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TTI: Estimate @llvm.fmuladd cost as fmul + fadd when FMA's aren't legal on the target.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208115 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2014-05-06 18:36:23 +00:00
parent 8a712ba229
commit 2c06cd8612
2 changed files with 35 additions and 1 deletions
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8
lib/CodeGen/BasicTargetTransformInfo.cpp
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@ -487,7 +487,7 @@ unsigned BasicTTI::getIntrinsicInstrCost(Intrinsic::ID IID, Type *RetTy,
case Intrinsic::round: ISD = ISD::FROUND; break;
case Intrinsic::pow: ISD = ISD::FPOW; break;
case Intrinsic::fma: ISD = ISD::FMA; break;
case Intrinsic::fmuladd: ISD = ISD::FMA; break; // FIXME: mul + add?
case Intrinsic::fmuladd: ISD = ISD::FMA; break;
case Intrinsic::lifetime_start:
case Intrinsic::lifetime_end:
return 0;
@ -512,6 +512,12 @@ unsigned BasicTTI::getIntrinsicInstrCost(Intrinsic::ID IID, Type *RetTy,
return LT.first * 2;
}
// If we can't lower fmuladd into an FMA estimate the cost as a floating
// point mul followed by an add.
if (IID == Intrinsic::fmuladd)
return TopTTI->getArithmeticInstrCost(BinaryOperator::FMul, RetTy) +
TopTTI->getArithmeticInstrCost(BinaryOperator::FAdd, RetTy);
// Else, assume that we need to scalarize this intrinsic. For math builtins
// this will emit a costly libcall, adding call overhead and spills. Make it
// very expensive.

28
test/Analysis/CostModel/X86/intrinsic-cost.ll
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@ -58,3 +58,31 @@ for.end: ; preds = %vector.body
}
declare <4 x float> @llvm.nearbyint.v4f32(<4 x float>) nounwind readnone
define void @test3(float* nocapture %f, <4 x float> %b, <4 x float> %c) nounwind {
vector.ph:
br label %vector.body
vector.body: ; preds = %vector.body, %vector.ph
%index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
%0 = getelementptr inbounds float* %f, i64 %index
%1 = bitcast float* %0 to <4 x float>*
%wide.load = load <4 x float>* %1, align 4
%2 = call <4 x float> @llvm.fmuladd.v4f32(<4 x float> %wide.load, <4 x float> %b, <4 x float> %c)
store <4 x float> %2, <4 x float>* %1, align 4
%index.next = add i64 %index, 4
%3 = icmp eq i64 %index.next, 1024
br i1 %3, label %for.end, label %vector.body
for.end: ; preds = %vector.body
ret void
; CORE2: Printing analysis 'Cost Model Analysis' for function 'test3':
; CORE2: Cost Model: Found an estimated cost of 4 for instruction: %2 = call <4 x float> @llvm.fmuladd.v4f32(<4 x float> %wide.load, <4 x float> %b, <4 x float> %c)
; COREI7: Printing analysis 'Cost Model Analysis' for function 'test3':
; COREI7: Cost Model: Found an estimated cost of 4 for instruction: %2 = call <4 x float> @llvm.fmuladd.v4f32(<4 x float> %wide.load, <4 x float> %b, <4 x float> %c)
}
declare <4 x float> @llvm.fmuladd.v4f32(<4 x float>, <4 x float>, <4 x float>) nounwind readnone