[Webkit-unassigned] [Bug 79554] DFG should support activations and nested functions

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=79554





--- Comment #3 from Filip Pizlo <fpizlo at apple.com>  2012-02-25 12:36:20 PST ---
(In reply to comment #2)
> (From update of attachment 128844 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=128844&action=review
> 
> Basically r=me, but it would be nice if you could try to remove the duplicated code :-(
> 
> Also we probably want a bug to track to do function instantiation inline like we do in the baseline JIT.
> 
> > Source/JavaScriptCore/dfg/DFGSpeculativeJIT32_64.cpp:3540
> > +    case CreateActivation: {
> > +        JSValueOperand value(this, node.child1());
> > +        GPRTemporary result(this, value);
> > +        
> > +        GPRReg valueTagGPR = value.tagGPR();
> > +        GPRReg valuePayloadGPR = value.payloadGPR();
> > +        GPRReg resultGPR = result.gpr();
> > +        
> > +        m_jit.move(valuePayloadGPR, resultGPR);
> > +        
> > +        JITCompiler::Jump alreadyCreated = m_jit.branch32(JITCompiler::NotEqual, valueTagGPR, TrustedImm32(JSValue::EmptyValueTag));
> > +        
> > +        silentSpillAllRegisters(resultGPR);
> > +        callOperation(operationCreateActivation, resultGPR);
> > +        silentFillAllRegisters(resultGPR);
> > +        
> > +        alreadyCreated.link(&m_jit);
> > +        
> > +        cellResult(resultGPR, m_compileIndex);
> > +        break;
> > +    }
> > +        
> > +    case TearOffActivation: {
> > +        JSValueOperand value(this, node.child1());
> > +        GPRTemporary result(this, value);
> > +        
> > +        GPRReg valueTagGPR = value.tagGPR();
> > +        GPRReg valuePayloadGPR = value.payloadGPR();
> > +        
> > +        JITCompiler::Jump notCreated = m_jit.branch32(JITCompiler::Equal, valueTagGPR, TrustedImm32(JSValue::EmptyValueTag));
> > +        
> > +        silentSpillAllRegisters(InvalidGPRReg);
> > +        callOperation(operationTearOffActivation, valuePayloadGPR);
> > +        silentFillAllRegisters(InvalidGPRReg);
> > +        
> > +        notCreated.link(&m_jit);
> > +        
> > +        noResult(m_compileIndex);
> > +        break;
> > +    }
> > +        
> > +    case NewFunctionNoCheck: {
> > +        GPRResult result(this);
> > +        GPRReg resultGPR = result.gpr();
> > +        flushRegisters();
> > +        callOperation(
> > +            operationNewFunction, resultGPR, m_jit.codeBlock()->functionDecl(node.functionDeclIndex()));
> > +        cellResult(resultGPR, m_compileIndex);
> > +        break;
> > +    }
> 
> It feels like these should be entirely sharable between  32bit and 64bit implementations

Actually not.  The only parts that are sharable are the really easy ones (NewFunctionNoCheck and NewFunctionExpression).  The others are not sharable because they have different numbers of registers and use different logic for testing empty values.

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