llvm dev - Mar 2011 - [LLVMdev] Make PPC JIT support inline assembly?

Hi, all

  It seems PPC JIT does not recognize inline assembly.
For example, when I give LLVM IR belows to PPC JIT,

%0 = tail call i32* asm "", "={r10}"() nounwind ;
<i32*> [#uses=1]

  it complaints that inline assembly is not a supported
instruction. x86 JIT works fine, however.

  Is there a reason that makes PPC JIT not support inline
assembly?

  Currently, we modify PPCGenCodeEmitter.inc, then rebuild
LLVM to let ppc recognize inline assembly (see attachment).
Is there a better way to make PPC JIT support inline assembly?

  Any suggestion appreciated.

Regards,
chenwj

-- 
Wei-Ren Chen (陳韋任)
Parallel Processing Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667
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Hi 陳韋任,
>    It seems PPC JIT does not recognize inline assembly.
> For example, when I give LLVM IR belows to PPC JIT,
>
> %0 = tail call i32* asm "", "={r10}"() nounwind
;<i32*>  [#uses=1]
>
>    it complaints that inline assembly is not a supported
> instruction. x86 JIT works fine, however.
I'm surprised this worked with the x86 JIT - I thought the JIT didn't
support any inline assembler on any platform, and that the plan was to
solve this with the new MC-JIT, see
   http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html

Ciao, Duncan.

Hi,

Very few inline assembly are supported for the X86 backend. As I see from
X86ISelLowering.cpp, only bswap, rorw, xchgl and simple register selections
(e.g. {=r10}) LLVM JIT can recoginze. But for PPC backend, I am not
sure why PPC JIT see all inline assembly IRs as an error.

Ding-Yong
On Thu, Mar 24, 2011 at 2:53 PM, Duncan Sands <baldrick at free.fr> wrote:
> Hi 陳韋任,
>
> >    It seems PPC JIT does not recognize inline assembly.
> > For example, when I give LLVM IR belows to PPC JIT,
> >
> > %0 = tail call i32* asm "", "={r10}"() nounwind
;<i32*>  [#uses=1]
> >
> >    it complaints that inline assembly is not a supported
> > instruction. x86 JIT works fine, however.
>
> I'm surprised this worked with the x86 JIT - I thought the JIT
didn't
> support any inline assembler on any platform, and that the plan was to
> solve this with the new MC-JIT, see
>   http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html
>
> Ciao, Duncan.
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
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Hi, Duncan
> support any inline assembler on any platform, and that the plan was to
> solve this with the new MC-JIT, see
>    http://blog.llvm.org/2010/04/intro-to-llvm-mc-project.html
  At the first glance, I think what llvm-mc does is, given an input,
llvm-mc will disassemble the input into assembly. I don't know the
MC-JIT you mentioned can be used as a JIT. Currently, a JIT is
created by ExecutionEngine::createJIT.

  Can you give more information about the MC-JIT? Is it already
included in llvm-2.8?

  Thank!

Regards,
chenwj

-- 
Wei-Ren Chen (陳韋任)
Parallel Processing Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667