[llvm] r204880 - X86: Correct vectorization cost model for v8f32->v8i8.

[Eric Christopher]

On Mar 27, 2014 8:41 AM, "Jim Grosbach" <grosbach at apple.com> wrote:
>
>
>
> > On Mar 26, 2014, at 10:32 PM, Eric Christopher <echristo at gmail.com>
wrote:
> >
> >> On Wed, Mar 26, 2014 at 5:04 PM, Jim Grosbach <grosbach at apple.com>
wrote:
> >> Author: grosbach
> >> Date: Wed Mar 26 19:04:11 2014
> >> New Revision: 204880
> >>
> >> URL: http://llvm.org/viewvc/llvm-project?rev=204880&view=rev
> >> Log:
> >> X86: Correct vectorization cost model for v8f32->v8i8.
> >>
> >> Fix the cost model to reflect the reality of our codegen.
> >
> > Reality of our codegen or reality of the processors?
> >
>
> The latter, though the cost model should be accurately reflecting both.

It should, but in the latter a bug should be filed and a comment to that
effect listed. "Realities of our CodeGen" really sounds like a deficiency
we're papering over.

-eric

PS. Reading more of the patches I'll just CC Quentin on this response too.
:)

> > -eric
> >
> >>
> >> rdar://16370633
> >>
> >> Added:
> >>
 llvm/trunk/test/Transforms/LoopVectorize/X86/fp_to_sint8-cost-model.ll
> >> Modified:
> >>    llvm/trunk/lib/Target/X86/X86TargetTransformInfo.cpp
> >>
> >> Modified: llvm/trunk/lib/Target/X86/X86TargetTransformInfo.cpp
> >> URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86TargetTransformInfo.cpp?rev=204880&r1=204879&r2=204880&view=diff
> >>
==============================================================================
> >> --- llvm/trunk/lib/Target/X86/X86TargetTransformInfo.cpp (original)
> >> +++ llvm/trunk/lib/Target/X86/X86TargetTransformInfo.cpp Wed Mar 26
19:04:11 2014
> >> @@ -513,7 +513,7 @@ unsigned X86TTI::getCastInstrCost(unsign
> >>     { ISD::UINT_TO_FP,  MVT::v4f64, MVT::v4i16, 2 },
> >>     { ISD::UINT_TO_FP,  MVT::v4f64, MVT::v4i32, 6 },
> >>
> >> -    { ISD::FP_TO_SINT,  MVT::v8i8,  MVT::v8f32, 1 },
> >> +    { ISD::FP_TO_SINT,  MVT::v8i8,  MVT::v8f32, 7 },
> >>     { ISD::FP_TO_SINT,  MVT::v4i8,  MVT::v4f32, 1 },
> >>   };
> >>
> >>
> >> Added:
llvm/trunk/test/Transforms/LoopVectorize/X86/fp_to_sint8-cost-model.ll
> >> URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/X86/fp_to_sint8-cost-model.ll?rev=204880&view=auto
> >>
==============================================================================
> >> ---
llvm/trunk/test/Transforms/LoopVectorize/X86/fp_to_sint8-cost-model.ll
(added)
> >> +++
llvm/trunk/test/Transforms/LoopVectorize/X86/fp_to_sint8-cost-model.ll Wed
Mar 26 19:04:11 2014
> >> @@ -0,0 +1,24 @@
> >> +; RUN: opt < %s  -loop-vectorize -mtriple=x86_64-apple-macosx10.8.0
-mcpu=corei7-avx -S -debug-only=loop-vectorize 2>&1 | FileCheck %s
> >> +
> >> +target datalayout =
"e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
> >> +target triple = "x86_64-apple-macosx10.8.0"
> >> +
> >> +
> >> +; CHECK: cost of 7 for VF 8 For instruction:   %conv = fptosi float
%tmp to i8
> >> +define void @float_to_sint8_cost(i8* noalias nocapture %a, float*
noalias nocapture readonly %b) nounwind {
> >> +entry:
> >> +  br label %for.body
> >> +for.body:
> >> +  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
> >> +  %arrayidx = getelementptr inbounds float* %b, i64 %indvars.iv
> >> +  %tmp = load float* %arrayidx, align 4
> >> +  %conv = fptosi float %tmp to i8
> >> +  %arrayidx2 = getelementptr inbounds i8* %a, i64 %indvars.iv
> >> +  store i8 %conv, i8* %arrayidx2, align 4
> >> +  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
> >> +  %exitcond = icmp eq i64 %indvars.iv.next, 256
> >> +  br i1 %exitcond, label %for.end, label %for.body
> >> +
> >> +for.end:
> >> +  ret void
> >> +}
> >>
> >>
> >> _______________________________________________
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> >> llvm-commits at cs.uiuc.edu
> >> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
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