[LLVMdev] Calling Conventions, function prologs and epilogs.

[Aaron Gray]

On Thu, Apr 9, 2009 at 7:19 PM, Dale Johannesen <dalej at apple.com> wrote:

>
>  On Apr 9, 2009, at 11:11 AMPDT, Aaron Gray wrote:
>
>  On Thu, Apr 9, 2009 at 4:34 PM, Anton Korobeynikov <
> anton at korobeynikov.info> wrote:
>
>> Hello, Aaron
>>
>> > How/where are function prologs and epilogs generated, is it bespoke C++
>> code
>> > or TableGen generated ?
>> >
>> > If someone could point me in the right direction please.
>> Calling convention is really-really far from prologue/epilogue emission :)
>> So:
>>
>> 1. Calling conventions
>> Partly tablegen / partly C++ code. Look for
>> CodeGen/SelectionDAG/CallingConvLower.cpp,
>> Target/X86/X86CallingConv.td and around. Usually this code is run
>> during different phases of sdag lowering.
>>
>> 2. Prologue / epilogue.
>> Pure C++ code. Look into CodeGen/PrologEpilogInserter.cpp (quite
>> obviously, right?) with bunch of target-specialized hooks, for
>> example, ones located in Target/X86/X86RegisterInfo.cpp. Information
>> about this is needed on different stages, some - even before regalloc,
>> some - in the late end of the codegen.
>>
>> Hope this will help.
>>
> Yes, great. One other question. AFAICS this does not allow specialization
> say for a new Windows platform (Not MinGW or Cygwin) /Target to produce
> different code from X86 Linux.
>
>
>  You would add a new Subtarget to do this.  That will affect a fair amount
> of code but it should all be in Target/X86.
>

Yes, I see now. Thanks,

Aaron
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