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- instcombine demorgan's law: and (not A), (not B) == not (or A, B)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3495 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -81,6 +81,8 @@ namespace {
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// in the program. Add the new instruction to the worklist.
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//
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void InsertNewInstBefore(Instruction *New, Instruction &Old) {
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assert(New && New->getParent() == 0 &&
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"New instruction already inserted into a basic block!");
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BasicBlock *BB = Old.getParent();
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BB->getInstList().insert(&Old, New); // Insert inst
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WorkList.push_back(New); // Add to worklist
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@ -292,6 +294,16 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
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if (RHS->isAllOnesValue())
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return ReplaceInstUsesWith(I, Op0);
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// and (not A), (not B) == not (or A, B)
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if (Op0->use_size() == 1 && Op1->use_size() == 1)
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if (Value *A = dyn_castNotInst(Op0))
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if (Value *B = dyn_castNotInst(Op1)) {
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Instruction *Or = BinaryOperator::create(Instruction::Or, A, B,
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I.getName()+".demorgan");
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InsertNewInstBefore(Or, I);
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return BinaryOperator::createNot(Or, I.getName());
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}
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return Changed ? &I : 0;
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}
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