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/IR/Constants.h"
17 #include "llvm/IR/DataLayout.h"
18 #include "llvm/IR/DerivedTypes.h"
19 #include "llvm/IR/LLVMContext.h"
20 #include "llvm/IR/Module.h"
21 #include "llvm/IR/Verifier.h"
22 #include "llvm/Pass.h"
23 #include "llvm/PassManager.h"
24 #include "llvm/Support/CommandLine.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/Support/FileUtilities.h"
27 #include "llvm/Support/Path.h"
28 #include "llvm/Support/Signals.h"
29 #include "llvm/Support/ToolOutputFile.h"
30 #include "llvm/Transforms/IPO.h"
31 #include "llvm/Transforms/Scalar.h"
32 #include "llvm/Transforms/Utils/Cloning.h"
33 #include "llvm/Transforms/Utils/CodeExtractor.h"
36 using std::error_code;
38 #define DEBUG_TYPE "bugpoint"
41 bool DisableSimplifyCFG = false;
42 extern cl::opt<std::string> OutputPrefix;
43 } // End llvm namespace
48 cl::desc("Do not use the -dce pass to reduce testcases"));
50 NoSCFG("disable-simplifycfg", cl::location(DisableSimplifyCFG),
51 cl::desc("Do not use the -simplifycfg pass to reduce testcases"));
53 Function* globalInitUsesExternalBA(GlobalVariable* GV) {
54 if (!GV->hasInitializer())
57 Constant *I = GV->getInitializer();
59 // walk the values used by the initializer
60 // (and recurse into things like ConstantExpr)
61 std::vector<Constant*> Todo;
62 std::set<Constant*> Done;
65 while (!Todo.empty()) {
66 Constant* V = Todo.back();
70 if (BlockAddress *BA = dyn_cast<BlockAddress>(V)) {
71 Function *F = BA->getFunction();
72 if (F->isDeclaration())
76 for (User::op_iterator i = V->op_begin(), e = V->op_end(); i != e; ++i) {
77 Constant *C = dyn_cast<Constant>(*i);
78 if (C && !isa<GlobalValue>(C) && !Done.count(C))
84 } // end anonymous namespace
86 /// deleteInstructionFromProgram - This method clones the current Program and
87 /// deletes the specified instruction from the cloned module. It then runs a
88 /// series of cleanup passes (ADCE and SimplifyCFG) to eliminate any code which
89 /// depends on the value. The modified module is then returned.
91 Module *BugDriver::deleteInstructionFromProgram(const Instruction *I,
92 unsigned Simplification) {
94 Module *Clone = CloneModule(Program);
96 const BasicBlock *PBB = I->getParent();
97 const Function *PF = PBB->getParent();
99 Module::iterator RFI = Clone->begin(); // Get iterator to corresponding fn
100 std::advance(RFI, std::distance(PF->getParent()->begin(),
101 Module::const_iterator(PF)));
103 Function::iterator RBI = RFI->begin(); // Get iterator to corresponding BB
104 std::advance(RBI, std::distance(PF->begin(), Function::const_iterator(PBB)));
106 BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst
107 std::advance(RI, std::distance(PBB->begin(), BasicBlock::const_iterator(I)));
108 Instruction *TheInst = RI; // Got the corresponding instruction!
110 // If this instruction produces a value, replace any users with null values
111 if (!TheInst->getType()->isVoidTy())
112 TheInst->replaceAllUsesWith(Constant::getNullValue(TheInst->getType()));
114 // Remove the instruction from the program.
115 TheInst->getParent()->getInstList().erase(TheInst);
117 // Spiff up the output a little bit.
118 std::vector<std::string> Passes;
120 /// Can we get rid of the -disable-* options?
121 if (Simplification > 1 && !NoDCE)
122 Passes.push_back("dce");
123 if (Simplification && !DisableSimplifyCFG)
124 Passes.push_back("simplifycfg"); // Delete dead control flow
126 Passes.push_back("verify");
127 Module *New = runPassesOn(Clone, Passes);
130 errs() << "Instruction removal failed. Sorry. :( Please report a bug!\n";
136 /// performFinalCleanups - This method clones the current Program and performs
137 /// a series of cleanups intended to get rid of extra cruft on the module
138 /// before handing it to the user.
140 Module *BugDriver::performFinalCleanups(Module *M, bool MayModifySemantics) {
141 // Make all functions external, so GlobalDCE doesn't delete them...
142 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
143 I->setLinkage(GlobalValue::ExternalLinkage);
145 std::vector<std::string> CleanupPasses;
146 CleanupPasses.push_back("globaldce");
148 if (MayModifySemantics)
149 CleanupPasses.push_back("deadarghaX0r");
151 CleanupPasses.push_back("deadargelim");
153 Module *New = runPassesOn(M, CleanupPasses);
155 errs() << "Final cleanups failed. Sorry. :( Please report a bug!\n";
163 /// ExtractLoop - Given a module, extract up to one loop from it into a new
164 /// function. This returns null if there are no extractable loops in the
165 /// program or if the loop extractor crashes.
166 Module *BugDriver::ExtractLoop(Module *M) {
167 std::vector<std::string> LoopExtractPasses;
168 LoopExtractPasses.push_back("loop-extract-single");
170 Module *NewM = runPassesOn(M, LoopExtractPasses);
172 outs() << "*** Loop extraction failed: ";
173 EmitProgressBitcode(M, "loopextraction", true);
174 outs() << "*** Sorry. :( Please report a bug!\n";
178 // Check to see if we created any new functions. If not, no loops were
179 // extracted and we should return null. Limit the number of loops we extract
180 // to avoid taking forever.
181 static unsigned NumExtracted = 32;
182 if (M->size() == NewM->size() || --NumExtracted == 0) {
186 assert(M->size() < NewM->size() && "Loop extract removed functions?");
187 Module::iterator MI = NewM->begin();
188 for (unsigned i = 0, e = M->size(); i != e; ++i)
196 // DeleteFunctionBody - "Remove" the function by deleting all of its basic
197 // blocks, making it external.
199 void llvm::DeleteFunctionBody(Function *F) {
200 // delete the body of the function...
202 assert(F->isDeclaration() && "This didn't make the function external!");
205 /// GetTorInit - Given a list of entries for static ctors/dtors, return them
206 /// as a constant array.
207 static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
208 assert(!TorList.empty() && "Don't create empty tor list!");
209 std::vector<Constant*> ArrayElts;
210 Type *Int32Ty = Type::getInt32Ty(TorList[0].first->getContext());
213 StructType::get(Int32Ty, TorList[0].first->getType(), NULL);
214 for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
216 ConstantInt::get(Int32Ty, TorList[i].second),
219 ArrayElts.push_back(ConstantStruct::get(STy, Elts));
221 return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(),
226 /// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
227 /// M1 has all of the global variables. If M2 contains any functions that are
228 /// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
229 /// prune appropriate entries out of M1s list.
230 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
231 ValueToValueMapTy &VMap) {
232 GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
233 if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() ||
234 !GV->use_empty()) return;
236 std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
237 ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
238 if (!InitList) return;
240 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
241 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
242 if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
244 if (CS->getOperand(1)->isNullValue())
245 break; // Found a null terminator, stop here.
247 ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
248 int Priority = CI ? CI->getSExtValue() : 0;
250 Constant *FP = CS->getOperand(1);
251 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
253 FP = CE->getOperand(0);
254 if (Function *F = dyn_cast<Function>(FP)) {
255 if (!F->isDeclaration())
256 M1Tors.push_back(std::make_pair(F, Priority));
258 // Map to M2's version of the function.
259 F = cast<Function>(VMap[F]);
260 M2Tors.push_back(std::make_pair(F, Priority));
266 GV->eraseFromParent();
267 if (!M1Tors.empty()) {
268 Constant *M1Init = GetTorInit(M1Tors);
269 new GlobalVariable(*M1, M1Init->getType(), false,
270 GlobalValue::AppendingLinkage,
274 GV = M2->getNamedGlobal(GlobalName);
275 assert(GV && "Not a clone of M1?");
276 assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
278 GV->eraseFromParent();
279 if (!M2Tors.empty()) {
280 Constant *M2Init = GetTorInit(M2Tors);
281 new GlobalVariable(*M2, M2Init->getType(), false,
282 GlobalValue::AppendingLinkage,
288 /// SplitFunctionsOutOfModule - Given a module and a list of functions in the
289 /// module, split the functions OUT of the specified module, and place them in
292 llvm::SplitFunctionsOutOfModule(Module *M,
293 const std::vector<Function*> &F,
294 ValueToValueMapTy &VMap) {
295 // Make sure functions & globals are all external so that linkage
296 // between the two modules will work.
297 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
298 I->setLinkage(GlobalValue::ExternalLinkage);
299 for (Module::global_iterator I = M->global_begin(), E = M->global_end();
301 if (I->hasName() && I->getName()[0] == '\01')
302 I->setName(I->getName().substr(1));
303 I->setLinkage(GlobalValue::ExternalLinkage);
306 ValueToValueMapTy NewVMap;
307 Module *New = CloneModule(M, NewVMap);
309 // Remove the Test functions from the Safe module
310 std::set<Function *> TestFunctions;
311 for (unsigned i = 0, e = F.size(); i != e; ++i) {
312 Function *TNOF = cast<Function>(VMap[F[i]]);
313 DEBUG(errs() << "Removing function ");
314 DEBUG(TNOF->printAsOperand(errs(), false));
315 DEBUG(errs() << "\n");
316 TestFunctions.insert(cast<Function>(NewVMap[TNOF]));
317 DeleteFunctionBody(TNOF); // Function is now external in this module!
321 // Remove the Safe functions from the Test module
322 for (Module::iterator I = New->begin(), E = New->end(); I != E; ++I)
323 if (!TestFunctions.count(I))
324 DeleteFunctionBody(I);
327 // Try to split the global initializers evenly
328 for (Module::global_iterator I = M->global_begin(), E = M->global_end();
330 GlobalVariable *GV = cast<GlobalVariable>(NewVMap[I]);
331 if (Function *TestFn = globalInitUsesExternalBA(I)) {
332 if (Function *SafeFn = globalInitUsesExternalBA(GV)) {
333 errs() << "*** Error: when reducing functions, encountered "
335 GV->printAsOperand(errs(), false);
336 errs() << "' with an initializer that references blockaddresses "
337 "from safe function '" << SafeFn->getName()
338 << "' and from test function '" << TestFn->getName() << "'.\n";
341 I->setInitializer(nullptr); // Delete the initializer to make it external
343 // If we keep it in the safe module, then delete it in the test module
344 GV->setInitializer(nullptr);
348 // Make sure that there is a global ctor/dtor array in both halves of the
349 // module if they both have static ctor/dtor functions.
350 SplitStaticCtorDtor("llvm.global_ctors", M, New, NewVMap);
351 SplitStaticCtorDtor("llvm.global_dtors", M, New, NewVMap);
356 //===----------------------------------------------------------------------===//
357 // Basic Block Extraction Code
358 //===----------------------------------------------------------------------===//
360 /// ExtractMappedBlocksFromModule - Extract all but the specified basic blocks
361 /// into their own functions. The only detail is that M is actually a module
362 /// cloned from the one the BBs are in, so some mapping needs to be performed.
363 /// If this operation fails for some reason (ie the implementation is buggy),
364 /// this function should return null, otherwise it returns a new Module.
365 Module *BugDriver::ExtractMappedBlocksFromModule(const
366 std::vector<BasicBlock*> &BBs,
368 SmallString<128> Filename;
370 error_code EC = sys::fs::createUniqueFile(
371 OutputPrefix + "-extractblocks%%%%%%%", FD, Filename);
373 outs() << "*** Basic Block extraction failed!\n";
374 errs() << "Error creating temporary file: " << EC.message() << "\n";
375 EmitProgressBitcode(M, "basicblockextractfail", true);
378 sys::RemoveFileOnSignal(Filename);
380 tool_output_file BlocksToNotExtractFile(Filename.c_str(), FD);
381 for (std::vector<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
384 // If the BB doesn't have a name, give it one so we have something to key
386 if (!BB->hasName()) BB->setName("tmpbb");
387 BlocksToNotExtractFile.os() << BB->getParent()->getName() << " "
388 << BB->getName() << "\n";
390 BlocksToNotExtractFile.os().close();
391 if (BlocksToNotExtractFile.os().has_error()) {
392 errs() << "Error writing list of blocks to not extract\n";
393 EmitProgressBitcode(M, "basicblockextractfail", true);
394 BlocksToNotExtractFile.os().clear_error();
397 BlocksToNotExtractFile.keep();
399 std::string uniqueFN = "--extract-blocks-file=";
400 uniqueFN += Filename.str();
401 const char *ExtraArg = uniqueFN.c_str();
403 std::vector<std::string> PI;
404 PI.push_back("extract-blocks");
405 Module *Ret = runPassesOn(M, PI, false, 1, &ExtraArg);
407 sys::fs::remove(Filename.c_str());
410 outs() << "*** Basic Block extraction failed, please report a bug!\n";
411 EmitProgressBitcode(M, "basicblockextractfail", true);