Back out Devang's fix for PR1320 because it causes PR1542.

llvm-svn: 37966

lib/Transforms/Scalar/LoopRotation.cpp

@@ -18,10 +18,7 @@
 #include "llvm/Instructions.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/Analysis/LoopPass.h"
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/Analysis/ScalarEvolution.h"
 #include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/ADT/Statistic.h"
@@ -58,17 +55,6 @@ namespace {
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.addRequiredID(LCSSAID);
       AU.addPreservedID(LCSSAID);
-      AU.addPreserved<ScalarEvolution>();
-      AU.addPreserved<LoopInfo>();
-      AU.addRequiredID(LoopSimplifyID);
-      AU.addPreservedID(LoopSimplifyID);
-      AU.addPreserved<DominatorTree>();
-      // Request DominanceFrontier now, even though Loop Rotate does
-      // not use it. This allows Pass Manager to schedule Dominance
-      // Frontier early enough such that one LPPassManager can handle
-      // loop rotate as well as licm pass.
-      AU.addRequired<DominanceFrontier>(); 
-      AU.addPreserved<DominanceFrontier>();
     }
 
     // Helper functions
@@ -104,7 +90,7 @@ namespace {
     BasicBlock *OrigLatch;
     BasicBlock *NewHeader;
     BasicBlock *Exit;
-    LPPassManager *LPM_Ptr;
+
     SmallVector<RenameData, MAX_HEADER_SIZE> LoopHeaderInfo;
   };
   
@@ -120,7 +106,6 @@ bool LoopRotate::runOnLoop(Loop *Lp, LPPassManager &LPM) {
   
   bool RotatedOneLoop = false;
   initialize();
-  LPM_Ptr = &LPM;
 
   // One loop can be rotated multiple times.
   while (rotateLoop(Lp,LPM)) {
@@ -167,13 +152,6 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
   if (ExitBlocks.size() > 1)
     return false;
 
-  // Check size of original header and reject
-  // loop if it is very big.
-  if (OrigHeader->getInstList().size() > MAX_HEADER_SIZE)
-    return false;
-
-  // Now, this loop is suitable for rotation.
-
   // Find new Loop header. NewHeader is a Header's one and only successor
   // that is inside loop.  Header's other successor is out side the
   // loop. Otherwise loop is not suitable for rotation.
@@ -185,6 +163,13 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
   assert(L->contains(NewHeader) && !L->contains(Exit) && 
          "Unable to determine loop header and exit blocks");
 
+  // Check size of original header and reject
+  // loop if it is very big.
+  if (OrigHeader->getInstList().size() > MAX_HEADER_SIZE)
+    return false;
+
+  // Now, this loop is suitable for rotation.
+
   // Copy PHI nodes and other instructions from original header
   // into original pre-header. Unlike original header, original pre-header is
   // not a member of loop. 
@@ -329,24 +314,18 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
           U->replaceUsesOfWith(OldPhi, NewPhi);
         continue;
       }
-      
+
       // Used inside Exit Block. Since we are in LCSSA form, U must be PHINode.
-      if (U->getParent() == Exit) {
+      assert (U->getParent() == Exit 
-        assert (isa<PHINode>(U) && "Use in Exit Block that is not PHINode");
+              && "Need to propagate new PHI into Exit blocks");
-        
+      assert (isa<PHINode>(U) && "Use in Exit Block that is not PHINode");
-        PHINode *UPhi = cast<PHINode>(U);
+
-        // UPhi already has one incoming argument from original header. 
+      PHINode *UPhi = cast<PHINode>(U);
-        // Add second incoming argument from new Pre header.
+
-        UPhi->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
+      // UPhi already has one incoming argument from original header. 
-      } else {
+      // Add second incoming argument from new Pre header.
-        // Used outside Exit block. Create a new PHI node from exit block
+      
-        // to receive value from ne new header ane pre header.
+      UPhi->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
-        PHINode *PN = new PHINode(U->getType(), U->getName());
-        PN->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
-        PN->addIncoming(OldPhi, OrigHeader);
-        Exit->getInstList().push_front(PN);
-        U->replaceUsesOfWith(OldPhi, PN);
-      }
     }
   }
   
@@ -482,63 +461,10 @@ void LoopRotate::preserveCanonicalLoopForm(LPPassManager &LPM) {
             "Expected only one incoming value from Original PreHeader");
   }
 
-  SplitEdge(L->getLoopLatch(), Exit, this);
-
-  if (DominatorTree *DT = getAnalysisToUpdate<DominatorTree>()) {
-    DT->addNewBlock(NewPreHeader, OrigPreHeader);
-    DT->changeImmediateDominator(L->getHeader(), NewPreHeader);
-    DT->changeImmediateDominator(Exit, OrigPreHeader);
-    for (Loop::block_iterator BI = L->block_begin(), BE = L->block_end();
-         BI != BE; ++BI) {
-      BasicBlock *B = *BI;
-      if (L->getHeader() != B) {
-        DomTreeNode *Node = DT->getNode(B);
-        if (Node && Node->getBlock() == OrigHeader)
-          DT->changeImmediateDominator(*BI, L->getHeader());
-      }
-    }
-    DT->changeImmediateDominator(OrigHeader, OrigLatch);
-  }
-
-  if(DominanceFrontier *DF = getAnalysisToUpdate<DominanceFrontier>()) {
-
-    // New Preheader's dominance frontier is same as original preheader.
-    DominanceFrontier::iterator DFI = DF->find(OrigPreHeader);
-    if (DFI != DF->end()) {
-      DominanceFrontier::DomSetType NPHSet(DFI->second), NHSet(DFI->second);
-      //      NPHSet.insert(DFI->second.begin(), DFI->second.end(), NPHSet.begin());
-      DF->addBasicBlock(NewPreHeader, NPHSet);
-      
-      DominanceFrontier::iterator DHI = DF->find(L->getHeader());
-      if (DHI != DF->end()) {
-        DominanceFrontier::DomSetType DHSet = DHI->second;
-        DHSet.clear();
-        DHSet.insert(DFI->second.begin(), DFI->second.end());
-      } else {
-        DominanceFrontier::DomSetType NHSet(DFI->second);
-        //      NHSet.insert(DFI->second.begin(), DFI->second.end(), NHSet.begin());
-        DF->addBasicBlock(L->getHeader(), NHSet);
-      }
-    }
-
-    // Original header no longer dominates Exit
-    DFI = DF->find(OrigHeader);
-    if (DFI != DF->end()) {
-      for (succ_iterator SI = succ_begin(Exit), SE = succ_end(Exit);
-           SI != SE; ++SI) {
-        BasicBlock *Succ = *SI;
-        DominanceFrontier::DomSetType::iterator DSI = DFI->second.find(Succ);
-        if (DSI != DFI->second.end())
-          DFI->second.erase(DSI);
-      }
-    }
-  }
-
   assert (NewHeader && L->getHeader() == NewHeader 
           && "Invalid loop header after loop rotation");
   assert (NewPreHeader && L->getLoopPreheader() == NewPreHeader
           && "Invalid loop preheader after loop rotation");
   assert (L->getLoopLatch() 
           && "Invalid loop latch after loop rotation");
-
 }