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When GVN needs to split critical edges for load PRE, check all of the

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predecessors before returning.  Otherwise, if multiple predecessor edges need
splitting, we only get one of them per iteration.  This makes a small but
measurable compile time improvement with -enable-full-load-pre.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97521 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bob Wilson 2010-03-01 23:37:32 +00:00
parent 8b30b8dd33
commit 70704978af
1 changed files with 4 additions and 1 deletions
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5
lib/Transforms/Scalar/GVN.cpp
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@ -1580,6 +1580,7 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
for (unsigned i = 0, e = UnavailableBlocks.size(); i != e; ++i)
FullyAvailableBlocks[UnavailableBlocks[i]] = false;
bool NeedToSplitEdges = false;
for (pred_iterator PI = pred_begin(LoadBB), E = pred_end(LoadBB);
PI != E; ++PI) {
BasicBlock *Pred = *PI;
@ -1596,9 +1597,11 @@ bool GVN::processNonLocalLoad(LoadInst *LI,
}
unsigned SuccNum = GetSuccessorNumber(Pred, LoadBB);
toSplit.push_back(std::make_pair(Pred->getTerminator(), SuccNum));
return false;
NeedToSplitEdges = true;
}
}
if (NeedToSplitEdges)
return false;
// Decide whether PRE is profitable for this load.
unsigned NumUnavailablePreds = PredLoads.size();