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