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ExtractValue instruction costs

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Instruction ExtractValue wasn't handled in
LoopVectorizationCostModel::getInstructionCost(). As a result, it was modeled
as a mul which is not really accurate. Since it is free (most of the times),
this now gets a cost of 0 using getInstructionCost.

This is a follow-up of D92208, that required changing this regression test.
In a follow up I will look at InsertValue which also isn't handled yet.

Differential Revision: https://reviews.llvm.org/D92317
This commit is contained in:
Sjoerd Meijer 2020-12-01 09:17:10 +00:00
parent de6fd49a53
commit c00b31be29
2 changed files with 8 additions and 9 deletions
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2
lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -6853,6 +6853,8 @@ unsigned LoopVectorizationCostModel::getInstructionCost(Instruction *I,
return std::min(CallCost, getVectorIntrinsicCost(CI, VF));
return CallCost;
}
case Instruction::ExtractValue:
return TTI.getInstructionCost(I, TTI::TCK_RecipThroughput);
default:
// The cost of executing VF copies of the scalar instruction. This opcode
// is unknown. Assume that it is the same as 'mul'.

15
test/Transforms/LoopVectorize/AArch64/extractvalue-no-scalarization-required.ll
View File

@ -8,9 +8,9 @@
; Check scalar cost for extractvalue. The constant and loop invariant operands are free,
; leaving cost 3 for scalarizing the result + 2 for executing the op with VF 2.
; CM: LV: Scalar loop costs: 7.
; CM: LV: Found an estimated cost of 19 for VF 2 For instruction: %a = extractvalue { i64, i64 } %sv, 0
; CM-NEXT: LV: Found an estimated cost of 19 for VF 2 For instruction: %b = extractvalue { i64, i64 } %sv, 1
; CM: LV: Scalar loop costs: 5.
; CM: LV: Found an estimated cost of 0 for VF 2 For instruction: %a = extractvalue { i64, i64 } %sv, 0
; CM-NEXT: LV: Found an estimated cost of 0 for VF 2 For instruction: %b = extractvalue { i64, i64 } %sv, 1
; Check that the extractvalue operands are actually free in vector code.
@ -57,9 +57,9 @@ exit:
; Similar to the test case above, but checks getVectorCallCost as well.
declare float @pow(float, float) readnone nounwind
; CM: LV: Scalar loop costs: 16.
; CM: LV: Found an estimated cost of 5 for VF 2 For instruction: %a = extractvalue { float, float } %sv, 0
; CM-NEXT: LV: Found an estimated cost of 5 for VF 2 For instruction: %b = extractvalue { float, float } %sv, 1
; CM: LV: Scalar loop costs: 14.
; CM: LV: Found an estimated cost of 0 for VF 2 For instruction: %a = extractvalue { float, float } %sv, 0
; CM-NEXT: LV: Found an estimated cost of 0 for VF 2 For instruction: %b = extractvalue { float, float } %sv, 1
; FORCED-LABEL: define void @test_getVectorCallCost
@ -101,6 +101,3 @@ loop.body:
exit:
ret void
}