1 //===- ExtractFunction.cpp - Extract a function from Program --------------===//
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 // 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/Module.h"
19 #include "llvm/PassManager.h"
20 #include "llvm/Pass.h"
21 #include "llvm/Analysis/Verifier.h"
22 #include "llvm/Transforms/IPO.h"
23 #include "llvm/Transforms/Scalar.h"
24 #include "llvm/Transforms/Utils/Cloning.h"
25 #include "llvm/Transforms/Utils/FunctionUtils.h"
26 #include "llvm/Target/TargetData.h"
27 #include "llvm/Support/CommandLine.h"
28 #include "llvm/Support/Debug.h"
29 #include "llvm/Support/FileUtilities.h"
35 bool DisableSimplifyCFG = false;
36 } // End llvm namespace
41 cl::desc("Do not use the -dce pass to reduce testcases"));
43 NoSCFG("disable-simplifycfg", cl::location(DisableSimplifyCFG),
44 cl::desc("Do not use the -simplifycfg pass to reduce testcases"));
47 /// deleteInstructionFromProgram - This method clones the current Program and
48 /// deletes the specified instruction from the cloned module. It then runs a
49 /// series of cleanup passes (ADCE and SimplifyCFG) to eliminate any code which
50 /// depends on the value. The modified module is then returned.
52 Module *BugDriver::deleteInstructionFromProgram(const Instruction *I,
53 unsigned Simplification) const {
54 Module *Result = CloneModule(Program);
56 const BasicBlock *PBB = I->getParent();
57 const Function *PF = PBB->getParent();
59 Module::iterator RFI = Result->begin(); // Get iterator to corresponding fn
60 std::advance(RFI, std::distance(PF->getParent()->begin(),
61 Module::const_iterator(PF)));
63 Function::iterator RBI = RFI->begin(); // Get iterator to corresponding BB
64 std::advance(RBI, std::distance(PF->begin(), Function::const_iterator(PBB)));
66 BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst
67 std::advance(RI, std::distance(PBB->begin(), BasicBlock::const_iterator(I)));
68 Instruction *TheInst = RI; // Got the corresponding instruction!
70 // If this instruction produces a value, replace any users with null values
71 if (TheInst->getType() != Type::VoidTy)
72 TheInst->replaceAllUsesWith(Constant::getNullValue(TheInst->getType()));
74 // Remove the instruction from the program.
75 TheInst->getParent()->getInstList().erase(TheInst);
78 //writeProgramToFile("current.bc", Result);
80 // Spiff up the output a little bit.
82 // Make sure that the appropriate target data is always used...
83 Passes.add(new TargetData("bugpoint", Result));
85 /// FIXME: If this used runPasses() like the methods below, we could get rid
86 /// of the -disable-* options!
87 if (Simplification > 1 && !NoDCE)
88 Passes.add(createDeadCodeEliminationPass());
89 if (Simplification && !DisableSimplifyCFG)
90 Passes.add(createCFGSimplificationPass()); // Delete dead control flow
92 Passes.add(createVerifierPass());
97 static const PassInfo *getPI(Pass *P) {
98 const PassInfo *PI = P->getPassInfo();
103 /// performFinalCleanups - This method clones the current Program and performs
104 /// a series of cleanups intended to get rid of extra cruft on the module
105 /// before handing it to the user.
107 Module *BugDriver::performFinalCleanups(Module *M, bool MayModifySemantics) {
108 // Make all functions external, so GlobalDCE doesn't delete them...
109 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
110 I->setLinkage(GlobalValue::ExternalLinkage);
112 std::vector<const PassInfo*> CleanupPasses;
113 CleanupPasses.push_back(getPI(createFunctionResolvingPass()));
114 CleanupPasses.push_back(getPI(createGlobalDCEPass()));
115 CleanupPasses.push_back(getPI(createDeadTypeEliminationPass()));
117 if (MayModifySemantics)
118 CleanupPasses.push_back(getPI(createDeadArgHackingPass()));
120 CleanupPasses.push_back(getPI(createDeadArgEliminationPass()));
122 Module *New = runPassesOn(M, CleanupPasses);
124 std::cerr << "Final cleanups failed. Sorry. :( Please report a bug!\n";
132 /// ExtractLoop - Given a module, extract up to one loop from it into a new
133 /// function. This returns null if there are no extractable loops in the
134 /// program or if the loop extractor crashes.
135 Module *BugDriver::ExtractLoop(Module *M) {
136 std::vector<const PassInfo*> LoopExtractPasses;
137 LoopExtractPasses.push_back(getPI(createSingleLoopExtractorPass()));
139 Module *NewM = runPassesOn(M, LoopExtractPasses);
141 Module *Old = swapProgramIn(M);
142 std::cout << "*** Loop extraction failed: ";
143 EmitProgressBytecode("loopextraction", true);
144 std::cout << "*** Sorry. :( Please report a bug!\n";
149 // Check to see if we created any new functions. If not, no loops were
150 // extracted and we should return null. Limit the number of loops we extract
151 // to avoid taking forever.
152 static unsigned NumExtracted = 32;
153 if (M->size() == NewM->size() || --NumExtracted == 0) {
157 assert(M->size() < NewM->size() && "Loop extract removed functions?");
158 Module::iterator MI = NewM->begin();
159 for (unsigned i = 0, e = M->size(); i != e; ++i)
167 // DeleteFunctionBody - "Remove" the function by deleting all of its basic
168 // blocks, making it external.
170 void llvm::DeleteFunctionBody(Function *F) {
171 // delete the body of the function...
173 assert(F->isExternal() && "This didn't make the function external!");
176 /// GetTorInit - Given a list of entries for static ctors/dtors, return them
177 /// as a constant array.
178 static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
179 assert(!TorList.empty() && "Don't create empty tor list!");
180 std::vector<Constant*> ArrayElts;
181 for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
182 std::vector<Constant*> Elts;
183 Elts.push_back(ConstantSInt::get(Type::IntTy, TorList[i].second));
184 Elts.push_back(TorList[i].first);
185 ArrayElts.push_back(ConstantStruct::get(Elts));
187 return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(),
192 /// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
193 /// M1 has all of the global variables. If M2 contains any functions that are
194 /// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
195 /// prune appropriate entries out of M1s list.
196 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2){
197 GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
198 if (!GV || GV->isExternal() || GV->hasInternalLinkage() ||
199 !GV->use_empty()) return;
201 std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
202 ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
203 if (!InitList) return;
205 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
206 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
207 if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
209 if (CS->getOperand(1)->isNullValue())
210 break; // Found a null terminator, stop here.
212 ConstantSInt *CI = dyn_cast<ConstantSInt>(CS->getOperand(0));
213 int Priority = CI ? CI->getValue() : 0;
215 Constant *FP = CS->getOperand(1);
216 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
217 if (CE->getOpcode() == Instruction::Cast)
218 FP = CE->getOperand(0);
219 if (Function *F = dyn_cast<Function>(FP)) {
220 if (!F->isExternal())
221 M1Tors.push_back(std::make_pair(F, Priority));
223 // Map to M2's version of the function.
224 F = M2->getFunction(F->getName(), F->getFunctionType());
225 M2Tors.push_back(std::make_pair(F, Priority));
231 GV->eraseFromParent();
232 if (!M1Tors.empty()) {
233 Constant *M1Init = GetTorInit(M1Tors);
234 new GlobalVariable(M1Init->getType(), false, GlobalValue::AppendingLinkage,
235 M1Init, GlobalName, M1);
238 GV = M2->getNamedGlobal(GlobalName);
239 assert(GV && "Not a clone of M1?");
240 assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
242 GV->eraseFromParent();
243 if (!M2Tors.empty()) {
244 Constant *M2Init = GetTorInit(M2Tors);
245 new GlobalVariable(M2Init->getType(), false, GlobalValue::AppendingLinkage,
246 M2Init, GlobalName, M2);
250 /// SplitFunctionsOutOfModule - Given a module and a list of functions in the
251 /// module, split the functions OUT of the specified module, and place them in
254 /// FIXME: this could be made DRAMATICALLY more efficient for large programs if
255 /// we just MOVED functions from one module to the other, instead of cloning the
256 /// whole module, then proceeding to delete an entire module's worth of stuff.
258 Module *llvm::SplitFunctionsOutOfModule(Module *M,
259 const std::vector<Function*> &F) {
260 // Make sure functions & globals are all external so that linkage
261 // between the two modules will work.
262 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
263 I->setLinkage(GlobalValue::ExternalLinkage);
264 for (Module::global_iterator I = M->global_begin(), E = M->global_end();
266 I->setLinkage(GlobalValue::ExternalLinkage);
268 Module *New = CloneModule(M);
270 // Make sure global initializers exist only in the safe module (CBE->.so)
271 for (Module::global_iterator I = New->global_begin(), E = New->global_end();
273 I->setInitializer(0); // Delete the initializer to make it external
275 // Remove the Test functions from the Safe module
276 std::set<std::pair<std::string, const PointerType*> > TestFunctions;
277 for (unsigned i = 0, e = F.size(); i != e; ++i) {
278 TestFunctions.insert(std::make_pair(F[i]->getName(), F[i]->getType()));
279 Function *TNOF = M->getFunction(F[i]->getName(), F[i]->getFunctionType());
280 DEBUG(std::cerr << "Removing function " << F[i]->getName() << "\n");
281 assert(TNOF && "Function doesn't exist in module!");
282 DeleteFunctionBody(TNOF); // Function is now external in this module!
285 // Remove the Safe functions from the Test module
286 for (Module::iterator I = New->begin(), E = New->end(); I != E; ++I)
287 if (!TestFunctions.count(std::make_pair(I->getName(), I->getType())))
288 DeleteFunctionBody(I);
290 // Make sure that there is a global ctor/dtor array in both halves of the
291 // module if they both have static ctor/dtor functions.
292 SplitStaticCtorDtor("llvm.global_ctors", M, New);
293 SplitStaticCtorDtor("llvm.global_dtors", M, New);
298 //===----------------------------------------------------------------------===//
299 // Basic Block Extraction Code
300 //===----------------------------------------------------------------------===//
303 std::vector<BasicBlock*> BlocksToNotExtract;
305 /// BlockExtractorPass - This pass is used by bugpoint to extract all blocks
306 /// from the module into their own functions except for those specified by the
307 /// BlocksToNotExtract list.
308 class BlockExtractorPass : public ModulePass {
309 bool runOnModule(Module &M);
311 RegisterOpt<BlockExtractorPass>
312 XX("extract-bbs", "Extract Basic Blocks From Module (for bugpoint use)");
315 bool BlockExtractorPass::runOnModule(Module &M) {
316 std::set<BasicBlock*> TranslatedBlocksToNotExtract;
317 for (unsigned i = 0, e = BlocksToNotExtract.size(); i != e; ++i) {
318 BasicBlock *BB = BlocksToNotExtract[i];
319 Function *F = BB->getParent();
321 // Map the corresponding function in this module.
322 Function *MF = M.getFunction(F->getName(), F->getFunctionType());
324 // Figure out which index the basic block is in its function.
325 Function::iterator BBI = MF->begin();
326 std::advance(BBI, std::distance(F->begin(), Function::iterator(BB)));
327 TranslatedBlocksToNotExtract.insert(BBI);
330 // Now that we know which blocks to not extract, figure out which ones we WANT
332 std::vector<BasicBlock*> BlocksToExtract;
333 for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
334 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
335 if (!TranslatedBlocksToNotExtract.count(BB))
336 BlocksToExtract.push_back(BB);
338 for (unsigned i = 0, e = BlocksToExtract.size(); i != e; ++i)
339 ExtractBasicBlock(BlocksToExtract[i]);
341 return !BlocksToExtract.empty();
344 /// ExtractMappedBlocksFromModule - Extract all but the specified basic blocks
345 /// into their own functions. The only detail is that M is actually a module
346 /// cloned from the one the BBs are in, so some mapping needs to be performed.
347 /// If this operation fails for some reason (ie the implementation is buggy),
348 /// this function should return null, otherwise it returns a new Module.
349 Module *BugDriver::ExtractMappedBlocksFromModule(const
350 std::vector<BasicBlock*> &BBs,
352 // Set the global list so that pass will be able to access it.
353 BlocksToNotExtract = BBs;
355 std::vector<const PassInfo*> PI;
356 PI.push_back(getPI(new BlockExtractorPass()));
357 Module *Ret = runPassesOn(M, PI);
358 BlocksToNotExtract.clear();
360 std::cout << "*** Basic Block extraction failed, please report a bug!\n";
361 M = swapProgramIn(M);
362 EmitProgressBytecode("basicblockextractfail", true);
363 M = swapProgramIn(M);