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

[Jim Grosbach]

> 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. 
> -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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