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speed up CGP a bit by scanning predecessors through phi operands 

instead of with pred_begin/end.

llvm-svn: 96078
This commit is contained in:
Chris Lattner 2010-02-13 04:04:42 +00:00
parent bb79b5f6f3
commit 96b8826542
1 changed files with 22 additions and 22 deletions
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44
llvm/lib/Transforms/Scalar/CodeGenPrepare.cpp
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@ -315,13 +315,12 @@ static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum,
BasicBlock *Dest = TI->getSuccessor(SuccNum);
assert(isa<PHINode>(Dest->begin()) &&
"This should only be called if Dest has a PHI!");
PHINode *DestPHI = cast<PHINode>(Dest->begin());
// Do not split edges to EH landing pads.
if (InvokeInst *Invoke = dyn_cast<InvokeInst>(TI)) {
if (InvokeInst *Invoke = dyn_cast<InvokeInst>(TI))
if (Invoke->getSuccessor(1) == Dest)
return;
}
// As a hack, never split backedges of loops. Even though the copy for any
// PHIs inserted on the backedge would be dead for exits from the loop, we
@ -333,11 +332,11 @@ static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum,
/// TIPHIValues - This array is lazily computed to determine the values of
/// PHIs in Dest that TI would provide.
SmallVector<Value*, 32> TIPHIValues;
// Check to see if Dest has any blocks that can be used as a split edge for
// this terminator.
for (pred_iterator PI = pred_begin(Dest), E = pred_end(Dest); PI != E; ++PI) {
BasicBlock *Pred = *PI;
for (unsigned pi = 0, e = DestPHI->getNumIncomingValues(); pi != e; ++pi) {
BasicBlock *Pred = DestPHI->getIncomingBlock(pi);
// To be usable, the pred has to end with an uncond branch to the dest.
BranchInst *PredBr = dyn_cast<BranchInst>(Pred->getTerminator());
if (!PredBr || !PredBr->isUnconditional())
@ -346,10 +345,10 @@ static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum,
BasicBlock::iterator I = Pred->begin();
while (isa<DbgInfoIntrinsic>(I))
I++;
if (dyn_cast<Instruction>(I) != PredBr)
if (&*I != PredBr)
continue;
// Cannot be the entry block; its label does not get emitted.
if (Pred == &(Dest->getParent()->getEntryBlock()))
if (Pred == &Dest->getParent()->getEntryBlock())
continue;
// Finally, since we know that Dest has phi nodes in it, we have to make
@ -392,24 +391,25 @@ static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum,
TIPHIValues.push_back(PN->getIncomingValueForBlock(TIBB));
SmallVector<BasicBlock*, 8> IdenticalPreds;
for (pred_iterator PI = pred_begin(Dest), E = pred_end(Dest); PI != E; ++PI) {
BasicBlock *Pred = *PI;
for (unsigned pi = 0, e = DestPHI->getNumIncomingValues(); pi != e; ++pi) {
BasicBlock *Pred = DestPHI->getIncomingBlock(pi);
if (BackEdges.count(std::make_pair(Pred, Dest)))
continue;
if (PI == TIBB)
if (Pred == TIBB) {
IdenticalPreds.push_back(Pred);
else {
bool Identical = true;
unsigned PHINo = 0;
for (BasicBlock::iterator I = Dest->begin();
(PN = dyn_cast<PHINode>(I)); ++I, ++PHINo)
if (TIPHIValues[PHINo] != PN->getIncomingValueForBlock(Pred)) {
Identical = false;
break;
}
if (Identical)
IdenticalPreds.push_back(Pred);
continue;
}
bool Identical = true;
unsigned PHINo = 0;
for (BasicBlock::iterator I = Dest->begin();
(PN = dyn_cast<PHINode>(I)); ++I, ++PHINo)
if (TIPHIValues[PHINo] != PN->getIncomingValueForBlock(Pred)) {
Identical = false;
break;
}
if (Identical)
IdenticalPreds.push_back(Pred);
}
assert(!IdenticalPreds.empty());