[PATCH] D18410: ELF: Split BitcodeCompiler::compile.

[Rui Ueyama via llvm-commits]

+rafael because he added this FIXME.

On Wed, Mar 23, 2016 at 8:26 PM, Mehdi Amini <mehdi.amini at apple.com> wrote:

>
> > On Mar 23, 2016, at 11:38 AM, Rui Ueyama <ruiu at google.com> wrote:
> >
> > ruiu created this revision.
> > ruiu added a reviewer: davide.
> > ruiu added a subscriber: llvm-commits.
> > Herald added a subscriber: joker.eph.
> >
> > ELF: Split BitcodeCompiler::compile.
> >
> > http://reviews.llvm.org/D18410
> >
> > Files:
> >  ELF/LTO.cpp
> >  ELF/LTO.h
> >
> > Index: ELF/LTO.h
> > ===================================================================
> > --- ELF/LTO.h
> > +++ ELF/LTO.h
> > @@ -39,6 +39,8 @@
> >   template <class ELFT> std::unique_ptr<ObjectFile<ELFT>> compile();
> >
> > private:
> > +  llvm::TargetMachine *getTargetMachine();
> > +
> >   llvm::LLVMContext Context;
> >   llvm::Module Combined{"ld-temp.o", Context};
> >   llvm::IRMover Mover{Combined};
> > Index: ELF/LTO.cpp
> > ===================================================================
> > --- ELF/LTO.cpp
> > +++ ELF/LTO.cpp
> > @@ -103,23 +103,7 @@
> >   if (Config->SaveTemps)
> >     saveBCFile(Combined, ".lto.bc");
> >
> > -  StringRef TripleStr = Combined.getTargetTriple();
> > -  Triple TheTriple(TripleStr);
> > -
> > -  // FIXME: Should we have a default triple? The gold plugin uses
> > -  // sys::getDefaultTargetTriple(), but that is probably wrong given
> that this
> > -  // might be a cross linker.
> > -
> > -  std::string ErrMsg;
> > -  const Target *TheTarget = TargetRegistry::lookupTarget(TripleStr,
> ErrMsg);
> > -  if (!TheTarget)
> > -    fatal("target not found: " + ErrMsg);
> > -
> > -  TargetOptions Options;
> > -  Reloc::Model R = Config->Pic ? Reloc::PIC_ : Reloc::Static;
> > -  std::unique_ptr<TargetMachine> TM(
> > -      TheTarget->createTargetMachine(TripleStr, "", "", Options, R));
> > -
> > +  std::unique_ptr<TargetMachine> TM(getTargetMachine());
> >   runLTOPasses(Combined, *TM);
> >
> >   raw_svector_ostream OS(OwningData);
> > @@ -138,6 +122,22 @@
> >   return std::unique_ptr<ObjectFile<ELFT>>(OF);
> > }
> >
> > +TargetMachine *BitcodeCompiler::getTargetMachine() {
> > +  StringRef TripleStr = Combined.getTargetTriple();
> > +
> > +  // FIXME: Should we have a default triple? The gold plugin uses
> > +  // sys::getDefaultTargetTriple(), but that is probably wrong given
> that this
> > +  // might be a cross linker.
>
> My 2 cents for the "FIXME" (I know it is code motion): error is the only
> sane solution when a bitcode has been optimized for a Target (using some
> TTI) and the target backend is not available at link time.
> Silently falling back to the host triple could lead to surprises for the
> user. I'm curious if I'm missing a real use case for that?
>
> --
> Mehdi
>
>
> > +  std::string Msg;
> > +  const Target *T = TargetRegistry::lookupTarget(TripleStr, Msg);
> > +  if (!T)
> > +    fatal("target not found: " + Msg);
> > +
> > +  TargetOptions Options;
> > +  Reloc::Model R = Config->Pic ? Reloc::PIC_ : Reloc::Static;
> > +  return T->createTargetMachine(TripleStr, "", "", Options, R);
> > +}
> > +
> > template std::unique_ptr<elf::ObjectFile<ELF32LE>>
> BitcodeCompiler::compile();
> > template std::unique_ptr<elf::ObjectFile<ELF32BE>>
> BitcodeCompiler::compile();
> > template std::unique_ptr<elf::ObjectFile<ELF64LE>>
> BitcodeCompiler::compile();
> >
> >
> > <D18410.51455.patch>
>
>
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