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- Fix a problematic way in creating all-the-1 APInt.
- Propagate "exact" bit of [l|a]shr instruction. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169942 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -858,8 +858,8 @@ Value *InstCombiner::SimplifyShrShlDemandedBits(Instruction *Shr,
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Value *VarX = Shr->getOperand(0);
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Type *Ty = VarX->getType();
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APInt BitMask1(Ty->getIntegerBitWidth(), (uint64_t)-1);
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APInt BitMask2(Ty->getIntegerBitWidth(), (uint64_t)-1);
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APInt BitMask1(APInt::getAllOnesValue(Ty->getIntegerBitWidth()));
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APInt BitMask2(APInt::getAllOnesValue(Ty->getIntegerBitWidth()));
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bool isLshr = (Shr->getOpcode() == Instruction::LShr);
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BitMask1 = isLshr ? (BitMask1.lshr(ShrAmt) << ShlAmt) :
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@ -891,6 +891,8 @@ Value *InstCombiner::SimplifyShrShlDemandedBits(Instruction *Shr,
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Constant *Amt = ConstantInt::get(VarX->getType(), ShrAmt - ShlAmt);
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New = isLshr ? BinaryOperator::CreateLShr(VarX, Amt) :
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BinaryOperator::CreateAShr(VarX, Amt);
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if (cast<BinaryOperator>(Shr)->isExact())
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New->setIsExact(true);
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}
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return InsertNewInstWith(New, *Shl);
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@ -735,3 +735,13 @@ define i32 @test61(i32 %x) {
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; CHECK: @test61
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; CHECK: ashr i32 %x, 4
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}
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; propagate "exact" trait
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define i32 @test62(i32 %x) {
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%shr = ashr exact i32 %x, 4
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%shl = shl i32 %shr, 1
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%or = or i32 %shl, 1
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ret i32 %or
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; CHECK: @test62
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; CHECK: ashr exact i32 %x, 3
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}
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