1 //===- ExtractFunction.cpp - Extract a function from Program --------------===//
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 // This file implements several methods that are used to extract functions,
11 // loops, or portions of a module from the rest of the module.
13 //===----------------------------------------------------------------------===//
15 #include "BugDriver.h"
16 #include "llvm/Constants.h"
17 #include "llvm/DerivedTypes.h"
18 #include "llvm/LLVMContext.h"
19 #include "llvm/Module.h"
20 #include "llvm/PassManager.h"
21 #include "llvm/Pass.h"
22 #include "llvm/Analysis/Verifier.h"
23 #include "llvm/Assembly/Writer.h"
24 #include "llvm/Transforms/IPO.h"
25 #include "llvm/Transforms/Scalar.h"
26 #include "llvm/Transforms/Utils/Cloning.h"
27 #include "llvm/Transforms/Utils/FunctionUtils.h"
28 #include "llvm/Target/TargetData.h"
29 #include "llvm/Support/CommandLine.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/FileUtilities.h"
32 #include "llvm/Support/raw_ostream.h"
33 #include "llvm/System/Path.h"
34 #include "llvm/System/Signals.h"
39 bool DisableSimplifyCFG = false;
40 extern cl::opt<std::string> OutputPrefix;
41 } // End llvm namespace
46 cl::desc("Do not use the -dce pass to reduce testcases"));
48 NoSCFG("disable-simplifycfg", cl::location(DisableSimplifyCFG),
49 cl::desc("Do not use the -simplifycfg pass to reduce testcases"));
52 /// deleteInstructionFromProgram - This method clones the current Program and
53 /// deletes the specified instruction from the cloned module. It then runs a
54 /// series of cleanup passes (ADCE and SimplifyCFG) to eliminate any code which
55 /// depends on the value. The modified module is then returned.
57 Module *BugDriver::deleteInstructionFromProgram(const Instruction *I,
58 unsigned Simplification) const {
59 Module *Result = CloneModule(Program);
61 const BasicBlock *PBB = I->getParent();
62 const Function *PF = PBB->getParent();
64 Module::iterator RFI = Result->begin(); // Get iterator to corresponding fn
65 std::advance(RFI, std::distance(PF->getParent()->begin(),
66 Module::const_iterator(PF)));
68 Function::iterator RBI = RFI->begin(); // Get iterator to corresponding BB
69 std::advance(RBI, std::distance(PF->begin(), Function::const_iterator(PBB)));
71 BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst
72 std::advance(RI, std::distance(PBB->begin(), BasicBlock::const_iterator(I)));
73 Instruction *TheInst = RI; // Got the corresponding instruction!
75 // If this instruction produces a value, replace any users with null values
76 if (!TheInst->getType()->isVoidTy())
77 TheInst->replaceAllUsesWith(Constant::getNullValue(TheInst->getType()));
79 // Remove the instruction from the program.
80 TheInst->getParent()->getInstList().erase(TheInst);
83 //writeProgramToFile("current.bc", Result);
85 // Spiff up the output a little bit.
87 // Make sure that the appropriate target data is always used...
88 Passes.add(new TargetData(Result));
90 /// FIXME: If this used runPasses() like the methods below, we could get rid
91 /// of the -disable-* options!
92 if (Simplification > 1 && !NoDCE)
93 Passes.add(createDeadCodeEliminationPass());
94 if (Simplification && !DisableSimplifyCFG)
95 Passes.add(createCFGSimplificationPass()); // Delete dead control flow
97 Passes.add(createVerifierPass());
102 static const PassInfo *getPI(Pass *P) {
103 const PassInfo *PI = P->getPassInfo();
108 /// performFinalCleanups - This method clones the current Program and performs
109 /// a series of cleanups intended to get rid of extra cruft on the module
110 /// before handing it to the user.
112 Module *BugDriver::performFinalCleanups(Module *M, bool MayModifySemantics) {
113 // Make all functions external, so GlobalDCE doesn't delete them...
114 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
115 I->setLinkage(GlobalValue::ExternalLinkage);
117 std::vector<const PassInfo*> CleanupPasses;
118 CleanupPasses.push_back(getPI(createGlobalDCEPass()));
120 if (MayModifySemantics)
121 CleanupPasses.push_back(getPI(createDeadArgHackingPass()));
123 CleanupPasses.push_back(getPI(createDeadArgEliminationPass()));
125 CleanupPasses.push_back(getPI(createDeadTypeEliminationPass()));
127 Module *New = runPassesOn(M, CleanupPasses);
129 errs() << "Final cleanups failed. Sorry. :( Please report a bug!\n";
137 /// ExtractLoop - Given a module, extract up to one loop from it into a new
138 /// function. This returns null if there are no extractable loops in the
139 /// program or if the loop extractor crashes.
140 Module *BugDriver::ExtractLoop(Module *M) {
141 std::vector<const PassInfo*> LoopExtractPasses;
142 LoopExtractPasses.push_back(getPI(createSingleLoopExtractorPass()));
144 Module *NewM = runPassesOn(M, LoopExtractPasses);
146 Module *Old = swapProgramIn(M);
147 outs() << "*** Loop extraction failed: ";
148 EmitProgressBitcode("loopextraction", true);
149 outs() << "*** Sorry. :( Please report a bug!\n";
154 // Check to see if we created any new functions. If not, no loops were
155 // extracted and we should return null. Limit the number of loops we extract
156 // to avoid taking forever.
157 static unsigned NumExtracted = 32;
158 if (M->size() == NewM->size() || --NumExtracted == 0) {
162 assert(M->size() < NewM->size() && "Loop extract removed functions?");
163 Module::iterator MI = NewM->begin();
164 for (unsigned i = 0, e = M->size(); i != e; ++i)
172 // DeleteFunctionBody - "Remove" the function by deleting all of its basic
173 // blocks, making it external.
175 void llvm::DeleteFunctionBody(Function *F) {
176 // delete the body of the function...
178 assert(F->isDeclaration() && "This didn't make the function external!");
181 /// GetTorInit - Given a list of entries for static ctors/dtors, return them
182 /// as a constant array.
183 static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
184 assert(!TorList.empty() && "Don't create empty tor list!");
185 std::vector<Constant*> ArrayElts;
186 for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
187 std::vector<Constant*> Elts;
188 Elts.push_back(ConstantInt::get(
189 Type::getInt32Ty(TorList[i].first->getContext()), TorList[i].second));
190 Elts.push_back(TorList[i].first);
191 ArrayElts.push_back(ConstantStruct::get(TorList[i].first->getContext(),
194 return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(),
199 /// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
200 /// M1 has all of the global variables. If M2 contains any functions that are
201 /// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
202 /// prune appropriate entries out of M1s list.
203 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
204 ValueMap<const Value*, Value*> VMap) {
205 GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
206 if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() ||
207 !GV->use_empty()) return;
209 std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
210 ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
211 if (!InitList) return;
213 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
214 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
215 if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
217 if (CS->getOperand(1)->isNullValue())
218 break; // Found a null terminator, stop here.
220 ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
221 int Priority = CI ? CI->getSExtValue() : 0;
223 Constant *FP = CS->getOperand(1);
224 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
226 FP = CE->getOperand(0);
227 if (Function *F = dyn_cast<Function>(FP)) {
228 if (!F->isDeclaration())
229 M1Tors.push_back(std::make_pair(F, Priority));
231 // Map to M2's version of the function.
232 F = cast<Function>(VMap[F]);
233 M2Tors.push_back(std::make_pair(F, Priority));
239 GV->eraseFromParent();
240 if (!M1Tors.empty()) {
241 Constant *M1Init = GetTorInit(M1Tors);
242 new GlobalVariable(*M1, M1Init->getType(), false,
243 GlobalValue::AppendingLinkage,
247 GV = M2->getNamedGlobal(GlobalName);
248 assert(GV && "Not a clone of M1?");
249 assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
251 GV->eraseFromParent();
252 if (!M2Tors.empty()) {
253 Constant *M2Init = GetTorInit(M2Tors);
254 new GlobalVariable(*M2, M2Init->getType(), false,
255 GlobalValue::AppendingLinkage,
261 /// SplitFunctionsOutOfModule - Given a module and a list of functions in the
262 /// module, split the functions OUT of the specified module, and place them in
265 llvm::SplitFunctionsOutOfModule(Module *M,
266 const std::vector<Function*> &F,
267 ValueMap<const Value*, Value*> &VMap) {
268 // Make sure functions & globals are all external so that linkage
269 // between the two modules will work.
270 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
271 I->setLinkage(GlobalValue::ExternalLinkage);
272 for (Module::global_iterator I = M->global_begin(), E = M->global_end();
274 if (I->hasName() && I->getName()[0] == '\01')
275 I->setName(I->getName().substr(1));
276 I->setLinkage(GlobalValue::ExternalLinkage);
279 ValueMap<const Value*, Value*> NewVMap;
280 Module *New = CloneModule(M, NewVMap);
282 // Make sure global initializers exist only in the safe module (CBE->.so)
283 for (Module::global_iterator I = New->global_begin(), E = New->global_end();
285 I->setInitializer(0); // Delete the initializer to make it external
287 // Remove the Test functions from the Safe module
288 std::set<Function *> TestFunctions;
289 for (unsigned i = 0, e = F.size(); i != e; ++i) {
290 Function *TNOF = cast<Function>(VMap[F[i]]);
291 DEBUG(errs() << "Removing function ");
292 DEBUG(WriteAsOperand(errs(), TNOF, false));
293 DEBUG(errs() << "\n");
294 TestFunctions.insert(cast<Function>(NewVMap[TNOF]));
295 DeleteFunctionBody(TNOF); // Function is now external in this module!
299 // Remove the Safe functions from the Test module
300 for (Module::iterator I = New->begin(), E = New->end(); I != E; ++I)
301 if (!TestFunctions.count(I))
302 DeleteFunctionBody(I);
305 // Make sure that there is a global ctor/dtor array in both halves of the
306 // module if they both have static ctor/dtor functions.
307 SplitStaticCtorDtor("llvm.global_ctors", M, New, NewVMap);
308 SplitStaticCtorDtor("llvm.global_dtors", M, New, NewVMap);
313 //===----------------------------------------------------------------------===//
314 // Basic Block Extraction Code
315 //===----------------------------------------------------------------------===//
317 /// ExtractMappedBlocksFromModule - Extract all but the specified basic blocks
318 /// into their own functions. The only detail is that M is actually a module
319 /// cloned from the one the BBs are in, so some mapping needs to be performed.
320 /// If this operation fails for some reason (ie the implementation is buggy),
321 /// this function should return null, otherwise it returns a new Module.
322 Module *BugDriver::ExtractMappedBlocksFromModule(const
323 std::vector<BasicBlock*> &BBs,
325 sys::Path uniqueFilename(OutputPrefix + "-extractblocks");
327 if (uniqueFilename.createTemporaryFileOnDisk(true, &ErrMsg)) {
328 outs() << "*** Basic Block extraction failed!\n";
329 errs() << "Error creating temporary file: " << ErrMsg << "\n";
330 M = swapProgramIn(M);
331 EmitProgressBitcode("basicblockextractfail", true);
335 sys::RemoveFileOnSignal(uniqueFilename);
337 std::string ErrorInfo;
338 raw_fd_ostream BlocksToNotExtractFile(uniqueFilename.c_str(), ErrorInfo);
339 if (!ErrorInfo.empty()) {
340 outs() << "*** Basic Block extraction failed!\n";
341 errs() << "Error writing list of blocks to not extract: " << ErrorInfo
343 M = swapProgramIn(M);
344 EmitProgressBitcode("basicblockextractfail", true);
348 for (std::vector<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
351 // If the BB doesn't have a name, give it one so we have something to key
353 if (!BB->hasName()) BB->setName("tmpbb");
354 BlocksToNotExtractFile << BB->getParent()->getNameStr() << " "
355 << BB->getName() << "\n";
357 BlocksToNotExtractFile.close();
359 std::string uniqueFN = "--extract-blocks-file=" + uniqueFilename.str();
360 const char *ExtraArg = uniqueFN.c_str();
362 std::vector<const PassInfo*> PI;
363 std::vector<BasicBlock *> EmptyBBs; // This parameter is ignored.
364 PI.push_back(getPI(createBlockExtractorPass(EmptyBBs)));
365 Module *Ret = runPassesOn(M, PI, false, 1, &ExtraArg);
367 uniqueFilename.eraseFromDisk(); // Free disk space
370 outs() << "*** Basic Block extraction failed, please report a bug!\n";
371 M = swapProgramIn(M);
372 EmitProgressBitcode("basicblockextractfail", true);