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actually add the file...
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122563 91177308-0d34-0410-b5e6-96231b3b80d8
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103
lib/Transforms/Scalar/LoopIdiomRecognize.cpp
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103
lib/Transforms/Scalar/LoopIdiomRecognize.cpp
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//===-- LoopIdiomRecognize.cpp - Loop idiom recognition -------------------===//
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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 pass implements an idiom recognizer that transforms simple loops into a
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// non-loop form. In cases that this kicks in, it can be a significant
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// performance win.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "loop-idiom"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Analysis/LoopPass.h"
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#include "llvm/Analysis/ScalarEvolutionExpressions.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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// TODO: Recognize "N" size array multiplies: replace with call to blas or
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// something.
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namespace {
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class LoopIdiomRecognize : public LoopPass {
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public:
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static char ID;
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explicit LoopIdiomRecognize() : LoopPass(ID) {
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initializeLoopIdiomRecognizePass(*PassRegistry::getPassRegistry());
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}
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bool runOnLoop(Loop *L, LPPassManager &LPM);
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bool scanBlock(BasicBlock *BB, Loop *L);
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/// This transformation requires natural loop information & requires that
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/// loop preheaders be inserted into the CFG.
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///
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.addRequired<LoopInfo>();
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AU.addPreserved<LoopInfo>();
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AU.addRequiredID(LoopSimplifyID);
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AU.addPreservedID(LoopSimplifyID);
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AU.addRequiredID(LCSSAID);
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AU.addPreservedID(LCSSAID);
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AU.addRequired<ScalarEvolution>();
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AU.addPreserved<ScalarEvolution>();
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AU.addPreserved<DominatorTree>();
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}
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};
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}
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char LoopIdiomRecognize::ID = 0;
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INITIALIZE_PASS_BEGIN(LoopIdiomRecognize, "loop-idiom", "Recognize loop idioms",
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false, false)
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INITIALIZE_PASS_DEPENDENCY(LoopInfo)
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INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
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INITIALIZE_PASS_DEPENDENCY(LCSSA)
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INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
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INITIALIZE_PASS_END(LoopIdiomRecognize, "loop-idiom", "Recognize loop idioms",
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false, false)
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Pass *llvm::createLoopIdiomPass() { return new LoopIdiomRecognize(); }
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bool LoopIdiomRecognize::runOnLoop(Loop *L, LPPassManager &LPM) {
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// We only look at trivial single basic block loops.
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// TODO: eventually support more complex loops, scanning the header.
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if (L->getBlocks().size() != 1)
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return false;
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BasicBlock *BB = L->getHeader();
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DEBUG(dbgs() << "Loop Idiom Recognize: F[" << BB->getParent()->getName()
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<< "] Loop %" << BB->getName() << "\n");
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return scanBlock(BB, L);
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}
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/// scanBlock - Look over a block to see if we can promote anything out of it.
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bool LoopIdiomRecognize::scanBlock(BasicBlock *BB, Loop *L) {
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ScalarEvolution &SE = getAnalysis<ScalarEvolution>();
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for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
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// Look for store instructions, which may be memsets.
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StoreInst *SI = dyn_cast<StoreInst>(I++);
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if (SI == 0) continue;
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// See if the pointer expression is an AddRec like {base,+,1} on the current
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// loop, which indicates a strided store. If we have something else, it's a
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// random store we can't handle.
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const SCEVAddRecExpr *Ev =
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dyn_cast<SCEVAddRecExpr>(SE.getSCEV(SI->getPointerOperand()));
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if (Ev == 0 || Ev->getLoop() != L)
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continue;
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errs() << "Found strided store: " << *Ev << "\n";
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}
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return false;
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}
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