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* Fix bug: test/Regression/Transforms/GCSE/2002-05-14-OperandSwap.ll

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By making sure to consider binary expressions identical if their operands
are backwards, but swappable.

llvm-svn: 2629
This commit is contained in:
Chris Lattner 2002-05-14 19:57:25 +00:00
parent 4859d6b591
commit fc21b26332
1 changed files with 32 additions and 7 deletions
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39
lib/Transforms/Scalar/GCSE.cpp
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@ -256,6 +256,37 @@ bool GCSE::visitUnaryOperator(Instruction *I) {
return false;
}
// isIdenticalBinaryInst - Return true if the two binary instructions are
// identical.
//
static inline bool isIdenticalBinaryInst(const Instruction *I1,
const Instruction *I2) {
// Is it embeded in the same function? (This could be false if LHS
// is a constant or global!)
if (I1->getOpcode() != I2->getOpcode() ||
I1->getParent()->getParent() != I2->getParent()->getParent())
return false;
// They are identical if both operands are the same!
if (I1->getOperand(0) == I2->getOperand(0) &&
I1->getOperand(1) == I2->getOperand(1))
return true;
// If the instruction is commutative and associative, the instruction can
// match if the operands are swapped!
//
if ((I1->getOperand(0) == I2->getOperand(1) &&
I1->getOperand(1) == I2->getOperand(0)) &&
(I1->getOpcode() == Instruction::Add ||
I1->getOpcode() == Instruction::Mul ||
I1->getOpcode() == Instruction::And ||
I1->getOpcode() == Instruction::Or ||
I1->getOpcode() == Instruction::Xor))
return true;
return false;
}
bool GCSE::visitBinaryOperator(Instruction *I) {
Value *LHS = I->getOperand(0), *RHS = I->getOperand(1);
Function *F = I->getParent()->getParent();
@ -264,13 +295,7 @@ bool GCSE::visitBinaryOperator(Instruction *I) {
UI != UE; ++UI)
if (Instruction *Other = dyn_cast<Instruction>(*UI))
// Check to see if this new binary operator is not I, but same operand...
if (Other != I && Other->getOpcode() == I->getOpcode() &&
// Are the LHS and RHS the same?
Other->getOperand(0) == LHS && Other->getOperand(1) == RHS &&
// Is it embeded in the same function? (This could be false if LHS
// is a constant or global!)
Other->getParent()->getParent() == F) {
if (Other != I && isIdenticalBinaryInst(I, Other)) {
// These instructions are identical. Handle the situation.
CommonSubExpressionFound(I, Other);
return true; // One instruction eliminated!