Add a DominatorTree argument to isLCSSA so that it doesn't have to

compute a set of reachable blocks for itself each time it is called, which
is fairly frequently.

llvm-svn: 98179

include/llvm/Analysis/LoopInfo.h

@@ -571,7 +571,7 @@ public:
   unsigned getSmallConstantTripMultiple() const;
 
   /// isLCSSAForm - Return true if the Loop is in LCSSA form
-  bool isLCSSAForm() const;
+  bool isLCSSAForm(DominatorTree &DT) const;
 
   /// isLoopSimplifyForm - Return true if the Loop is in the form that
   /// the LoopSimplify form transforms loops to, which is sometimes called

lib/Analysis/LoopInfo.cpp

@@ -263,14 +263,7 @@ unsigned Loop::getSmallConstantTripMultiple() const {
 }
 
 /// isLCSSAForm - Return true if the Loop is in LCSSA form
-bool Loop::isLCSSAForm() const {
-  // Collect all the reachable blocks in the function, for fast lookups.
-  SmallPtrSet<BasicBlock *, 32> ReachableBBs;
-  BasicBlock *EntryBB = getHeader()->getParent()->begin();
-  for (df_iterator<BasicBlock *> NI = df_begin(EntryBB),
-       NE = df_end(EntryBB); NI != NE; ++NI)
-    ReachableBBs.insert(*NI);
-
+bool Loop::isLCSSAForm(DominatorTree &DT) const {
   // Sort the blocks vector so that we can use binary search to do quick
   // lookups.
   SmallPtrSet<BasicBlock *, 16> LoopBBs(block_begin(), block_end());
@@ -290,7 +283,7 @@ bool Loop::isLCSSAForm() const {
         // entry are special; uses in them don't need to go through PHIs.
         if (UserBB != BB &&
             !LoopBBs.count(UserBB) &&
-            ReachableBBs.count(UserBB))
+            DT.isReachableFromEntry(UserBB))
           return false;
       }
   }

lib/Transforms/Scalar/IndVarSimplify.cpp

@@ -215,7 +215,7 @@ ICmpInst *IndVarSimplify::LinearFunctionTestReplace(Loop *L,
 void IndVarSimplify::RewriteLoopExitValues(Loop *L,
                                            SCEVExpander &Rewriter) {
   // Verify the input to the pass in already in LCSSA form.
-  assert(L->isLCSSAForm());
+  assert(L->isLCSSAForm(*DT));
 
   SmallVector<BasicBlock*, 8> ExitBlocks;
   L->getUniqueExitBlocks(ExitBlocks);
@@ -445,7 +445,7 @@ bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
   // Clean up dead instructions.
   Changed |= DeleteDeadPHIs(L->getHeader());
   // Check a post-condition.
-  assert(L->isLCSSAForm() && "Indvars did not leave the loop in lcssa form!");
+  assert(L->isLCSSAForm(*DT) && "Indvars did not leave the loop in lcssa form!");
   return Changed;
 }
 

lib/Transforms/Scalar/LoopUnrollPass.cpp

@@ -86,7 +86,6 @@ static unsigned ApproximateLoopSize(const Loop *L, unsigned &NumCalls) {
 }
 
 bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
-  assert(L->isLCSSAForm());
   LoopInfo *LI = &getAnalysis<LoopInfo>();
 
   BasicBlock *Header = L->getHeader();

lib/Transforms/Scalar/LoopUnswitch.cpp

@@ -206,7 +206,7 @@ bool LoopUnswitch::runOnLoop(Loop *L, LPPassManager &LPM_Ref) {
   Function *F = currentLoop->getHeader()->getParent();
   bool Changed = false;
   do {
-    assert(currentLoop->isLCSSAForm());
+    assert(currentLoop->isLCSSAForm(*DT));
     redoLoop = false;
     Changed |= processCurrentLoop();
   } while(redoLoop);

lib/Transforms/Utils/LCSSA.cpp

@@ -88,7 +88,7 @@ namespace {
     /// verifyAnalysis() - Verify loop nest.
     virtual void verifyAnalysis() const {
       // Check the special guarantees that LCSSA makes.
-      assert(L->isLCSSAForm() && "LCSSA form not preserved!");
+      assert(L->isLCSSAForm(*DT) && "LCSSA form not preserved!");
     }
 
     /// inLoop - returns true if the given block is within the current loop
@@ -164,7 +164,7 @@ bool LCSSA::runOnLoop(Loop *TheLoop, LPPassManager &LPM) {
     }
   }
   
-  assert(L->isLCSSAForm());
+  assert(L->isLCSSAForm(*DT));
   PredCache.clear();
 
   return MadeChange;

lib/Transforms/Utils/LoopUnroll.cpp

@@ -105,8 +105,6 @@ static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI) {
 /// If a LoopPassManager is passed in, and the loop is fully removed, it will be
 /// removed from the LoopPassManager as well. LPM can also be NULL.
 bool llvm::UnrollLoop(Loop *L, unsigned Count, LoopInfo* LI, LPPassManager* LPM) {
-  assert(L->isLCSSAForm());
-
   BasicBlock *Preheader = L->getLoopPreheader();
   if (!Preheader) {
     DEBUG(dbgs() << "  Can't unroll; loop preheader-insertion failed.\n");
@@ -370,9 +368,5 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, LoopInfo* LI, LPPassManager* LPM)
   if (CompletelyUnroll && LPM != NULL)
     LPM->deleteLoopFromQueue(L);
 
-  // If we didn't completely unroll the loop, it should still be in LCSSA form.
-  if (!CompletelyUnroll)
-    assert(L->isLCSSAForm());
-
   return true;
 }