Merge "Update aosp/master LLVM for rebase to r230699."

1 files changed, 382 insertions, 0 deletions

diff --git a/lib/Target/PowerPC/PPCLoopPreIncPrep.cpp b/lib/Target/PowerPC/PPCLoopPreIncPrep.cpp
new file mode 100644
index 0000000..df65227
--- /dev/null
+++ b/lib/Target/PowerPC/PPCLoopPreIncPrep.cpp
@@ -0,0 +1,382 @@
+//===------ PPCLoopPreIncPrep.cpp - Loop Pre-Inc. AM Prep. Pass -----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a pass to prepare loops for pre-increment addressing
+// modes. Additional PHIs are created for loop induction variables used by
+// load/store instructions so that the pre-increment forms can be used.
+// Generically, this means transforming loops like this:
+//   for (int i = 0; i < n; ++i)
+//     array[i] = c;
+// to look like this:
+//   T *p = array[-1];
+//   for (int i = 0; i < n; ++i)
+//     *++p = c;
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "ppc-loop-preinc-prep"
+#include "PPC.h"
+#include "PPCTargetMachine.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/CodeMetrics.h"
+#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/LoopUtils.h"
+#include "llvm/Transforms/Utils/ValueMapper.h"
+using namespace llvm;
+
+// By default, we limit this to creating 16 PHIs (which is a little over half
+// of the allocatable register set).
+static cl::opt<unsigned> MaxVars("ppc-preinc-prep-max-vars",
+                                 cl::Hidden, cl::init(16),
+  cl::desc("Potential PHI threshold for PPC preinc loop prep"));
+
+namespace llvm {
+  void initializePPCLoopPreIncPrepPass(PassRegistry&);
+}
+
+namespace {
+
+  class PPCLoopPreIncPrep : public FunctionPass {
+  public:
+    static char ID; // Pass ID, replacement for typeid
+    PPCLoopPreIncPrep() : FunctionPass(ID), TM(nullptr) {
+      initializePPCLoopPreIncPrepPass(*PassRegistry::getPassRegistry());
+    }
+    PPCLoopPreIncPrep(PPCTargetMachine &TM) : FunctionPass(ID), TM(&TM) {
+      initializePPCLoopPreIncPrepPass(*PassRegistry::getPassRegistry());
+    }
+
+    void getAnalysisUsage(AnalysisUsage &AU) const override {
+      AU.addPreserved<DominatorTreeWrapperPass>();
+      AU.addRequired<LoopInfoWrapperPass>();
+      AU.addPreserved<LoopInfoWrapperPass>();
+      AU.addRequired<ScalarEvolution>();
+    }
+
+    bool runOnFunction(Function &F) override;
+
+    bool runOnLoop(Loop *L);
+    void simplifyLoopLatch(Loop *L);
+    bool rotateLoop(Loop *L);
+
+  private:
+    PPCTargetMachine *TM;
+    LoopInfo *LI;
+    ScalarEvolution *SE;
+    const DataLayout *DL;
+  };
+}
+
+char PPCLoopPreIncPrep::ID = 0;
+static const char *name = "Prepare loop for pre-inc. addressing modes";
+INITIALIZE_PASS_BEGIN(PPCLoopPreIncPrep, DEBUG_TYPE, name, false, false)
+INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
+INITIALIZE_PASS_END(PPCLoopPreIncPrep, DEBUG_TYPE, name, false, false)
+
+FunctionPass *llvm::createPPCLoopPreIncPrepPass(PPCTargetMachine &TM) {
+  return new PPCLoopPreIncPrep(TM);
+}
+
+namespace {
+  struct SCEVLess : std::binary_function<const SCEV *, const SCEV *, bool>
+  {
+    SCEVLess(ScalarEvolution *SE) : SE(SE) {}
+
+    bool operator() (const SCEV *X, const SCEV *Y) const {
+      const SCEV *Diff = SE->getMinusSCEV(X, Y);
+      return cast<SCEVConstant>(Diff)->getValue()->getSExtValue() < 0;
+    }
+
+  protected:
+    ScalarEvolution *SE;
+  };
+}
+
+static bool IsPtrInBounds(Value *BasePtr) {
+  Value *StrippedBasePtr = BasePtr;
+  while (BitCastInst *BC = dyn_cast<BitCastInst>(StrippedBasePtr))
+    StrippedBasePtr = BC->getOperand(0);
+  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(StrippedBasePtr))
+    return GEP->isInBounds();
+
+  return false;
+}
+
+static Value *GetPointerOperand(Value *MemI) {
+  if (LoadInst *LMemI = dyn_cast<LoadInst>(MemI)) {
+    return LMemI->getPointerOperand();
+  } else if (StoreInst *SMemI = dyn_cast<StoreInst>(MemI)) {
+    return SMemI->getPointerOperand();
+  } else if (IntrinsicInst *IMemI = dyn_cast<IntrinsicInst>(MemI)) {
+    if (IMemI->getIntrinsicID() == Intrinsic::prefetch)
+      return IMemI->getArgOperand(0);
+  }
+
+  return 0;
+}
+
+bool PPCLoopPreIncPrep::runOnFunction(Function &F) {
+  LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
+  SE = &getAnalysis<ScalarEvolution>();
+
+  DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
+  DL = DLP ? &DLP->getDataLayout() : 0;
+
+  bool MadeChange = false;
+
+  for (LoopInfo::iterator I = LI->begin(), E = LI->end();
+       I != E; ++I) {
+    Loop *L = *I;
+    MadeChange |= runOnLoop(L);
+  }
+
+  return MadeChange;
+}
+
+bool PPCLoopPreIncPrep::runOnLoop(Loop *L) {
+  bool MadeChange = false;
+
+  if (!DL)
+    return MadeChange;
+
+  // Only prep. the inner-most loop
+  if (!L->empty())
+    return MadeChange;
+
+  BasicBlock *Header = L->getHeader();
+
+  const PPCSubtarget *ST =
+    TM ? TM->getSubtargetImpl(*Header->getParent()) : nullptr;
+
+  unsigned HeaderLoopPredCount = 0;
+  for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
+       PI != PE; ++PI) {
+    ++HeaderLoopPredCount;
+  }
+
+  // Collect buckets of comparable addresses used by loads and stores.
+  typedef std::multimap<const SCEV *, Instruction *, SCEVLess> Bucket;
+  SmallVector<Bucket, 16> Buckets;
+  for (Loop::block_iterator I = L->block_begin(), IE = L->block_end();
+       I != IE; ++I) {
+    for (BasicBlock::iterator J = (*I)->begin(), JE = (*I)->end();
+        J != JE; ++J) {
+      Value *PtrValue;
+      Instruction *MemI;
+
+      if (LoadInst *LMemI = dyn_cast<LoadInst>(J)) {
+        MemI = LMemI;
+        PtrValue = LMemI->getPointerOperand();
+      } else if (StoreInst *SMemI = dyn_cast<StoreInst>(J)) {
+        MemI = SMemI;
+        PtrValue = SMemI->getPointerOperand();
+      } else if (IntrinsicInst *IMemI = dyn_cast<IntrinsicInst>(J)) {
+        if (IMemI->getIntrinsicID() == Intrinsic::prefetch) {
+          MemI = IMemI;
+          PtrValue = IMemI->getArgOperand(0);
+        } else continue;
+      } else continue;
+
+      unsigned PtrAddrSpace = PtrValue->getType()->getPointerAddressSpace();
+      if (PtrAddrSpace)
+        continue;
+
+      // There are no update forms for Altivec vector load/stores.
+      if (ST && ST->hasAltivec() &&
+          PtrValue->getType()->getPointerElementType()->isVectorTy())
+        continue;
+
+      if (L->isLoopInvariant(PtrValue))
+        continue;
+
+      const SCEV *LSCEV = SE->getSCEV(PtrValue);
+      if (!isa<SCEVAddRecExpr>(LSCEV))
+        continue;
+
+      bool FoundBucket = false;
+      for (unsigned i = 0, e = Buckets.size(); i != e; ++i)
+        for (Bucket::iterator K = Buckets[i].begin(), KE = Buckets[i].end();
+             K != KE; ++K) {
+          const SCEV *Diff = SE->getMinusSCEV(K->first, LSCEV);
+          if (isa<SCEVConstant>(Diff)) {
+            Buckets[i].insert(std::make_pair(LSCEV, MemI));
+            FoundBucket = true;
+            break;
+          }
+        }
+
+      if (!FoundBucket) {
+        Buckets.push_back(Bucket(SCEVLess(SE)));
+        Buckets[Buckets.size()-1].insert(std::make_pair(LSCEV, MemI));
+      }
+    }
+  }
+
+  if (Buckets.empty() || Buckets.size() > MaxVars)
+    return MadeChange;
+
+  BasicBlock *LoopPredecessor = L->getLoopPredecessor();
+  // If there is no loop predecessor, or the loop predecessor's terminator
+  // returns a value (which might contribute to determining the loop's
+  // iteration space), insert a new preheader for the loop.
+  if (!LoopPredecessor ||
+      !LoopPredecessor->getTerminator()->getType()->isVoidTy())
+    LoopPredecessor = InsertPreheaderForLoop(L, this);
+  if (!LoopPredecessor)
+    return MadeChange;
+
+  SmallSet<BasicBlock *, 16> BBChanged;
+  for (unsigned i = 0, e = Buckets.size(); i != e; ++i) {
+    // The base address of each bucket is transformed into a phi and the others
+    // are rewritten as offsets of that variable.
+
+    const SCEVAddRecExpr *BasePtrSCEV =
+      cast<SCEVAddRecExpr>(Buckets[i].begin()->first);
+    if (!BasePtrSCEV->isAffine())
+      continue;
+
+    Instruction *MemI = Buckets[i].begin()->second;
+    Value *BasePtr = GetPointerOperand(MemI);
+    assert(BasePtr && "No pointer operand");
+
+    Type *I8PtrTy = Type::getInt8PtrTy(MemI->getParent()->getContext(),
+      BasePtr->getType()->getPointerAddressSpace());
+
+    const SCEV *BasePtrStartSCEV = BasePtrSCEV->getStart();
+    if (!SE->isLoopInvariant(BasePtrStartSCEV, L))
+      continue;
+
+    const SCEVConstant *BasePtrIncSCEV =
+      dyn_cast<SCEVConstant>(BasePtrSCEV->getStepRecurrence(*SE));
+    if (!BasePtrIncSCEV)
+      continue;
+    BasePtrStartSCEV = SE->getMinusSCEV(BasePtrStartSCEV, BasePtrIncSCEV);
+    if (!isSafeToExpand(BasePtrStartSCEV, *SE))
+      continue;
+
+    PHINode *NewPHI = PHINode::Create(I8PtrTy, HeaderLoopPredCount,
+      MemI->hasName() ? MemI->getName() + ".phi" : "",
+      Header->getFirstNonPHI());
+
+    SCEVExpander SCEVE(*SE, "pistart");
+    Value *BasePtrStart = SCEVE.expandCodeFor(BasePtrStartSCEV, I8PtrTy,
+      LoopPredecessor->getTerminator());
+
+    // Note that LoopPredecessor might occur in the predecessor list multiple
+    // times, and we need to add it the right number of times.
+    for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
+         PI != PE; ++PI) {
+      if (*PI != LoopPredecessor)
+        continue;
+
+      NewPHI->addIncoming(BasePtrStart, LoopPredecessor);
+    }
+
+    Instruction *InsPoint = Header->getFirstInsertionPt();
+    GetElementPtrInst *PtrInc =
+      GetElementPtrInst::Create(NewPHI, BasePtrIncSCEV->getValue(),
+        MemI->hasName() ? MemI->getName() + ".inc" : "", InsPoint);
+    PtrInc->setIsInBounds(IsPtrInBounds(BasePtr));
+    for (pred_iterator PI = pred_begin(Header), PE = pred_end(Header);
+         PI != PE; ++PI) {
+      if (*PI == LoopPredecessor)
+        continue;
+
+      NewPHI->addIncoming(PtrInc, *PI);
+    }
+
+    Instruction *NewBasePtr;
+    if (PtrInc->getType() != BasePtr->getType())
+      NewBasePtr = new BitCastInst(PtrInc, BasePtr->getType(),
+        PtrInc->hasName() ? PtrInc->getName() + ".cast" : "", InsPoint);
+    else
+      NewBasePtr = PtrInc;
+
+    if (Instruction *IDel = dyn_cast<Instruction>(BasePtr))
+      BBChanged.insert(IDel->getParent());
+    BasePtr->replaceAllUsesWith(NewBasePtr);
+    RecursivelyDeleteTriviallyDeadInstructions(BasePtr);
+
+    Value *LastNewPtr = NewBasePtr;
+    for (Bucket::iterator I = std::next(Buckets[i].begin()),
+         IE = Buckets[i].end(); I != IE; ++I) {
+      Value *Ptr = GetPointerOperand(I->second);
+      assert(Ptr && "No pointer operand");
+      if (Ptr == LastNewPtr)
+        continue;
+
+      Instruction *RealNewPtr;
+      const SCEVConstant *Diff =
+        cast<SCEVConstant>(SE->getMinusSCEV(I->first, BasePtrSCEV));
+      if (Diff->isZero()) {
+        RealNewPtr = NewBasePtr;
+      } else {
+        Instruction *PtrIP = dyn_cast<Instruction>(Ptr);
+        if (PtrIP && isa<Instruction>(NewBasePtr) &&
+            cast<Instruction>(NewBasePtr)->getParent() == PtrIP->getParent())
+          PtrIP = 0;
+        else if (isa<PHINode>(PtrIP))
+          PtrIP = PtrIP->getParent()->getFirstInsertionPt();
+        else if (!PtrIP)
+          PtrIP = I->second;
+  
+        GetElementPtrInst *NewPtr =
+          GetElementPtrInst::Create(PtrInc, Diff->getValue(),
+            I->second->hasName() ? I->second->getName() + ".off" : "", PtrIP);
+        if (!PtrIP)
+          NewPtr->insertAfter(cast<Instruction>(PtrInc));
+        NewPtr->setIsInBounds(IsPtrInBounds(Ptr));
+        RealNewPtr = NewPtr;
+      }
+
+      if (Instruction *IDel = dyn_cast<Instruction>(Ptr))
+        BBChanged.insert(IDel->getParent());
+
+      Instruction *ReplNewPtr;
+      if (Ptr->getType() != RealNewPtr->getType()) {
+        ReplNewPtr = new BitCastInst(RealNewPtr, Ptr->getType(),
+          Ptr->hasName() ? Ptr->getName() + ".cast" : "");
+        ReplNewPtr->insertAfter(RealNewPtr);
+      } else
+        ReplNewPtr = RealNewPtr;
+
+      Ptr->replaceAllUsesWith(ReplNewPtr);
+      RecursivelyDeleteTriviallyDeadInstructions(Ptr);
+
+      LastNewPtr = RealNewPtr;
+    }
+
+    MadeChange = true;
+  }
+
+  for (Loop::block_iterator I = L->block_begin(), IE = L->block_end();
+       I != IE; ++I) {
+    if (BBChanged.count(*I))
+      DeleteDeadPHIs(*I);
+  }
+
+  return MadeChange;
+}
+