Change how PHINodes store their operands.
Change PHINodes to store simple pointers to their incoming basic blocks,
instead of full-blown Uses.
Note that this loses an optimization in SplitCriticalEdge(), because we
can no longer walk the use list of a BasicBlock to find phi nodes. See
the comment I removed starting "However, the foreach loop is slow for
blocks with lots of predecessors".
Extend replaceAllUsesWith() on a BasicBlock to also update any phi
nodes in the block's successors. This mimics what would have happened
when PHINodes were proper Users of their incoming blocks. (Note that
this only works if OldBB->replaceAllUsesWith(NewBB) is called when
OldBB still has a terminator instruction, so it still has some
successors.)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133435 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/LoopUnroll.cpp b/lib/Transforms/Utils/LoopUnroll.cpp
index 7da7271..c91bf82 100644
--- a/lib/Transforms/Utils/LoopUnroll.cpp
+++ b/lib/Transforms/Utils/LoopUnroll.cpp
@@ -47,6 +47,14 @@
if (It != VMap.end())
I->setOperand(op, It->second);
}
+
+ if (PHINode *PN = dyn_cast<PHINode>(I)) {
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ ValueToValueMapTy::iterator It = VMap.find(PN->getIncomingBlock(i));
+ if (It != VMap.end())
+ PN->setIncomingBlock(i, cast<BasicBlock>(It->second));
+ }
+ }
}
/// FoldBlockIntoPredecessor - Folds a basic block into its predecessor if it
@@ -75,13 +83,13 @@
// Delete the unconditional branch from the predecessor...
OnlyPred->getInstList().pop_back();
- // Move all definitions in the successor to the predecessor...
- OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList());
-
// Make all PHI nodes that referred to BB now refer to Pred as their
// source...
BB->replaceAllUsesWith(OnlyPred);
+ // Move all definitions in the successor to the predecessor...
+ OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList());
+
std::string OldName = BB->getName();
// Erase basic block from the function...
@@ -247,16 +255,14 @@
// the successor of the latch block. The successor of the exit block will
// be updated specially after unrolling all the way.
if (*BB != LatchBlock)
- for (Value::use_iterator UI = (*BB)->use_begin(), UE = (*BB)->use_end();
- UI != UE;) {
- Instruction *UseInst = cast<Instruction>(*UI);
- ++UI;
- if (isa<PHINode>(UseInst) && !L->contains(UseInst)) {
- PHINode *phi = cast<PHINode>(UseInst);
- Value *Incoming = phi->getIncomingValueForBlock(*BB);
- phi->addIncoming(Incoming, New);
- }
- }
+ for (succ_iterator SI = succ_begin(*BB), SE = succ_end(*BB); SI != SE;
+ ++SI)
+ if (!L->contains(*SI))
+ for (BasicBlock::iterator BBI = (*SI)->begin(), BBE = (*SI)->end();
+ PHINode *phi = dyn_cast<PHINode>(BBI); ++BBI) {
+ Value *Incoming = phi->getIncomingValueForBlock(*BB);
+ phi->addIncoming(Incoming, New);
+ }
// Keep track of new headers and latches as we create them, so that
// we can insert the proper branches later.
@@ -288,24 +294,20 @@
// successor blocks, update them to use the appropriate values computed as the
// last iteration of the loop.
if (Count != 1) {
- SmallPtrSet<PHINode*, 8> Users;
- for (Value::use_iterator UI = LatchBlock->use_begin(),
- UE = LatchBlock->use_end(); UI != UE; ++UI)
- if (PHINode *phi = dyn_cast<PHINode>(*UI))
- Users.insert(phi);
-
BasicBlock *LastIterationBB = cast<BasicBlock>(LastValueMap[LatchBlock]);
- for (SmallPtrSet<PHINode*,8>::iterator SI = Users.begin(), SE = Users.end();
+ for (succ_iterator SI = succ_begin(LatchBlock), SE = succ_end(LatchBlock);
SI != SE; ++SI) {
- PHINode *PN = *SI;
- Value *InVal = PN->removeIncomingValue(LatchBlock, false);
- // If this value was defined in the loop, take the value defined by the
- // last iteration of the loop.
- if (Instruction *InValI = dyn_cast<Instruction>(InVal)) {
- if (L->contains(InValI))
- InVal = LastValueMap[InVal];
+ for (BasicBlock::iterator BBI = (*SI)->begin(), BBE = (*SI)->end();
+ PHINode *PN = dyn_cast<PHINode>(BBI); ++BBI) {
+ Value *InVal = PN->removeIncomingValue(LatchBlock, false);
+ // If this value was defined in the loop, take the value defined by the
+ // last iteration of the loop.
+ if (Instruction *InValI = dyn_cast<Instruction>(InVal)) {
+ if (L->contains(InValI))
+ InVal = LastValueMap[InVal];
+ }
+ PN->addIncoming(InVal, LastIterationBB);
}
- PN->addIncoming(InVal, LastIterationBB);
}
}
@@ -352,11 +354,16 @@
// Replace the conditional branch with an unconditional one.
BranchInst::Create(Dest, Term);
Term->eraseFromParent();
- // Merge adjacent basic blocks, if possible.
- if (BasicBlock *Fold = FoldBlockIntoPredecessor(Dest, LI)) {
+ }
+ }
+
+ // Merge adjacent basic blocks, if possible.
+ for (unsigned i = 0, e = Latches.size(); i != e; ++i) {
+ BranchInst *Term = cast<BranchInst>(Latches[i]->getTerminator());
+ if (Term->isUnconditional()) {
+ BasicBlock *Dest = Term->getSuccessor(0);
+ if (BasicBlock *Fold = FoldBlockIntoPredecessor(Dest, LI))
std::replace(Latches.begin(), Latches.end(), Dest, Fold);
- std::replace(Headers.begin(), Headers.end(), Dest, Fold);
- }
}
}