| //===- LoopExtractor.cpp - Extract each loop into a new function ----------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // A pass wrapper around the ExtractLoop() scalar transformation to extract each |
| // top-level loop into its own new function. If the loop is the ONLY loop in a |
| // given function, it is not touched. This is a pass most useful for debugging |
| // via bugpoint. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Transforms/IPO.h" |
| #include "llvm/Instructions.h" |
| #include "llvm/Module.h" |
| #include "llvm/Pass.h" |
| #include "llvm/Analysis/Dominators.h" |
| #include "llvm/Analysis/LoopInfo.h" |
| #include "llvm/Transforms/Scalar.h" |
| #include "llvm/Transforms/Utils/FunctionUtils.h" |
| #include "Support/Statistic.h" |
| using namespace llvm; |
| |
| namespace { |
| Statistic<> NumExtracted("loop-extract", "Number of loops extracted"); |
| |
| // FIXME: This is not a function pass, but the PassManager doesn't allow |
| // Module passes to require FunctionPasses, so we can't get loop info if we're |
| // not a function pass. |
| struct LoopExtractor : public FunctionPass { |
| unsigned NumLoops; |
| |
| LoopExtractor(unsigned numLoops = ~0) : NumLoops(numLoops) {} |
| |
| virtual bool runOnFunction(Function &F); |
| |
| virtual void getAnalysisUsage(AnalysisUsage &AU) const { |
| AU.addRequiredID(BreakCriticalEdgesID); |
| AU.addRequiredID(LoopSimplifyID); |
| AU.addRequired<DominatorSet>(); |
| AU.addRequired<LoopInfo>(); |
| } |
| }; |
| |
| RegisterOpt<LoopExtractor> |
| X("loop-extract", "Extract loops into new functions"); |
| |
| /// SingleLoopExtractor - For bugpoint. |
| struct SingleLoopExtractor : public LoopExtractor { |
| SingleLoopExtractor() : LoopExtractor(1) {} |
| }; |
| |
| RegisterOpt<SingleLoopExtractor> |
| Y("loop-extract-single", "Extract at most one loop into a new function"); |
| } // End anonymous namespace |
| |
| bool LoopExtractor::runOnFunction(Function &F) { |
| LoopInfo &LI = getAnalysis<LoopInfo>(); |
| |
| // If this function has no loops, there is nothing to do. |
| if (LI.begin() == LI.end()) |
| return false; |
| |
| DominatorSet &DS = getAnalysis<DominatorSet>(); |
| |
| // If there is more than one top-level loop in this function, extract all of |
| // the loops. |
| bool Changed = false; |
| if (LI.end()-LI.begin() > 1) { |
| for (LoopInfo::iterator i = LI.begin(), e = LI.end(); i != e; ++i) { |
| if (NumLoops == 0) return Changed; |
| --NumLoops; |
| Changed |= ExtractLoop(DS, *i) != 0; |
| ++NumExtracted; |
| } |
| } else { |
| // Otherwise there is exactly one top-level loop. If this function is more |
| // than a minimal wrapper around the loop, extract the loop. |
| Loop *TLL = *LI.begin(); |
| bool ShouldExtractLoop = false; |
| |
| // Extract the loop if the entry block doesn't branch to the loop header. |
| TerminatorInst *EntryTI = F.getEntryBlock().getTerminator(); |
| if (!isa<BranchInst>(EntryTI) || |
| !cast<BranchInst>(EntryTI)->isUnconditional() || |
| EntryTI->getSuccessor(0) != TLL->getHeader()) |
| ShouldExtractLoop = true; |
| else { |
| // Check to see if any exits from the loop are more than just return |
| // blocks. |
| std::vector<BasicBlock*> ExitBlocks; |
| TLL->getExitBlocks(ExitBlocks); |
| for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i) |
| if (!isa<ReturnInst>(ExitBlocks[i]->getTerminator())) { |
| ShouldExtractLoop = true; |
| break; |
| } |
| } |
| |
| if (ShouldExtractLoop) { |
| if (NumLoops == 0) return Changed; |
| --NumLoops; |
| Changed |= ExtractLoop(DS, TLL) != 0; |
| ++NumExtracted; |
| } else { |
| // Okay, this function is a minimal container around the specified loop. |
| // If we extract the loop, we will continue to just keep extracting it |
| // infinitely... so don't extract it. However, if the loop contains any |
| // subloops, extract them. |
| for (Loop::iterator i = TLL->begin(), e = TLL->end(); i != e; ++i) { |
| if (NumLoops == 0) return Changed; |
| --NumLoops; |
| Changed |= ExtractLoop(DS, *i) != 0; |
| ++NumExtracted; |
| } |
| } |
| } |
| |
| return Changed; |
| } |
| |
| // createSingleLoopExtractorPass - This pass extracts one natural loop from the |
| // program into a function if it can. This is used by bugpoint. |
| // |
| Pass *llvm::createSingleLoopExtractorPass() { |
| return new SingleLoopExtractor(); |
| } |