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[InstCombine] Do not fold scalar ops over select with vector condition.

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If OtherOpT or OtherOpF have scalar types and the condition is a vector,
we would create an invalid select.

Reviewers: spatel, john.brawn, mssimpso, craig.topper

Reviewed By: spatel

Differential Revision: https://reviews.llvm.org/D51781

llvm-svn: 341666
This commit is contained in:
Florian Hahn 2018-09-07 14:40:06 +00:00
parent 565aeb86aa
commit 4480a19a6e
2 changed files with 22 additions and 0 deletions
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8
lib/Transforms/InstCombine/InstCombineSelect.cpp
View File

@ -362,6 +362,14 @@ Instruction *InstCombiner::foldSelectOpOp(SelectInst &SI, Instruction *TI,
return nullptr; return nullptr;
} }
// If the select condition is a vector, the operands of the original select's
// operands also must be vectors. This may not be the case for getelementptr
// for example.
if (SI.getCondition()->getType()->isVectorTy() &&
(!OtherOpT->getType()->isVectorTy() ||
!OtherOpF->getType()->isVectorTy()))
return nullptr;
// If we reach here, they do have operations in common. // If we reach here, they do have operations in common.
Value *NewSI = Builder.CreateSelect(SI.getCondition(), OtherOpT, OtherOpF, Value *NewSI = Builder.CreateSelect(SI.getCondition(), OtherOpT, OtherOpF,
SI.getName() + ".v", &SI); SI.getName() + ".v", &SI);

14
test/Transforms/InstCombine/select-gep.ll
View File

@ -136,3 +136,17 @@ define i32* @test4(i32* %p, i32* %q, i64 %x, i64 %y) {
ret i32* %select ret i32* %select
} }
; We cannot create a select with a vector condition but scalar operands.
define <2 x i64*> @test5(i64* %p1, i64* %p2, <2 x i64> %idx, <2 x i1> %cc) {
; CHECK-LABEL: @test5(
; CHECK-NEXT: [[GEP1:%.*]] = getelementptr i64, i64* %p1, <2 x i64> %idx
; CHECK-NEXT: [[GEP2:%.*]] = getelementptr i64, i64* %p2, <2 x i64> %idx
; CHECK-NEXT: [[SELECT:%.*]] = select <2 x i1> %cc, <2 x i64*> [[GEP1]], <2 x i64*> [[GEP2]]
; CHECK-NEXT: ret <2 x i64*> [[SELECT]]
;
%gep1 = getelementptr i64, i64* %p1, <2 x i64> %idx
%gep2 = getelementptr i64, i64* %p2, <2 x i64> %idx
%select = select <2 x i1> %cc, <2 x i64*> %gep1, <2 x i64*> %gep2
ret <2 x i64*> %select
}