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Minor changes:

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* 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
This commit is contained in:
Chris Lattner 2002-12-15 03:49:50 +00:00
parent debb5ee6c0
commit 680f0c283d
1 changed files with 13 additions and 19 deletions
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32
lib/Transforms/Scalar/Reassociate.cpp
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@ -68,7 +68,7 @@ unsigned Reassociate::getRank(Value *V) {
// If this is an expression, return the MAX(rank(LHS), rank(RHS)) so that we // If this is an expression, return the MAX(rank(LHS), rank(RHS)) so that we
// can reassociate expressions for code motion! Since we do not recurse for // can reassociate expressions for code motion! Since we do not recurse for
// PHI nodes, we cannot have infinite recursion here, because there cannot // PHI nodes, we cannot have infinite recursion here, because there cannot
// be loops in the value graph (except for PHI nodes). // be loops in the value graph that do not go through PHI nodes.
// //
if (I->getOpcode() == Instruction::PHINode || if (I->getOpcode() == Instruction::PHINode ||
I->getOpcode() == Instruction::Alloca || I->getOpcode() == Instruction::Alloca ||
@ -106,7 +106,8 @@ bool Reassociate::ReassociateExpr(BinaryOperator *I) {
std::swap(LHSRank, RHSRank); std::swap(LHSRank, RHSRank);
Changed = true; Changed = true;
++NumSwapped; ++NumSwapped;
DEBUG(std::cerr << "Transposed: " << I << " Result BB: " << I->getParent()); DEBUG(std::cerr << "Transposed: " << I
/* << " Result BB: " << I->getParent()*/);
} }
// If the LHS is the same operator as the current one is, and if we are the // If the LHS is the same operator as the current one is, and if we are the
@ -124,28 +125,20 @@ bool Reassociate::ReassociateExpr(BinaryOperator *I) {
// Convert ((a + 12) + 10) into (a + (12 + 10)) // Convert ((a + 12) + 10) into (a + (12 + 10))
I->setOperand(0, LHSI->getOperand(TakeOp)); I->setOperand(0, LHSI->getOperand(TakeOp));
LHSI->setOperand(TakeOp, RHS);
I->setOperand(1, LHSI);
// Move the LHS expression forward, to ensure that it is dominated by // Move the LHS expression forward, to ensure that it is dominated by
// its operands. // its operands.
std::string Name = LHSI->getName(); LHSI->getParent()->getInstList().remove(LHSI);
LHSI->setName(""); I->getParent()->getInstList().insert(I, LHSI);
BinaryOperator *NewLHS =
BinaryOperator::create(LHSI->getOpcode(),
LHSI->getOperand(0), LHSI->getOperand(1),
Name, I);
NewLHS->setOperand(TakeOp, RHS);
I->setOperand(1, NewLHS);
assert(LHSI->use_size() == 0 && "References to LHS shouldn't exist!");
LHSI->getParent()->getInstList().erase(LHSI);
++NumChanged; ++NumChanged;
DEBUG(std::cerr << "Reassociated: " << I << " Result BB: " DEBUG(std::cerr << "Reassociated: " << I/* << " Result BB: "
<< I->getParent()); << I->getParent()*/);
// Since we modified the RHS instruction, make sure that we recheck it. // Since we modified the RHS instruction, make sure that we recheck it.
ReassociateExpr(NewLHS); ReassociateExpr(LHSI);
return true; return true;
} }
} }
@ -195,6 +188,7 @@ bool Reassociate::ReassociateBB(BasicBlock *BB) {
bool Changed = false; bool Changed = false;
for (BasicBlock::iterator BI = BB->begin(); BI != BB->end(); ++BI) { for (BasicBlock::iterator BI = BB->begin(); BI != BB->end(); ++BI) {
DEBUG(std::cerr << "Processing: " << *BI);
if (BI->getOpcode() == Instruction::Sub && !BinaryOperator::isNeg(BI)) { if (BI->getOpcode() == Instruction::Sub && !BinaryOperator::isNeg(BI)) {
// Convert a subtract into an add and a neg instruction... so that sub // Convert a subtract into an add and a neg instruction... so that sub
// instructions can be commuted with other add instructions... // instructions can be commuted with other add instructions...
@ -218,7 +212,7 @@ bool Reassociate::ReassociateBB(BasicBlock *BB) {
New->setOperand(1, NegateValue(New->getOperand(1), BI)); New->setOperand(1, NegateValue(New->getOperand(1), BI));
Changed = true; Changed = true;
DEBUG(std::cerr << "Negated: " << New << " Result BB: " << BB); DEBUG(std::cerr << "Negated: " << New /*<< " Result BB: " << BB*/);
} }
// If this instruction is a commutative binary operator, and the ranks of // If this instruction is a commutative binary operator, and the ranks of
@ -248,7 +242,7 @@ bool Reassociate::ReassociateBB(BasicBlock *BB) {
I = Tmp; I = Tmp;
++NumLinear; ++NumLinear;
Changed = true; Changed = true;
DEBUG(std::cerr << "Linearized: " << I << " Result BB: " << BB); DEBUG(std::cerr << "Linearized: " << I/* << " Result BB: " << BB*/);
} }
// Make sure that this expression is correctly reassociated with respect // Make sure that this expression is correctly reassociated with respect