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[InstCombine] Handle saddo always overflow

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Followup to D60483: Handle AlwaysOverflow conditions for saddo as
well.

Differential Revision: https://reviews.llvm.org/D60497

llvm-svn: 358095
This commit is contained in:
Nikita Popov 2019-04-10 16:18:01 +00:00
parent 0f1b0f0d1b
commit 87602bfacc
2 changed files with 6 additions and 5 deletions
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6
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -3973,15 +3973,15 @@ bool InstCombiner::OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS,
if (OR == OverflowResult::NeverOverflows)
return SetResult(Builder.CreateNUWAdd(LHS, RHS), Builder.getFalse(),
true);
if (OR == OverflowResult::AlwaysOverflows)
return SetResult(Builder.CreateAdd(LHS, RHS), Builder.getTrue(), true);
} else {
OR = computeOverflowForSignedAdd(LHS, RHS, &OrigI);
if (OR == OverflowResult::NeverOverflows)
return SetResult(Builder.CreateNSWAdd(LHS, RHS), Builder.getFalse(),
true);
}
if (OR == OverflowResult::AlwaysOverflows)
return SetResult(Builder.CreateAdd(LHS, RHS), Builder.getTrue(), true);
break;
}

5
test/Transforms/InstCombine/with_overflow.ll
View File

@ -568,8 +568,9 @@ define { i8, i1 } @sadd_always_overflow(i8 %x) nounwind {
; CHECK-LABEL: @sadd_always_overflow(
; CHECK-NEXT: [[C:%.*]] = icmp sgt i8 [[X:%.*]], 100
; CHECK-NEXT: [[Y:%.*]] = select i1 [[C]], i8 [[X]], i8 100
; CHECK-NEXT: [[A:%.*]] = call { i8, i1 } @llvm.sadd.with.overflow.i8(i8 [[Y]], i8 28)
; CHECK-NEXT: ret { i8, i1 } [[A]]
; CHECK-NEXT: [[A:%.*]] = add nuw i8 [[Y]], 28
; CHECK-NEXT: [[TMP1:%.*]] = insertvalue { i8, i1 } { i8 undef, i1 true }, i8 [[A]], 0
; CHECK-NEXT: ret { i8, i1 } [[TMP1]]
;
%c = icmp sgt i8 %x, 100
%y = select i1 %c, i8 %x, i8 100