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
219 // delete the body of the function...
220 F->deleteBody();
221 assert(F->isDeclaration() && "This didn't make the function external!");
222 }
223
224 /// GetTorInit - Given a list of entries for static ctors/dtors, return them
225 /// as a constant array.
GetTorInit(std::vector<std::pair<Function *,int>> & TorList)226 static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
227 assert(!TorList.empty() && "Don't create empty tor list!");
228 std::vector<Constant*> ArrayElts;
229 Type *Int32Ty = Type::getInt32Ty(TorList[0].first->getContext());
230
231 StructType *STy =
232 StructType::get(Int32Ty, TorList[0].first->getType(), nullptr);
233 for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
234 Constant *Elts[] = {
235 ConstantInt::get(Int32Ty, TorList[i].second),
236 TorList[i].first
237 };
238 ArrayElts.push_back(ConstantStruct::get(STy, Elts));
239 }
240 return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(),
241 ArrayElts.size()),
242 ArrayElts);
243 }
244
245 /// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
246 /// M1 has all of the global variables. If M2 contains any functions that are
247 /// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
248 /// prune appropriate entries out of M1s list.
SplitStaticCtorDtor(const char * GlobalName,Module * M1,Module * M2,ValueToValueMapTy & VMap)249 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
250 ValueToValueMapTy &VMap) {
251 GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
252 if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() ||
253 !GV->use_empty()) return;
254
255 std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
256 ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
257 if (!InitList) return;
258
259 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
260 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
261 if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
262
263 if (CS->getOperand(1)->isNullValue())
264 break; // Found a null terminator, stop here.
265
266 ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
267 int Priority = CI ? CI->getSExtValue() : 0;
268
269 Constant *FP = CS->getOperand(1);
270 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
271 if (CE->isCast())
272 FP = CE->getOperand(0);
273 if (Function *F = dyn_cast<Function>(FP)) {
274 if (!F->isDeclaration())
275 M1Tors.push_back(std::make_pair(F, Priority));
276 else {
277 // Map to M2's version of the function.
278 F = cast<Function>(VMap[F]);
279 M2Tors.push_back(std::make_pair(F, Priority));
280 }
281 }
282 }
283 }
284
285 GV->eraseFromParent();
286 if (!M1Tors.empty()) {
287 Constant *M1Init = GetTorInit(M1Tors);
288 new GlobalVariable(*M1, M1Init->getType(), false,
289 GlobalValue::AppendingLinkage,
290 M1Init, GlobalName);
291 }
292
293 GV = M2->getNamedGlobal(GlobalName);
294 assert(GV && "Not a clone of M1?");
295 assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
296
297 GV->eraseFromParent();
298 if (!M2Tors.empty()) {
299 Constant *M2Init = GetTorInit(M2Tors);
300 new GlobalVariable(*M2, M2Init->getType(), false,
301 GlobalValue::AppendingLinkage,
302 M2Init, GlobalName);
303 }
304 }
305
306 std::unique_ptr<Module>
SplitFunctionsOutOfModule(Module * M,const std::vector<Function * > & F,ValueToValueMapTy & VMap)307 llvm::SplitFunctionsOutOfModule(Module *M, const std::vector<Function *> &F,
308 ValueToValueMapTy &VMap) {
309 // Make sure functions & globals are all external so that linkage
310 // between the two modules will work.
311 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
312 I->setLinkage(GlobalValue::ExternalLinkage);
313 for (Module::global_iterator I = M->global_begin(), E = M->global_end();
314 I != E; ++I) {
315 if (I->hasName() && I->getName()[0] == '\01')
316 I->setName(I->getName().substr(1));
317 I->setLinkage(GlobalValue::ExternalLinkage);
318 }
319
320 ValueToValueMapTy NewVMap;
321 std::unique_ptr<Module> New = CloneModule(M, NewVMap);
322
323 // Remove the Test functions from the Safe module
324 std::set<Function *> TestFunctions;
325 for (unsigned i = 0, e = F.size(); i != e; ++i) {
326 Function *TNOF = cast<Function>(VMap[F[i]]);
327 DEBUG(errs() << "Removing function ");
328 DEBUG(TNOF->printAsOperand(errs(), false));
329 DEBUG(errs() << "\n");
330 TestFunctions.insert(cast<Function>(NewVMap[TNOF]));
331 DeleteFunctionBody(TNOF); // Function is now external in this module!
332 }
333
334
335 // Remove the Safe functions from the Test module
336 for (Function &I : *New)
337 if (!TestFunctions.count(&I))
338 DeleteFunctionBody(&I);
339
340 // Try to split the global initializers evenly
341 for (GlobalVariable &I : M->globals()) {
342 GlobalVariable *GV = cast<GlobalVariable>(NewVMap[&I]);
343 if (Function *TestFn = globalInitUsesExternalBA(&I)) {
344 if (Function *SafeFn = globalInitUsesExternalBA(GV)) {
345 errs() << "*** Error: when reducing functions, encountered "
346 "the global '";
347 GV->printAsOperand(errs(), false);
348 errs() << "' with an initializer that references blockaddresses "
349 "from safe function '" << SafeFn->getName()
350 << "' and from test function '" << TestFn->getName() << "'.\n";
351 exit(1);
352 }
353 DeleteGlobalInitializer(&I); // Delete the initializer to make it external
354 } else {
355 // If we keep it in the safe module, then delete it in the test module
356 DeleteGlobalInitializer(GV);
357 }
358 }
359
360 // Make sure that there is a global ctor/dtor array in both halves of the
361 // module if they both have static ctor/dtor functions.
362 SplitStaticCtorDtor("llvm.global_ctors", M, New.get(), NewVMap);
363 SplitStaticCtorDtor("llvm.global_dtors", M, New.get(), NewVMap);
364
365 return New;
366 }
367
368 //===----------------------------------------------------------------------===//
369 // Basic Block Extraction Code
370 //===----------------------------------------------------------------------===//
371
372 std::unique_ptr<Module>
extractMappedBlocksFromModule(const std::vector<BasicBlock * > & BBs,Module * M)373 BugDriver::extractMappedBlocksFromModule(const std::vector<BasicBlock *> &BBs,
374 Module *M) {
375 SmallString<128> Filename;
376 int FD;
377 std::error_code EC = sys::fs::createUniqueFile(
378 OutputPrefix + "-extractblocks%%%%%%%", FD, Filename);
379 if (EC) {
380 outs() << "*** Basic Block extraction failed!\n";
381 errs() << "Error creating temporary file: " << EC.message() << "\n";
382 EmitProgressBitcode(M, "basicblockextractfail", true);
383 return nullptr;
384 }
385 sys::RemoveFileOnSignal(Filename);
386
387 tool_output_file BlocksToNotExtractFile(Filename.c_str(), FD);
388 for (std::vector<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
389 I != E; ++I) {
390 BasicBlock *BB = *I;
391 // If the BB doesn't have a name, give it one so we have something to key
392 // off of.
393 if (!BB->hasName()) BB->setName("tmpbb");
394 BlocksToNotExtractFile.os() << BB->getParent()->getName() << " "
395 << BB->getName() << "\n";
396 }
397 BlocksToNotExtractFile.os().close();
398 if (BlocksToNotExtractFile.os().has_error()) {
399 errs() << "Error writing list of blocks to not extract\n";
400 EmitProgressBitcode(M, "basicblockextractfail", true);
401 BlocksToNotExtractFile.os().clear_error();
402 return nullptr;
403 }
404 BlocksToNotExtractFile.keep();
405
406 std::string uniqueFN = "--extract-blocks-file=";
407 uniqueFN += Filename.str();
408 const char *ExtraArg = uniqueFN.c_str();
409
410 std::vector<std::string> PI;
411 PI.push_back("extract-blocks");
412 std::unique_ptr<Module> Ret = runPassesOn(M, PI, false, 1, &ExtraArg);
413
414 sys::fs::remove(Filename.c_str());
415
416 if (!Ret) {
417 outs() << "*** Basic Block extraction failed, please report a bug!\n";
418 EmitProgressBitcode(M, "basicblockextractfail", true);
419 }
420 return Ret;
421 }
422