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There is no need for separate WriteSets and PhiNodeBlocks lists. It is just a

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work-list of value definitions.  This allows elimination of the explicit
'iterative' step of the algorithm, and also reuses temporary memory better.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8861 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-10-05 03:39:10 +00:00
parent 036f1e7478
commit 92581c24a3
1 changed files with 8 additions and 18 deletions
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26
lib/Transforms/Utils/PromoteMemoryToRegister.cpp
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@ -81,7 +81,6 @@ namespace {
};
} // end of anonymous namespace
void PromoteMem2Reg::run() {
Function &F = *DF.getRoot()->getParent();
@ -97,11 +96,11 @@ void PromoteMem2Reg::run() {
// Calculate the set of write-locations for each alloca. This is analogous
// to counting the number of 'redefinitions' of each variable.
std::vector<BasicBlock*> WriteSets;
std::vector<BasicBlock*> DefiningBlocks;
for (Value::use_iterator U =AI->use_begin(), E = AI->use_end(); U != E; ++U)
if (StoreInst *SI = dyn_cast<StoreInst>(cast<Instruction>(*U)))
// jot down the basic-block it came from
WriteSets.push_back(SI->getParent());
DefiningBlocks.push_back(SI->getParent());
AllocaLookup[Allocas[i]] = i;
@ -112,27 +111,18 @@ void PromoteMem2Reg::run() {
// Compute the locations where PhiNodes need to be inserted. Look at the
// dominance frontier of EACH basic-block we have a write in.
//
for (unsigned j = 0; j != WriteSets.size(); j++) {
while (!DefiningBlocks.empty()) {
BasicBlock *BB = DefiningBlocks.back();
DefiningBlocks.pop_back();
// Look up the DF for this write, add it to PhiNodes
DominanceFrontier::const_iterator it = DF.find(WriteSets[j]);
DominanceFrontier::const_iterator it = DF.find(BB);
if (it != DF.end()) {
const DominanceFrontier::DomSetType &S = it->second;
for (DominanceFrontier::DomSetType::iterator P = S.begin(),PE = S.end();
P != PE; ++P)
if (QueuePhiNode(*P, i))
PhiNodeBlocks.push_back(*P);
}
}
// Perform iterative step
for (unsigned k = 0; k != PhiNodeBlocks.size(); k++) {
DominanceFrontier::const_iterator it = DF.find(PhiNodeBlocks[k]);
if (it != DF.end()) {
const DominanceFrontier::DomSetType &S = it->second;
for (DominanceFrontier::DomSetType::iterator
P = S.begin(), PE = S.end(); P != PE; ++P)
if (QueuePhiNode(*P, i))
PhiNodeBlocks.push_back(*P);
DefiningBlocks.push_back(*P);
}
}
}