[LLVMdev] Calling Conventions, function prologs and epilogs.
dalej at apple.com
Thu Apr 9 11:19:16 PDT 2009
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
> 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.
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