namespace {
struct LCSSA : public LoopPass {
static char ID; // Pass identification, replacement for typeid
- LCSSA() : LoopPass(ID) {}
+ LCSSA() : LoopPass(ID) {
+ initializeLCSSAPass(*PassRegistry::getPassRegistry());
+ }
// Cached analysis information for the current function.
DominatorTree *DT;
+ LoopInfo *LI;
+ ScalarEvolution *SE;
std::vector<BasicBlock*> LoopBlocks;
PredIteratorCache PredCache;
Loop *L;
AU.setPreservesCFG();
AU.addRequired<DominatorTree>();
- AU.addPreserved<DominatorTree>();
- AU.addPreserved<DominanceFrontier>();
AU.addRequired<LoopInfo>();
- AU.addPreserved<LoopInfo>();
AU.addPreservedID(LoopSimplifyID);
AU.addPreserved<ScalarEvolution>();
}
}
char LCSSA::ID = 0;
-INITIALIZE_PASS(LCSSA, "lcssa", "Loop-Closed SSA Form Pass", false, false);
+INITIALIZE_PASS_BEGIN(LCSSA, "lcssa", "Loop-Closed SSA Form Pass", false, false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTree)
+INITIALIZE_PASS_DEPENDENCY(LoopInfo)
+INITIALIZE_PASS_END(LCSSA, "lcssa", "Loop-Closed SSA Form Pass", false, false)
Pass *llvm::createLCSSAPass() { return new LCSSA(); }
char &llvm::LCSSAID = LCSSA::ID;
L = TheLoop;
DT = &getAnalysis<DominatorTree>();
+ LI = &getAnalysis<LoopInfo>();
+ SE = getAnalysisIfAvailable<ScalarEvolution>();
// Get the set of exiting blocks.
SmallVector<BasicBlock*, 8> ExitBlocks;
MadeChange |= ProcessInstruction(I, ExitBlocks);
}
}
+
+ // If we modified the code, remove any caches about the loop from SCEV to
+ // avoid dangling entries.
+ // FIXME: This is a big hammer, can we clear the cache more selectively?
+ if (SE && MadeChange)
+ SE->forgetLoop(L);
assert(L->isLCSSAForm(*DT));
PredCache.clear();
DomTreeNode *DomNode = DT->getNode(DomBB);
+ SmallVector<PHINode*, 16> AddedPHIs;
+
SSAUpdater SSAUpdate;
SSAUpdate.Initialize(Inst->getType(), Inst->getName());
// If we already inserted something for this BB, don't reprocess it.
if (SSAUpdate.HasValueForBlock(ExitBB)) continue;
- PHINode *PN = PHINode::Create(Inst->getType(), Inst->getName()+".lcssa",
+ PHINode *PN = PHINode::Create(Inst->getType(),
+ PredCache.GetNumPreds(ExitBB),
+ Inst->getName()+".lcssa",
ExitBB->begin());
- PN->reserveOperandSpace(PredCache.GetNumPreds(ExitBB));
// Add inputs from inside the loop for this PHI.
for (BasicBlock **PI = PredCache.GetPreds(ExitBB); *PI; ++PI) {
&PN->getOperandUse(
PN->getOperandNumForIncomingValue(PN->getNumIncomingValues()-1)));
}
+
+ AddedPHIs.push_back(PN);
// Remember that this phi makes the value alive in this block.
SSAUpdate.AddAvailableValue(ExitBB, PN);
}
-
+
// Rewrite all uses outside the loop in terms of the new PHIs we just
// inserted.
for (unsigned i = 0, e = UsesToRewrite.size(); i != e; ++i) {
if (isa<PHINode>(UserBB->begin()) &&
isExitBlock(UserBB, ExitBlocks)) {
+ // Tell the VHs that the uses changed. This updates SCEV's caches.
+ if (UsesToRewrite[i]->get()->hasValueHandle())
+ ValueHandleBase::ValueIsRAUWd(*UsesToRewrite[i], UserBB->begin());
UsesToRewrite[i]->set(UserBB->begin());
continue;
}
// Otherwise, do full PHI insertion.
SSAUpdate.RewriteUse(*UsesToRewrite[i]);
}
+
+ // Remove PHI nodes that did not have any uses rewritten.
+ for (unsigned i = 0, e = AddedPHIs.size(); i != e; ++i) {
+ if (AddedPHIs[i]->use_empty())
+ AddedPHIs[i]->eraseFromParent();
+ }
return true;
}