Remove LoopDependenceAnalysis.

It was unmaintained and not much more than a stub. The new DependenceAnalysis
pass is both more general and complete.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166810 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 0 insertions, 364 deletions

diff --git a/lib/Analysis/Analysis.cpp b/lib/Analysis/Analysis.cpp
index 588206e915..8969ea9563 100644
--- a/lib/Analysis/Analysis.cpp
+++ b/lib/Analysis/Analysis.cpp
@@ -47,7 +47,6 @@ void llvm::initializeAnalysis(PassRegistry &Registry) {
   initializeLazyValueInfoPass(Registry);
   initializeLibCallAliasAnalysisPass(Registry);
   initializeLintPass(Registry);
-  initializeLoopDependenceAnalysisPass(Registry);
   initializeLoopInfoPass(Registry);
   initializeMemDepPrinterPass(Registry);
   initializeMemoryDependenceAnalysisPass(Registry);
diff --git a/lib/Analysis/CMakeLists.txt b/lib/Analysis/CMakeLists.txt
index 3ce888fefa..8f5a2f2893 100644
--- a/lib/Analysis/CMakeLists.txt
+++ b/lib/Analysis/CMakeLists.txt
@@ -27,7 +27,6 @@ add_llvm_library(LLVMAnalysis
   LibCallSemantics.cpp
   Lint.cpp
   Loads.cpp
-  LoopDependenceAnalysis.cpp
   LoopInfo.cpp
   LoopPass.cpp
   MemDepPrinter.cpp
diff --git a/lib/Analysis/LoopDependenceAnalysis.cpp b/lib/Analysis/LoopDependenceAnalysis.cpp
deleted file mode 100644
index b696e5fae1..0000000000
--- a/lib/Analysis/LoopDependenceAnalysis.cpp
+++ /dev/null
@@ -1,362 +0,0 @@
-//===- LoopDependenceAnalysis.cpp - LDA Implementation ----------*- C++ -*-===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This is the (beginning) of an implementation of a loop dependence analysis
-// framework, which is used to detect dependences in memory accesses in loops.
-//
-// Please note that this is work in progress and the interface is subject to
-// change.
-//
-// TODO: adapt as implementation progresses.
-//
-// TODO: document lingo (pair, subscript, index)
-//
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "lda"
-#include "llvm/ADT/DenseSet.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/LoopDependenceAnalysis.h"
-#include "llvm/Analysis/LoopPass.h"
-#include "llvm/Analysis/ScalarEvolution.h"
-#include "llvm/Analysis/ScalarEvolutionExpressions.h"
-#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/Assembly/Writer.h"
-#include "llvm/Instructions.h"
-#include "llvm/Operator.h"
-#include "llvm/Support/Allocator.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/DataLayout.h"
-using namespace llvm;
-
-STATISTIC(NumAnswered,    "Number of dependence queries answered");
-STATISTIC(NumAnalysed,    "Number of distinct dependence pairs analysed");
-STATISTIC(NumDependent,   "Number of pairs with dependent accesses");
-STATISTIC(NumIndependent, "Number of pairs with independent accesses");
-STATISTIC(NumUnknown,     "Number of pairs with unknown accesses");
-
-LoopPass *llvm::createLoopDependenceAnalysisPass() {
-  return new LoopDependenceAnalysis();
-}
-
-INITIALIZE_PASS_BEGIN(LoopDependenceAnalysis, "lda",
-                "Loop Dependence Analysis", false, true)
-INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
-INITIALIZE_AG_DEPENDENCY(AliasAnalysis)
-INITIALIZE_PASS_END(LoopDependenceAnalysis, "lda",
-                "Loop Dependence Analysis", false, true)
-char LoopDependenceAnalysis::ID = 0;
-
-//===----------------------------------------------------------------------===//
-//                             Utility Functions
-//===----------------------------------------------------------------------===//
-
-static inline bool IsMemRefInstr(const Value *V) {
-  const Instruction *I = dyn_cast<const Instruction>(V);
-  return I && (I->mayReadFromMemory() || I->mayWriteToMemory());
-}
-
-static void GetMemRefInstrs(const Loop *L,
-                            SmallVectorImpl<Instruction*> &Memrefs) {
-  for (Loop::block_iterator b = L->block_begin(), be = L->block_end();
-       b != be; ++b)
-    for (BasicBlock::iterator i = (*b)->begin(), ie = (*b)->end();
-         i != ie; ++i)
-      if (IsMemRefInstr(i))
-        Memrefs.push_back(i);
-}
-
-static bool IsLoadOrStoreInst(Value *I) {
-  // Returns true if the load or store can be analyzed. Atomic and volatile
-  // operations have properties which this analysis does not understand.
-  if (LoadInst *LI = dyn_cast<LoadInst>(I))
-    return LI->isUnordered();
-  else if (StoreInst *SI = dyn_cast<StoreInst>(I))
-    return SI->isUnordered();
-  return false;
-}
-
-static Value *GetPointerOperand(Value *I) {
-  if (LoadInst *i = dyn_cast<LoadInst>(I))
-    return i->getPointerOperand();
-  if (StoreInst *i = dyn_cast<StoreInst>(I))
-    return i->getPointerOperand();
-  llvm_unreachable("Value is no load or store instruction!");
-}
-
-static AliasAnalysis::AliasResult UnderlyingObjectsAlias(AliasAnalysis *AA,
-                                                         const Value *A,
-                                                         const Value *B) {
-  const Value *aObj = GetUnderlyingObject(A);
-  const Value *bObj = GetUnderlyingObject(B);
-  return AA->alias(aObj, AA->getTypeStoreSize(aObj->getType()),
-                   bObj, AA->getTypeStoreSize(bObj->getType()));
-}
-
-static inline const SCEV *GetZeroSCEV(ScalarEvolution *SE) {
-  return SE->getConstant(Type::getInt32Ty(SE->getContext()), 0L);
-}
-
-//===----------------------------------------------------------------------===//
-//                             Dependence Testing
-//===----------------------------------------------------------------------===//
-
-bool LoopDependenceAnalysis::isDependencePair(const Value *A,
-                                              const Value *B) const {
-  return IsMemRefInstr(A) &&
-         IsMemRefInstr(B) &&
-         (cast<const Instruction>(A)->mayWriteToMemory() ||
-          cast<const Instruction>(B)->mayWriteToMemory());
-}
-
-bool LoopDependenceAnalysis::findOrInsertDependencePair(Value *A,
-                                                        Value *B,
-                                                        DependencePair *&P) {
-  void *insertPos = 0;
-  FoldingSetNodeID id;
-  id.AddPointer(A);
-  id.AddPointer(B);
-
-  P = Pairs.FindNodeOrInsertPos(id, insertPos);
-  if (P) return true;
-
-  P = new (PairAllocator) DependencePair(id, A, B);
-  Pairs.InsertNode(P, insertPos);
-  return false;
-}
-
-void LoopDependenceAnalysis::getLoops(const SCEV *S,
-                                      DenseSet<const Loop*>* Loops) const {
-  // Refactor this into an SCEVVisitor, if efficiency becomes a concern.
-  for (const Loop *L = this->L; L != 0; L = L->getParentLoop())
-    if (!SE->isLoopInvariant(S, L))
-      Loops->insert(L);
-}
-
-bool LoopDependenceAnalysis::isLoopInvariant(const SCEV *S) const {
-  DenseSet<const Loop*> loops;
-  getLoops(S, &loops);
-  return loops.empty();
-}
-
-bool LoopDependenceAnalysis::isAffine(const SCEV *S) const {
-  const SCEVAddRecExpr *rec = dyn_cast<SCEVAddRecExpr>(S);
-  return isLoopInvariant(S) || (rec && rec->isAffine());
-}
-
-bool LoopDependenceAnalysis::isZIVPair(const SCEV *A, const SCEV *B) const {
-  return isLoopInvariant(A) && isLoopInvariant(B);
-}
-
-bool LoopDependenceAnalysis::isSIVPair(const SCEV *A, const SCEV *B) const {
-  DenseSet<const Loop*> loops;
-  getLoops(A, &loops);
-  getLoops(B, &loops);
-  return loops.size() == 1;
-}
-
-LoopDependenceAnalysis::DependenceResult
-LoopDependenceAnalysis::analyseZIV(const SCEV *A,
-                                   const SCEV *B,
-                                   Subscript *S) const {
-  assert(isZIVPair(A, B) && "Attempted to ZIV-test non-ZIV SCEVs!");
-  return A == B ? Dependent : Independent;
-}
-
-LoopDependenceAnalysis::DependenceResult
-LoopDependenceAnalysis::analyseSIV(const SCEV *A,
-                                   const SCEV *B,
-                                   Subscript *S) const {
-  return Unknown; // TODO: Implement.
-}
-
-LoopDependenceAnalysis::DependenceResult
-LoopDependenceAnalysis::analyseMIV(const SCEV *A,
-                                   const SCEV *B,
-                                   Subscript *S) const {
-  return Unknown; // TODO: Implement.
-}
-
-LoopDependenceAnalysis::DependenceResult
-LoopDependenceAnalysis::analyseSubscript(const SCEV *A,
-                                         const SCEV *B,
-                                         Subscript *S) const {
-  DEBUG(dbgs() << "  Testing subscript: " << *A << ", " << *B << "\n");
-
-  if (A == B) {
-    DEBUG(dbgs() << "  -> [D] same SCEV\n");
-    return Dependent;
-  }
-
-  if (!isAffine(A) || !isAffine(B)) {
-    DEBUG(dbgs() << "  -> [?] not affine\n");
-    return Unknown;
-  }
-
-  if (isZIVPair(A, B))
-    return analyseZIV(A, B, S);
-
-  if (isSIVPair(A, B))
-    return analyseSIV(A, B, S);
-
-  return analyseMIV(A, B, S);
-}
-
-LoopDependenceAnalysis::DependenceResult
-LoopDependenceAnalysis::analysePair(DependencePair *P) const {
-  DEBUG(dbgs() << "Analysing:\n" << *P->A << "\n" << *P->B << "\n");
-
-  // We only analyse loads and stores but no possible memory accesses by e.g.
-  // free, call, or invoke instructions.
-  if (!IsLoadOrStoreInst(P->A) || !IsLoadOrStoreInst(P->B)) {
-    DEBUG(dbgs() << "--> [?] no load/store\n");
-    return Unknown;
-  }
-
-  Value *aPtr = GetPointerOperand(P->A);
-  Value *bPtr = GetPointerOperand(P->B);
-
-  switch (UnderlyingObjectsAlias(AA, aPtr, bPtr)) {
-  case AliasAnalysis::MayAlias:
-  case AliasAnalysis::PartialAlias:
-    // We can not analyse objects if we do not know about their aliasing.
-    DEBUG(dbgs() << "---> [?] may alias\n");
-    return Unknown;
-
-  case AliasAnalysis::NoAlias:
-    // If the objects noalias, they are distinct, accesses are independent.
-    DEBUG(dbgs() << "---> [I] no alias\n");
-    return Independent;
-
-  case AliasAnalysis::MustAlias:
-    break; // The underlying objects alias, test accesses for dependence.
-  }
-
-  const GEPOperator *aGEP = dyn_cast<GEPOperator>(aPtr);
-  const GEPOperator *bGEP = dyn_cast<GEPOperator>(bPtr);
-
-  if (!aGEP || !bGEP)
-    return Unknown;
-
-  // FIXME: Is filtering coupled subscripts necessary?
-
-  // Collect GEP operand pairs (FIXME: use GetGEPOperands from BasicAA), adding
-  // trailing zeroes to the smaller GEP, if needed.
-  typedef SmallVector<std::pair<const SCEV*, const SCEV*>, 4> GEPOpdPairsTy;
-  GEPOpdPairsTy opds;
-  for(GEPOperator::const_op_iterator aIdx = aGEP->idx_begin(),
-                                     aEnd = aGEP->idx_end(),
-                                     bIdx = bGEP->idx_begin(),
-                                     bEnd = bGEP->idx_end();
-      aIdx != aEnd && bIdx != bEnd;
-      aIdx += (aIdx != aEnd), bIdx += (bIdx != bEnd)) {
-    const SCEV* aSCEV = (aIdx != aEnd) ? SE->getSCEV(*aIdx) : GetZeroSCEV(SE);
-    const SCEV* bSCEV = (bIdx != bEnd) ? SE->getSCEV(*bIdx) : GetZeroSCEV(SE);
-    opds.push_back(std::make_pair(aSCEV, bSCEV));
-  }
-
-  if (!opds.empty() && opds[0].first != opds[0].second) {
-    // We cannot (yet) handle arbitrary GEP pointer offsets. By limiting
-    //
-    // TODO: this could be relaxed by adding the size of the underlying object
-    // to the first subscript. If we have e.g. (GEP x,0,i; GEP x,2,-i) and we
-    // know that x is a [100 x i8]*, we could modify the first subscript to be
-    // (i, 200-i) instead of (i, -i).
-    return Unknown;
-  }
-
-  // Now analyse the collected operand pairs (skipping the GEP ptr offsets).
-  for (GEPOpdPairsTy::const_iterator i = opds.begin() + 1, end = opds.end();
-       i != end; ++i) {
-    Subscript subscript;
-    DependenceResult result = analyseSubscript(i->first, i->second, &subscript);
-    if (result != Dependent) {
-      // We either proved independence or failed to analyse this subscript.
-      // Further subscripts will not improve the situation, so abort early.
-      return result;
-    }
-    P->Subscripts.push_back(subscript);
-  }
-  // We successfully analysed all subscripts but failed to prove independence.
-  return Dependent;
-}
-
-bool LoopDependenceAnalysis::depends(Value *A, Value *B) {
-  assert(isDependencePair(A, B) && "Values form no dependence pair!");
-  ++NumAnswered;
-
-  DependencePair *p;
-  if (!findOrInsertDependencePair(A, B, p)) {
-    // The pair is not cached, so analyse it.
-    ++NumAnalysed;
-    switch (p->Result = analysePair(p)) {
-    case Dependent:   ++NumDependent;   break;
-    case Independent: ++NumIndependent; break;
-    case Unknown:     ++NumUnknown;     break;
-    }
-  }
-  return p->Result != Independent;
-}
-
-//===----------------------------------------------------------------------===//
-//                   LoopDependenceAnalysis Implementation
-//===----------------------------------------------------------------------===//
-
-bool LoopDependenceAnalysis::runOnLoop(Loop *L, LPPassManager &) {
-  this->L = L;
-  AA = &getAnalysis<AliasAnalysis>();
-  SE = &getAnalysis<ScalarEvolution>();
-  return false;
-}
-
-void LoopDependenceAnalysis::releaseMemory() {
-  Pairs.clear();
-  PairAllocator.Reset();
-}
-
-void LoopDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
-  AU.setPreservesAll();
-  AU.addRequiredTransitive<AliasAnalysis>();
-  AU.addRequiredTransitive<ScalarEvolution>();
-}
-
-static void PrintLoopInfo(raw_ostream &OS,
-                          LoopDependenceAnalysis *LDA, const Loop *L) {
-  if (!L->empty()) return; // ignore non-innermost loops
-
-  SmallVector<Instruction*, 8> memrefs;
-  GetMemRefInstrs(L, memrefs);
-
-  OS << "Loop at depth " << L->getLoopDepth() << ", header block: ";
-  WriteAsOperand(OS, L->getHeader(), false);
-  OS << "\n";
-
-  OS << "  Load/store instructions: " << memrefs.size() << "\n";
-  for (SmallVector<Instruction*, 8>::const_iterator x = memrefs.begin(),
-       end = memrefs.end(); x != end; ++x)
-    OS << "\t" << (x - memrefs.begin()) << ": " << **x << "\n";
-
-  OS << "  Pairwise dependence results:\n";
-  for (SmallVector<Instruction*, 8>::const_iterator x = memrefs.begin(),
-       end = memrefs.end(); x != end; ++x)
-    for (SmallVector<Instruction*, 8>::const_iterator y = x + 1;
-         y != end; ++y)
-      if (LDA->isDependencePair(*x, *y))
-        OS << "\t" << (x - memrefs.begin()) << "," << (y - memrefs.begin())
-           << ": " << (LDA->depends(*x, *y) ? "dependent" : "independent")
-           << "\n";
-}
-
-void LoopDependenceAnalysis::print(raw_ostream &OS, const Module*) const {
-  // TODO: doc why const_cast is safe
-  PrintLoopInfo(OS, const_cast<LoopDependenceAnalysis*>(this), this->L);
-}