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 INITIALIZE_PASS_BEGIN(LoopExtractor, "loop-extract",
54 "Extract loops into new functions", false, false)
55 INITIALIZE_PASS_DEPENDENCY(BreakCriticalEdges)
56 INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
57 INITIALIZE_PASS_DEPENDENCY(DominatorTree)
58 INITIALIZE_PASS_END(LoopExtractor, "loop-extract",
59 "Extract loops into new functions", false, false)
62 /// SingleLoopExtractor - For bugpoint.
63 struct SingleLoopExtractor : public LoopExtractor {
64 static char ID; // Pass identification, replacement for typeid
65 SingleLoopExtractor() : LoopExtractor(1) {}
67 } // End anonymous namespace
69 char SingleLoopExtractor::ID = 0;
70 INITIALIZE_PASS(SingleLoopExtractor, "loop-extract-single",
71 "Extract at most one loop into a new function", false, false)
73 // createLoopExtractorPass - This pass extracts all natural loops from the
74 // program into a function if it can.
76 Pass *llvm::createLoopExtractorPass() { return new LoopExtractor(); }
78 bool LoopExtractor::runOnLoop(Loop *L, LPPassManager &LPM) {
79 // Only visit top-level loops.
80 if (L->getParentLoop())
83 // If LoopSimplify form is not available, stay out of trouble.
84 if (!L->isLoopSimplifyForm())
87 DominatorTree &DT = getAnalysis<DominatorTree>();
90 // If there is more than one top-level loop in this function, extract all of
91 // the loops. Otherwise there is exactly one top-level loop; in this case if
92 // this function is more than a minimal wrapper around the loop, extract
94 bool ShouldExtractLoop = false;
96 // Extract the loop if the entry block doesn't branch to the loop header.
97 TerminatorInst *EntryTI =
98 L->getHeader()->getParent()->getEntryBlock().getTerminator();
99 if (!isa<BranchInst>(EntryTI) ||
100 !cast<BranchInst>(EntryTI)->isUnconditional() ||
101 EntryTI->getSuccessor(0) != L->getHeader())
102 ShouldExtractLoop = true;
104 // Check to see if any exits from the loop are more than just return
106 SmallVector<BasicBlock*, 8> ExitBlocks;
107 L->getExitBlocks(ExitBlocks);
108 for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
109 if (!isa<ReturnInst>(ExitBlocks[i]->getTerminator())) {
110 ShouldExtractLoop = true;
114 if (ShouldExtractLoop) {
115 if (NumLoops == 0) return Changed;
117 if (ExtractLoop(DT, L) != 0) {
119 // After extraction, the loop is replaced by a function call, so
120 // we shouldn't try to run any more loop passes on it.
121 LPM.deleteLoopFromQueue(L);
129 // createSingleLoopExtractorPass - This pass extracts one natural loop from the
130 // program into a function if it can. This is used by bugpoint.
132 Pass *llvm::createSingleLoopExtractorPass() {
133 return new SingleLoopExtractor();
137 // BlockFile - A file which contains a list of blocks that should not be
139 static cl::opt<std::string>
140 BlockFile("extract-blocks-file", cl::value_desc("filename"),
141 cl::desc("A file containing list of basic blocks to not extract"),
145 /// BlockExtractorPass - This pass is used by bugpoint to extract all blocks
146 /// from the module into their own functions except for those specified by the
147 /// BlocksToNotExtract list.
148 class BlockExtractorPass : public ModulePass {
149 void LoadFile(const char *Filename);
151 std::vector<BasicBlock*> BlocksToNotExtract;
152 std::vector<std::pair<std::string, std::string> > BlocksToNotExtractByName;
154 static char ID; // Pass identification, replacement for typeid
155 BlockExtractorPass() : ModulePass(ID) {
156 if (!BlockFile.empty())
157 LoadFile(BlockFile.c_str());
160 bool runOnModule(Module &M);
164 char BlockExtractorPass::ID = 0;
165 INITIALIZE_PASS(BlockExtractorPass, "extract-blocks",
166 "Extract Basic Blocks From Module (for bugpoint use)",
169 // createBlockExtractorPass - This pass extracts all blocks (except those
170 // specified in the argument list) from the functions in the module.
172 ModulePass *llvm::createBlockExtractorPass()
174 return new BlockExtractorPass();
177 void BlockExtractorPass::LoadFile(const char *Filename) {
178 // Load the BlockFile...
179 std::ifstream In(Filename);
181 errs() << "WARNING: BlockExtractor couldn't load file '" << Filename
186 std::string FunctionName, BlockName;
189 if (!BlockName.empty())
190 BlocksToNotExtractByName.push_back(
191 std::make_pair(FunctionName, BlockName));
195 bool BlockExtractorPass::runOnModule(Module &M) {
196 std::set<BasicBlock*> TranslatedBlocksToNotExtract;
197 for (unsigned i = 0, e = BlocksToNotExtract.size(); i != e; ++i) {
198 BasicBlock *BB = BlocksToNotExtract[i];
199 Function *F = BB->getParent();
201 // Map the corresponding function in this module.
202 Function *MF = M.getFunction(F->getName());
203 assert(MF->getFunctionType() == F->getFunctionType() && "Wrong function?");
205 // Figure out which index the basic block is in its function.
206 Function::iterator BBI = MF->begin();
207 std::advance(BBI, std::distance(F->begin(), Function::iterator(BB)));
208 TranslatedBlocksToNotExtract.insert(BBI);
211 while (!BlocksToNotExtractByName.empty()) {
212 // There's no way to find BBs by name without looking at every BB inside
213 // every Function. Fortunately, this is always empty except when used by
214 // bugpoint in which case correctness is more important than performance.
216 std::string &FuncName = BlocksToNotExtractByName.back().first;
217 std::string &BlockName = BlocksToNotExtractByName.back().second;
219 for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI) {
221 if (F.getName() != FuncName) continue;
223 for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
224 BasicBlock &BB = *BI;
225 if (BB.getName() != BlockName) continue;
227 TranslatedBlocksToNotExtract.insert(BI);
231 BlocksToNotExtractByName.pop_back();
234 // Now that we know which blocks to not extract, figure out which ones we WANT
236 std::vector<BasicBlock*> BlocksToExtract;
237 for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
238 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
239 if (!TranslatedBlocksToNotExtract.count(BB))
240 BlocksToExtract.push_back(BB);
242 for (unsigned i = 0, e = BlocksToExtract.size(); i != e; ++i)
243 ExtractBasicBlock(BlocksToExtract[i]);
245 return !BlocksToExtract.empty();