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In SimplifyICmpOperands, avoid needlessly swapping the operands in the

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case where both are addrecs in unrelated loops.

llvm-svn: 102924
This commit is contained in:
Dan Gohman 2010-05-03 17:00:11 +00:00
parent 02c26ed601
commit 043875bc90
1 changed files with 6 additions and 3 deletions
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9
lib/Analysis/ScalarEvolution.cpp
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@ -4783,13 +4783,16 @@ bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
}
// If we're comparing an addrec with a value which is loop-invariant in the
// addrec's loop, put the addrec on the left.
if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS))
if (LHS->isLoopInvariant(AR->getLoop())) {
// addrec's loop, put the addrec on the left. Also make a dominance check,
// as both operands could be addrecs loop-invariant in each other's loop.
if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) {
const Loop *L = AR->getLoop();
if (LHS->isLoopInvariant(L) && LHS->properlyDominates(L->getHeader(), DT)) {
std::swap(LHS, RHS);
Pred = ICmpInst::getSwappedPredicate(Pred);
Changed = true;
}
}
// If there's a constant operand, canonicalize comparisons with boundary
// cases, and canonicalize *-or-equal comparisons to regular comparisons.