[LLVMdev] arch-specific predefines in LLVM's source

[Hal Finkel]

----- Original Message -----
> > ----- Original Message -----
> >> Hi all,
> >>  	My recent commit r187027 fixed a simple oversight of forgetting
> >>  	to
> >> check for __ppc__ (only checking __powerpc__), which broke my
> >> powerpc-apple-darwin8 stage1 tests, since the system gcc only
> >> provided
> >> __ppc__.  I was wondering if this justifies using simpler macros
> >> like
> >>
> >> #define LLVM_PPC	(defined(__ppc__) || defined(__powerpc__) ...)
> >> #define LLVM_PPC64	(defined(__ppc64__) || defined(__powerpc64__)
> >> ...)
> >
> > A general note: Given all of the compiler variance out there
> > regarding whether the 32-bit macros are also defined on the 64-bit
> > systems, I really think that you'll need to arrange these as:
> >
> > #define LLVM_PPC64	(defined(__ppc64__) || defined(__powerpc64__)
> > ...)
> > #define LLVM_PPC	!LLVM_PPC64 && (defined(__ppc__) ||
> > defined(__powerpc__) ...)
> 
> or define more clearly:
> 
> #define	LLVM_PPC32	(((defined(__ppc__) || defined(__powerpc__)) &&
> !LLVM_PPC64)
> #define	LLVM_PPC_ANY	(LLVM_PPC32 || LLVM_PPC64)
> 
> or
> 
> #define	LLVM_PPC_ANY	(defined(__ppc__) || defined(__powerpc__))
> #define	LLVM_PPC32	(LLVM_PPC_ANY && !LLVM_PPC64)

I thought that you had discovered that on Darwin __ppc__, etc. are defined only for 32-bit builds. Is that correct?

 -Hal

> 
> ?
> 
> >> I've even seen __POWERPC__, _POWER, _ARCH_PPC being tested in
> >> conditionals.
> >>
> >> These proposed standardized macros would only be used in LLVM
> >> project
> >> sources; there's no reason to exported them.
> >> The standardized macros would simplify conditionals and make their
> >> use
> >> less error-prone.
> >>
> >> What predefines do other architectures use?
> >
> > Would all uses of these macros be restricted to the PPC backend, or
> > would they appear elsewhere as well?
> 
> One place I see these predefines outside of the PPC backend is
> lib/Support/Host.cpp
> 
> Fang
> 
> > -Hal
> >
> >>
> >> What would be a suitable place for these proposed macros?
> >> include/llvm/Support/Compiler.h?
> >> include/llvm/Support/Arch.h (new)?
> >>
> >> Fang
> 
> 
> --
> David Fang
> http://www.csl.cornell.edu/~fang/
> 
> 

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory