148 lines
4.9 KiB
C++
148 lines
4.9 KiB
C++
//===---- Delinearization.cpp - MultiDimensional Index Delinearization ----===//
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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 implements an analysis pass that tries to delinearize all GEP
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// instructions in all loops using the SCEV analysis functionality. This pass is
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// only used for testing purposes: if your pass needs delinearization, please
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// use the on-demand SCEVAddRecExpr::delinearize() function.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/IR/Constants.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/Analysis/Passes.h"
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#include "llvm/Analysis/ScalarEvolution.h"
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#include "llvm/Analysis/ScalarEvolutionExpressions.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/InstIterator.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/Type.h"
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#include "llvm/Pass.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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#define DL_NAME "delinearize"
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#define DEBUG_TYPE DL_NAME
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namespace {
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class Delinearization : public FunctionPass {
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Delinearization(const Delinearization &); // do not implement
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protected:
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Function *F;
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LoopInfo *LI;
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ScalarEvolution *SE;
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public:
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static char ID; // Pass identification, replacement for typeid
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Delinearization() : FunctionPass(ID) {
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initializeDelinearizationPass(*PassRegistry::getPassRegistry());
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}
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bool runOnFunction(Function &F) override;
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void getAnalysisUsage(AnalysisUsage &AU) const override;
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void print(raw_ostream &O, const Module *M = nullptr) const override;
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};
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} // end anonymous namespace
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void Delinearization::getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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AU.addRequired<LoopInfoWrapperPass>();
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AU.addRequired<ScalarEvolution>();
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}
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bool Delinearization::runOnFunction(Function &F) {
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this->F = &F;
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SE = &getAnalysis<ScalarEvolution>();
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LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
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return false;
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}
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static Value *getPointerOperand(Instruction &Inst) {
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if (LoadInst *Load = dyn_cast<LoadInst>(&Inst))
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return Load->getPointerOperand();
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else if (StoreInst *Store = dyn_cast<StoreInst>(&Inst))
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return Store->getPointerOperand();
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else if (GetElementPtrInst *Gep = dyn_cast<GetElementPtrInst>(&Inst))
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return Gep->getPointerOperand();
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return nullptr;
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}
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void Delinearization::print(raw_ostream &O, const Module *) const {
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O << "Delinearization on function " << F->getName() << ":\n";
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for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
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Instruction *Inst = &(*I);
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// Only analyze loads and stores.
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if (!isa<StoreInst>(Inst) && !isa<LoadInst>(Inst) &&
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!isa<GetElementPtrInst>(Inst))
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continue;
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const BasicBlock *BB = Inst->getParent();
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// Delinearize the memory access as analyzed in all the surrounding loops.
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// Do not analyze memory accesses outside loops.
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for (Loop *L = LI->getLoopFor(BB); L != nullptr; L = L->getParentLoop()) {
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const SCEV *AccessFn = SE->getSCEVAtScope(getPointerOperand(*Inst), L);
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const SCEVUnknown *BasePointer =
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dyn_cast<SCEVUnknown>(SE->getPointerBase(AccessFn));
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// Do not delinearize if we cannot find the base pointer.
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if (!BasePointer)
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break;
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AccessFn = SE->getMinusSCEV(AccessFn, BasePointer);
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const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(AccessFn);
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// Do not try to delinearize memory accesses that are not AddRecs.
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if (!AR)
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break;
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O << "\n";
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O << "Inst:" << *Inst << "\n";
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O << "In Loop with Header: " << L->getHeader()->getName() << "\n";
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O << "AddRec: " << *AR << "\n";
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SmallVector<const SCEV *, 3> Subscripts, Sizes;
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SE->delinearize(AR, Subscripts, Sizes, SE->getElementSize(Inst));
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if (Subscripts.size() == 0 || Sizes.size() == 0 ||
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Subscripts.size() != Sizes.size()) {
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O << "failed to delinearize\n";
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continue;
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}
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O << "Base offset: " << *BasePointer << "\n";
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O << "ArrayDecl[UnknownSize]";
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int Size = Subscripts.size();
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for (int i = 0; i < Size - 1; i++)
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O << "[" << *Sizes[i] << "]";
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O << " with elements of " << *Sizes[Size - 1] << " bytes.\n";
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O << "ArrayRef";
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for (int i = 0; i < Size; i++)
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O << "[" << *Subscripts[i] << "]";
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O << "\n";
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}
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}
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}
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char Delinearization::ID = 0;
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static const char delinearization_name[] = "Delinearization";
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INITIALIZE_PASS_BEGIN(Delinearization, DL_NAME, delinearization_name, true,
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true)
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INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
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INITIALIZE_PASS_END(Delinearization, DL_NAME, delinearization_name, true, true)
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FunctionPass *llvm::createDelinearizationPass() { return new Delinearization; }
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