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BBVectorize: Don't over-search when building the dependency map 

When building the pairable-instruction dependency map, don't search
past the last pairable instruction. For large blocks that have been
divided into multiple instruction groups, searching past the last
instruction in each group is very wasteful. This gives a 32% speedup
on the csa.ll test case from PR15222 (when using 50 instructions
in each group).

No functionality change intended.

llvm-svn: 174915
This commit is contained in:
Hal Finkel 2013-02-11 23:02:17 +00:00
parent 39a95032d2
commit 6ae564b4a0
1 changed files with 10 additions and 2 deletions
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12
llvm/lib/Transforms/Vectorize/BBVectorize.cpp
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@ -1380,20 +1380,28 @@ namespace {
// Iterate through the basic block, recording all users of each
// pairable instruction.
BasicBlock::iterator E = BB.end();
BasicBlock::iterator E = BB.end(), EL =
BasicBlock::iterator(cast<Instruction>(PairableInsts.back()));
for (BasicBlock::iterator I = BB.getFirstInsertionPt(); I != E; ++I) {
if (IsInPair.find(I) == IsInPair.end()) continue;
DenseSet<Value *> Users;
AliasSetTracker WriteSet(*AA);
for (BasicBlock::iterator J = llvm::next(I); J != E; ++J)
for (BasicBlock::iterator J = llvm::next(I); J != E; ++J) {
(void) trackUsesOfI(Users, WriteSet, I, J);
if (J == EL)
break;
}
for (DenseSet<Value *>::iterator U = Users.begin(), E = Users.end();
U != E; ++U) {
if (IsInPair.find(*U) == IsInPair.end()) continue;
PairableInstUsers.insert(ValuePair(I, *U));
}
if (I == EL)
break;
}
}