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https://github.com/c64scene-ar/llvm-6502.git
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2fbb770d40
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74439 91177308-0d34-0410-b5e6-96231b3b80d8
117 lines
4.2 KiB
C++
117 lines
4.2 KiB
C++
//===- LoopDependenceAnalysis.cpp - LDA Implementation ----------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This is the (beginning) of an implementation of a loop dependence analysis
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// framework, which is used to detect dependences in memory accesses in loops.
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//
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// Please note that this is work in progress and the interface is subject to
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// change.
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//
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// TODO: adapt as implementation progresses.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "lda"
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#include "llvm/Analysis/LoopDependenceAnalysis.h"
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#include "llvm/Analysis/LoopPass.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Instructions.h"
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using namespace llvm;
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LoopPass *llvm::createLoopDependenceAnalysisPass() {
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return new LoopDependenceAnalysis();
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}
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static RegisterPass<LoopDependenceAnalysis>
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R("lda", "Loop Dependence Analysis", false, true);
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char LoopDependenceAnalysis::ID = 0;
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//===----------------------------------------------------------------------===//
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// Utility Functions
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//===----------------------------------------------------------------------===//
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static inline bool IsMemRefInstr(const Value *V) {
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const Instruction *I = dyn_cast<const Instruction>(V);
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return I && (I->mayReadFromMemory() || I->mayWriteToMemory());
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}
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static void GetMemRefInstrs(
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const Loop *L, SmallVectorImpl<Instruction*> &memrefs) {
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for (Loop::block_iterator b = L->block_begin(), be = L->block_end();
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b != be; ++b)
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for (BasicBlock::iterator i = (*b)->begin(), ie = (*b)->end();
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i != ie; ++i)
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if (IsMemRefInstr(i))
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memrefs.push_back(i);
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}
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//===----------------------------------------------------------------------===//
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// Dependence Testing
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//===----------------------------------------------------------------------===//
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bool LoopDependenceAnalysis::isDependencePair(const Value *x,
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const Value *y) const {
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return IsMemRefInstr(x) &&
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IsMemRefInstr(y) &&
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(cast<const Instruction>(x)->mayWriteToMemory() ||
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cast<const Instruction>(y)->mayWriteToMemory());
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}
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bool LoopDependenceAnalysis::depends(Value *src, Value *dst) {
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assert(isDependencePair(src, dst) && "Values form no dependence pair!");
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return true;
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}
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//===----------------------------------------------------------------------===//
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// LoopDependenceAnalysis Implementation
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//===----------------------------------------------------------------------===//
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bool LoopDependenceAnalysis::runOnLoop(Loop *L, LPPassManager &) {
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this->L = L;
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SE = &getAnalysis<ScalarEvolution>();
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return false;
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}
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void LoopDependenceAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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AU.addRequiredTransitive<ScalarEvolution>();
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}
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static void PrintLoopInfo(
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raw_ostream &OS, LoopDependenceAnalysis *LDA, const Loop *L) {
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if (!L->empty()) return; // ignore non-innermost loops
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OS << "Loop at depth " << L->getLoopDepth() << ", header block: ";
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WriteAsOperand(OS, L->getHeader(), false);
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OS << "\n";
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SmallVector<Instruction*, 8> memrefs;
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GetMemRefInstrs(L, memrefs);
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OS << " Load/store instructions: " << memrefs.size() << "\n";
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OS << " Pairwise dependence results:\n";
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for (SmallVector<Instruction*, 8>::const_iterator x = memrefs.begin(),
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end = memrefs.end(); x != end; ++x)
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for (SmallVector<Instruction*, 8>::const_iterator y = x + 1;
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y != end; ++y)
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if (LDA->isDependencePair(*x, *y))
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OS << "\t" << (x - memrefs.begin()) << "," << (y - memrefs.begin())
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<< ": " << (LDA->depends(*x, *y) ? "dependent" : "independent")
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<< "\n";
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}
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void LoopDependenceAnalysis::print(raw_ostream &OS, const Module*) const {
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// TODO: doc why const_cast is safe
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PrintLoopInfo(OS, const_cast<LoopDependenceAnalysis*>(this), this->L);
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}
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void LoopDependenceAnalysis::print(std::ostream &OS, const Module *M) const {
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raw_os_ostream os(OS);
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print(os, M);
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}
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