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Add InEdges (edges from header to the loop) in Loop Branch Heuristics, so

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there is no frequency difference whether condition is in the header or in
the latch.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136398 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakub Staszak 2011-07-28 21:33:46 +00:00
parent 1ddaa9c1c6
commit fa44725233
1 changed files with 17 additions and 0 deletions
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17
lib/Analysis/BranchProbabilityInfo.cpp
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@ -205,6 +205,9 @@ void BranchProbabilityAnalysis::calcLoopBranchHeuristics(BasicBlock *BB) {
SmallVector<BasicBlock *, 8> BackEdges;
SmallVector<BasicBlock *, 8> ExitingEdges;
SmallVector<BasicBlock *, 8> InEdges; // Edges from header to the loop.
bool isHeader = BB == L->getHeader();
for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) {
BasicBlock *Succ = *I;
@ -213,6 +216,8 @@ void BranchProbabilityAnalysis::calcLoopBranchHeuristics(BasicBlock *BB) {
ExitingEdges.push_back(Succ);
else if (Succ == L->getHeader())
BackEdges.push_back(Succ);
else if (isHeader)
InEdges.push_back(Succ);
}
if (uint32_t numBackEdges = BackEdges.size()) {
@ -227,6 +232,18 @@ void BranchProbabilityAnalysis::calcLoopBranchHeuristics(BasicBlock *BB) {
}
}
if (uint32_t numInEdges = InEdges.size()) {
uint32_t inWeight = LBH_TAKEN_WEIGHT / numInEdges;
if (inWeight < NORMAL_WEIGHT)
inWeight = NORMAL_WEIGHT;
for (SmallVector<BasicBlock *, 8>::iterator EI = InEdges.begin(),
EE = InEdges.end(); EI != EE; ++EI) {
BasicBlock *Back = *EI;
BP->setEdgeWeight(BB, Back, inWeight);
}
}
uint32_t numExitingEdges = ExitingEdges.size();
if (uint32_t numNonExitingEdges = numSuccs - numExitingEdges) {
uint32_t exitWeight = LBH_NONTAKEN_WEIGHT / numNonExitingEdges;