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InstSimplify: div %X, 0 -> undef

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We already optimized rem %X, 0 to undef, we should do the same for div.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223919 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2014-12-10 07:52:18 +00:00
parent f492c9e612
commit 1297775557
2 changed files with 18 additions and 0 deletions
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4
lib/Analysis/InstructionSimplify.cpp
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@ -1011,6 +1011,10 @@ static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
if (match(Op1, m_Undef())) if (match(Op1, m_Undef()))
return Op1; return Op1;
// X / 0 -> undef, we don't need to preserve faults!
if (match(Op1, m_Zero()))
return UndefValue::get(Op1->getType());
// undef / X -> 0 // undef / X -> 0
if (match(Op0, m_Undef())) if (match(Op0, m_Undef()))
return Constant::getNullValue(Op0->getType()); return Constant::getNullValue(Op0->getType());

14
test/Transforms/InstSimplify/undef.ll
View File

@ -160,3 +160,17 @@ define <4 x i8> @test19(<4 x i8> %a) {
%b = shl <4 x i8> %a, <i8 8, i8 9, i8 undef, i8 -1> %b = shl <4 x i8> %a, <i8 8, i8 9, i8 undef, i8 -1>
ret <4 x i8> %b ret <4 x i8> %b
} }
; CHECK-LABEL: @test20
; CHECK: ret i32 undef
define i32 @test20(i32 %a) {
%b = udiv i32 %a, 0
ret i32 %b
}
; CHECK-LABEL: @test21
; CHECK: ret i32 undef
define i32 @test21(i32 %a) {
%b = sdiv i32 %a, 0
ret i32 %b
}