return false;
}
-/// Return true if this loop and all loop headers that dominate it are in
-/// simplified form.
-static bool isSimplifiedLoopNest(Loop *L, const DominatorTree *DT,
- const LoopInfo *LI) {
- if (!L->isLoopSimplifyForm())
- return false;
-
- for (DomTreeNode *Rung = DT->getNode(L->getLoopPreheader());
+/// Return true if all loop headers that dominate this block are in simplified
+/// form.
+static bool isSimplifiedLoopNest(BasicBlock *BB, const DominatorTree *DT,
+ const LoopInfo *LI,
+ SmallPtrSet<Loop*,16> &SimpleLoopNests) {
+ Loop *NearestLoop = 0;
+ for (DomTreeNode *Rung = DT->getNode(BB);
Rung; Rung = Rung->getIDom()) {
- BasicBlock *BB = Rung->getBlock();
- const Loop *DomLoop = LI->getLoopFor(BB);
- if (DomLoop && DomLoop->getHeader() == BB) {
+ BasicBlock *DomBB = Rung->getBlock();
+ Loop *DomLoop = LI->getLoopFor(DomBB);
+ if (DomLoop && DomLoop->getHeader() == DomBB) {
+ // If the domtree walk reaches a loop with no preheader, return false.
if (!DomLoop->isLoopSimplifyForm())
return false;
+ // If we have already checked this loop nest, stop checking.
+ if (SimpleLoopNests.count(DomLoop))
+ break;
+ // If we have not already checked this loop nest, remember the loop
+ // header nearest to BB. The nearest loop may not contain BB.
+ if (!NearestLoop)
+ NearestLoop = DomLoop;
}
}
+ if (NearestLoop)
+ SimpleLoopNests.insert(NearestLoop);
return true;
}
-/// AddUsersIfInteresting - Inspect the specified instruction. If it is a
+/// AddUsersImpl - Inspect the specified instruction. If it is a
/// reducible SCEV, recursively add its users to the IVUsesByStride set and
/// return true. Otherwise, return false.
-bool IVUsers::AddUsersIfInteresting(Instruction *I,
- SmallPtrSet<Loop*,16> &SimpleLoopNests) {
+bool IVUsers::AddUsersImpl(Instruction *I,
+ SmallPtrSet<Loop*,16> &SimpleLoopNests) {
// Add this IV user to the Processed set before returning false to ensure that
// all IV users are members of the set. See IVUsers::isIVUserOrOperand.
if (!Processed.insert(I))
if (isa<PHINode>(User) && Processed.count(User))
continue;
- Loop *UserLoop = LI->getLoopFor(User->getParent());
-
// Only consider IVUsers that are dominated by simplified loop
// headers. Otherwise, SCEVExpander will crash.
- if (UserLoop && !SimpleLoopNests.count(UserLoop)) {
- if (!isSimplifiedLoopNest(UserLoop, DT, LI))
- return false;
- SimpleLoopNests.insert(UserLoop);
+ BasicBlock *UseBB = User->getParent();
+ // A phi's use is live out of its predecessor block.
+ if (PHINode *PHI = dyn_cast<PHINode>(User)) {
+ unsigned OperandNo = UI.getOperandNo();
+ unsigned ValNo = PHINode::getIncomingValueNumForOperand(OperandNo);
+ UseBB = PHI->getIncomingBlock(ValNo);
}
+ if (!isSimplifiedLoopNest(UseBB, DT, LI, SimpleLoopNests))
+ return false;
// Descend recursively, but not into PHI nodes outside the current loop.
// It's important to see the entire expression outside the loop to get
// If User is already in Processed, we don't want to recurse into it again,
// but do want to record a second reference in the same instruction.
bool AddUserToIVUsers = false;
- if (UserLoop != L) {
+ if (LI->getLoopFor(User->getParent()) != L) {
if (isa<PHINode>(User) || Processed.count(User) ||
- !AddUsersIfInteresting(User, SimpleLoopNests)) {
+ !AddUsersImpl(User, SimpleLoopNests)) {
DEBUG(dbgs() << "FOUND USER in other loop: " << *User << '\n'
<< " OF SCEV: " << *ISE << '\n');
AddUserToIVUsers = true;
}
- } else if (Processed.count(User)
- || !AddUsersIfInteresting(User, SimpleLoopNests)) {
+ } else if (Processed.count(User) || !AddUsersImpl(User, SimpleLoopNests)) {
DEBUG(dbgs() << "FOUND USER: " << *User << '\n'
<< " OF SCEV: " << *ISE << '\n');
AddUserToIVUsers = true;
return true;
}
+bool IVUsers::AddUsersIfInteresting(Instruction *I) {
+ // SCEVExpander can only handle users that are dominated by simplified loop
+ // entries. Keep track of all loops that are only dominated by other simple
+ // loops so we don't traverse the domtree for each user.
+ SmallPtrSet<Loop*,16> SimpleLoopNests;
+
+ return AddUsersImpl(I, SimpleLoopNests);
+}
+
IVStrideUse &IVUsers::AddUser(Instruction *User, Value *Operand) {
IVUses.push_back(new IVStrideUse(this, User, Operand));
return IVUses.back();
SE = &getAnalysis<ScalarEvolution>();
TD = getAnalysisIfAvailable<TargetData>();
- // SCEVExpander can only handle users that are dominated by simplified loop
- // entries. Keep track of all loops that are only dominated by other simple
- // loops so we don't traverse the domtree for each user.
- SmallPtrSet<Loop*,16> SimpleLoopNests;
-
// Find all uses of induction variables in this loop, and categorize
// them by stride. Start by finding all of the PHI nodes in the header for
// this loop. If they are induction variables, inspect their uses.
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I)
- (void)AddUsersIfInteresting(I, SimpleLoopNests);
+ (void)AddUsersIfInteresting(I);
return false;
}