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fix a nice subtle reassociate bug which would only occur

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in a very specific use pattern embodied in the carefully
reduced testcase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97794 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2010-03-05 07:18:54 +00:00
parent 25ec483cfc
commit 893075f46e
2 changed files with 34 additions and 7 deletions
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26
lib/Transforms/Scalar/Reassociate.cpp
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@@ -597,19 +597,35 @@ Value *Reassociate::RemoveFactorFromExpression(Value *V, Value *Factor) {
/// FindSingleUseMultiplyFactors - If V is a single-use multiply, recursively
/// add its operands as factors, otherwise add V to the list of factors.
///
/// Ops is the top-level list of add operands we're trying to factor.
static void FindSingleUseMultiplyFactors(Value *V,
SmallVectorImpl<Value*> &Factors) {
SmallVectorImpl<Value*> &Factors,
const SmallVectorImpl<ValueEntry> &Ops,
bool IsRoot) {
BinaryOperator *BO;
if ((!V->hasOneUse() && !V->use_empty()) ||
if (!(V->hasOneUse() || V->use_empty()) || // More than one use.
!(BO = dyn_cast<BinaryOperator>(V)) ||
BO->getOpcode() != Instruction::Mul) {
Factors.push_back(V);
return;
}
// If this value has a single use because it is another input to the add
// tree we're reassociating and we dropped its use, it actually has two
// uses and we can't factor it.
if (!IsRoot) {
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
if (Ops[i].Op == V) {
Factors.push_back(V);
return;
}
}
// Otherwise, add the LHS and RHS to the list of factors.
FindSingleUseMultiplyFactors(BO->getOperand(1), Factors);
FindSingleUseMultiplyFactors(BO->getOperand(0), Factors);
FindSingleUseMultiplyFactors(BO->getOperand(1), Factors, Ops, false);
FindSingleUseMultiplyFactors(BO->getOperand(0), Factors, Ops, false);
}
/// OptimizeAndOrXor - Optimize a series of operands to an 'and', 'or', or 'xor'
@@ -753,7 +769,7 @@ Value *Reassociate::OptimizeAdd(Instruction *I,
// Compute all of the factors of this added value.
SmallVector<Value*, 8> Factors;
FindSingleUseMultiplyFactors(BOp, Factors);
FindSingleUseMultiplyFactors(BOp, Factors, Ops, true);
assert(Factors.size() > 1 && "Bad linearize!");
// Add one to FactorOccurrences for each unique factor in this op.