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[InstCombine] Fix extractelement use before def

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This fixes a bug that can cause extractelements with operands that
haven't been defined yet to be inserted at a wrong point when
optimising insertelements.

Patch by Karl Hylen.

Differential Revision: https://reviews.llvm.org/D33449


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304701 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sven van Haastregt 2017-06-05 09:18:10 +00:00
parent 3b482e4bca
commit 3303806a3d
2 changed files with 24 additions and 1 deletions
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2
lib/Transforms/InstCombine/InstCombineVectorOps.cpp
View File

@ -440,7 +440,7 @@ static void replaceExtractElements(InsertElementInst *InsElt,
if (!OldExt || OldExt->getParent() != WideVec->getParent())
continue;
auto *NewExt = ExtractElementInst::Create(WideVec, OldExt->getOperand(1));
NewExt->insertAfter(WideVec);
NewExt->insertAfter(OldExt);
IC.replaceInstUsesWith(*OldExt, NewExt);
}
}

23
test/Transforms/InstCombine/insert-extract-shuffle.ll
View File

@ -260,3 +260,26 @@ bb2:
%ins2 = insertelement <4 x float> %ins1, float %ext1, i32 3
ret <4 x float> %ins2
}
; Don't insert extractelements from the wider vector before the def of the index operand.
define <4 x i32> @extractelt_insertion(<2 x i32> %x, i32 %y) {
; CHECK-LABEL: @extractelt_insertion(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = shufflevector <2 x i32> [[X:%.*]], <2 x i32> undef, <4 x i32> <i32 0, i32 1, i32 undef, i32 undef>
; CHECK-NEXT: [[B:%.*]] = shufflevector <4 x i32> <i32 0, i32 0, i32 0, i32 undef>, <4 x i32> [[TMP0]], <4 x i32> <i32 0, i32 1, i32 2, i32 5>
; CHECK-NEXT: [[C:%.*]] = add i32 [[Y:%.*]], 3
; CHECK-NEXT: [[TMP1:%.*]] = extractelement <4 x i32> [[TMP0]], i32 [[C]]
; CHECK-NEXT: [[E:%.*]] = icmp eq i32 [[TMP1]], 0
; CHECK-NEXT: [[RET:%.*]] = select i1 [[E]], <4 x i32> [[B]], <4 x i32> zeroinitializer
; CHECK-NEXT: ret <4 x i32> [[RET]]
;
entry:
%a = extractelement <2 x i32> %x, i32 1
%b = insertelement <4 x i32> zeroinitializer, i32 %a, i64 3
%c = add i32 %y, 3
%d = extractelement <2 x i32> %x, i32 %c
%e = icmp eq i32 %d, 0
%ret = select i1 %e, <4 x i32> %b, <4 x i32> zeroinitializer
ret <4 x i32> %ret
}