[llvm] r220345 - LTO: respect command-line options that disable vectorization.

Arnold Schwaighofer aschwaighofer at apple.com
Fri Oct 24 09:06:51 PDT 2014


See my other mail.

> On Oct 24, 2014, at 8:53 AM, JF Bastien <jfb at google.com> wrote:
> 
> Hi Alexey,
> 
> vectorize-loops and vectorize-slp are off by default (though now they can be turned on/off with this patch). Adding Nadav, I'm not the right person to decide whether they should be on by default or not.
> 
> JF
> 
> On Fri, Oct 24, 2014 at 5:27 AM, Alexey Volkov <avolkov.intel at gmail.com <mailto:avolkov.intel at gmail.com>> wrote:
> Hi JF,
> 
> After your commit I saw a performance regression because of disabled Loop Vectorizer:
>  LV: Not vectorizing: No #pragma vectorize enable.
> It is really strange since I used -Ofast -flto clang's options to build an application.
> Before this change loop was successfully vectorized by Loop Vectorizer.
> 
> Thanks, Alexey.
> 
> 2014-10-22 3:18 GMT+04:00 JF Bastien <jfb at google.com <mailto:jfb at google.com>>:
> Author: jfb
> Date: Tue Oct 21 18:18:21 2014
> New Revision: 220345
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=220345&view=rev <http://llvm.org/viewvc/llvm-project?rev=220345&view=rev>
> Log:
> LTO: respect command-line options that disable vectorization.
> 
> Summary: Patches 202051 and 208013 added calls to LTO's PassManager which unconditionally add LoopVectorizePass and SLPVectorizerPass instead of following the logic in PassManagerBuilder::populateModulePassManager and honoring the -vectorize-loops -run-slp-after-loop-vectorization flags.
> 
> Reviewers: nadav, aschwaighofer, yijiang
> 
> Subscribers: llvm-commits
> 
> Differential Revision: http://reviews.llvm.org/D5884 <http://reviews.llvm.org/D5884>
> 
> Modified:
>     llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> 
> Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=220345&r1=220344&r2=220345&view=diff <http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=220345&r1=220344&r2=220345&view=diff>
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Tue Oct 21 18:18:21 2014
> @@ -440,10 +440,12 @@ void PassManagerBuilder::addLTOOptimizat
>    // More loops are countable; try to optimize them.
>    PM.add(createIndVarSimplifyPass());
>    PM.add(createLoopDeletionPass());
> -  PM.add(createLoopVectorizePass(true, true));
> +  PM.add(createLoopVectorizePass(DisableUnrollLoops, LoopVectorize));
> 
>    // More scalar chains could be vectorized due to more alias information
> -  PM.add(createSLPVectorizerPass()); // Vectorize parallel scalar chains.
> +  if (RunSLPAfterLoopVectorization)
> +    if (SLPVectorize)
> +      PM.add(createSLPVectorizerPass()); // Vectorize parallel scalar chains.
> 
>    // After vectorization, assume intrinsics may tell us more about pointer
>    // alignments.
> 
> 
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> 
> 
> -- 
> Alexey Volkov
> Intel Corporation
> 
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