1 //===- ExtractFunction.cpp - Extract a function from Program --------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
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.
12 //
13 //===----------------------------------------------------------------------===//
14
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/LegacyPassManager.h"
21 #include "llvm/IR/Module.h"
22 #include "llvm/IR/Verifier.h"
23 #include "llvm/Pass.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"
34 #include <set>
35 using namespace llvm;
36
37 #define DEBUG_TYPE "bugpoint"
38
39 namespace llvm {
40 bool DisableSimplifyCFG = false;
41 extern cl::opt<std::string> OutputPrefix;
42 } // End llvm namespace
43
44 namespace {
45 cl::opt<bool>
46 NoDCE ("disable-dce",
47 cl::desc("Do not use the -dce pass to reduce testcases"));
48 cl::opt<bool, true>
49 NoSCFG("disable-simplifycfg", cl::location(DisableSimplifyCFG),
50 cl::desc("Do not use the -simplifycfg pass to reduce testcases"));
51
globalInitUsesExternalBA(GlobalVariable * GV)52 Function* globalInitUsesExternalBA(GlobalVariable* GV) {
53 if (!GV->hasInitializer())
54 return nullptr;
55
56 Constant *I = GV->getInitializer();
57
58 // walk the values used by the initializer
59 // (and recurse into things like ConstantExpr)
60 std::vector<Constant*> Todo;
61 std::set<Constant*> Done;
62 Todo.push_back(I);
63
64 while (!Todo.empty()) {
65 Constant* V = Todo.back();
66 Todo.pop_back();
67 Done.insert(V);
68
69 if (BlockAddress *BA = dyn_cast<BlockAddress>(V)) {
70 Function *F = BA->getFunction();
71 if (F->isDeclaration())
72 return F;
73 }
74
75 for (User::op_iterator i = V->op_begin(), e = V->op_end(); i != e; ++i) {
76 Constant *C = dyn_cast<Constant>(*i);
77 if (C && !isa<GlobalValue>(C) && !Done.count(C))
78 Todo.push_back(C);
79 }
80 }
81 return nullptr;
82 }
83 } // end anonymous namespace
84
85 std::unique_ptr<Module>
deleteInstructionFromProgram(const Instruction * I,unsigned Simplification)86 BugDriver::deleteInstructionFromProgram(const Instruction *I,
87 unsigned Simplification) {
88 // FIXME, use vmap?
89 Module *Clone = CloneModule(Program).release();
90
91 const BasicBlock *PBB = I->getParent();
92 const Function *PF = PBB->getParent();
93
94 Module::iterator RFI = Clone->begin(); // Get iterator to corresponding fn
95 std::advance(RFI, std::distance(PF->getParent()->begin(),
96 Module::const_iterator(PF)));
97
98 Function::iterator RBI = RFI->begin(); // Get iterator to corresponding BB
99 std::advance(RBI, std::distance(PF->begin(), Function::const_iterator(PBB)));
100
101 BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst
102 std::advance(RI, std::distance(PBB->begin(), BasicBlock::const_iterator(I)));
103 Instruction *TheInst = &*RI; // Got the corresponding instruction!
104
105 // If this instruction produces a value, replace any users with null values
106 if (!TheInst->getType()->isVoidTy())
107 TheInst->replaceAllUsesWith(Constant::getNullValue(TheInst->getType()));
108
109 // Remove the instruction from the program.
110 TheInst->getParent()->getInstList().erase(TheInst);
111
112 // Spiff up the output a little bit.
113 std::vector<std::string> Passes;
114
115 /// Can we get rid of the -disable-* options?
116 if (Simplification > 1 && !NoDCE)
117 Passes.push_back("dce");
118 if (Simplification && !DisableSimplifyCFG)
119 Passes.push_back("simplifycfg"); // Delete dead control flow
120
121 Passes.push_back("verify");
122 std::unique_ptr<Module> New = runPassesOn(Clone, Passes);
123 delete Clone;
124 if (!New) {
125 errs() << "Instruction removal failed. Sorry. :( Please report a bug!\n";
126 exit(1);
127 }
128 return New;
129 }
130
131 std::unique_ptr<Module>
performFinalCleanups(Module * M,bool MayModifySemantics)132 BugDriver::performFinalCleanups(Module *M, bool MayModifySemantics) {
133 // Make all functions external, so GlobalDCE doesn't delete them...
134 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
135 I->setLinkage(GlobalValue::ExternalLinkage);
136
137 std::vector<std::string> CleanupPasses;
138 CleanupPasses.push_back("globaldce");
139
140 if (MayModifySemantics)
141 CleanupPasses.push_back("deadarghaX0r");
142 else
143 CleanupPasses.push_back("deadargelim");
144
145 std::unique_ptr<Module> New = runPassesOn(M, CleanupPasses);
146 if (!New) {
147 errs() << "Final cleanups failed. Sorry. :( Please report a bug!\n";
148 return nullptr;
149 }
150 delete M;
151 return New;
152 }
153
extractLoop(Module * M)154 std::unique_ptr<Module> BugDriver::extractLoop(Module *M) {
155 std::vector<std::string> LoopExtractPasses;
156 LoopExtractPasses.push_back("loop-extract-single");
157
158 std::unique_ptr<Module> NewM = runPassesOn(M, LoopExtractPasses);
159 if (!NewM) {
160 outs() << "*** Loop extraction failed: ";
161 EmitProgressBitcode(M, "loopextraction", true);
162 outs() << "*** Sorry. :( Please report a bug!\n";
163 return nullptr;
164 }
165
166 // Check to see if we created any new functions. If not, no loops were
167 // extracted and we should return null. Limit the number of loops we extract
168 // to avoid taking forever.
169 static unsigned NumExtracted = 32;
170 if (M->size() == NewM->size() || --NumExtracted == 0) {
171 return nullptr;
172 } else {
173 assert(M->size() < NewM->size() && "Loop extract removed functions?");
174 Module::iterator MI = NewM->begin();
175 for (unsigned i = 0, e = M->size(); i != e; ++i)
176 ++MI;
177 }
178
179 return NewM;
180 }
181
eliminateAliases(GlobalValue * GV)182 static void eliminateAliases(GlobalValue *GV) {
183 // First, check whether a GlobalAlias references this definition.
184 // GlobalAlias MAY NOT reference declarations.
185 for (;;) {
186 // 1. Find aliases
187 SmallVector<GlobalAlias*,1> aliases;
188 Module *M = GV->getParent();
189 for (Module::alias_iterator I=M->alias_begin(), E=M->alias_end(); I!=E; ++I)
190 if (I->getAliasee()->stripPointerCasts() == GV)
191 aliases.push_back(&*I);
192 if (aliases.empty())
193 break;
194 // 2. Resolve aliases
195 for (unsigned i=0, e=aliases.size(); i<e; ++i) {
196 aliases[i]->replaceAllUsesWith(aliases[i]->getAliasee());
197 aliases[i]->eraseFromParent();
198 }
199 // 3. Repeat until no more aliases found; there might
200 // be an alias to an alias...
201 }
202 }
203
204 //
205 // DeleteGlobalInitializer - "Remove" the global variable by deleting its initializer,
206 // making it external.
207 //
DeleteGlobalInitializer(GlobalVariable * GV)208 void llvm::DeleteGlobalInitializer(GlobalVariable *GV) {
209 eliminateAliases(GV);
210 GV->setInitializer(nullptr);
211 }
212
213 // DeleteFunctionBody - "Remove" the function by deleting all of its basic
214 // blocks, making it external.
215 //
DeleteFunctionBody(Function * F)216 void llvm::DeleteFunctionBody(Function *F) {
217 eliminateAliases(F);
218 // Function declarations can't have comdats.
219 F->setComdat(nullptr);
220
221 // delete the body of the function...
222 F->deleteBody();
223 assert(F->isDeclaration() && "This didn't make the function external!");
224 }
225
226 /// GetTorInit - Given a list of entries for static ctors/dtors, return them
227 /// as a constant array.
GetTorInit(std::vector<std::pair<Function *,int>> & TorList)228 static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
229 assert(!TorList.empty() && "Don't create empty tor list!");
230 std::vector<Constant*> ArrayElts;
231 Type *Int32Ty = Type::getInt32Ty(TorList[0].first->getContext());
232
233 StructType *STy =
234 StructType::get(Int32Ty, TorList[0].first->getType(), nullptr);
235 for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
236 Constant *Elts[] = {
237 ConstantInt::get(Int32Ty, TorList[i].second),
238 TorList[i].first
239 };
240 ArrayElts.push_back(ConstantStruct::get(STy, Elts));
241 }
242 return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(),
243 ArrayElts.size()),
244 ArrayElts);
245 }
246
247 /// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
248 /// M1 has all of the global variables. If M2 contains any functions that are
249 /// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
250 /// prune appropriate entries out of M1s list.
SplitStaticCtorDtor(const char * GlobalName,Module * M1,Module * M2,ValueToValueMapTy & VMap)251 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
252 ValueToValueMapTy &VMap) {
253 GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
254 if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() ||
255 !GV->use_empty()) return;
256
257 std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
258 ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
259 if (!InitList) return;
260
261 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
262 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
263 if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
264
265 if (CS->getOperand(1)->isNullValue())
266 break; // Found a null terminator, stop here.
267
268 ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
269 int Priority = CI ? CI->getSExtValue() : 0;
270
271 Constant *FP = CS->getOperand(1);
272 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
273 if (CE->isCast())
274 FP = CE->getOperand(0);
275 if (Function *F = dyn_cast<Function>(FP)) {
276 if (!F->isDeclaration())
277 M1Tors.push_back(std::make_pair(F, Priority));
278 else {
279 // Map to M2's version of the function.
280 F = cast<Function>(VMap[F]);
281 M2Tors.push_back(std::make_pair(F, Priority));
282 }
283 }
284 }
285 }
286
287 GV->eraseFromParent();
288 if (!M1Tors.empty()) {
289 Constant *M1Init = GetTorInit(M1Tors);
290 new GlobalVariable(*M1, M1Init->getType(), false,
291 GlobalValue::AppendingLinkage,
292 M1Init, GlobalName);
293 }
294
295 GV = M2->getNamedGlobal(GlobalName);
296 assert(GV && "Not a clone of M1?");
297 assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
298
299 GV->eraseFromParent();
300 if (!M2Tors.empty()) {
301 Constant *M2Init = GetTorInit(M2Tors);
302 new GlobalVariable(*M2, M2Init->getType(), false,
303 GlobalValue::AppendingLinkage,
304 M2Init, GlobalName);
305 }
306 }
307
308 std::unique_ptr<Module>
SplitFunctionsOutOfModule(Module * M,const std::vector<Function * > & F,ValueToValueMapTy & VMap)309 llvm::SplitFunctionsOutOfModule(Module *M, const std::vector<Function *> &F,
310 ValueToValueMapTy &VMap) {
311 // Make sure functions & globals are all external so that linkage
312 // between the two modules will work.
313 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
314 I->setLinkage(GlobalValue::ExternalLinkage);
315 for (Module::global_iterator I = M->global_begin(), E = M->global_end();
316 I != E; ++I) {
317 if (I->hasName() && I->getName()[0] == '\01')
318 I->setName(I->getName().substr(1));
319 I->setLinkage(GlobalValue::ExternalLinkage);
320 }
321
322 ValueToValueMapTy NewVMap;
323 std::unique_ptr<Module> New = CloneModule(M, NewVMap);
324
325 // Remove the Test functions from the Safe module
326 std::set<Function *> TestFunctions;
327 for (unsigned i = 0, e = F.size(); i != e; ++i) {
328 Function *TNOF = cast<Function>(VMap[F[i]]);
329 DEBUG(errs() << "Removing function ");
330 DEBUG(TNOF->printAsOperand(errs(), false));
331 DEBUG(errs() << "\n");
332 TestFunctions.insert(cast<Function>(NewVMap[TNOF]));
333 DeleteFunctionBody(TNOF); // Function is now external in this module!
334 }
335
336
337 // Remove the Safe functions from the Test module
338 for (Function &I : *New)
339 if (!TestFunctions.count(&I))
340 DeleteFunctionBody(&I);
341
342 // Try to split the global initializers evenly
343 for (GlobalVariable &I : M->globals()) {
344 GlobalVariable *GV = cast<GlobalVariable>(NewVMap[&I]);
345 if (Function *TestFn = globalInitUsesExternalBA(&I)) {
346 if (Function *SafeFn = globalInitUsesExternalBA(GV)) {
347 errs() << "*** Error: when reducing functions, encountered "
348 "the global '";
349 GV->printAsOperand(errs(), false);
350 errs() << "' with an initializer that references blockaddresses "
351 "from safe function '" << SafeFn->getName()
352 << "' and from test function '" << TestFn->getName() << "'.\n";
353 exit(1);
354 }
355 DeleteGlobalInitializer(&I); // Delete the initializer to make it external
356 } else {
357 // If we keep it in the safe module, then delete it in the test module
358 DeleteGlobalInitializer(GV);
359 }
360 }
361
362 // Make sure that there is a global ctor/dtor array in both halves of the
363 // module if they both have static ctor/dtor functions.
364 SplitStaticCtorDtor("llvm.global_ctors", M, New.get(), NewVMap);
365 SplitStaticCtorDtor("llvm.global_dtors", M, New.get(), NewVMap);
366
367 return New;
368 }
369
370 //===----------------------------------------------------------------------===//
371 // Basic Block Extraction Code
372 //===----------------------------------------------------------------------===//
373
374 std::unique_ptr<Module>
extractMappedBlocksFromModule(const std::vector<BasicBlock * > & BBs,Module * M)375 BugDriver::extractMappedBlocksFromModule(const std::vector<BasicBlock *> &BBs,
376 Module *M) {
377 SmallString<128> Filename;
378 int FD;
379 std::error_code EC = sys::fs::createUniqueFile(
380 OutputPrefix + "-extractblocks%%%%%%%", FD, Filename);
381 if (EC) {
382 outs() << "*** Basic Block extraction failed!\n";
383 errs() << "Error creating temporary file: " << EC.message() << "\n";
384 EmitProgressBitcode(M, "basicblockextractfail", true);
385 return nullptr;
386 }
387 sys::RemoveFileOnSignal(Filename);
388
389 tool_output_file BlocksToNotExtractFile(Filename.c_str(), FD);
390 for (std::vector<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
391 I != E; ++I) {
392 BasicBlock *BB = *I;
393 // If the BB doesn't have a name, give it one so we have something to key
394 // off of.
395 if (!BB->hasName()) BB->setName("tmpbb");
396 BlocksToNotExtractFile.os() << BB->getParent()->getName() << " "
397 << BB->getName() << "\n";
398 }
399 BlocksToNotExtractFile.os().close();
400 if (BlocksToNotExtractFile.os().has_error()) {
401 errs() << "Error writing list of blocks to not extract\n";
402 EmitProgressBitcode(M, "basicblockextractfail", true);
403 BlocksToNotExtractFile.os().clear_error();
404 return nullptr;
405 }
406 BlocksToNotExtractFile.keep();
407
408 std::string uniqueFN = "--extract-blocks-file=";
409 uniqueFN += Filename.str();
410 const char *ExtraArg = uniqueFN.c_str();
411
412 std::vector<std::string> PI;
413 PI.push_back("extract-blocks");
414 std::unique_ptr<Module> Ret = runPassesOn(M, PI, 1, &ExtraArg);
415
416 sys::fs::remove(Filename.c_str());
417
418 if (!Ret) {
419 outs() << "*** Basic Block extraction failed, please report a bug!\n";
420 EmitProgressBitcode(M, "basicblockextractfail", true);
421 }
422 return Ret;
423 }
424