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InstCombine: Propagate exact for (sdiv X, Y) -> (udiv X, Y)

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222624 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2014-11-22 20:00:38 +00:00
parent 91349eecb0
commit 89bcfdb956
2 changed files with 13 additions and 1 deletions
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4
lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
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@ -1097,7 +1097,9 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
if (MaskedValueIsZero(Op0, Mask, 0, &I)) {
if (MaskedValueIsZero(Op1, Mask, 0, &I)) {
// X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
auto *BO = BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
BO->setIsExact(I.isExact());
return BO;
}
if (match(Op1, m_Shl(m_Power2(), m_Value()))) {

10
test/Transforms/InstCombine/div.ll
View File

@ -304,3 +304,13 @@ define <2 x i64> @test34(<2 x i64> %x) nounwind {
; CHECK-NEXT: sdiv exact <2 x i64> %x, <i64 -3, i64 -4>
; CHECK-NEXT: ret <2 x i64>
}
define i32 @test35(i32 %A) {
%and = and i32 %A, 2147483647
%mul = sdiv exact i32 %and, 2147483647
ret i32 %mul
; CHECK-LABEL: @test35(
; CHECK-NEXT: %[[and:.*]] = and i32 %A, 2147483647
; CHECK-NEXT: %[[udiv:.*]] = udiv exact i32 %[[and]], 2147483647
; CHECK-NEXT: ret i32 %[[udiv]]
}