From b8b3f6081f8dc409e7281e1597d8d94e50e4b028 Mon Sep 17 00:00:00 2001 From: Benjamin Kramer Date: Fri, 26 Oct 2012 20:25:01 +0000 Subject: 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 --- lib/Analysis/Analysis.cpp | 1 - lib/Analysis/CMakeLists.txt | 1 - lib/Analysis/LoopDependenceAnalysis.cpp | 362 -------------------------------- 3 files changed, 364 deletions(-) delete mode 100644 lib/Analysis/LoopDependenceAnalysis.cpp (limited to 'lib') 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(V); - return I && (I->mayReadFromMemory() || I->mayWriteToMemory()); -} - -static void GetMemRefInstrs(const Loop *L, - SmallVectorImpl &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(I)) - return LI->isUnordered(); - else if (StoreInst *SI = dyn_cast(I)) - return SI->isUnordered(); - return false; -} - -static Value *GetPointerOperand(Value *I) { - if (LoadInst *i = dyn_cast(I)) - return i->getPointerOperand(); - if (StoreInst *i = dyn_cast(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(A)->mayWriteToMemory() || - cast(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* 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 loops; - getLoops(S, &loops); - return loops.empty(); -} - -bool LoopDependenceAnalysis::isAffine(const SCEV *S) const { - const SCEVAddRecExpr *rec = dyn_cast(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 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(aPtr); - const GEPOperator *bGEP = dyn_cast(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, 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(); - SE = &getAnalysis(); - return false; -} - -void LoopDependenceAnalysis::releaseMemory() { - Pairs.clear(); - PairAllocator.Reset(); -} - -void LoopDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const { - AU.setPreservesAll(); - AU.addRequiredTransitive(); - AU.addRequiredTransitive(); -} - -static void PrintLoopInfo(raw_ostream &OS, - LoopDependenceAnalysis *LDA, const Loop *L) { - if (!L->empty()) return; // ignore non-innermost loops - - SmallVector 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::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::const_iterator x = memrefs.begin(), - end = memrefs.end(); x != end; ++x) - for (SmallVector::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(this), this->L); -} -- cgit v1.2.3