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()->isStructTy())
77 TheInst->replaceAllUsesWith(UndefValue::get(TheInst->getType()));
78 else if (TheInst->getType() != Type::getVoidTy(I->getContext()))
79 TheInst->replaceAllUsesWith(Constant::getNullValue(TheInst->getType()));
81 // Remove the instruction from the program.
82 TheInst->getParent()->getInstList().erase(TheInst);
85 //writeProgramToFile("current.bc", Result);
87 // Spiff up the output a little bit.
89 // Make sure that the appropriate target data is always used...
90 Passes.add(new TargetData(Result));
92 /// FIXME: If this used runPasses() like the methods below, we could get rid
93 /// of the -disable-* options!
94 if (Simplification > 1 && !NoDCE)
95 Passes.add(createDeadCodeEliminationPass());
96 if (Simplification && !DisableSimplifyCFG)
97 Passes.add(createCFGSimplificationPass()); // Delete dead control flow
99 Passes.add(createVerifierPass());
104 static const PassInfo *getPI(Pass *P) {
105 const PassInfo *PI = P->getPassInfo();
110 /// performFinalCleanups - This method clones the current Program and performs
111 /// a series of cleanups intended to get rid of extra cruft on the module
112 /// before handing it to the user.
114 Module *BugDriver::performFinalCleanups(Module *M, bool MayModifySemantics) {
115 // Make all functions external, so GlobalDCE doesn't delete them...
116 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
117 I->setLinkage(GlobalValue::ExternalLinkage);
119 std::vector<const PassInfo*> CleanupPasses;
120 CleanupPasses.push_back(getPI(createGlobalDCEPass()));
121 CleanupPasses.push_back(getPI(createDeadTypeEliminationPass()));
123 if (MayModifySemantics)
124 CleanupPasses.push_back(getPI(createDeadArgHackingPass()));
126 CleanupPasses.push_back(getPI(createDeadArgEliminationPass()));
128 Module *New = runPassesOn(M, CleanupPasses);
130 errs() << "Final cleanups failed. Sorry. :( Please report a bug!\n";
138 /// ExtractLoop - Given a module, extract up to one loop from it into a new
139 /// function. This returns null if there are no extractable loops in the
140 /// program or if the loop extractor crashes.
141 Module *BugDriver::ExtractLoop(Module *M) {
142 std::vector<const PassInfo*> LoopExtractPasses;
143 LoopExtractPasses.push_back(getPI(createSingleLoopExtractorPass()));
145 Module *NewM = runPassesOn(M, LoopExtractPasses);
147 Module *Old = swapProgramIn(M);
148 outs() << "*** Loop extraction failed: ";
149 EmitProgressBitcode("loopextraction", true);
150 outs() << "*** Sorry. :( Please report a bug!\n";
155 // Check to see if we created any new functions. If not, no loops were
156 // extracted and we should return null. Limit the number of loops we extract
157 // to avoid taking forever.
158 static unsigned NumExtracted = 32;
159 if (M->size() == NewM->size() || --NumExtracted == 0) {
163 assert(M->size() < NewM->size() && "Loop extract removed functions?");
164 Module::iterator MI = NewM->begin();
165 for (unsigned i = 0, e = M->size(); i != e; ++i)
173 // DeleteFunctionBody - "Remove" the function by deleting all of its basic
174 // blocks, making it external.
176 void llvm::DeleteFunctionBody(Function *F) {
177 // delete the body of the function...
179 assert(F->isDeclaration() && "This didn't make the function external!");
182 /// GetTorInit - Given a list of entries for static ctors/dtors, return them
183 /// as a constant array.
184 static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
185 assert(!TorList.empty() && "Don't create empty tor list!");
186 std::vector<Constant*> ArrayElts;
187 for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
188 std::vector<Constant*> Elts;
189 Elts.push_back(ConstantInt::get(
190 Type::getInt32Ty(TorList[i].first->getContext()), TorList[i].second));
191 Elts.push_back(TorList[i].first);
192 ArrayElts.push_back(ConstantStruct::get(TorList[i].first->getContext(),
195 return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(),
200 /// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
201 /// M1 has all of the global variables. If M2 contains any functions that are
202 /// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
203 /// prune appropriate entries out of M1s list.
204 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
205 DenseMap<const Value*, Value*> ValueMap) {
206 GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
207 if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() ||
208 !GV->use_empty()) return;
210 std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
211 ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
212 if (!InitList) return;
214 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
215 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
216 if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
218 if (CS->getOperand(1)->isNullValue())
219 break; // Found a null terminator, stop here.
221 ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
222 int Priority = CI ? CI->getSExtValue() : 0;
224 Constant *FP = CS->getOperand(1);
225 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
227 FP = CE->getOperand(0);
228 if (Function *F = dyn_cast<Function>(FP)) {
229 if (!F->isDeclaration())
230 M1Tors.push_back(std::make_pair(F, Priority));
232 // Map to M2's version of the function.
233 F = cast<Function>(ValueMap[F]);
234 M2Tors.push_back(std::make_pair(F, Priority));
240 GV->eraseFromParent();
241 if (!M1Tors.empty()) {
242 Constant *M1Init = GetTorInit(M1Tors);
243 new GlobalVariable(*M1, M1Init->getType(), false,
244 GlobalValue::AppendingLinkage,
248 GV = M2->getNamedGlobal(GlobalName);
249 assert(GV && "Not a clone of M1?");
250 assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
252 GV->eraseFromParent();
253 if (!M2Tors.empty()) {
254 Constant *M2Init = GetTorInit(M2Tors);
255 new GlobalVariable(*M2, M2Init->getType(), false,
256 GlobalValue::AppendingLinkage,
262 /// SplitFunctionsOutOfModule - Given a module and a list of functions in the
263 /// module, split the functions OUT of the specified module, and place them in
266 llvm::SplitFunctionsOutOfModule(Module *M,
267 const std::vector<Function*> &F,
268 DenseMap<const Value*, Value*> &ValueMap) {
269 // Make sure functions & globals are all external so that linkage
270 // between the two modules will work.
271 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
272 I->setLinkage(GlobalValue::ExternalLinkage);
273 for (Module::global_iterator I = M->global_begin(), E = M->global_end();
275 if (I->hasName() && I->getName()[0] == '\01')
276 I->setName(I->getName().substr(1));
277 I->setLinkage(GlobalValue::ExternalLinkage);
280 DenseMap<const Value*, Value*> NewValueMap;
281 Module *New = CloneModule(M, NewValueMap);
283 // Make sure global initializers exist only in the safe module (CBE->.so)
284 for (Module::global_iterator I = New->global_begin(), E = New->global_end();
286 I->setInitializer(0); // Delete the initializer to make it external
288 // Remove the Test functions from the Safe module
289 std::set<Function *> TestFunctions;
290 for (unsigned i = 0, e = F.size(); i != e; ++i) {
291 Function *TNOF = cast<Function>(ValueMap[F[i]]);
292 DEBUG(errs() << "Removing function ");
293 DEBUG(WriteAsOperand(errs(), TNOF, false));
294 DEBUG(errs() << "\n");
295 TestFunctions.insert(cast<Function>(NewValueMap[TNOF]));
296 DeleteFunctionBody(TNOF); // Function is now external in this module!
300 // Remove the Safe functions from the Test module
301 for (Module::iterator I = New->begin(), E = New->end(); I != E; ++I)
302 if (!TestFunctions.count(I))
303 DeleteFunctionBody(I);
306 // Make sure that there is a global ctor/dtor array in both halves of the
307 // module if they both have static ctor/dtor functions.
308 SplitStaticCtorDtor("llvm.global_ctors", M, New, NewValueMap);
309 SplitStaticCtorDtor("llvm.global_dtors", M, New, NewValueMap);
314 //===----------------------------------------------------------------------===//
315 // Basic Block Extraction Code
316 //===----------------------------------------------------------------------===//
318 /// ExtractMappedBlocksFromModule - Extract all but the specified basic blocks
319 /// into their own functions. The only detail is that M is actually a module
320 /// cloned from the one the BBs are in, so some mapping needs to be performed.
321 /// If this operation fails for some reason (ie the implementation is buggy),
322 /// this function should return null, otherwise it returns a new Module.
323 Module *BugDriver::ExtractMappedBlocksFromModule(const
324 std::vector<BasicBlock*> &BBs,
326 sys::Path uniqueFilename(OutputPrefix + "-extractblocks");
328 if (uniqueFilename.createTemporaryFileOnDisk(true, &ErrMsg)) {
329 outs() << "*** Basic Block extraction failed!\n";
330 errs() << "Error creating temporary file: " << ErrMsg << "\n";
331 M = swapProgramIn(M);
332 EmitProgressBitcode("basicblockextractfail", true);
336 sys::RemoveFileOnSignal(uniqueFilename);
338 std::string ErrorInfo;
339 raw_fd_ostream BlocksToNotExtractFile(uniqueFilename.c_str(), ErrorInfo);
340 if (!ErrorInfo.empty()) {
341 outs() << "*** Basic Block extraction failed!\n";
342 errs() << "Error writing list of blocks to not extract: " << ErrorInfo
344 M = swapProgramIn(M);
345 EmitProgressBitcode("basicblockextractfail", true);
349 for (std::vector<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
352 // If the BB doesn't have a name, give it one so we have something to key
354 if (!BB->hasName()) BB->setName("tmpbb");
355 BlocksToNotExtractFile << BB->getParent()->getNameStr() << " "
356 << BB->getName() << "\n";
358 BlocksToNotExtractFile.close();
360 std::string uniqueFN = "--extract-blocks-file=" + uniqueFilename.str();
361 const char *ExtraArg = uniqueFN.c_str();
363 std::vector<const PassInfo*> PI;
364 std::vector<BasicBlock *> EmptyBBs; // This parameter is ignored.
365 PI.push_back(getPI(createBlockExtractorPass(EmptyBBs)));
366 Module *Ret = runPassesOn(M, PI, false, 1, &ExtraArg);
368 if (uniqueFilename.exists())
369 uniqueFilename.eraseFromDisk(); // Free disk space
372 outs() << "*** Basic Block extraction failed, please report a bug!\n";
373 M = swapProgramIn(M);
374 EmitProgressBitcode("basicblockextractfail", true);