1 //===- LoopExtractor.cpp - Extract each loop into a new function ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // 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 #define DEBUG_TYPE "loop-extract"
18 #include "llvm/Transforms/IPO.h"
19 #include "llvm/Instructions.h"
20 #include "llvm/Module.h"
21 #include "llvm/Pass.h"
22 #include "llvm/Analysis/Dominators.h"
23 #include "llvm/Analysis/LoopPass.h"
24 #include "llvm/Support/CommandLine.h"
25 #include "llvm/Transforms/Scalar.h"
26 #include "llvm/Transforms/Utils/FunctionUtils.h"
27 #include "llvm/ADT/Statistic.h"
32 STATISTIC(NumExtracted, "Number of loops extracted");
35 struct LoopExtractor : public LoopPass {
36 static char ID; // Pass identification, replacement for typeid
39 explicit LoopExtractor(unsigned numLoops = ~0)
40 : LoopPass(&ID), NumLoops(numLoops) {}
42 virtual bool runOnLoop(Loop *L, LPPassManager &LPM);
44 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
45 AU.addRequiredID(BreakCriticalEdgesID);
46 AU.addRequiredID(LoopSimplifyID);
47 AU.addRequired<DominatorTree>();
52 char LoopExtractor::ID = 0;
53 static RegisterPass<LoopExtractor>
54 X("loop-extract", "Extract loops into new functions");
57 /// SingleLoopExtractor - For bugpoint.
58 struct SingleLoopExtractor : public LoopExtractor {
59 static char ID; // Pass identification, replacement for typeid
60 SingleLoopExtractor() : LoopExtractor(1) {}
62 } // End anonymous namespace
64 char SingleLoopExtractor::ID = 0;
65 static RegisterPass<SingleLoopExtractor>
66 Y("loop-extract-single", "Extract at most one loop into a new function");
68 // createLoopExtractorPass - This pass extracts all natural loops from the
69 // program into a function if it can.
71 Pass *llvm::createLoopExtractorPass() { return new LoopExtractor(); }
73 bool LoopExtractor::runOnLoop(Loop *L, LPPassManager &LPM) {
74 // Only visit top-level loops.
75 if (L->getParentLoop())
78 DominatorTree &DT = getAnalysis<DominatorTree>();
81 // If there is more than one top-level loop in this function, extract all of
82 // the loops. Otherwise there is exactly one top-level loop; in this case if
83 // this function is more than a minimal wrapper around the loop, extract
85 bool ShouldExtractLoop = false;
87 // Extract the loop if the entry block doesn't branch to the loop header.
88 TerminatorInst *EntryTI =
89 L->getHeader()->getParent()->getEntryBlock().getTerminator();
90 if (!isa<BranchInst>(EntryTI) ||
91 !cast<BranchInst>(EntryTI)->isUnconditional() ||
92 EntryTI->getSuccessor(0) != L->getHeader())
93 ShouldExtractLoop = true;
95 // Check to see if any exits from the loop are more than just return
97 SmallVector<BasicBlock*, 8> ExitBlocks;
98 L->getExitBlocks(ExitBlocks);
99 for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
100 if (!isa<ReturnInst>(ExitBlocks[i]->getTerminator())) {
101 ShouldExtractLoop = true;
105 if (ShouldExtractLoop) {
106 if (NumLoops == 0) return Changed;
108 if (ExtractLoop(DT, L) != 0) {
110 // After extraction, the loop is replaced by a function call, so
111 // we shouldn't try to run any more loop passes on it.
112 LPM.deleteLoopFromQueue(L);
120 // createSingleLoopExtractorPass - This pass extracts one natural loop from the
121 // program into a function if it can. This is used by bugpoint.
123 Pass *llvm::createSingleLoopExtractorPass() {
124 return new SingleLoopExtractor();
128 // BlockFile - A file which contains a list of blocks that should not be
130 static cl::opt<std::string>
131 BlockFile("extract-blocks-file", cl::value_desc("filename"),
132 cl::desc("A file containing list of basic blocks to not extract"),
136 /// BlockExtractorPass - This pass is used by bugpoint to extract all blocks
137 /// from the module into their own functions except for those specified by the
138 /// BlocksToNotExtract list.
139 class BlockExtractorPass : public ModulePass {
140 void LoadFile(const char *Filename);
142 std::vector<BasicBlock*> BlocksToNotExtract;
143 std::vector<std::pair<std::string, std::string> > BlocksToNotExtractByName;
145 static char ID; // Pass identification, replacement for typeid
146 explicit BlockExtractorPass(const std::vector<BasicBlock*> &B)
147 : ModulePass(&ID), BlocksToNotExtract(B) {
148 if (!BlockFile.empty())
149 LoadFile(BlockFile.c_str());
151 BlockExtractorPass() : ModulePass(&ID) {}
153 bool runOnModule(Module &M);
157 char BlockExtractorPass::ID = 0;
158 static RegisterPass<BlockExtractorPass>
159 XX("extract-blocks", "Extract Basic Blocks From Module (for bugpoint use)");
161 // createBlockExtractorPass - This pass extracts all blocks (except those
162 // specified in the argument list) from the functions in the module.
164 ModulePass *llvm::createBlockExtractorPass(const std::vector<BasicBlock*> &BTNE)
166 return new BlockExtractorPass(BTNE);
169 void BlockExtractorPass::LoadFile(const char *Filename) {
170 // Load the BlockFile...
171 std::ifstream In(Filename);
173 errs() << "WARNING: BlockExtractor couldn't load file '" << Filename
178 std::string FunctionName, BlockName;
181 if (!BlockName.empty())
182 BlocksToNotExtractByName.push_back(
183 std::make_pair(FunctionName, BlockName));
187 bool BlockExtractorPass::runOnModule(Module &M) {
188 std::set<BasicBlock*> TranslatedBlocksToNotExtract;
189 for (unsigned i = 0, e = BlocksToNotExtract.size(); i != e; ++i) {
190 BasicBlock *BB = BlocksToNotExtract[i];
191 Function *F = BB->getParent();
193 // Map the corresponding function in this module.
194 Function *MF = M.getFunction(F->getName());
195 assert(MF->getFunctionType() == F->getFunctionType() && "Wrong function?");
197 // Figure out which index the basic block is in its function.
198 Function::iterator BBI = MF->begin();
199 std::advance(BBI, std::distance(F->begin(), Function::iterator(BB)));
200 TranslatedBlocksToNotExtract.insert(BBI);
203 while (!BlocksToNotExtractByName.empty()) {
204 // There's no way to find BBs by name without looking at every BB inside
205 // every Function. Fortunately, this is always empty except when used by
206 // bugpoint in which case correctness is more important than performance.
208 std::string &FuncName = BlocksToNotExtractByName.back().first;
209 std::string &BlockName = BlocksToNotExtractByName.back().second;
211 for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI) {
213 if (F.getName() != FuncName) continue;
215 for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
216 BasicBlock &BB = *BI;
217 if (BB.getName() != BlockName) continue;
219 TranslatedBlocksToNotExtract.insert(BI);
223 BlocksToNotExtractByName.pop_back();
226 // Now that we know which blocks to not extract, figure out which ones we WANT
228 std::vector<BasicBlock*> BlocksToExtract;
229 for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
230 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
231 if (!TranslatedBlocksToNotExtract.count(BB))
232 BlocksToExtract.push_back(BB);
234 for (unsigned i = 0, e = BlocksToExtract.size(); i != e; ++i)
235 ExtractBasicBlock(BlocksToExtract[i]);
237 return !BlocksToExtract.empty();