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Fold away one multiply in instcombine. This would normally be caught in
reassociate anyways, but they could be generated during instcombine's run. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46683 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -2123,6 +2123,30 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
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if (Instruction *R = AssociativeOpt(I, AddMaskingAnd(C2)))
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return R;
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// W*X + Y*Z --> W * (X+Z) iff W == Y
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if (I.getType()->isInteger()) {
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Value *W, *X, *Y, *Z;
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if (match(LHS, m_Mul(m_Value(W), m_Value(X))) &&
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match(RHS, m_Mul(m_Value(Y), m_Value(Z)))) {
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if (W != Y) {
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if (W == Z) {
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std::swap(Y, Z);
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} else if (Y == X) {
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std::swap(W, X);
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} else if (X == Z) {
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std::swap(Y, Z);
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std::swap(W, X);
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}
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}
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if (W == Y) {
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Value *NewAdd = InsertNewInstBefore(BinaryOperator::createAdd(X, Z,
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LHS->getName()), I);
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return BinaryOperator::createMul(W, NewAdd);
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}
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}
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}
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if (ConstantInt *CRHS = dyn_cast<ConstantInt>(RHS)) {
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Value *X = 0;
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if (match(LHS, m_Not(m_Value(X)))) // ~X + C --> (C-1) - X
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