Fix batch of converting RegisterPass<> to INTIALIZE_PASS().

[oota-llvm.git] / lib / Transforms / Scalar / LoopDeletion.cpp

diff --git a/lib/Transforms/Scalar/LoopDeletion.cpp b/lib/Transforms/Scalar/LoopDeletion.cpp
index 5f93756a05c07388cd8280620f59629298d84078..354b033db7896ee9d17929ed1906802c79f91289 100644 (file)
--- a/lib/Transforms/Scalar/LoopDeletion.cpp
+++ b/lib/Transforms/Scalar/LoopDeletion.cpp
@@ -33,8 +33,6 @@ namespace {
     // Possibly eliminate loop L if it is dead.
     bool runOnLoop(Loop* L, LPPassManager& LPM);
     
-    bool SingleDominatingExit(Loop* L,
-                              SmallVector<BasicBlock*, 4>& exitingBlocks);
     bool IsLoopDead(Loop* L, SmallVector<BasicBlock*, 4>& exitingBlocks,
                     SmallVector<BasicBlock*, 4>& exitBlocks,
                     bool &Changed, BasicBlock *Preheader);
@@ -57,31 +55,13 @@ namespace {
 }
   
 char LoopDeletion::ID = 0;
-static RegisterPass<LoopDeletion> X("loop-deletion", "Delete dead loops");
+INITIALIZE_PASS(LoopDeletion, "loop-deletion",
+                "Delete dead loops", false, false);
 
 Pass* llvm::createLoopDeletionPass() {
   return new LoopDeletion();
 }
 
-/// SingleDominatingExit - Checks that there is only a single blocks that 
-/// branches out of the loop, and that it also g the latch block.  Loops
-/// with multiple or non-latch-dominating exiting blocks could be dead, but we'd
-/// have to do more extensive analysis to make sure, for instance, that the 
-/// control flow logic involved was or could be made loop-invariant.
-bool LoopDeletion::SingleDominatingExit(Loop* L,
-                                   SmallVector<BasicBlock*, 4>& exitingBlocks) {
-  
-  if (exitingBlocks.size() != 1)
-    return false;
-  
-  BasicBlock* latch = L->getLoopLatch();
-  if (!latch)
-    return false;
-  
-  DominatorTree& DT = getAnalysis<DominatorTree>();
-  return DT.dominates(exitingBlocks[0], latch);
-}
-
 /// IsLoopDead - Determined if a loop is dead.  This assumes that we've already
 /// checked for unique exit and exiting blocks, and that the code is in LCSSA
 /// form.
@@ -104,7 +84,7 @@ bool LoopDeletion::IsLoopDead(Loop* L,
       if (!L->makeLoopInvariant(I, Changed, Preheader->getTerminator()))
         return false;
       
-    BI++;
+    ++BI;
   }
   
   // Make sure that no instructions in the block have potential side-effects.
@@ -136,6 +116,10 @@ bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) {
   if (!preheader)
     return false;
   
+  // If LoopSimplify form is not available, stay out of trouble.
+  if (!L->hasDedicatedExits())
+    return false;
+
   // We can't remove loops that contain subloops.  If the subloops were dead,
   // they would already have been removed in earlier executions of this pass.
   if (L->begin() != L->end())
@@ -154,9 +138,8 @@ bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) {
   if (exitBlocks.size() != 1)
     return false;
   
-  // Loops with multiple exits or exits that don't dominate the latch
-  // are too complicated to handle correctly.
-  if (!SingleDominatingExit(L, exitingBlocks))
+  // Loops with multiple exits are too complicated to handle correctly.
+  if (exitingBlocks.size() != 1)
     return false;
   
   // Finally, we have to check that the loop really is dead.
@@ -167,7 +150,7 @@ bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) {
   // Don't remove loops for which we can't solve the trip count.
   // They could be infinite, in which case we'd be changing program behavior.
   ScalarEvolution& SE = getAnalysis<ScalarEvolution>();
-  const SCEV *S = SE.getBackedgeTakenCount(L);
+  const SCEV *S = SE.getMaxBackedgeTakenCount(L);
   if (isa<SCEVCouldNotCompute>(S))
     return Changed;
   
@@ -183,7 +166,7 @@ bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) {
   // Tell ScalarEvolution that the loop is deleted. Do this before
   // deleting the loop so that ScalarEvolution can look at the loop
   // to determine what it needs to clean up.
-  SE.forgetLoopBackedgeTakenCount(L);
+  SE.forgetLoop(L);
 
   // Connect the preheader directly to the exit block.
   TerminatorInst* TI = preheader->getTerminator();
@@ -194,7 +177,7 @@ bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) {
   BasicBlock::iterator BI = exitBlock->begin();
   while (PHINode* P = dyn_cast<PHINode>(BI)) {
     P->replaceUsesOfWith(exitingBlock, preheader);
-    BI++;
+    ++BI;
   }
   
   // Update the dominator tree and remove the instructions and blocks that will
@@ -244,7 +227,7 @@ bool LoopDeletion::runOnLoop(Loop* L, LPPassManager& LPM) {
   LPM.deleteLoopFromQueue(L);
   Changed = true;
   
-  NumDeleted++;
+  ++NumDeleted;
   
   return Changed;
 }