1 //===- LoopExtractor.cpp - Extract each loop into a new function ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // A pass wrapper around the ExtractLoop() scalar transformation to extract each
11 // top-level loop into its own new function. If the loop is the ONLY loop in a
12 // given function, it is not touched. This is a pass most useful for debugging
15 //===----------------------------------------------------------------------===//
17 #include "llvm/Transforms/IPO.h"
18 #include "llvm/Instructions.h"
19 #include "llvm/Module.h"
20 #include "llvm/Pass.h"
21 #include "llvm/Analysis/Dominators.h"
22 #include "llvm/Analysis/LoopInfo.h"
23 #include "llvm/Transforms/Scalar.h"
24 #include "llvm/Transforms/Utils/FunctionUtils.h"
25 #include "llvm/ADT/Statistic.h"
29 Statistic<> NumExtracted("loop-extract", "Number of loops extracted");
31 // FIXME: This is not a function pass, but the PassManager doesn't allow
32 // Module passes to require FunctionPasses, so we can't get loop info if we're
33 // not a function pass.
34 struct LoopExtractor : public FunctionPass {
37 LoopExtractor(unsigned numLoops = ~0) : NumLoops(numLoops) {}
39 virtual bool runOnFunction(Function &F);
41 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
42 AU.addRequiredID(BreakCriticalEdgesID);
43 AU.addRequiredID(LoopSimplifyID);
44 AU.addRequired<DominatorSet>();
45 AU.addRequired<LoopInfo>();
49 RegisterOpt<LoopExtractor>
50 X("loop-extract", "Extract loops into new functions");
52 /// SingleLoopExtractor - For bugpoint.
53 struct SingleLoopExtractor : public LoopExtractor {
54 SingleLoopExtractor() : LoopExtractor(1) {}
57 RegisterOpt<SingleLoopExtractor>
58 Y("loop-extract-single", "Extract at most one loop into a new function");
59 } // End anonymous namespace
61 bool LoopExtractor::runOnFunction(Function &F) {
62 LoopInfo &LI = getAnalysis<LoopInfo>();
64 // If this function has no loops, there is nothing to do.
65 if (LI.begin() == LI.end())
68 DominatorSet &DS = getAnalysis<DominatorSet>();
70 // If there is more than one top-level loop in this function, extract all of
73 if (LI.end()-LI.begin() > 1) {
74 for (LoopInfo::iterator i = LI.begin(), e = LI.end(); i != e; ++i) {
75 if (NumLoops == 0) return Changed;
77 Changed |= ExtractLoop(DS, *i) != 0;
81 // Otherwise there is exactly one top-level loop. If this function is more
82 // than a minimal wrapper around the loop, extract the loop.
83 Loop *TLL = *LI.begin();
84 bool ShouldExtractLoop = false;
86 // Extract the loop if the entry block doesn't branch to the loop header.
87 TerminatorInst *EntryTI = F.getEntryBlock().getTerminator();
88 if (!isa<BranchInst>(EntryTI) ||
89 !cast<BranchInst>(EntryTI)->isUnconditional() ||
90 EntryTI->getSuccessor(0) != TLL->getHeader())
91 ShouldExtractLoop = true;
93 // Check to see if any exits from the loop are more than just return
95 std::vector<BasicBlock*> ExitBlocks;
96 TLL->getExitBlocks(ExitBlocks);
97 for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
98 if (!isa<ReturnInst>(ExitBlocks[i]->getTerminator())) {
99 ShouldExtractLoop = true;
104 if (ShouldExtractLoop) {
105 if (NumLoops == 0) return Changed;
107 Changed |= ExtractLoop(DS, TLL) != 0;
110 // Okay, this function is a minimal container around the specified loop.
111 // If we extract the loop, we will continue to just keep extracting it
112 // infinitely... so don't extract it. However, if the loop contains any
113 // subloops, extract them.
114 for (Loop::iterator i = TLL->begin(), e = TLL->end(); i != e; ++i) {
115 if (NumLoops == 0) return Changed;
117 Changed |= ExtractLoop(DS, *i) != 0;
126 // createSingleLoopExtractorPass - This pass extracts one natural loop from the
127 // program into a function if it can. This is used by bugpoint.
129 ModulePass *llvm::createSingleLoopExtractorPass() {
130 return new SingleLoopExtractor();
135 /// BlockExtractorPass - This pass is used by bugpoint to extract all blocks
136 /// from the module into their own functions except for those specified by the
137 /// BlocksToNotExtract list.
138 class BlockExtractorPass : public ModulePass {
139 std::vector<BasicBlock*> BlocksToNotExtract;
141 BlockExtractorPass(std::vector<BasicBlock*> &B) : BlocksToNotExtract(B) {}
142 BlockExtractorPass() {}
144 bool runOnModule(Module &M);
146 RegisterOpt<BlockExtractorPass>
147 XX("extract-blocks", "Extract Basic Blocks From Module (for bugpoint use)");
150 // createBlockExtractorPass - This pass extracts all blocks (except those
151 // specified in the argument list) from the functions in the module.
153 ModulePass *llvm::createBlockExtractorPass(std::vector<BasicBlock*> &BTNE) {
154 return new BlockExtractorPass(BTNE);
157 bool BlockExtractorPass::runOnModule(Module &M) {
158 std::set<BasicBlock*> TranslatedBlocksToNotExtract;
159 for (unsigned i = 0, e = BlocksToNotExtract.size(); i != e; ++i) {
160 BasicBlock *BB = BlocksToNotExtract[i];
161 Function *F = BB->getParent();
163 // Map the corresponding function in this module.
164 Function *MF = M.getFunction(F->getName(), F->getFunctionType());
166 // Figure out which index the basic block is in its function.
167 Function::iterator BBI = MF->begin();
168 std::advance(BBI, std::distance(F->begin(), Function::iterator(BB)));
169 TranslatedBlocksToNotExtract.insert(BBI);
172 // Now that we know which blocks to not extract, figure out which ones we WANT
174 std::vector<BasicBlock*> BlocksToExtract;
175 for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
176 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
177 if (!TranslatedBlocksToNotExtract.count(BB))
178 BlocksToExtract.push_back(BB);
180 for (unsigned i = 0, e = BlocksToExtract.size(); i != e; ++i)
181 ExtractBasicBlock(BlocksToExtract[i]);
183 return !BlocksToExtract.empty();