[PATCH] D18490: [PGO] Comment how function pointers for indirect calls are mapped to function names

[David Li via Phabricator via llvm-commits]

davidxl added inline comments.


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Comment at: llvm/trunk/include/llvm/ProfileData/InstrProfData.inc:78
+// function name hashes during the conversion from raw to merged profile data.
 INSTR_PROF_DATA(const IntPtrT, llvm::Type::getInt8PtrTy(Ctx), FunctionPointer, \
                 FunctionAddr)
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MaskRay wrote:
> MaskRay wrote:
> > Is `FunctionPointer` still used by the runtime? @davidxl @vsk 
> > 
> > I can only find one reference `__llvm_get_function_addr`, which is a public API.
> Hmm. It is used by `ProfileData/InstrProfReader.cpp`
> 
> So it seems that value profiling adds quite a bit size overhead to the metadata sections.
Right -- it is used by the profile reader to build mapping from func->name so that indirect call target profile can be translated to func names.  Changing the llvm-profdata workflow by forcing binary as an input will allow the field to be removed -- but things get complicated with -fPIE build.


Repository:
  rL LLVM

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  https://reviews.llvm.org/D18490/new/

https://reviews.llvm.org/D18490