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Make MaskedValueIsZero a bit more aggressive
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23677 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -404,11 +404,17 @@ static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
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switch (I->getOpcode()) {
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case Instruction::And:
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// (X & C1) & C2 == 0 iff C1 & C2 == 0.
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if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1)))
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if (ConstantExpr::getAnd(CI, Mask)->isNullValue())
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if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1))) {
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ConstantIntegral *C1C2 =
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cast<ConstantIntegral>(ConstantExpr::getAnd(CI, Mask));
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if (MaskedValueIsZero(I->getOperand(0), C1C2))
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return true;
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break;
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}
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// If either the LHS or the RHS are MaskedValueIsZero, the result is zero.
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return MaskedValueIsZero(I->getOperand(1), Mask) ||
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MaskedValueIsZero(I->getOperand(0), Mask);
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case Instruction::Or:
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case Instruction::Xor:
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// If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
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return MaskedValueIsZero(I->getOperand(1), Mask) &&
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MaskedValueIsZero(I->getOperand(0), Mask);
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