[webkit-dev] Non JS Function call.

[Oliver Hunt]

op_call_NotJSFunction is only referenced during the final linking phase.

Actual compilation requires two distinct operations:  1) planting the call instruction and 2) linking the call target after the code has been relocated.  Here is the (64-bit) version of the call + link logic:

...
    preserveReturnAddressAfterCall(regT3);
    emitPutToCallFrameHeader(regT3, RegisterFile::ReturnPC);
    emitPutImmediateToCallFrameHeader(0, RegisterFile::CodeBlock);

    storePtr(callFrameRegister, &m_globalData->topCallFrame);
    restoreArgumentReference();
    Call callCallNotJSFunction = call();     <-- here is the call
    emitGetFromCallFrameHeaderPtr(RegisterFile::CallerFrame, callFrameRegister);
    restoreReturnAddressBeforeReturn(regT3);
    ret();
...
    patchBuffer.link(callCallNotJSFunction, FunctionPtr(cti_op_call_NotJSFunction));  <-- here is us linking the call

--Oliver



On Jul 24, 2012, at 1:45 PM, vahe vardanyan wrote:

> Grep gives nothing, there is only one mention of op_call_NotJSFunction in privateCompileCTIMachineTrampolines(JITOpcodes.cpp), but I don't see any call instruction there.
> 
> Still can't understand how calls orgonized in SXF.  
> 
> On 24 July 2012 20:07, Filip Pizlo <fpizlo at apple.com> wrote:
> 
> On Jul 24, 2012, at 5:51 AM, vahe vardanyan <vahagner at gmail.com> wrote:
> 
> > Hi all.
> >
> > As I understand in SFX all non JS functions calls go trough JITStubs:op_call_NotJSFunction function.
> >
> > But in which point, where, the op_call_NotJSFunction function is called?
> 
> It's called from code generated by the JIT. I would start by running a command called "grep" on the code in the "jit" directory to search for mentions of NotJSFunction.
> 
> >
> > Can anyone please explain how function calls are implemented in SFX(simple jit).
> >
> > Thanks for attention
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> > webkit-dev at lists.webkit.org
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