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Minor changes:
* Reword comment to make more clear * Don't print out BB's after modification made * Don't delete and new an instruction when we need to move something, just move it. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5029 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -68,7 +68,7 @@ unsigned Reassociate::getRank(Value *V) {
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// If this is an expression, return the MAX(rank(LHS), rank(RHS)) so that we
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// can reassociate expressions for code motion! Since we do not recurse for
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// PHI nodes, we cannot have infinite recursion here, because there cannot
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// be loops in the value graph (except for PHI nodes).
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// be loops in the value graph that do not go through PHI nodes.
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//
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if (I->getOpcode() == Instruction::PHINode ||
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I->getOpcode() == Instruction::Alloca ||
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@ -106,7 +106,8 @@ bool Reassociate::ReassociateExpr(BinaryOperator *I) {
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std::swap(LHSRank, RHSRank);
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Changed = true;
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++NumSwapped;
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DEBUG(std::cerr << "Transposed: " << I << " Result BB: " << I->getParent());
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DEBUG(std::cerr << "Transposed: " << I
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/* << " Result BB: " << I->getParent()*/);
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}
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// If the LHS is the same operator as the current one is, and if we are the
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@ -124,28 +125,20 @@ bool Reassociate::ReassociateExpr(BinaryOperator *I) {
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// Convert ((a + 12) + 10) into (a + (12 + 10))
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I->setOperand(0, LHSI->getOperand(TakeOp));
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LHSI->setOperand(TakeOp, RHS);
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I->setOperand(1, LHSI);
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// Move the LHS expression forward, to ensure that it is dominated by
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// its operands.
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std::string Name = LHSI->getName();
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LHSI->setName("");
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BinaryOperator *NewLHS =
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BinaryOperator::create(LHSI->getOpcode(),
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LHSI->getOperand(0), LHSI->getOperand(1),
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Name, I);
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NewLHS->setOperand(TakeOp, RHS);
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I->setOperand(1, NewLHS);
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assert(LHSI->use_size() == 0 && "References to LHS shouldn't exist!");
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LHSI->getParent()->getInstList().erase(LHSI);
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LHSI->getParent()->getInstList().remove(LHSI);
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I->getParent()->getInstList().insert(I, LHSI);
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++NumChanged;
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DEBUG(std::cerr << "Reassociated: " << I << " Result BB: "
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<< I->getParent());
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DEBUG(std::cerr << "Reassociated: " << I/* << " Result BB: "
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<< I->getParent()*/);
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// Since we modified the RHS instruction, make sure that we recheck it.
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ReassociateExpr(NewLHS);
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ReassociateExpr(LHSI);
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return true;
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}
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}
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@ -195,6 +188,7 @@ bool Reassociate::ReassociateBB(BasicBlock *BB) {
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bool Changed = false;
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for (BasicBlock::iterator BI = BB->begin(); BI != BB->end(); ++BI) {
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DEBUG(std::cerr << "Processing: " << *BI);
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if (BI->getOpcode() == Instruction::Sub && !BinaryOperator::isNeg(BI)) {
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// Convert a subtract into an add and a neg instruction... so that sub
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// instructions can be commuted with other add instructions...
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@ -218,7 +212,7 @@ bool Reassociate::ReassociateBB(BasicBlock *BB) {
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New->setOperand(1, NegateValue(New->getOperand(1), BI));
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Changed = true;
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DEBUG(std::cerr << "Negated: " << New << " Result BB: " << BB);
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DEBUG(std::cerr << "Negated: " << New /*<< " Result BB: " << BB*/);
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}
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// If this instruction is a commutative binary operator, and the ranks of
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@ -248,7 +242,7 @@ bool Reassociate::ReassociateBB(BasicBlock *BB) {
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I = Tmp;
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++NumLinear;
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Changed = true;
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DEBUG(std::cerr << "Linearized: " << I << " Result BB: " << BB);
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DEBUG(std::cerr << "Linearized: " << I/* << " Result BB: " << BB*/);
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}
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// Make sure that this expression is correctly reassociated with respect
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