Rename UnrollLoop.cpp to LoopUnroll.cpp, and LoopUnroll.cpp to

LoopUnrollPass.cpp, for consistency with other passes which are
similarly split.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85659 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 0 insertions, 372 deletions

diff --git a/lib/Transforms/Utils/UnrollLoop.cpp b/lib/Transforms/Utils/UnrollLoop.cpp
deleted file mode 100644
index 4d838b50e3..0000000000
--- a/lib/Transforms/Utils/UnrollLoop.cpp
+++ /dev/null
@@ -1,372 +0,0 @@
-//===-- UnrollLoop.cpp - Loop unrolling utilities -------------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements some loop unrolling utilities. It does not define any
-// actual pass or policy, but provides a single function to perform loop
-// unrolling.
-//
-// It works best when loops have been canonicalized by the -indvars pass,
-// allowing it to determine the trip counts of loops easily.
-//
-// The process of unrolling can produce extraneous basic blocks linked with
-// unconditional branches.  This will be corrected in the future.
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "loop-unroll"
-#include "llvm/Transforms/Utils/UnrollLoop.h"
-#include "llvm/BasicBlock.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Analysis/LoopPass.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/Cloning.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include <cstdio>
-
-using namespace llvm;
-
-// TODO: Should these be here or in LoopUnroll?
-STATISTIC(NumCompletelyUnrolled, "Number of loops completely unrolled");
-STATISTIC(NumUnrolled,    "Number of loops unrolled (completely or otherwise)");
-
-/// RemapInstruction - Convert the instruction operands from referencing the
-/// current values into those specified by ValueMap.
-static inline void RemapInstruction(Instruction *I,
-                                    DenseMap<const Value *, Value*> &ValueMap) {
-  for (unsigned op = 0, E = I->getNumOperands(); op != E; ++op) {
-    Value *Op = I->getOperand(op);
-    DenseMap<const Value *, Value*>::iterator It = ValueMap.find(Op);
-    if (It != ValueMap.end()) Op = It->second;
-    I->setOperand(op, Op);
-  }
-}
-
-/// FoldBlockIntoPredecessor - Folds a basic block into its predecessor if it
-/// only has one predecessor, and that predecessor only has one successor.
-/// The LoopInfo Analysis that is passed will be kept consistent.
-/// Returns the new combined block.
-static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI) {
-  // Merge basic blocks into their predecessor if there is only one distinct
-  // pred, and if there is only one distinct successor of the predecessor, and
-  // if there are no PHI nodes.
-  BasicBlock *OnlyPred = BB->getSinglePredecessor();
-  if (!OnlyPred) return 0;
-
-  if (OnlyPred->getTerminator()->getNumSuccessors() != 1)
-    return 0;
-
-  DEBUG(errs() << "Merging: " << *BB << "into: " << *OnlyPred);
-
-  // Resolve any PHI nodes at the start of the block.  They are all
-  // guaranteed to have exactly one entry if they exist, unless there are
-  // multiple duplicate (but guaranteed to be equal) entries for the
-  // incoming edges.  This occurs when there are multiple edges from
-  // OnlyPred to OnlySucc.
-  FoldSingleEntryPHINodes(BB);
-
-  // Delete the unconditional branch from the predecessor...
-  OnlyPred->getInstList().pop_back();
-
-  // Move all definitions in the successor to the predecessor...
-  OnlyPred->getInstList().splice(OnlyPred->end(), BB->getInstList());
-
-  // Make all PHI nodes that referred to BB now refer to Pred as their
-  // source...
-  BB->replaceAllUsesWith(OnlyPred);
-
-  std::string OldName = BB->getName();
-
-  // Erase basic block from the function...
-  LI->removeBlock(BB);
-  BB->eraseFromParent();
-
-  // Inherit predecessor's name if it exists...
-  if (!OldName.empty() && !OnlyPred->hasName())
-    OnlyPred->setName(OldName);
-
-  return OnlyPred;
-}
-
-/// Unroll the given loop by Count. The loop must be in LCSSA form. Returns true
-/// if unrolling was succesful, or false if the loop was unmodified. Unrolling
-/// can only fail when the loop's latch block is not terminated by a conditional
-/// branch instruction. However, if the trip count (and multiple) are not known,
-/// loop unrolling will mostly produce more code that is no faster.
-///
-/// The LoopInfo Analysis that is passed will be kept consistent.
-///
-/// 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 *Header = L->getHeader();
-  BasicBlock *LatchBlock = L->getLoopLatch();
-  BranchInst *BI = dyn_cast<BranchInst>(LatchBlock->getTerminator());
-  
-  if (!BI || BI->isUnconditional()) {
-    // The loop-rotate pass can be helpful to avoid this in many cases.
-    DEBUG(errs() <<
-             "  Can't unroll; loop not terminated by a conditional branch.\n");
-    return false;
-  }
-
-  // Find trip count
-  unsigned TripCount = L->getSmallConstantTripCount();
-  // Find trip multiple if count is not available
-  unsigned TripMultiple = 1;
-  if (TripCount == 0)
-    TripMultiple = L->getSmallConstantTripMultiple();
-
-  if (TripCount != 0)
-    DEBUG(errs() << "  Trip Count = " << TripCount << "\n");
-  if (TripMultiple != 1)
-    DEBUG(errs() << "  Trip Multiple = " << TripMultiple << "\n");
-
-  // Effectively "DCE" unrolled iterations that are beyond the tripcount
-  // and will never be executed.
-  if (TripCount != 0 && Count > TripCount)
-    Count = TripCount;
-
-  assert(Count > 0);
-  assert(TripMultiple > 0);
-  assert(TripCount == 0 || TripCount % TripMultiple == 0);
-
-  // Are we eliminating the loop control altogether?
-  bool CompletelyUnroll = Count == TripCount;
-
-  // If we know the trip count, we know the multiple...
-  unsigned BreakoutTrip = 0;
-  if (TripCount != 0) {
-    BreakoutTrip = TripCount % Count;
-    TripMultiple = 0;
-  } else {
-    // Figure out what multiple to use.
-    BreakoutTrip = TripMultiple =
-      (unsigned)GreatestCommonDivisor64(Count, TripMultiple);
-  }
-
-  if (CompletelyUnroll) {
-    DEBUG(errs() << "COMPLETELY UNROLLING loop %" << Header->getName()
-          << " with trip count " << TripCount << "!\n");
-  } else {
-    DEBUG(errs() << "UNROLLING loop %" << Header->getName()
-          << " by " << Count);
-    if (TripMultiple == 0 || BreakoutTrip != TripMultiple) {
-      DEBUG(errs() << " with a breakout at trip " << BreakoutTrip);
-    } else if (TripMultiple != 1) {
-      DEBUG(errs() << " with " << TripMultiple << " trips per branch");
-    }
-    DEBUG(errs() << "!\n");
-  }
-
-  std::vector<BasicBlock*> LoopBlocks = L->getBlocks();
-
-  bool ContinueOnTrue = L->contains(BI->getSuccessor(0));
-  BasicBlock *LoopExit = BI->getSuccessor(ContinueOnTrue);
-
-  // For the first iteration of the loop, we should use the precloned values for
-  // PHI nodes.  Insert associations now.
-  typedef DenseMap<const Value*, Value*> ValueMapTy;
-  ValueMapTy LastValueMap;
-  std::vector<PHINode*> OrigPHINode;
-  for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
-    PHINode *PN = cast<PHINode>(I);
-    OrigPHINode.push_back(PN);
-    if (Instruction *I = 
-                dyn_cast<Instruction>(PN->getIncomingValueForBlock(LatchBlock)))
-      if (L->contains(I->getParent()))
-        LastValueMap[I] = I;
-  }
-
-  std::vector<BasicBlock*> Headers;
-  std::vector<BasicBlock*> Latches;
-  Headers.push_back(Header);
-  Latches.push_back(LatchBlock);
-
-  for (unsigned It = 1; It != Count; ++It) {
-    char SuffixBuffer[100];
-    sprintf(SuffixBuffer, ".%d", It);
-    
-    std::vector<BasicBlock*> NewBlocks;
-    
-    for (std::vector<BasicBlock*>::iterator BB = LoopBlocks.begin(),
-         E = LoopBlocks.end(); BB != E; ++BB) {
-      ValueMapTy ValueMap;
-      BasicBlock *New = CloneBasicBlock(*BB, ValueMap, SuffixBuffer);
-      Header->getParent()->getBasicBlockList().push_back(New);
-
-      // Loop over all of the PHI nodes in the block, changing them to use the
-      // incoming values from the previous block.
-      if (*BB == Header)
-        for (unsigned i = 0, e = OrigPHINode.size(); i != e; ++i) {
-          PHINode *NewPHI = cast<PHINode>(ValueMap[OrigPHINode[i]]);
-          Value *InVal = NewPHI->getIncomingValueForBlock(LatchBlock);
-          if (Instruction *InValI = dyn_cast<Instruction>(InVal))
-            if (It > 1 && L->contains(InValI->getParent()))
-              InVal = LastValueMap[InValI];
-          ValueMap[OrigPHINode[i]] = InVal;
-          New->getInstList().erase(NewPHI);
-        }
-
-      // Update our running map of newest clones
-      LastValueMap[*BB] = New;
-      for (ValueMapTy::iterator VI = ValueMap.begin(), VE = ValueMap.end();
-           VI != VE; ++VI)
-        LastValueMap[VI->first] = VI->second;
-
-      L->addBasicBlockToLoop(New, LI->getBase());
-
-      // Add phi entries for newly created values to all exit blocks except
-      // the successor of the latch block.  The successor of the exit block will
-      // be updated specially after unrolling all the way.
-      if (*BB != LatchBlock)
-        for (Value::use_iterator UI = (*BB)->use_begin(), UE = (*BB)->use_end();
-             UI != UE;) {
-          Instruction *UseInst = cast<Instruction>(*UI);
-          ++UI;
-          if (isa<PHINode>(UseInst) && !L->contains(UseInst->getParent())) {
-            PHINode *phi = cast<PHINode>(UseInst);
-            Value *Incoming = phi->getIncomingValueForBlock(*BB);
-            phi->addIncoming(Incoming, New);
-          }
-        }
-
-      // Keep track of new headers and latches as we create them, so that
-      // we can insert the proper branches later.
-      if (*BB == Header)
-        Headers.push_back(New);
-      if (*BB == LatchBlock) {
-        Latches.push_back(New);
-
-        // Also, clear out the new latch's back edge so that it doesn't look
-        // like a new loop, so that it's amenable to being merged with adjacent
-        // blocks later on.
-        TerminatorInst *Term = New->getTerminator();
-        assert(L->contains(Term->getSuccessor(!ContinueOnTrue)));
-        assert(Term->getSuccessor(ContinueOnTrue) == LoopExit);
-        Term->setSuccessor(!ContinueOnTrue, NULL);
-      }
-
-      NewBlocks.push_back(New);
-    }
-    
-    // Remap all instructions in the most recent iteration
-    for (unsigned i = 0; i < NewBlocks.size(); ++i)
-      for (BasicBlock::iterator I = NewBlocks[i]->begin(),
-           E = NewBlocks[i]->end(); I != E; ++I)
-        RemapInstruction(I, LastValueMap);
-  }
-  
-  // The latch block exits the loop.  If there are any PHI nodes in the
-  // successor blocks, update them to use the appropriate values computed as the
-  // last iteration of the loop.
-  if (Count != 1) {
-    SmallPtrSet<PHINode*, 8> Users;
-    for (Value::use_iterator UI = LatchBlock->use_begin(),
-         UE = LatchBlock->use_end(); UI != UE; ++UI)
-      if (PHINode *phi = dyn_cast<PHINode>(*UI))
-        Users.insert(phi);
-    
-    BasicBlock *LastIterationBB = cast<BasicBlock>(LastValueMap[LatchBlock]);
-    for (SmallPtrSet<PHINode*,8>::iterator SI = Users.begin(), SE = Users.end();
-         SI != SE; ++SI) {
-      PHINode *PN = *SI;
-      Value *InVal = PN->removeIncomingValue(LatchBlock, false);
-      // If this value was defined in the loop, take the value defined by the
-      // last iteration of the loop.
-      if (Instruction *InValI = dyn_cast<Instruction>(InVal)) {
-        if (L->contains(InValI->getParent()))
-          InVal = LastValueMap[InVal];
-      }
-      PN->addIncoming(InVal, LastIterationBB);
-    }
-  }
-
-  // Now, if we're doing complete unrolling, loop over the PHI nodes in the
-  // original block, setting them to their incoming values.
-  if (CompletelyUnroll) {
-    BasicBlock *Preheader = L->getLoopPreheader();
-    for (unsigned i = 0, e = OrigPHINode.size(); i != e; ++i) {
-      PHINode *PN = OrigPHINode[i];
-      PN->replaceAllUsesWith(PN->getIncomingValueForBlock(Preheader));
-      Header->getInstList().erase(PN);
-    }
-  }
-
-  // Now that all the basic blocks for the unrolled iterations are in place,
-  // set up the branches to connect them.
-  for (unsigned i = 0, e = Latches.size(); i != e; ++i) {
-    // The original branch was replicated in each unrolled iteration.
-    BranchInst *Term = cast<BranchInst>(Latches[i]->getTerminator());
-
-    // The branch destination.
-    unsigned j = (i + 1) % e;
-    BasicBlock *Dest = Headers[j];
-    bool NeedConditional = true;
-
-    // For a complete unroll, make the last iteration end with a branch
-    // to the exit block.
-    if (CompletelyUnroll && j == 0) {
-      Dest = LoopExit;
-      NeedConditional = false;
-    }
-
-    // If we know the trip count or a multiple of it, we can safely use an
-    // unconditional branch for some iterations.
-    if (j != BreakoutTrip && (TripMultiple == 0 || j % TripMultiple != 0)) {
-      NeedConditional = false;
-    }
-
-    if (NeedConditional) {
-      // Update the conditional branch's successor for the following
-      // iteration.
-      Term->setSuccessor(!ContinueOnTrue, Dest);
-    } else {
-      Term->setUnconditionalDest(Dest);
-      // Merge adjacent basic blocks, if possible.
-      if (BasicBlock *Fold = FoldBlockIntoPredecessor(Dest, LI)) {
-        std::replace(Latches.begin(), Latches.end(), Dest, Fold);
-        std::replace(Headers.begin(), Headers.end(), Dest, Fold);
-      }
-    }
-  }
-  
-  // At this point, the code is well formed.  We now do a quick sweep over the
-  // inserted code, doing constant propagation and dead code elimination as we
-  // go.
-  const std::vector<BasicBlock*> &NewLoopBlocks = L->getBlocks();
-  for (std::vector<BasicBlock*>::const_iterator BB = NewLoopBlocks.begin(),
-       BBE = NewLoopBlocks.end(); BB != BBE; ++BB)
-    for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end(); I != E; ) {
-      Instruction *Inst = I++;
-
-      if (isInstructionTriviallyDead(Inst))
-        (*BB)->getInstList().erase(Inst);
-      else if (Constant *C = ConstantFoldInstruction(Inst, 
-                                                     Header->getContext())) {
-        Inst->replaceAllUsesWith(C);
-        (*BB)->getInstList().erase(Inst);
-      }
-    }
-
-  NumCompletelyUnrolled += CompletelyUnroll;
-  ++NumUnrolled;
-  // Remove the loop from the LoopPassManager if it's completely removed.
-  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;
-}