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Tightenup loop filter.

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llvm-svn: 41356
This commit is contained in:
Devang Patel 2007-08-24 05:36:56 +00:00
parent 8b1d0a1ad2
commit 4b52632179
1 changed files with 22 additions and 2 deletions
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24
lib/Transforms/Scalar/LoopIndexSplit.cpp
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@ -272,7 +272,12 @@ void LoopIndexSplit::findLoopConditionals() {
if (!ExitingBlock)
return;
// If exiting block is neither loop header nor loop latch then this loop is
// not suitable.
if (ExitingBlock != L->getHeader() && ExitingBlock != L->getLoopLatch())
return;
// If exit block's terminator is conditional branch inst then we have found
// exit condition.
BranchInst *BR = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
@ -705,7 +710,22 @@ bool LoopIndexSplit::safeSplitCondition(SplitInfo &SD) {
if (Succ0 == *PI)
return false;
return true;
// Finally this split condition is safe only if merge point for
// split condition branch is loop latch. This check along with previous
// check, to ensure that exit condition is in either loop latch or header,
// filters all loops with non-empty loop body between merge point
// and exit condition.
DominanceFrontier::iterator Succ0DF = DF->find(Succ0);
assert (Succ0DF != DF->end() && "Unable to find Succ0 dominance frontier");
if (Succ0DF->second.count(Latch))
return true;
DominanceFrontier::iterator Succ1DF = DF->find(Succ1);
assert (Succ1DF != DF->end() && "Unable to find Succ1 dominance frontier");
if (Succ1DF->second.count(Latch))
return true;
return false;
}
/// splitLoop - Split current loop L in two loops using split information