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InstCombine: Don't take A-B<0 into A<B if A-B has other uses

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This fixes PR22226.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226023 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer
2015-01-14 19:26:56 +00:00
parent 8327f0bca1
commit 5e8cd99f55
2 changed files with 42 additions and 25 deletions
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15
test/Transforms/InstCombine/icmp.ll
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@@ -1558,3 +1558,18 @@ define i1 @f4(i64 %a, i64 %b) {
%v = icmp sle i64 %t, 0
ret i1 %v
}
; CHECK-LABEL: @f5
; CHECK: %[[cmp:.*]] = icmp slt i32 %[[sub:.*]], 0
; CHECK: %[[neg:.*]] = sub nsw i32 0, %[[sub]]
; CHECK: %[[sel:.*]] = select i1 %[[cmp]], i32 %[[neg]], i32 %[[sub]]
; CHECK: ret i32 %[[sel]]
define i32 @f5(i8 %a, i8 %b) {
%conv = zext i8 %a to i32
%conv3 = zext i8 %b to i32
%sub = sub nsw i32 %conv, %conv3
%cmp4 = icmp slt i32 %sub, 0
%sub7 = sub nsw i32 0, %sub
%sub7.sub = select i1 %cmp4, i32 %sub7, i32 %sub
ret i32 %sub7.sub
}