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[InstCombine] Fix miscompile in FoldSPFofSPF

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We had a select of a cast of a select but attempted to replace the outer
select with the inner select dispite their incompatible types.

Patch by Anton Korobeynikov!

This fixes PR27236.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265805 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2016-04-08 16:51:49 +00:00
parent 0874850952
commit 2e912162e4
2 changed files with 22 additions and 0 deletions
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3
lib/Transforms/InstCombine/InstCombineSelect.cpp
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@ -642,6 +642,9 @@ Instruction *InstCombiner::FoldSPFofSPF(Instruction *Inner,
Value *A, Value *B,
Instruction &Outer,
SelectPatternFlavor SPF2, Value *C) {
if (Outer.getType() != Inner->getType())
return nullptr;
if (C == A || C == B) {
// MAX(MAX(A, B), B) -> MAX(A, B)
// MIN(MIN(a, b), a) -> MIN(a, b)

19
test/Transforms/InstCombine/pr27236.ll Normal file
View File

@ -0,0 +1,19 @@
; RUN: opt -S -instcombine < %s | FileCheck %s
define float @test1(i32 %scale) {
entry:
%tmp1 = icmp sgt i32 1, %scale
%tmp2 = select i1 %tmp1, i32 1, i32 %scale
%tmp3 = sitofp i32 %tmp2 to float
%tmp4 = icmp sgt i32 %tmp2, 0
%sel = select i1 %tmp4, float %tmp3, float 0.000000e+00
ret float %sel
}
; CHECK-LABEL: define float @test1(
; CHECK: %[[tmp1:.*]] = icmp slt i32 %scale, 1
; CHECK: %[[tmp2:.*]] = select i1 %[[tmp1]], i32 1, i32 %scale
; CHECK: %[[tmp3:.*]] = sitofp i32 %[[tmp2]] to float
; CHECK: %[[tmp4:.*]] = icmp sgt i32 %[[tmp2]], 0
; CHECK: %[[sel:.*]] = select i1 %[[tmp4]], float %[[tmp3]], float 0.000000e+00
; CHECK: ret float %[[sel]]