XCore target: disable vectorization

[Eric Christopher]

Drive by comment, should probably be "getNumberOfVectorRegisters" or
some sort of query with vector in the name :)

-eric

On Mon, Sep 9, 2013 at 8:43 AM, Arnold Schwaighofer
<aschwaighofer at apple.com> wrote:
> Hi Robert,
>
> I think Nadav meant to add code to the LoopVectorizer and SLPVectorizer that calls "TTI.getNumberOfRegisters(true)” and stops vectorization if it returns 0. Something like:
>
> --- a/lib/Transforms/Vectorize/LoopVectorize.cpp
> +++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
> @@ -906,6 +906,11 @@ struct LoopVectorize : public LoopPass {
>      DT = &getAnalysis<DominatorTree>();
>      TLI = getAnalysisIfAvailable<TargetLibraryInfo>();
>
> +    // If the target claims to have no vector registers don't attempt
> +    // vectorization.
> +    if (!TTI->getNumberOfRegisters(true))
> +      return false;
> +
>      if (DL == NULL) {
>        DEBUG(dbgs() << "LV: Not vectorizing because of missing data layout");
>        return false;
>
>
>
> diff --git a/lib/Transforms/Vectorize/SLPVectorizer.cpp b/lib/Transforms/Vectorize/SLPVectorizer.cpp
> index 1f288bc..6ddcc51 100644
> --- a/lib/Transforms/Vectorize/SLPVectorizer.cpp
> +++ b/lib/Transforms/Vectorize/SLPVectorizer.cpp
> @@ -1565,6 +1565,11 @@ struct SLPVectorizer : public FunctionPass {
>      if (!DL)
>        return false;
>
> +    // If the target claims to have no vector registers don't attempt
> +    // vectorization.
> +    if (!TTI->getNumberOfRegisters(true))
> +      return false;
> +
>      // Don't vectorize when the attribute NoImplicitFloat is used.
>      if (F.hasFnAttribute(Attribute::NoImplicitFloat))
>        return false;
>
> On Sep 9, 2013, at 7:13 AM, Robert Lytton <robert at xmos.com> wrote:
>
>> Hi Rafael, Nadav,
>>
>> Thank you for the input but I don't follow where the change needs to be made.
>>
>> Are you suggesting changes to llvm's  lib/Transforms/IPO/PassManagerBuilder.cpp?
>> This approach would  make the '-vectorize-loops' & '-vectorize-slp' flags  only relevant for targets with vector registers?
>>
>> Or in clang/lib/Driver/Tools.cpp?
>>
>> In either case, I can't see how to get hold of the TargetTransformInfo cleanly.
>>
>> Robert
>>
>> ________________________________________
>> From: Rafael Espíndola [rafael.espindola at gmail.com]
>> Sent: 06 September 2013 18:43
>> To: Nadav Rotem
>> Cc: Robert Lytton; cfe-commits at cs.uiuc.edu; Arnold Schwaighofer
>> Subject: Re: XCore target: disable vectorization
>>
>>> unsigned TargetVectorRegisters = TTI.getNumberOfRegisters(true);
>>
>> And not vectorize if the target says 0? I like that idea.
>>
>> Cheers,
>> Rafael
>
>
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