Target independent Hexagon Packetizer fix.

[oota-llvm.git] / lib / Analysis / IVUsers.cpp

diff --git a/lib/Analysis/IVUsers.cpp b/lib/Analysis/IVUsers.cpp
index c598b72c0de560c481884e5534b664265892725a..b80966b65a17708cee58135ed6f752c33da8460f 100644 (file)
--- a/lib/Analysis/IVUsers.cpp
+++ b/lib/Analysis/IVUsers.cpp
@@ -79,30 +79,39 @@ static bool isInteresting(const SCEV *S, const Instruction *I, const Loop *L,
   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))
@@ -137,15 +146,17 @@ bool IVUsers::AddUsersIfInteresting(Instruction *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
@@ -154,15 +165,14 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I,
     // 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;
@@ -186,6 +196,15 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I,
   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();
@@ -211,16 +230,11 @@ bool IVUsers::runOnLoop(Loop *l, LPPassManager &LPM) {
   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;
 }