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(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(createGlobalDCEPass()));
114 CleanupPasses.push_back(getPI(createDeadTypeEliminationPass()));
116 if (MayModifySemantics)
117 CleanupPasses.push_back(getPI(createDeadArgHackingPass()));
119 CleanupPasses.push_back(getPI(createDeadArgEliminationPass()));
121 Module *New = runPassesOn(M, CleanupPasses);
123 std::cerr << "Final cleanups failed. Sorry. :( Please report a bug!\n";
131 /// ExtractLoop - Given a module, extract up to one loop from it into a new
132 /// function. This returns null if there are no extractable loops in the
133 /// program or if the loop extractor crashes.
134 Module *BugDriver::ExtractLoop(Module *M) {
135 std::vector<const PassInfo*> LoopExtractPasses;
136 LoopExtractPasses.push_back(getPI(createSingleLoopExtractorPass()));
138 Module *NewM = runPassesOn(M, LoopExtractPasses);
140 Module *Old = swapProgramIn(M);
141 std::cout << "*** Loop extraction failed: ";
142 EmitProgressBytecode("loopextraction", true);
143 std::cout << "*** Sorry. :( Please report a bug!\n";
148 // Check to see if we created any new functions. If not, no loops were
149 // extracted and we should return null. Limit the number of loops we extract
150 // to avoid taking forever.
151 static unsigned NumExtracted = 32;
152 if (M->size() == NewM->size() || --NumExtracted == 0) {
156 assert(M->size() < NewM->size() && "Loop extract removed functions?");
157 Module::iterator MI = NewM->begin();
158 for (unsigned i = 0, e = M->size(); i != e; ++i)
166 // DeleteFunctionBody - "Remove" the function by deleting all of its basic
167 // blocks, making it external.
169 void llvm::DeleteFunctionBody(Function *F) {
170 // delete the body of the function...
172 assert(F->isDeclaration() && "This didn't make the function external!");
175 /// GetTorInit - Given a list of entries for static ctors/dtors, return them
176 /// as a constant array.
177 static Constant *GetTorInit(std::vector<std::pair<Function*, int> > &TorList) {
178 assert(!TorList.empty() && "Don't create empty tor list!");
179 std::vector<Constant*> ArrayElts;
180 for (unsigned i = 0, e = TorList.size(); i != e; ++i) {
181 std::vector<Constant*> Elts;
182 Elts.push_back(ConstantInt::get(Type::Int32Ty, TorList[i].second));
183 Elts.push_back(TorList[i].first);
184 ArrayElts.push_back(ConstantStruct::get(Elts));
186 return ConstantArray::get(ArrayType::get(ArrayElts[0]->getType(),
191 /// SplitStaticCtorDtor - A module was recently split into two parts, M1/M2, and
192 /// M1 has all of the global variables. If M2 contains any functions that are
193 /// static ctors/dtors, we need to add an llvm.global_[cd]tors global to M2, and
194 /// prune appropriate entries out of M1s list.
195 static void SplitStaticCtorDtor(const char *GlobalName, Module *M1, Module *M2){
196 GlobalVariable *GV = M1->getNamedGlobal(GlobalName);
197 if (!GV || GV->isDeclaration() || GV->hasInternalLinkage() ||
198 !GV->use_empty()) return;
200 std::vector<std::pair<Function*, int> > M1Tors, M2Tors;
201 ConstantArray *InitList = dyn_cast<ConstantArray>(GV->getInitializer());
202 if (!InitList) return;
204 for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
205 if (ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(i))){
206 if (CS->getNumOperands() != 2) return; // Not array of 2-element structs.
208 if (CS->getOperand(1)->isNullValue())
209 break; // Found a null terminator, stop here.
211 ConstantInt *CI = dyn_cast<ConstantInt>(CS->getOperand(0));
212 int Priority = CI ? CI->getSExtValue() : 0;
214 Constant *FP = CS->getOperand(1);
215 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(FP))
217 FP = CE->getOperand(0);
218 if (Function *F = dyn_cast<Function>(FP)) {
219 if (!F->isDeclaration())
220 M1Tors.push_back(std::make_pair(F, Priority));
222 // Map to M2's version of the function.
223 F = M2->getFunction(F->getName());
224 M2Tors.push_back(std::make_pair(F, Priority));
230 GV->eraseFromParent();
231 if (!M1Tors.empty()) {
232 Constant *M1Init = GetTorInit(M1Tors);
233 new GlobalVariable(M1Init->getType(), false, GlobalValue::AppendingLinkage,
234 M1Init, GlobalName, M1);
237 GV = M2->getNamedGlobal(GlobalName);
238 assert(GV && "Not a clone of M1?");
239 assert(GV->use_empty() && "llvm.ctors shouldn't have uses!");
241 GV->eraseFromParent();
242 if (!M2Tors.empty()) {
243 Constant *M2Init = GetTorInit(M2Tors);
244 new GlobalVariable(M2Init->getType(), false, GlobalValue::AppendingLinkage,
245 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
253 Module *llvm::SplitFunctionsOutOfModule(Module *M,
254 const std::vector<Function*> &F) {
255 // Make sure functions & globals are all external so that linkage
256 // between the two modules will work.
257 for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I)
258 I->setLinkage(GlobalValue::ExternalLinkage);
259 for (Module::global_iterator I = M->global_begin(), E = M->global_end();
261 I->setLinkage(GlobalValue::ExternalLinkage);
263 Module *New = CloneModule(M);
265 // Make sure global initializers exist only in the safe module (CBE->.so)
266 for (Module::global_iterator I = New->global_begin(), E = New->global_end();
268 I->setInitializer(0); // Delete the initializer to make it external
270 // Remove the Test functions from the Safe module
271 std::set<std::pair<std::string, const PointerType*> > TestFunctions;
272 for (unsigned i = 0, e = F.size(); i != e; ++i) {
273 TestFunctions.insert(std::make_pair(F[i]->getName(), F[i]->getType()));
274 Function *TNOF = M->getFunction(F[i]->getName());
275 assert(TNOF && "Function doesn't exist in module!");
276 assert(TNOF->getFunctionType() == F[i]->getFunctionType() && "wrong type?");
277 DEBUG(std::cerr << "Removing function " << F[i]->getName() << "\n");
278 DeleteFunctionBody(TNOF); // Function is now external in this module!
282 // Remove the Safe functions from the Test module
283 for (Module::iterator I = New->begin(), E = New->end(); I != E; ++I)
284 if (!TestFunctions.count(std::make_pair(I->getName(), I->getType())))
285 DeleteFunctionBody(I);
288 // Make sure that there is a global ctor/dtor array in both halves of the
289 // module if they both have static ctor/dtor functions.
290 SplitStaticCtorDtor("llvm.global_ctors", M, New);
291 SplitStaticCtorDtor("llvm.global_dtors", M, New);
296 //===----------------------------------------------------------------------===//
297 // Basic Block Extraction Code
298 //===----------------------------------------------------------------------===//
301 std::vector<BasicBlock*> BlocksToNotExtract;
303 /// BlockExtractorPass - This pass is used by bugpoint to extract all blocks
304 /// from the module into their own functions except for those specified by the
305 /// BlocksToNotExtract list.
306 class BlockExtractorPass : public ModulePass {
307 bool runOnModule(Module &M);
309 static char ID; // Pass ID, replacement for typeid
310 BlockExtractorPass() : ModulePass((intptr_t)&ID) {}
312 char BlockExtractorPass::ID = 0;
313 RegisterPass<BlockExtractorPass>
314 XX("extract-bbs", "Extract Basic Blocks From Module (for bugpoint use)");
317 bool BlockExtractorPass::runOnModule(Module &M) {
318 std::set<BasicBlock*> TranslatedBlocksToNotExtract;
319 for (unsigned i = 0, e = BlocksToNotExtract.size(); i != e; ++i) {
320 BasicBlock *BB = BlocksToNotExtract[i];
321 Function *F = BB->getParent();
323 // Map the corresponding function in this module.
324 Function *MF = M.getFunction(F->getName());
326 // Figure out which index the basic block is in its function.
327 Function::iterator BBI = MF->begin();
328 std::advance(BBI, std::distance(F->begin(), Function::iterator(BB)));
329 TranslatedBlocksToNotExtract.insert(BBI);
332 // Now that we know which blocks to not extract, figure out which ones we WANT
334 std::vector<BasicBlock*> BlocksToExtract;
335 for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F)
336 for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
337 if (!TranslatedBlocksToNotExtract.count(BB))
338 BlocksToExtract.push_back(BB);
340 for (unsigned i = 0, e = BlocksToExtract.size(); i != e; ++i)
341 ExtractBasicBlock(BlocksToExtract[i]);
343 return !BlocksToExtract.empty();
346 /// ExtractMappedBlocksFromModule - Extract all but the specified basic blocks
347 /// into their own functions. The only detail is that M is actually a module
348 /// cloned from the one the BBs are in, so some mapping needs to be performed.
349 /// If this operation fails for some reason (ie the implementation is buggy),
350 /// this function should return null, otherwise it returns a new Module.
351 Module *BugDriver::ExtractMappedBlocksFromModule(const
352 std::vector<BasicBlock*> &BBs,
354 // Set the global list so that pass will be able to access it.
355 BlocksToNotExtract = BBs;
357 std::vector<const PassInfo*> PI;
358 PI.push_back(getPI(new BlockExtractorPass()));
359 Module *Ret = runPassesOn(M, PI);
360 BlocksToNotExtract.clear();
362 std::cout << "*** Basic Block extraction failed, please report a bug!\n";
363 M = swapProgramIn(M);
364 EmitProgressBytecode("basicblockextractfail", true);