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/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/ToolOutputFile.h"
33 #include "llvm/Support/Path.h"
34 #include "llvm/Support/Signals.h"
35 #include <set>
36 using namespace llvm;
37
38 namespace llvm {
39 bool DisableSimplifyCFG = false;
40 extern cl::opt<std::string> OutputPrefix;
41 } // End llvm namespace
42
43 namespace {
44 cl::opt<bool>
45 NoDCE ("disable-dce",
46 cl::desc("Do not use the -dce pass to reduce testcases"));
47 cl::opt<bool, true>
48 NoSCFG("disable-simplifycfg", cl::location(DisableSimplifyCFG),
49 cl::desc("Do not use the -simplifycfg pass to reduce testcases"));
50 }
51
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.
56 ///
deleteInstructionFromProgram(const Instruction * I,unsigned Simplification)57 Module *BugDriver::deleteInstructionFromProgram(const Instruction *I,
58 unsigned Simplification) {
59 // FIXME, use vmap?
60 Module *Clone = CloneModule(Program);
61
62 const BasicBlock *PBB = I->getParent();
63 const Function *PF = PBB->getParent();
64
65 Module::iterator RFI = Clone->begin(); // Get iterator to corresponding fn
66 std::advance(RFI, std::distance(PF->getParent()->begin(),
67 Module::const_iterator(PF)));
68
69 Function::iterator RBI = RFI->begin(); // Get iterator to corresponding BB
70 std::advance(RBI, std::distance(PF->begin(), Function::const_iterator(PBB)));
71
72 BasicBlock::iterator RI = RBI->begin(); // Get iterator to corresponding inst
73 std::advance(RI, std::distance(PBB->begin(), BasicBlock::const_iterator(I)));
74 Instruction *TheInst = RI; // Got the corresponding instruction!
75
76 // If this instruction produces a value, replace any users with null values
77 if (!TheInst->getType()->isVoidTy())
78 TheInst->replaceAllUsesWith(Constant::getNullValue(TheInst->getType()));
79
80 // Remove the instruction from the program.
81 TheInst->getParent()->getInstList().erase(TheInst);
82
83 // Spiff up the output a little bit.
84 std::vector<std::string> Passes;
85
86 /// Can we get rid of the -disable-* options?
87 if (Simplification > 1 && !NoDCE)
88 Passes.push_back("dce");
89 if (Simplification && !DisableSimplifyCFG)
90 Passes.push_back("simplifycfg"); // Delete dead control flow
91
92 Passes.push_back("verify");
93 Module *New = runPassesOn(Clone, Passes);
94 delete Clone;
95 if (!New) {
96 errs() << "Instruction removal failed. Sorry. :( Please report a bug!\n";
97 exit(1);
98 }
99 return New;
100 }
101
102 /// performFinalCleanups - This method clones the current Program and performs
103 /// a series of cleanups intended to get rid of extra cruft on the module
104 /// before handing it to the user.
105 ///
performFinalCleanups(Module * M,bool MayModifySemantics)106 Module *BugDriver::performFinalCleanups(Module *M, bool MayModifySemantics) {
107 // Make all functions external, so GlobalDCE doesn't delete them...
108 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
109 I->setLinkage(GlobalValue::ExternalLinkage);
110
111 std::vector<std::string> CleanupPasses;
112 CleanupPasses.push_back("globaldce");
113
114 if (MayModifySemantics)
115 CleanupPasses.push_back("deadarghaX0r");
116 else
117 CleanupPasses.push_back("deadargelim");
118
119 Module *New = runPassesOn(M, CleanupPasses);
120 if (New == 0) {
121 errs() << "Final cleanups failed. Sorry. :( Please report a bug!\n";
122 return M;
123 }
124 delete M;
125 return New;
126 }
127
128
129 /// ExtractLoop - Given a module, extract up to one loop from it into a new
130 /// function. This returns null if there are no extractable loops in the
131 /// program or if the loop extractor crashes.
ExtractLoop(Module * M)132 Module *BugDriver::ExtractLoop(Module *M) {
133 std::vector<std::string> LoopExtractPasses;
134 LoopExtractPasses.push_back("loop-extract-single");
135
136 Module *NewM = runPassesOn(M, LoopExtractPasses);
137 if (NewM == 0) {
138 outs() << "*** Loop extraction failed: ";
139 EmitProgressBitcode(M, "loopextraction", true);
140 outs() << "*** Sorry. :( Please report a bug!\n";
141 return 0;
142 }
143
144 // Check to see if we created any new functions. If not, no loops were
145 // extracted and we should return null. Limit the number of loops we extract
146 // to avoid taking forever.
147 static unsigned NumExtracted = 32;
148 if (M->size() == NewM->size() || --NumExtracted == 0) {
149 delete NewM;
150 return 0;
151 } else {
152 assert(M->size() < NewM->size() && "Loop extract removed functions?");
153 Module::iterator MI = NewM->begin();
154 for (unsigned i = 0, e = M->size(); i != e; ++i)
155 ++MI;
156 }
157
158 return NewM;
159 }
160
161
162 // DeleteFunctionBody - "Remove" the function by deleting all of its basic
163 // blocks, making it external.
164 //
DeleteFunctionBody(Function * F)165 void llvm::DeleteFunctionBody(Function *F) {
166 // delete the body of the function...
167 F->deleteBody();
168 assert(F->isDeclaration() && "This didn't make the function external!");
169 }
170
171 /// GetTorInit - Given a list of entries for static ctors/dtors, return them
172 /// as a constant array.
GetTorInit(std::vector<std::pair<Function *,int>> & TorList)173 static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
174 assert(!TorList.empty() && "Don't create empty tor list!");
175 std::vector<Constant*> ArrayElts;
176 Type *Int32Ty = Type::getInt32Ty(TorList[0].first->getContext());
177
178 StructType *STy =
179 StructType::get(Int32Ty, TorList[0].first->getType(), NULL);
180 for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
181 Constant *Elts[] = {
182 ConstantInt::get(Int32Ty, TorList[i].second),
183 TorList[i].first
184 };
185 ArrayElts.push_back(ConstantStruct::get(STy, Elts));
186 }
187 return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(),
188 ArrayElts.size()),
189 ArrayElts);
190 }
191
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.
SplitStaticCtorDtor(const char * GlobalName,Module * M1,Module * M2,ValueToValueMapTy & VMap)196 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2,
197 ValueToValueMapTy &VMap) {
198 GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
199 if (!GV || GV->isDeclaration() || GV->hasLocalLinkage() ||
200 !GV->use_empty()) return;
201
202 std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
203 ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
204 if (!InitList) return;
205
206 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
207 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
208 if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
209
210 if (CS->getOperand(1)->isNullValue())
211 break; // Found a null terminator, stop here.
212
213 ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
214 int Priority = CI ? CI->getSExtValue() : 0;
215
216 Constant *FP = CS->getOperand(1);
217 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
218 if (CE->isCast())
219 FP = CE->getOperand(0);
220 if (Function *F = dyn_cast<Function>(FP)) {
221 if (!F->isDeclaration())
222 M1Tors.push_back(std::make_pair(F, Priority));
223 else {
224 // Map to M2's version of the function.
225 F = cast<Function>(VMap[F]);
226 M2Tors.push_back(std::make_pair(F, Priority));
227 }
228 }
229 }
230 }
231
232 GV->eraseFromParent();
233 if (!M1Tors.empty()) {
234 Constant *M1Init = GetTorInit(M1Tors);
235 new GlobalVariable(*M1, M1Init->getType(), false,
236 GlobalValue::AppendingLinkage,
237 M1Init, GlobalName);
238 }
239
240 GV = M2->getNamedGlobal(GlobalName);
241 assert(GV && "Not a clone of M1?");
242 assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
243
244 GV->eraseFromParent();
245 if (!M2Tors.empty()) {
246 Constant *M2Init = GetTorInit(M2Tors);
247 new GlobalVariable(*M2, M2Init->getType(), false,
248 GlobalValue::AppendingLinkage,
249 M2Init, GlobalName);
250 }
251 }
252
253
254 /// SplitFunctionsOutOfModule - Given a module and a list of functions in the
255 /// module, split the functions OUT of the specified module, and place them in
256 /// the new module.
257 Module *
SplitFunctionsOutOfModule(Module * M,const std::vector<Function * > & F,ValueToValueMapTy & VMap)258 llvm::SplitFunctionsOutOfModule(Module *M,
259 const std::vector<Function*> &F,
260 ValueToValueMapTy &VMap) {
261 // Make sure functions & globals are all external so that linkage
262 // between the two modules will work.
263 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
264 I->setLinkage(GlobalValue::ExternalLinkage);
265 for (Module::global_iterator I = M->global_begin(), E = M->global_end();
266 I != E; ++I) {
267 if (I->hasName() && I->getName()[0] == '\01')
268 I->setName(I->getName().substr(1));
269 I->setLinkage(GlobalValue::ExternalLinkage);
270 }
271
272 ValueToValueMapTy NewVMap;
273 Module *New = CloneModule(M, NewVMap);
274
275 // Make sure global initializers exist only in the safe module (CBE->.so)
276 for (Module::global_iterator I = New->global_begin(), E = New->global_end();
277 I != E; ++I)
278 I->setInitializer(0); // Delete the initializer to make it external
279
280 // Remove the Test functions from the Safe module
281 std::set<Function *> TestFunctions;
282 for (unsigned i = 0, e = F.size(); i != e; ++i) {
283 Function *TNOF = cast<Function>(VMap[F[i]]);
284 DEBUG(errs() << "Removing function ");
285 DEBUG(WriteAsOperand(errs(), TNOF, false));
286 DEBUG(errs() << "\n");
287 TestFunctions.insert(cast<Function>(NewVMap[TNOF]));
288 DeleteFunctionBody(TNOF); // Function is now external in this module!
289 }
290
291
292 // Remove the Safe functions from the Test module
293 for (Module::iterator I = New->begin(), E = New->end(); I != E; ++I)
294 if (!TestFunctions.count(I))
295 DeleteFunctionBody(I);
296
297
298 // Make sure that there is a global ctor/dtor array in both halves of the
299 // module if they both have static ctor/dtor functions.
300 SplitStaticCtorDtor("llvm.global_ctors", M, New, NewVMap);
301 SplitStaticCtorDtor("llvm.global_dtors", M, New, NewVMap);
302
303 return New;
304 }
305
306 //===----------------------------------------------------------------------===//
307 // Basic Block Extraction Code
308 //===----------------------------------------------------------------------===//
309
310 /// ExtractMappedBlocksFromModule - Extract all but the specified basic blocks
311 /// into their own functions. The only detail is that M is actually a module
312 /// cloned from the one the BBs are in, so some mapping needs to be performed.
313 /// If this operation fails for some reason (ie the implementation is buggy),
314 /// this function should return null, otherwise it returns a new Module.
ExtractMappedBlocksFromModule(const std::vector<BasicBlock * > & BBs,Module * M)315 Module *BugDriver::ExtractMappedBlocksFromModule(const
316 std::vector<BasicBlock*> &BBs,
317 Module *M) {
318 sys::Path uniqueFilename(OutputPrefix + "-extractblocks");
319 std::string ErrMsg;
320 if (uniqueFilename.createTemporaryFileOnDisk(true, &ErrMsg)) {
321 outs() << "*** Basic Block extraction failed!\n";
322 errs() << "Error creating temporary file: " << ErrMsg << "\n";
323 EmitProgressBitcode(M, "basicblockextractfail", true);
324 return 0;
325 }
326 sys::RemoveFileOnSignal(uniqueFilename);
327
328 std::string ErrorInfo;
329 tool_output_file BlocksToNotExtractFile(uniqueFilename.c_str(), ErrorInfo);
330 if (!ErrorInfo.empty()) {
331 outs() << "*** Basic Block extraction failed!\n";
332 errs() << "Error writing list of blocks to not extract: " << ErrorInfo
333 << "\n";
334 EmitProgressBitcode(M, "basicblockextractfail", true);
335 return 0;
336 }
337 for (std::vector<BasicBlock*>::const_iterator I = BBs.begin(), E = BBs.end();
338 I != E; ++I) {
339 BasicBlock *BB = *I;
340 // If the BB doesn't have a name, give it one so we have something to key
341 // off of.
342 if (!BB->hasName()) BB->setName("tmpbb");
343 BlocksToNotExtractFile.os() << BB->getParent()->getNameStr() << " "
344 << BB->getName() << "\n";
345 }
346 BlocksToNotExtractFile.os().close();
347 if (BlocksToNotExtractFile.os().has_error()) {
348 errs() << "Error writing list of blocks to not extract: " << ErrorInfo
349 << "\n";
350 EmitProgressBitcode(M, "basicblockextractfail", true);
351 BlocksToNotExtractFile.os().clear_error();
352 return 0;
353 }
354 BlocksToNotExtractFile.keep();
355
356 std::string uniqueFN = "--extract-blocks-file=" + uniqueFilename.str();
357 const char *ExtraArg = uniqueFN.c_str();
358
359 std::vector<std::string> PI;
360 PI.push_back("extract-blocks");
361 Module *Ret = runPassesOn(M, PI, false, 1, &ExtraArg);
362
363 uniqueFilename.eraseFromDisk(); // Free disk space
364
365 if (Ret == 0) {
366 outs() << "*** Basic Block extraction failed, please report a bug!\n";
367 EmitProgressBitcode(M, "basicblockextractfail", true);
368 }
369 return Ret;
370 }
371