[llvm] r218607 - [AArch64] Improve cost model to handle sdiv by a pow-of-two.

[Chad Rosier]

No problem, Jim.

> Woot! Thanks, Chad.
>
> -Jim
>
>> On Sep 29, 2014, at 6:59 AM, Chad Rosier <mcrosier at codeaurora.org>
>> wrote:
>>
>> Author: mcrosier
>> Date: Mon Sep 29 08:59:31 2014
>> New Revision: 218607
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=218607&view=rev
>> Log:
>> [AArch64] Improve cost model to handle sdiv by a pow-of-two.
>>
>> This patch improves the target-specific cost model to better handle
>> signed
>> division by a power of two. The immediate result is that this enables
>> the SLP
>> vectorizer to do a better job.
>>
>> http://reviews.llvm.org/D5469
>> PR20714
>>
>> Added:
>>    llvm/trunk/test/Transforms/SLPVectorizer/AArch64/sdiv-pow2.ll
>> Modified:
>>    llvm/trunk/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
>>
>> Modified: llvm/trunk/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64TargetTransformInfo.cpp?rev=218607&r1=218606&r2=218607&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/AArch64/AArch64TargetTransformInfo.cpp
>> (original)
>> +++ llvm/trunk/lib/Target/AArch64/AArch64TargetTransformInfo.cpp Mon Sep
>> 29 08:59:31 2014
>> @@ -413,6 +413,29 @@ unsigned AArch64TTI::getArithmeticInstrC
>>
>>   int ISD = TLI->InstructionOpcodeToISD(Opcode);
>>
>> +  if (ISD == ISD::SDIV &&
>> +      Opd2Info == TargetTransformInfo::OK_UniformConstantValue &&
>> +      Opd2PropInfo == TargetTransformInfo::OP_PowerOf2) {
>> +    // On AArch64, scalar signed division by constants power-of-two are
>> +    // normally expanded to the sequence ADD + CMP + SELECT + SRA.
>> +    // The OperandValue properties many not be same as that of previous
>> +    // operation; conservatively assume OP_None.
>> +    unsigned Cost =
>> +      getArithmeticInstrCost(Instruction::Add, Ty, Opd1Info, Opd2Info,
>> +                             TargetTransformInfo::OP_None,
>> +                             TargetTransformInfo::OP_None);
>> +    Cost += getArithmeticInstrCost(Instruction::Sub, Ty, Opd1Info,
>> Opd2Info,
>> +                                   TargetTransformInfo::OP_None,
>> +                                   TargetTransformInfo::OP_None);
>> +    Cost += getArithmeticInstrCost(Instruction::Select, Ty, Opd1Info,
>> Opd2Info,
>> +                                   TargetTransformInfo::OP_None,
>> +                                   TargetTransformInfo::OP_None);
>> +    Cost += getArithmeticInstrCost(Instruction::AShr, Ty, Opd1Info,
>> Opd2Info,
>> +                                   TargetTransformInfo::OP_None,
>> +                                   TargetTransformInfo::OP_None);
>> +    return Cost;
>> +  }
>> +
>>   switch (ISD) {
>>   default:
>>     return TargetTransformInfo::getArithmeticInstrCost(
>>
>> Added: llvm/trunk/test/Transforms/SLPVectorizer/AArch64/sdiv-pow2.ll
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SLPVectorizer/AArch64/sdiv-pow2.ll?rev=218607&view=auto
>> ==============================================================================
>> --- llvm/trunk/test/Transforms/SLPVectorizer/AArch64/sdiv-pow2.ll
>> (added)
>> +++ llvm/trunk/test/Transforms/SLPVectorizer/AArch64/sdiv-pow2.ll Mon
>> Sep 29 08:59:31 2014
>> @@ -0,0 +1,42 @@
>> +; RUN: opt < %s -basicaa -slp-vectorizer -S
>> -mtriple=aarch64-unknown-linux-gnu -mcpu=cortex-a57 | FileCheck %s
>> +target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
>> +target triple = "aarch64--linux-gnu"
>> +
>> +; CHECK-LABEL: @test1
>> +; CHECK: load <4 x i32>
>> +; CHECK: add nsw <4 x i32>
>> +; CHECK: sdiv <4 x i32>
>> +
>> +define void @test1(i32* noalias nocapture %a, i32* noalias nocapture
>> readonly %b, i32* noalias nocapture readonly %c) {
>> +entry:
>> +  %0 = load i32* %b, align 4
>> +  %1 = load i32* %c, align 4
>> +  %add = add nsw i32 %1, %0
>> +  %div = sdiv i32 %add, 2
>> +  store i32 %div, i32* %a, align 4
>> +  %arrayidx3 = getelementptr inbounds i32* %b, i64 1
>> +  %2 = load i32* %arrayidx3, align 4
>> +  %arrayidx4 = getelementptr inbounds i32* %c, i64 1
>> +  %3 = load i32* %arrayidx4, align 4
>> +  %add5 = add nsw i32 %3, %2
>> +  %div6 = sdiv i32 %add5, 2
>> +  %arrayidx7 = getelementptr inbounds i32* %a, i64 1
>> +  store i32 %div6, i32* %arrayidx7, align 4
>> +  %arrayidx8 = getelementptr inbounds i32* %b, i64 2
>> +  %4 = load i32* %arrayidx8, align 4
>> +  %arrayidx9 = getelementptr inbounds i32* %c, i64 2
>> +  %5 = load i32* %arrayidx9, align 4
>> +  %add10 = add nsw i32 %5, %4
>> +  %div11 = sdiv i32 %add10, 2
>> +  %arrayidx12 = getelementptr inbounds i32* %a, i64 2
>> +  store i32 %div11, i32* %arrayidx12, align 4
>> +  %arrayidx13 = getelementptr inbounds i32* %b, i64 3
>> +  %6 = load i32* %arrayidx13, align 4
>> +  %arrayidx14 = getelementptr inbounds i32* %c, i64 3
>> +  %7 = load i32* %arrayidx14, align 4
>> +  %add15 = add nsw i32 %7, %6
>> +  %div16 = sdiv i32 %add15, 2
>> +  %arrayidx17 = getelementptr inbounds i32* %a, i64 3
>> +  store i32 %div16, i32* %arrayidx17, align 4
>> +  ret void
>> +}
>>
>>
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