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Avoid creating garbage instructions, just move the old add instruction
to where we need it when converting -(A+B+C) -> -A + -B + -C. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23213 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -318,16 +318,18 @@ static Value *NegateValue(Value *V, Instruction *BI) {
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//
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//
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if (Instruction *I = dyn_cast<Instruction>(V))
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if (Instruction *I = dyn_cast<Instruction>(V))
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if (I->getOpcode() == Instruction::Add && I->hasOneUse()) {
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if (I->getOpcode() == Instruction::Add && I->hasOneUse()) {
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Value *RHS = NegateValue(I->getOperand(1), BI);
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// Push the negates through the add.
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Value *LHS = NegateValue(I->getOperand(0), BI);
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I->setOperand(0, NegateValue(I->getOperand(0), BI));
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I->setOperand(1, NegateValue(I->getOperand(1), BI));
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// We must actually insert a new add instruction here, because the neg
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// We must move the add instruction here, because the neg instructions do
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// instructions do not dominate the old add instruction in general. By
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// not dominate the old add instruction in general. By moving it, we are
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// adding it now, we are assured that the neg instructions we just
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// assured that the neg instructions we just inserted dominate the
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// inserted dominate the instruction we are about to insert after them.
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// instruction we are about to insert after them.
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//
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//
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return BinaryOperator::create(Instruction::Add, LHS, RHS,
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I->moveBefore(BI);
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I->getName()+".neg", BI);
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I->setName(I->getName()+".neg");
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return I;
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}
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}
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// Insert a 'neg' instruction that subtracts the value from zero to get the
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// Insert a 'neg' instruction that subtracts the value from zero to get the
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