llvm dev - Aug 2013 - [LLVMdev] how do I disable vectorization passes for a target by default?

Hi

I would like to disable vectorization on the XCore target by default.

I assume I need to push_back -fno-vectorize in clang/lib/driver/Tools.cpp for
Triple::xcore.

Should I also disable the pass in llvm explicitly?
I tried setting getNumberOfRegisters in XCoreTTI::TargetTransformInfo viz:

  unsigned getNumberOfRegisters(bool Vector) const {
    if (Vector) {
       return 0;
    }
    return 12;
  }

But this made no difference (I need to double check).

What is the correct way to disable vectorization passes?

Robert

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Hi Robert, 

The best way is to push “-vectorize-loops=false”. You can look at
PassManagerBuilder.cpp in LLVM to see the flag.  You can also run "clang
-###” to see which flags the compiler driver passes.  Setting the register
number will only influence the unroll-factor of the vectorized code. You would
also want to vectorize the SLP-vectorizer in a similar way.

Thanks,
Nadav

On Aug 23, 2013, at 10:30 AM, Robert Lytton <robert at xmos.com> wrote:
> Hi
> 
> I would like to disable vectorization on the XCore target by default.
> 
> I assume I need to push_back -fno-vectorize in clang/lib/driver/Tools.cpp
for Triple::xcore.
> 
> Should I also disable the pass in llvm explicitly?
> I tried setting getNumberOfRegisters in XCoreTTI::TargetTransformInfo viz:
> 
>   unsigned getNumberOfRegisters(bool Vector) const {
>     if (Vector) {
>        return 0;
>     }
>     return 12;
>   }
> 
> But this made no difference (I need to double check).
> 
> What is the correct way to disable vectorization passes?
> 
> Robert
> 
> _______________________________________________
> 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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