[cfe-dev] [LLVMdev] Odd PPC inline asm constraint

Roman Divacky rdivacky at freebsd.org
Sat Apr 28 23:04:15 PDT 2012

On Sat, Apr 28, 2012 at 11:19:13AM -0500, Peter Bergner wrote:
> On Fri, 2012-04-27 at 20:30 -0500, Hal Finkel wrote:
> > Thanks! Do you happen to know where this needs to be changed in clang
> > or LLVM. The code that actually interprets the constraints,
> > generically, is in CodeGen/SelectionDAG/TargetLowering.cpp, is clang
> > relying on that code, or is there some frontend code in clang itself
> > that is failing to initially interpret the string? If it is the code in
> > TargetLowering, then I don't see any support there for '*' or '#'.
> Heh, I'm afraid I have no clue as to where clang needs to be changed.
> I'm the team lead for IBM's Linux on POWER GCC development team, so
> I can help you with questions about PPC hardware, PPC ABIs and why
> GCC does things the way it does on PPC, but I'll not be of much
> help with LLVM itself.  I'm just a lurker here. :)
> That said, I'm curious about the extent of LLVM's support for PPC.
> How robust is it?  Does it support generating both 32-bit and 64-bit
> binaries?

Just two random points, we can compile and boot FreeBSD kernel and I was
able to selfhost statically compiled clang/llvm.

Beside missing PIC support and not saving FP args when CR bit 6 is not set
there's nothing (famous last words) preventing FreeBSD from using clang
as its default compiler on PPC.


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