++I; // Skip one edge due to the incoming arc from TI.
if (!AllowIdenticalEdges)
return I != E;
-
+
// If AllowIdenticalEdges is true, then we allow this edge to be considered
// non-critical iff all preds come from TI's block.
while (I != E) {
return false;
}
-/// CreatePHIsForSplitLoopExit - When a loop exit edge is split, LCSSA form
+/// createPHIsForSplitLoopExit - When a loop exit edge is split, LCSSA form
/// may require new PHIs in the new exit block. This function inserts the
-/// new PHIs, as needed. Preds is a list of preds inside the loop, SplitBB
+/// new PHIs, as needed. Preds is a list of preds inside the loop, SplitBB
/// is the new loop exit block, and DestBB is the old loop exit, now the
/// successor of SplitBB.
-static void CreatePHIsForSplitLoopExit(SmallVectorImpl<BasicBlock *> &Preds,
+static void createPHIsForSplitLoopExit(ArrayRef<BasicBlock *> Preds,
BasicBlock *SplitBB,
BasicBlock *DestBB) {
// SplitBB shouldn't have anything non-trivial in it yet.
- assert(SplitBB->getFirstNonPHI() == SplitBB->getTerminator() &&
- "SplitBB has non-PHI nodes!");
+ assert((SplitBB->getFirstNonPHI() == SplitBB->getTerminator() ||
+ SplitBB->isLandingPad()) && "SplitBB has non-PHI nodes!");
- // For each PHI in the destination block...
+ // For each PHI in the destination block.
for (BasicBlock::iterator I = DestBB->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I) {
unsigned Idx = PN->getBasicBlockIndex(SplitBB);
Value *V = PN->getIncomingValue(Idx);
+
// If the input is a PHI which already satisfies LCSSA, don't create
// a new one.
if (const PHINode *VP = dyn_cast<PHINode>(V))
if (VP->getParent() == SplitBB)
continue;
+
// Otherwise a new PHI is needed. Create one and populate it.
- PHINode *NewPN = PHINode::Create(PN->getType(), Preds.size(), "split",
- SplitBB->getTerminator());
+ PHINode *NewPN =
+ PHINode::Create(PN->getType(), Preds.size(), "split",
+ SplitBB->isLandingPad() ?
+ SplitBB->begin() : SplitBB->getTerminator());
for (unsigned i = 0, e = Preds.size(); i != e; ++i)
NewPN->addIncoming(V, Preds[i]);
+
// Update the original PHI.
PN->setIncomingValue(Idx, NewPN);
}
/// This returns the new block if the edge was split, null otherwise.
///
/// If MergeIdenticalEdges is true (not the default), *all* edges from TI to the
-/// specified successor will be merged into the same critical edge block.
-/// This is most commonly interesting with switch instructions, which may
+/// specified successor will be merged into the same critical edge block.
+/// This is most commonly interesting with switch instructions, which may
/// have many edges to any one destination. This ensures that all edges to that
-/// dest go to one block instead of each going to a different block, but isn't
+/// dest go to one block instead of each going to a different block, but isn't
/// the standard definition of a "critical edge".
///
/// It is invalid to call this function on a critical edge that starts at an
/// to.
///
BasicBlock *llvm::SplitCriticalEdge(TerminatorInst *TI, unsigned SuccNum,
- Pass *P, bool MergeIdenticalEdges) {
+ Pass *P, bool MergeIdenticalEdges,
+ bool DontDeleteUselessPhis,
+ bool SplitLandingPads) {
if (!isCriticalEdge(TI, SuccNum, MergeIdenticalEdges)) return 0;
-
+
assert(!isa<IndirectBrInst>(TI) &&
"Cannot split critical edge from IndirectBrInst");
-
+
BasicBlock *TIBB = TI->getParent();
BasicBlock *DestBB = TI->getSuccessor(SuccNum);
+ // Splitting the critical edge to a landing pad block is non-trivial. Don't do
+ // it in this generic function.
+ if (DestBB->isLandingPad()) return 0;
+
// Create a new basic block, linking it into the CFG.
BasicBlock *NewBB = BasicBlock::Create(TI->getContext(),
TIBB->getName() + "." + DestBB->getName() + "_crit_edge");
Function &F = *TIBB->getParent();
Function::iterator FBBI = TIBB;
F.getBasicBlockList().insert(++FBBI, NewBB);
-
+
// If there are any PHI nodes in DestBB, we need to update them so that they
// merge incoming values from NewBB instead of from TIBB.
{
// happens because the BB list of PHI nodes are usually in the same
// order.
if (PN->getIncomingBlock(BBIdx) != TIBB)
- BBIdx = PN->getBasicBlockIndex(TIBB);
+ BBIdx = PN->getBasicBlockIndex(TIBB);
PN->setIncomingBlock(BBIdx, NewBB);
}
}
-
+
// If there are any other edges from TIBB to DestBB, update those to go
// through the split block, making those edges non-critical as well (and
// reducing the number of phi entries in the DestBB if relevant).
if (MergeIdenticalEdges) {
for (unsigned i = SuccNum+1, e = TI->getNumSuccessors(); i != e; ++i) {
if (TI->getSuccessor(i) != DestBB) continue;
-
+
// Remove an entry for TIBB from DestBB phi nodes.
- DestBB->removePredecessor(TIBB);
-
+ DestBB->removePredecessor(TIBB, DontDeleteUselessPhis);
+
// We found another edge to DestBB, go to NewBB instead.
TI->setSuccessor(i, NewBB);
}
}
-
-
+
+
// If we don't have a pass object, we can't update anything...
if (P == 0) return NewBB;
-
+
DominatorTree *DT = P->getAnalysisIfAvailable<DominatorTree>();
LoopInfo *LI = P->getAnalysisIfAvailable<LoopInfo>();
ProfileInfo *PI = P->getAnalysisIfAvailable<ProfileInfo>();
-
+
// If we have nothing to update, just return.
if (DT == 0 && LI == 0 && PI == 0)
return NewBB;
}
bool NewBBDominatesDestBB = true;
-
+
// Should we update DominatorTree information?
if (DT) {
DomTreeNode *TINode = DT->getNode(TIBB);
if (TINode) { // Don't break unreachable code!
DomTreeNode *NewBBNode = DT->addNewBlock(NewBB, TIBB);
DomTreeNode *DestBBNode = 0;
-
+
// If NewBBDominatesDestBB hasn't been computed yet, do so with DT.
if (!OtherPreds.empty()) {
DestBBNode = DT->getNode(DestBB);
}
OtherPreds.clear();
}
-
+
// If NewBBDominatesDestBB, then NewBB dominates DestBB, otherwise it
// doesn't dominate anything.
if (NewBBDominatesDestBB) {
"Split point for loop exit is contained in loop!");
// Update LCSSA form in the newly created exit block.
- if (P->mustPreserveAnalysisID(LCSSAID)) {
- SmallVector<BasicBlock *, 1> OrigPred;
- OrigPred.push_back(TIBB);
- CreatePHIsForSplitLoopExit(OrigPred, NewBB, DestBB);
- }
+ if (P->mustPreserveAnalysisID(LCSSAID))
+ createPHIsForSplitLoopExit(TIBB, NewBB, DestBB);
// For each unique exit block...
+ // FIXME: This code is functionally equivalent to the corresponding
+ // loop in LoopSimplify.
SmallVector<BasicBlock *, 4> ExitBlocks;
TIL->getExitBlocks(ExitBlocks);
for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) {
for (pred_iterator I = pred_begin(Exit), E = pred_end(Exit);
I != E; ++I) {
BasicBlock *P = *I;
- if (TIL->contains(P))
+ if (TIL->contains(P)) {
+ if (isa<IndirectBrInst>(P->getTerminator())) {
+ Preds.clear();
+ break;
+ }
Preds.push_back(P);
- else
+ } else {
HasPredOutsideOfLoop = true;
+ }
}
// If there are any preds not in the loop, we'll need to split
// the edges. The Preds.empty() check is needed because a block
// getUniqueExitBlocks above because that depends on LoopSimplify
// form, which we're in the process of restoring!
if (!Preds.empty() && HasPredOutsideOfLoop) {
- BasicBlock *NewExitBB =
- SplitBlockPredecessors(Exit, Preds.data(), Preds.size(),
- "split", P);
- if (P->mustPreserveAnalysisID(LCSSAID))
- CreatePHIsForSplitLoopExit(Preds, NewExitBB, Exit);
+ if (!Exit->isLandingPad()) {
+ BasicBlock *NewExitBB =
+ SplitBlockPredecessors(Exit, Preds, "split", P);
+ if (P->mustPreserveAnalysisID(LCSSAID))
+ createPHIsForSplitLoopExit(Preds, NewExitBB, Exit);
+ } else if (SplitLandingPads) {
+ SmallVector<BasicBlock*, 8> NewBBs;
+ SplitLandingPadPredecessors(Exit, Preds,
+ ".split1", ".split2",
+ P, NewBBs);
+ if (P->mustPreserveAnalysisID(LCSSAID))
+ createPHIsForSplitLoopExit(Preds, NewBBs[0], Exit);
+ }
}
}
}
projects / oota-llvm.git / blobdiff