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 <[email protected]> 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 [[email protected]]
> Sent: 06 September 2013 18:43
> To: Nadav Rotem
> Cc: Robert Lytton; [email protected]; 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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