llvm dev - Jul 2008 - [LLVMdev] Implementing llvm.memory.barrier on PowerPC

Hi all,

I want to implement llvm.memory.barrier on PowerPC.  The
implementation would be the single instruction "sync", but
currently it's defined with:

 setOperationAction(ISD::MEMBARRIER, MVT::Other, Expand)

in lib/Target/PowerPC/PPCISelLowering.cpp, which causes it
to be a noop.  I replaced the "Expand" with "Legal" in the
hope I'd get an error message that'd point me to where I
need to start adding stuff, but I just got the cryptic:

  Cannot yet select: 0x10fc0500: ch = MemBarrier 0x10fc0368, 0x10fc0698,
0x10fc0610, 0x10fc0698, 0x10fc0698, 0x10fc0698".

Can anyone point me in the right direction?

Cheers,
Gary

-- 
http://gbenson.net/

Hi Gary,

You're probably missing the required recipe in the .td file. Look at  
the documentation for tablegen and maybe try to find some examples to  
copy.

Good luck!

-bw

On Jul 25, 2008, at 5:57 AM, Gary Benson <gbenson at redhat.com> wrote:
> Hi all,
>
> I want to implement llvm.memory.barrier on PowerPC.  The
> implementation would be the single instruction "sync", but
> currently it's defined with:
>
> setOperationAction(ISD::MEMBARRIER, MVT::Other, Expand)
>
> in lib/Target/PowerPC/PPCISelLowering.cpp, which causes it
> to be a noop.  I replaced the "Expand" with "Legal" in
the
> hope I'd get an error message that'd point me to where I
> need to start adding stuff, but I just got the cryptic:
>
>  Cannot yet select: 0x10fc0500: ch = MemBarrier 0x10fc0368,  
> 0x10fc0698, 0x10fc0610, 0x10fc0698, 0x10fc0698, 0x10fc0698".
>
> Can anyone point me in the right direction?
>
> Cheers,
> Gary
>
> -- 
> http://gbenson.net/
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

On Jul 25, 2008, at 3:57 AM, Gary Benson wrote:
> Hi all,
>
> I want to implement llvm.memory.barrier on PowerPC.  The
> implementation would be the single instruction "sync", but
> currently it's defined with:
>
> setOperationAction(ISD::MEMBARRIER, MVT::Other, Expand)
>
> in lib/Target/PowerPC/PPCISelLowering.cpp, which causes it
> to be a noop.  I replaced the "Expand" with "Legal" in
the
That's not necessary. You can just remove this line. The default  
action is "legal".
>
> hope I'd get an error message that'd point me to where I
> need to start adding stuff, but I just got the cryptic:
>
>  Cannot yet select: 0x10fc0500: ch = MemBarrier 0x10fc0368,  
> 0x10fc0698, 0x10fc0610, 0x10fc0698, 0x10fc0698, 0x10fc0698".
>
>
> Can anyone point me in the right direction?

You need to add a pattern to match "membarrier" (see Target/ 
TargetSelectionDAG.td) to the right target instruction(s) in  
PPCInstrInfo.td. You can take a look at the examples in X86InstrSSE.td.

Evan
>
>
> Cheers,
> Gary
>
> -- 
> http://gbenson.net/
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev