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cache computation of #preds for a BB. This speeds up 

mem2reg from 2.0742->2.0522s on PR1432.

llvm-svn: 40821
This commit is contained in:
Chris Lattner 2007-08-04 20:24:50 +00:00
parent 050bac4bed
commit 840259c8d3
1 changed files with 14 additions and 3 deletions
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17
llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
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@ -137,6 +137,8 @@ namespace {
/// non-determinstic behavior.
DenseMap<BasicBlock*, unsigned> BBNumbers;
/// BBNumPreds - Lazily compute the number of predecessors a block has.
DenseMap<const BasicBlock*, unsigned> BBNumPreds;
public:
PromoteMem2Reg(const std::vector<AllocaInst*> &A,
SmallVector<AllocaInst*, 16> &Retry, DominatorTree &dt,
@ -165,6 +167,14 @@ namespace {
Allocas.pop_back();
--AllocaIdx;
}
unsigned getNumPreds(const BasicBlock *BB) {
unsigned &NP = BBNumPreds[BB];
if (NP == 0)
NP = std::distance(pred_begin(BB), pred_end(BB))+1;
return NP-1;
}
void RewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info);
@ -209,7 +219,7 @@ namespace {
// and decide whether all of the loads and stores to the alloca are within
// the same basic block.
for (Value::use_iterator U = AI->use_begin(), E = AI->use_end();
U != E; ++U){
U != E; ++U) {
Instruction *User = cast<Instruction>(*U);
if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
// Remember the basic blocks which define new values for the alloca
@ -218,7 +228,8 @@ namespace {
OnlyStore = SI;
} else {
LoadInst *LI = cast<LoadInst>(User);
// Otherwise it must be a load instruction, keep track of variable reads
// Otherwise it must be a load instruction, keep track of variable
// reads.
UsingBlocks.push_back(LI->getParent());
AllocaPointerVal = LI;
}
@ -772,7 +783,7 @@ bool PromoteMem2Reg::QueuePhiNode(BasicBlock *BB, unsigned AllocaNo,
Allocas[AllocaNo]->getName() + "." +
utostr(Version++), BB->begin());
PhiToAllocaMap[PN] = AllocaNo;
PN->reserveOperandSpace(std::distance(pred_begin(BB), pred_end(BB)));
PN->reserveOperandSpace(getNumPreds(BB));
InsertedPHINodes.insert(PN);