenerator::emitCall):
+
+2011-09-25  Filip Pizlo  <fpizlo@apple.com>
+
         DFG tracking of the value in cachedResultRegister does not handle
         op_mov correctly
         https://bugs.webkit.org/show_bug.cgi?id=68781

diff --git a/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp b/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp
index 823fa8d..0e971a0 100644 (file)
--- a/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp
+++ b/Source/JavaScriptCore/dfg/DFGByteCodeParser.cpp
@@ -442,7 +442,7 @@ private:
         int argCount = currentInstruction[2].u.operand;
         int registerOffset = currentInstruction[3].u.operand;
         int firstArg = registerOffset - argCount - RegisterFile::CallFrameHeaderSize;
-        for (int argIdx = firstArg; argIdx < firstArg + argCount; argIdx++)
+        for (int argIdx = firstArg + (op == Construct ? 1 : 0); argIdx < firstArg + argCount; argIdx++)
             addVarArgChild(get(argIdx));
         NodeIndex call = addToGraph(Node::VarArg, op, OpInfo(0), OpInfo(prediction));
         if (interpreter->getOpcodeID(putInstruction->u.opcode) == op_call_put_result)

diff --git a/Source/JavaScriptCore/dfg/DFGJITCodeGenerator.cpp b/Source/JavaScriptCore/dfg/DFGJITCodeGenerator.cpp
index 297c9de..5df549d 100644 (file)
--- a/Source/JavaScriptCore/dfg/DFGJITCodeGenerator.cpp
+++ b/Source/JavaScriptCore/dfg/DFGJITCodeGenerator.cpp
@@ -1883,29 +1883,30 @@ void JITCodeGenerator::emitCall(Node& node)
     // receiver (method call). subsequent children are the arguments.
     int numArgs = node.numChildren() - 1;
     
+    // For constructors, the this argument is not passed but we have to make space
+    // for it.
+    int numPassedArgs = numArgs + (isCall ? 0 : 1);
+    
     // amount of stuff (in units of sizeof(Register)) that we need to place at the
     // top of the JS stack.
     int callDataSize = 0;
 
     // first there are the arguments
-    callDataSize += numArgs;
+    callDataSize += numPassedArgs;
     
     // and then there is the call frame header
     callDataSize += RegisterFile::CallFrameHeaderSize;
     
-    m_jit.storePtr(MacroAssembler::TrustedImmPtr(JSValue::encode(jsNumber(numArgs))), addressOfCallData(RegisterFile::ArgumentCount));
+    m_jit.storePtr(MacroAssembler::TrustedImmPtr(JSValue::encode(jsNumber(numPassedArgs))), addressOfCallData(RegisterFile::ArgumentCount));
     m_jit.storePtr(GPRInfo::callFrameRegister, addressOfCallData(RegisterFile::CallerFrame));
     
-    if (node.op == Construct)
-        use(m_jit.graph().m_varArgChildren[node.firstChild() + 1]);
-    
-    for (int argIdx = (node.op == Call ? 0 : 1); argIdx < numArgs; argIdx++) {
+    for (int argIdx = 0; argIdx < numArgs; argIdx++) {
         NodeIndex argNodeIndex = m_jit.graph().m_varArgChildren[node.firstChild() + 1 + argIdx];
         JSValueOperand arg(this, argNodeIndex);
         GPRReg argGPR = arg.gpr();
         use(argNodeIndex);
         
-        m_jit.storePtr(argGPR, addressOfCallData(-callDataSize + argIdx));
+        m_jit.storePtr(argGPR, addressOfCallData(-callDataSize + argIdx + (isCall ? 0 : 1)));
     }
     
     m_jit.storePtr(calleeGPR, addressOfCallData(RegisterFile::Callee));
@@ -1933,7 +1934,7 @@ void JITCodeGenerator::emitCall(Node& node)
     
     m_jit.addPtr(Imm32(m_jit.codeBlock()->m_numCalleeRegisters * sizeof(Register)), GPRInfo::callFrameRegister, GPRInfo::argumentGPR0);
     JITCompiler::Call slowCall = m_jit.appendCallWithFastExceptionCheck(slowCallFunction, m_jit.graph()[m_compileIndex].codeOrigin);
-    m_jit.move(Imm32(numArgs), GPRInfo::regT1);
+    m_jit.move(Imm32(numPassedArgs), GPRInfo::regT1);
     m_jit.addPtr(Imm32(m_jit.codeBlock()->m_numCalleeRegisters * sizeof(Register)), GPRInfo::callFrameRegister);
     m_jit.notifyCall(m_jit.call(GPRInfo::returnValueGPR), m_jit.graph()[m_compileIndex].codeOrigin);