Example #1
0
void ValueEnumerator::incorporateFunction(const Function &F) {
  InstructionCount = 0;
  NumModuleValues = Values.size();
  NumModuleMDs = MDs.size();

  // Adding function arguments to the value table.
  for (Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end();
       I != E; ++I)
    EnumerateValue(I);

  FirstFuncConstantID = Values.size();

  // Add all function-level constants to the value table.
  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I)
      for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
           OI != E; ++OI) {
        if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
            isa<InlineAsm>(*OI))
          EnumerateValue(*OI);
      }
    BasicBlocks.push_back(BB);
    ValueMap[BB] = BasicBlocks.size();
  }

  // Optimize the constant layout.
  OptimizeConstants(FirstFuncConstantID, Values.size());

  // Add the function's parameter attributes so they are available for use in
  // the function's instruction.
  EnumerateAttributes(F.getAttributes());

  FirstInstID = Values.size();

  SmallVector<LocalAsMetadata *, 8> FnLocalMDVector;
  // Add all of the instructions.
  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I) {
      for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
           OI != E; ++OI) {
        if (auto *MD = dyn_cast<MetadataAsValue>(&*OI))
          if (auto *Local = dyn_cast<LocalAsMetadata>(MD->getMetadata()))
            // Enumerate metadata after the instructions they might refer to.
            FnLocalMDVector.push_back(Local);
      }

      if (!I->getType()->isVoidTy())
        EnumerateValue(I);
    }
  }

  // Add all of the function-local metadata.
  for (unsigned i = 0, e = FnLocalMDVector.size(); i != e; ++i)
    EnumerateFunctionLocalMetadata(FnLocalMDVector[i]);
}
void NaClValueEnumerator::incorporateFunction(const Function &F) {
  InstructionCount = 0;
  NumModuleValues = Values.size();

  // Make sure no insertions outside of a function.
  assert(FnForwardTypeRefs.empty());

  // Adding function arguments to the value table.
  for (Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end();
       I != E; ++I)
    EnumerateValue(I);

  FirstFuncConstantID = Values.size();

  // Add all function-level constants to the value table.
  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I) {
      if (const SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
        // Handle switch instruction specially, so that we don't write
        // out unnecessary vector/array constants used to model case selectors.
        if (isa<Constant>(SI->getCondition())) {
          EnumerateValue(SI->getCondition());
        }
      } else {
        for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
             OI != E; ++OI) {
          if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
              isa<InlineAsm>(*OI))
            EnumerateValue(*OI);
        }
      }
    }
    BasicBlocks.push_back(BB);
    ValueMap[BB] = BasicBlocks.size();
  }

  // Optimize the constant layout.
  OptimizeConstants(FirstFuncConstantID, Values.size());

  FirstInstID = Values.size();

  // Add all of the instructions.
  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I) {
      if (!I->getType()->isVoidTy())
        EnumerateValue(I);
    }
  }
}
// Collect allocas
void AllocaManager::collectMarkedAllocas() {
  NamedRegionTimer Timer("Collect Marked Allocas", "AllocaManager",
                         TimePassesIsEnabled);

  // Weird semantics: If an alloca *ever* appears in a lifetime start or end
  // within the same function, its lifetime begins only at the explicit lifetime
  // starts and ends only at the explicit lifetime ends and function exit
  // points. Otherwise, its lifetime begins in the entry block and it is live
  // everywhere.
  //
  // And so, instead of just walking the entry block to find all the static
  // allocas, we walk the whole body to find the intrinsics so we can find the
  // set of static allocas referenced in the intrinsics.
  for (Function::const_iterator FI = F->begin(), FE = F->end();
       FI != FE; ++FI) {
    for (BasicBlock::const_iterator BI = FI->begin(), BE = FI->end();
         BI != BE; ++BI) {
      const CallInst *CI = dyn_cast<CallInst>(BI);
      if (!CI) continue;

      const Value *Callee = CI->getCalledValue();
      if (Callee == LifetimeStart || Callee == LifetimeEnd) {
        if (const Value *Ptr = getPointerFromIntrinsic(CI)) {
          if (const AllocaInst *AI = isFavorableAlloca(Ptr))
            Allocas.insert(std::make_pair(AI, 0));
        } else if (isa<Instruction>(CI->getArgOperand(1)->stripPointerCasts())) {
          // Oh noes, There's a lifetime intrinsics with something that
          // doesn't appear to resolve to an alloca. This means that it's
          // possible that it may be declaring a lifetime for some escaping
          // alloca. Look out!
          Allocas.clear();
          assert(AllocasByIndex.empty());
          return;
        }
      }
    }
  }

  // All that said, we still want the intrinsics in the order they appear in the
  // block, so that we can represent later ones with earlier ones and skip
  // worrying about dominance, so run through the entry block and index those
  // allocas which we identified above.
  AllocasByIndex.reserve(Allocas.size());
  const BasicBlock *EntryBB = &F->getEntryBlock();
  for (BasicBlock::const_iterator BI = EntryBB->begin(), BE = EntryBB->end();
       BI != BE; ++BI) {
    const AllocaInst *AI = dyn_cast<AllocaInst>(BI);
    if (!AI || !AI->isStaticAlloca()) continue;

    AllocaMap::iterator I = Allocas.find(AI);
    if (I != Allocas.end()) {
      I->second = AllocasByIndex.size();
      AllocasByIndex.push_back(getInfo(AI));
    }
  }
  assert(AllocasByIndex.size() == Allocas.size());
}
Example #4
0
void ValueEnumerator::incorporateFunction(const Function &F) {
  NumModuleValues = Values.size();

  // Adding function arguments to the value table.
  for(Function::const_arg_iterator I = F.arg_begin(), E = F.arg_end();
      I != E; ++I)
    EnumerateValue(I);

  FirstFuncConstantID = Values.size();

  // Add all function-level constants to the value table.
  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I)
      for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
           OI != E; ++OI) {
        if ((isa<Constant>(*OI) && !isa<GlobalValue>(*OI)) ||
            isa<InlineAsm>(*OI))
          EnumerateValue(*OI);
      }
    BasicBlocks.push_back(BB);
    ValueMap[BB] = BasicBlocks.size();
  }

  // Optimize the constant layout.
  OptimizeConstants(FirstFuncConstantID, Values.size());

  // Add the function's parameter attributes so they are available for use in
  // the function's instruction.
  EnumerateAttributes(F.getAttributes());

  FirstInstID = Values.size();

  // Add all of the instructions.
  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E; ++I) {
      if (I->getType() != Type::getVoidTy(F.getContext()))
        EnumerateValue(I);
    }
  }
}
Example #5
0
set<Strator::StratorWorker::LockSet>& Strator::StratorWorker::traverseFunction(const Function& f, LockSet lockSet){
	#ifdef DETAILED_DEBUG
	cerr << " Traversing: " << f.getName().str() << endl;
	#endif
	if("signal_threads" == f.getName().str())
		cerr << "signal" << endl;
	/// This should be OK even if not thread safe
	//TODO: Ali: why OK if not thread safe ?!
	parent->functionMap[f.getName().str()] = true;
	/// If the size of a basic block is 0, then we are in a function declaration.
	if (f.size() == 0){
		set<StratorWorker::LockSet>* emptySet = new set<StratorWorker::LockSet>();
		return *emptySet;
	}

	StratorFunction* sFunc = getStratorFunction(&f);

	/// Check if the function is in the cache
	vector<FunctionCacheEntry>::iterator it;
	for(it = sFunc->functionCache.functionCacheEntries.begin();
			it != sFunc->functionCache.functionCacheEntries.end(); ++it){
		if(it->entryLockSet == lockSet){
			return it->exitLockSets;
		}
	}
	/// Simply ignore recursion
	if(sFunc->onStack){
		set<StratorWorker::LockSet>* emptySet = new set<StratorWorker::LockSet>();
		return *emptySet;
	}

	sFunc->onStack= true;

	/// The function was not in the cache, so a new cache entry is being created for it
	FunctionCacheEntry* functionCacheEntry = new FunctionCacheEntry();
	functionCacheEntry->entryLockSet = lockSet;

	/// Start traversing the statements with the beginning statement of the function
	Function::const_iterator firstBB = f.begin();
	BasicBlock::const_iterator firstInstr = firstBB->begin();
	functionCacheEntry->exitLockSets = traverseStatement(f, firstInstr, lockSet, lockSet);

	/// We processes the current function, it is no longer on the stack
	sFunc->onStack= false;

	/// Add the exit lockset to the summary cache
	sFunc->functionCache.functionCacheEntries.push_back(*functionCacheEntry);

	return functionCacheEntry->exitLockSets;
}
Example #6
0
void TypeFinder::Run(const Module &M) {

	AddModuleTypesToPrinter(TP,&M);

    // Get types from the type symbol table.  This gets opaque types referened
    // only through derived named types.
    const TypeSymbolTable &ST = M.getTypeSymbolTable();
    for (TypeSymbolTable::const_iterator TI = ST.begin(), E = ST.end();
           TI != E; ++TI)
		IncorporateType(TI->second);

    // Get types from global variables.
	for (Module::const_global_iterator I = M.global_begin(),
           E = M.global_end(); I != E; ++I) {
        IncorporateType(I->getType());
        if (I->hasInitializer())
          IncorporateValue(I->getInitializer());
    }

    // Get types from aliases.
    for (Module::const_alias_iterator I = M.alias_begin(),
         E = M.alias_end(); I != E; ++I) {
		IncorporateType(I->getType());
        IncorporateValue(I->getAliasee());
    }

    // Get types from functions.
    for (Module::const_iterator FI = M.begin(), E = M.end(); FI != E; ++FI) {
        IncorporateType(FI->getType());

		for (Function::const_iterator BB = FI->begin(), E = FI->end();
             BB != E;++BB)
			for (BasicBlock::const_iterator II = BB->begin(),
               E = BB->end(); II != E; ++II) {
				const Instruction &I = *II;
				// Incorporate the type of the instruction and all its operands.
				IncorporateType(I.getType());
				for (User::const_op_iterator OI = I.op_begin(), OE = I.op_end();
					OI != OE; ++OI)
					IncorporateValue(*OI);
			}
      }
}
Example #7
0
void buildCallMaps(Module const& M, FunctionsMap& F,
		CallsMap& C) {
    for (Module::const_iterator f = M.begin(); f != M.end(); ++f) {
	if (!f->isDeclaration())
	    F.insert(std::make_pair(f->getFunctionType(), &*f));
	for (Function::const_iterator b = f->begin(); b != f->end(); ++b) {
	    for (BasicBlock::const_iterator i = b->begin(); i != b->end(); ++i)
		if (const CallInst *CI = dyn_cast<CallInst>(&*i)) {
		    if (!isInlineAssembly(CI) && !callToMemoryManStuff(CI))
			C.insert(std::make_pair(getCalleePrototype(CI), CI));
		} else if (const StoreInst *SI = dyn_cast<StoreInst>(&*i)) {
		    const Value *r = SI->getValueOperand();
		    if (hasExtraReference(r) && memoryManStuff(r)) {
			const Function *fn = dyn_cast<Function>(r);
			F.insert(std::make_pair(fn->getFunctionType(), fn));
		    }
		}
	}
    }
}
void ModuleSummaryIndexBuilder::computeFunctionSummary(
    const Function &F, BlockFrequencyInfo *BFI) {
  // Summary not currently supported for anonymous functions, they must
  // be renamed.
  if (!F.hasName())
    return;

  unsigned NumInsts = 0;
  // Map from callee ValueId to profile count. Used to accumulate profile
  // counts for all static calls to a given callee.
  DenseMap<const Value *, CalleeInfo> CallGraphEdges;
  DenseSet<const Value *> RefEdges;

  SmallPtrSet<const User *, 8> Visited;
  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E;
         ++I) {
      if (!isa<DbgInfoIntrinsic>(I))
        ++NumInsts;

      if (auto CS = ImmutableCallSite(&*I)) {
        auto *CalledFunction = CS.getCalledFunction();
        if (CalledFunction && CalledFunction->hasName() &&
            !CalledFunction->isIntrinsic()) {
          auto ScaledCount = BFI ? BFI->getBlockProfileCount(&*BB) : None;
          auto *CalleeId =
              M->getValueSymbolTable().lookup(CalledFunction->getName());
          CallGraphEdges[CalleeId] +=
              (ScaledCount ? ScaledCount.getValue() : 0);
        }
      }
      findRefEdges(&*I, RefEdges, Visited);
    }

  GlobalValueSummary::GVFlags Flags(F);
  std::unique_ptr<FunctionSummary> FuncSummary =
      llvm::make_unique<FunctionSummary>(Flags, NumInsts);
  FuncSummary->addCallGraphEdges(CallGraphEdges);
  FuncSummary->addRefEdges(RefEdges);
  Index->addGlobalValueSummary(F.getName(), std::move(FuncSummary));
}
/// WriteFunction - Emit a function body to the module stream.
static void WriteFunction(const Function &F, NaClValueEnumerator &VE,
                          NaClBitstreamWriter &Stream) {
  Stream.EnterSubblock(naclbitc::FUNCTION_BLOCK_ID);
  VE.incorporateFunction(F);

  SmallVector<unsigned, 64> Vals;

  // Emit the number of basic blocks, so the reader can create them ahead of
  // time.
  Vals.push_back(VE.getBasicBlocks().size());
  Stream.EmitRecord(naclbitc::FUNC_CODE_DECLAREBLOCKS, Vals);
  Vals.clear();

  // If there are function-local constants, emit them now.
  unsigned CstStart, CstEnd;
  VE.getFunctionConstantRange(CstStart, CstEnd);
  WriteConstants(CstStart, CstEnd, VE, Stream);

  // Keep a running idea of what the instruction ID is.
  unsigned InstID = CstEnd;

  // Finally, emit all the instructions, in order.
  for (Function::const_iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
         I != E; ++I) {
      if (WriteInstruction(*I, InstID, VE, Stream, Vals) &&
          !I->getType()->isVoidTy())
        ++InstID;
    }

  // Emit names for instructions etc.
  if (PNaClAllowLocalSymbolTables)
    WriteValueSymbolTable(F.getValueSymbolTable(), VE, Stream);

  VE.purgeFunction();
  Stream.ExitBlock();
}
/// ValueEnumerator - Enumerate module-level information.
ValueEnumerator::ValueEnumerator(const Module *M) {
  // Enumerate the global variables.
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    EnumerateValue(I);

  // Enumerate the functions.
  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
    EnumerateValue(I);
    EnumerateAttributes(cast<Function>(I)->getAttributes());
  }

  // Enumerate the aliases.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I);

  // Remember what is the cutoff between globalvalue's and other constants.
  unsigned FirstConstant = Values.size();

  // Enumerate the global variable initializers.
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    if (I->hasInitializer())
      EnumerateValue(I->getInitializer());

  // Enumerate the aliasees.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I->getAliasee());

  // Insert constants and metadata that are named at module level into the slot
  // pool so that the module symbol table can refer to them...
  EnumerateValueSymbolTable(M->getValueSymbolTable());
  EnumerateNamedMetadata(M);

  SmallVector<std::pair<unsigned, MDNode*>, 8> MDs;

  // Enumerate types used by function bodies and argument lists.
  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {

    for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
         I != E; ++I)
      EnumerateType(I->getType());

    for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
      for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
        for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
             OI != E; ++OI) {
          if (MDNode *MD = dyn_cast<MDNode>(*OI))
            if (MD->isFunctionLocal() && MD->getFunction())
              // These will get enumerated during function-incorporation.
              continue;
          EnumerateOperandType(*OI);
        }
        EnumerateType(I->getType());
        if (const CallInst *CI = dyn_cast<CallInst>(I))
          EnumerateAttributes(CI->getAttributes());
        else if (const InvokeInst *II = dyn_cast<InvokeInst>(I))
          EnumerateAttributes(II->getAttributes());

        // Enumerate metadata attached with this instruction.
        MDs.clear();
        I->getAllMetadataOtherThanDebugLoc(MDs);
        for (unsigned i = 0, e = MDs.size(); i != e; ++i)
          EnumerateMetadata(MDs[i].second);

        if (!I->getDebugLoc().isUnknown()) {
          MDNode *Scope, *IA;
          I->getDebugLoc().getScopeAndInlinedAt(Scope, IA, I->getContext());
          if (Scope) EnumerateMetadata(Scope);
          if (IA) EnumerateMetadata(IA);
        }
      }
  }

  // Optimize constant ordering.
  OptimizeConstants(FirstConstant, Values.size());
}
Example #11
0
static Error ReduceInsts(BugDriver &BD,
                        bool (*TestFn)(const BugDriver &, Module *)) {
  // Attempt to delete instructions using bisection. This should help out nasty
  // cases with large basic blocks where the problem is at one end.
  if (!BugpointIsInterrupted) {
    std::vector<const Instruction *> Insts;
    for (const Function &F : *BD.getProgram())
      for (const BasicBlock &BB : F)
        for (const Instruction &I : BB)
          if (!isa<TerminatorInst>(&I))
            Insts.push_back(&I);

    Expected<bool> Result =
        ReduceCrashingInstructions(BD, TestFn).reduceList(Insts);
    if (Error E = Result.takeError())
      return E;
  }

  unsigned Simplification = 2;
  do {
    if (BugpointIsInterrupted)
      // TODO: Should we distinguish this with an "interrupted error"?
      return Error::success();
    --Simplification;
    outs() << "\n*** Attempting to reduce testcase by deleting instruc"
           << "tions: Simplification Level #" << Simplification << '\n';

    // Now that we have deleted the functions that are unnecessary for the
    // program, try to remove instructions that are not necessary to cause the
    // crash.  To do this, we loop through all of the instructions in the
    // remaining functions, deleting them (replacing any values produced with
    // nulls), and then running ADCE and SimplifyCFG.  If the transformed input
    // still triggers failure, keep deleting until we cannot trigger failure
    // anymore.
    //
    unsigned InstructionsToSkipBeforeDeleting = 0;
  TryAgain:

    // Loop over all of the (non-terminator) instructions remaining in the
    // function, attempting to delete them.
    unsigned CurInstructionNum = 0;
    for (Module::const_iterator FI = BD.getProgram()->begin(),
                                E = BD.getProgram()->end();
         FI != E; ++FI)
      if (!FI->isDeclaration())
        for (Function::const_iterator BI = FI->begin(), E = FI->end(); BI != E;
             ++BI)
          for (BasicBlock::const_iterator I = BI->begin(), E = --BI->end();
               I != E; ++I, ++CurInstructionNum) {
            if (InstructionsToSkipBeforeDeleting) {
              --InstructionsToSkipBeforeDeleting;
            } else {
              if (BugpointIsInterrupted)
                // TODO: Should this be some kind of interrupted error?
                return Error::success();

              if (I->isEHPad() || I->getType()->isTokenTy())
                continue;

              outs() << "Checking instruction: " << *I;
              std::unique_ptr<Module> M =
                  BD.deleteInstructionFromProgram(&*I, Simplification);

              // Find out if the pass still crashes on this pass...
              if (TestFn(BD, M.get())) {
                // Yup, it does, we delete the old module, and continue trying
                // to reduce the testcase...
                BD.setNewProgram(M.release());
                InstructionsToSkipBeforeDeleting = CurInstructionNum;
                goto TryAgain; // I wish I had a multi-level break here!
              }
            }
          }

    if (InstructionsToSkipBeforeDeleting) {
      InstructionsToSkipBeforeDeleting = 0;
      goto TryAgain;
    }

  } while (Simplification);
  BD.EmitProgressBitcode(BD.getProgram(), "reduced-instructions");
  return Error::success();
}
Example #12
0
void externalsAndGlobalsCheck(const Module *m) {
  std::map<std::string, bool> externals;
  std::set<std::string> modelled(modelledExternals,
                                 modelledExternals+NELEMS(modelledExternals));
  std::set<std::string> dontCare(dontCareExternals,
                                 dontCareExternals+NELEMS(dontCareExternals));
  std::set<std::string> unsafe(unsafeExternals,
                               unsafeExternals+NELEMS(unsafeExternals));

  switch (Libc) {
  case KleeLibc:
    dontCare.insert(dontCareKlee, dontCareKlee+NELEMS(dontCareKlee));
    break;
  case UcLibc:
    dontCare.insert(dontCareUclibc,
                    dontCareUclibc+NELEMS(dontCareUclibc));
    break;
  case NoLibc: /* silence compiler warning */
    break;
  }

  if (WithPOSIXRuntime)
    dontCare.insert("syscall");

  for (Module::const_iterator fnIt = m->begin(), fn_ie = m->end();
       fnIt != fn_ie; ++fnIt) {
    if (fnIt->isDeclaration() && !fnIt->use_empty())
      externals.insert(std::make_pair(fnIt->getName(), false));
    for (Function::const_iterator bbIt = fnIt->begin(), bb_ie = fnIt->end();
         bbIt != bb_ie; ++bbIt) {
      for (BasicBlock::const_iterator it = bbIt->begin(), ie = bbIt->end();
           it != ie; ++it) {
        if (const CallInst *ci = dyn_cast<CallInst>(it)) {
          if (isa<InlineAsm>(ci->getCalledValue())) {
            klee_warning_once(&*fnIt,
                              "function \"%s\" has inline asm",
                              fnIt->getName().data());
          }
        }
      }
    }
  }
  for (Module::const_global_iterator
         it = m->global_begin(), ie = m->global_end();
       it != ie; ++it)
    if (it->isDeclaration() && !it->use_empty())
      externals.insert(std::make_pair(it->getName(), true));
  // and remove aliases (they define the symbol after global
  // initialization)
  for (Module::const_alias_iterator
         it = m->alias_begin(), ie = m->alias_end();
       it != ie; ++it) {
    std::map<std::string, bool>::iterator it2 =
      externals.find(it->getName());
    if (it2!=externals.end())
      externals.erase(it2);
  }

  std::map<std::string, bool> foundUnsafe;
  for (std::map<std::string, bool>::iterator
         it = externals.begin(), ie = externals.end();
       it != ie; ++it) {
    const std::string &ext = it->first;
    if (!modelled.count(ext) && (WarnAllExternals ||
                                 !dontCare.count(ext))) {
      if (unsafe.count(ext)) {
        foundUnsafe.insert(*it);
      } else {
        klee_warning("undefined reference to %s: %s",
                     it->second ? "variable" : "function",
                     ext.c_str());
      }
    }
  }

  for (std::map<std::string, bool>::iterator
         it = foundUnsafe.begin(), ie = foundUnsafe.end();
       it != ie; ++it) {
    const std::string &ext = it->first;
    klee_warning("undefined reference to %s: %s (UNSAFE)!",
                 it->second ? "variable" : "function",
                 ext.c_str());
  }
}
void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
                               SelectionDAG *DAG) {
    const TargetLowering *TLI = TM.getTargetLowering();

    Fn = &fn;
    MF = &mf;
    RegInfo = &MF->getRegInfo();

    // Check whether the function can return without sret-demotion.
    SmallVector<ISD::OutputArg, 4> Outs;
    GetReturnInfo(Fn->getReturnType(), Fn->getAttributes(), Outs, *TLI);
    CanLowerReturn = TLI->CanLowerReturn(Fn->getCallingConv(), *MF,
                                         Fn->isVarArg(),
                                         Outs, Fn->getContext());

    // Initialize the mapping of values to registers.  This is only set up for
    // instruction values that are used outside of the block that defines
    // them.
    Function::const_iterator BB = Fn->begin(), EB = Fn->end();
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
        if (const AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
            // Don't fold inalloca allocas or other dynamic allocas into the initial
            // stack frame allocation, even if they are in the entry block.
            if (!AI->isStaticAlloca())
                continue;

            if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
                Type *Ty = AI->getAllocatedType();
                uint64_t TySize = TLI->getDataLayout()->getTypeAllocSize(Ty);
                unsigned Align =
                    std::max((unsigned)TLI->getDataLayout()->getPrefTypeAlignment(Ty),
                             AI->getAlignment());

                TySize *= CUI->getZExtValue();   // Get total allocated size.
                if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.

                StaticAllocaMap[AI] =
                    MF->getFrameInfo()->CreateStackObject(TySize, Align, false, AI);
            }
        }

    for (; BB != EB; ++BB)
        for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
                I != E; ++I) {
            // Look for dynamic allocas.
            if (const AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
                if (!AI->isStaticAlloca()) {
                    unsigned Align = std::max(
                                         (unsigned)TLI->getDataLayout()->getPrefTypeAlignment(
                                             AI->getAllocatedType()),
                                         AI->getAlignment());
                    unsigned StackAlign = TM.getFrameLowering()->getStackAlignment();
                    if (Align <= StackAlign)
                        Align = 0;
                    // Inform the Frame Information that we have variable-sized objects.
                    MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1, AI);
                }
            }

            // Look for inline asm that clobbers the SP register.
            if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
                ImmutableCallSite CS(I);
                if (isa<InlineAsm>(CS.getCalledValue())) {
                    unsigned SP = TLI->getStackPointerRegisterToSaveRestore();
                    std::vector<TargetLowering::AsmOperandInfo> Ops =
                        TLI->ParseConstraints(CS);
                    for (size_t I = 0, E = Ops.size(); I != E; ++I) {
                        TargetLowering::AsmOperandInfo &Op = Ops[I];
                        if (Op.Type == InlineAsm::isClobber) {
                            // Clobbers don't have SDValue operands, hence SDValue().
                            TLI->ComputeConstraintToUse(Op, SDValue(), DAG);
                            std::pair<unsigned, const TargetRegisterClass*> PhysReg =
                                TLI->getRegForInlineAsmConstraint(Op.ConstraintCode,
                                                                  Op.ConstraintVT);
                            if (PhysReg.first == SP)
                                MF->getFrameInfo()->setHasInlineAsmWithSPAdjust(true);
                        }
                    }
                }
            }

            // Mark values used outside their block as exported, by allocating
            // a virtual register for them.
            if (isUsedOutsideOfDefiningBlock(I))
                if (!isa<AllocaInst>(I) ||
                        !StaticAllocaMap.count(cast<AllocaInst>(I)))
                    InitializeRegForValue(I);

            // Collect llvm.dbg.declare information. This is done now instead of
            // during the initial isel pass through the IR so that it is done
            // in a predictable order.
            if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
                MachineModuleInfo &MMI = MF->getMMI();
                DIVariable DIVar(DI->getVariable());
                assert((!DIVar || DIVar.isVariable()) &&
                       "Variable in DbgDeclareInst should be either null or a DIVariable.");
                if (MMI.hasDebugInfo() &&
                        DIVar &&
                        !DI->getDebugLoc().isUnknown()) {
                    // Don't handle byval struct arguments or VLAs, for example.
                    // Non-byval arguments are handled here (they refer to the stack
                    // temporary alloca at this point).
                    const Value *Address = DI->getAddress();
                    if (Address) {
                        if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
                            Address = BCI->getOperand(0);
                        if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
                            DenseMap<const AllocaInst *, int>::iterator SI =
                                StaticAllocaMap.find(AI);
                            if (SI != StaticAllocaMap.end()) { // Check for VLAs.
                                int FI = SI->second;
                                MMI.setVariableDbgInfo(DI->getVariable(),
                                                       FI, DI->getDebugLoc());
                            }
                        }
                    }
                }
            }
        }

    // Create an initial MachineBasicBlock for each LLVM BasicBlock in F.  This
    // also creates the initial PHI MachineInstrs, though none of the input
    // operands are populated.
    for (BB = Fn->begin(); BB != EB; ++BB) {
        MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
        MBBMap[BB] = MBB;
        MF->push_back(MBB);

        // Transfer the address-taken flag. This is necessary because there could
        // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
        // the first one should be marked.
        if (BB->hasAddressTaken())
            MBB->setHasAddressTaken();

        // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
        // appropriate.
        for (BasicBlock::const_iterator I = BB->begin();
                const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
            if (PN->use_empty()) continue;

            // Skip empty types
            if (PN->getType()->isEmptyTy())
                continue;

            DebugLoc DL = PN->getDebugLoc();
            unsigned PHIReg = ValueMap[PN];
            assert(PHIReg && "PHI node does not have an assigned virtual register!");

            SmallVector<EVT, 4> ValueVTs;
            ComputeValueVTs(*TLI, PN->getType(), ValueVTs);
            for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
                EVT VT = ValueVTs[vti];
                unsigned NumRegisters = TLI->getNumRegisters(Fn->getContext(), VT);
                const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
                for (unsigned i = 0; i != NumRegisters; ++i)
                    BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
                PHIReg += NumRegisters;
            }
        }
    }

    // Mark landing pad blocks.
    for (BB = Fn->begin(); BB != EB; ++BB)
        if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
            MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
}
Example #14
0
void TypeFinder::run(const Module &M, bool onlyNamed) {
    OnlyNamed = onlyNamed;

    // Get types from global variables.
    for (Module::const_global_iterator I = M.global_begin(),
            E = M.global_end(); I != E; ++I) {
        incorporateType(I->getType());
        if (I->hasInitializer())
            incorporateValue(I->getInitializer());
    }

    // Get types from aliases.
    for (Module::const_alias_iterator I = M.alias_begin(),
            E = M.alias_end(); I != E; ++I) {
        incorporateType(I->getType());
        if (const Value *Aliasee = I->getAliasee())
            incorporateValue(Aliasee);
    }

    // Get types from functions.
    SmallVector<std::pair<unsigned, MDNode *>, 4> MDForInst;
    for (Module::const_iterator FI = M.begin(), E = M.end(); FI != E; ++FI) {
        incorporateType(FI->getType());

        if (FI->hasPrefixData())
            incorporateValue(FI->getPrefixData());

        if (FI->hasPrologueData())
            incorporateValue(FI->getPrologueData());

        if (FI->hasPersonalityFn())
            incorporateValue(FI->getPersonalityFn());

        // First incorporate the arguments.
        for (Function::const_arg_iterator AI = FI->arg_begin(),
                AE = FI->arg_end(); AI != AE; ++AI)
            incorporateValue(AI);

        for (Function::const_iterator BB = FI->begin(), E = FI->end();
                BB != E; ++BB)
            for (BasicBlock::const_iterator II = BB->begin(),
                    E = BB->end(); II != E; ++II) {
                const Instruction &I = *II;

                // Incorporate the type of the instruction.
                incorporateType(I.getType());

                // Incorporate non-instruction operand types. (We are incorporating all
                // instructions with this loop.)
                for (User::const_op_iterator OI = I.op_begin(), OE = I.op_end();
                        OI != OE; ++OI)
                    if (*OI && !isa<Instruction>(OI))
                        incorporateValue(*OI);

                // Incorporate types hiding in metadata.
                I.getAllMetadataOtherThanDebugLoc(MDForInst);
                for (unsigned i = 0, e = MDForInst.size(); i != e; ++i)
                    incorporateMDNode(MDForInst[i].second);

                MDForInst.clear();
            }
    }

    for (Module::const_named_metadata_iterator I = M.named_metadata_begin(),
            E = M.named_metadata_end(); I != E; ++I) {
        const NamedMDNode *NMD = I;
        for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
            incorporateMDNode(NMD->getOperand(i));
    }
}
Example #15
0
void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
  Fn = &fn;
  MF = &mf;
  RegInfo = &MF->getRegInfo();

  // Check whether the function can return without sret-demotion.
  SmallVector<ISD::OutputArg, 4> Outs;
  GetReturnInfo(Fn->getReturnType(),
                Fn->getAttributes().getRetAttributes(), Outs, TLI);
  CanLowerReturn = TLI.CanLowerReturn(Fn->getCallingConv(), *MF,
				      Fn->isVarArg(),
                                      Outs, Fn->getContext());

  // Initialize the mapping of values to registers.  This is only set up for
  // instruction values that are used outside of the block that defines
  // them.
  Function::const_iterator BB = Fn->begin(), EB = Fn->end();
  for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
    if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
      if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
        const Type *Ty = AI->getAllocatedType();
        uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
        unsigned Align =
          std::max((unsigned)TLI.getTargetData()->getPrefTypeAlignment(Ty),
                   AI->getAlignment());

        TySize *= CUI->getZExtValue();   // Get total allocated size.
        if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.

        // The object may need to be placed onto the stack near the stack
        // protector if one exists. Determine here if this object is a suitable
        // candidate. I.e., it would trigger the creation of a stack protector.
        bool MayNeedSP =
          (AI->isArrayAllocation() ||
           (TySize > 8 && isa<ArrayType>(Ty) &&
            cast<ArrayType>(Ty)->getElementType()->isIntegerTy(8)));
        StaticAllocaMap[AI] =
          MF->getFrameInfo()->CreateStackObject(TySize, Align, false, MayNeedSP);
      }

  for (; BB != EB; ++BB)
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
      // Mark values used outside their block as exported, by allocating
      // a virtual register for them.
      if (isUsedOutsideOfDefiningBlock(I))
        if (!isa<AllocaInst>(I) ||
            !StaticAllocaMap.count(cast<AllocaInst>(I)))
          InitializeRegForValue(I);

      // Collect llvm.dbg.declare information. This is done now instead of
      // during the initial isel pass through the IR so that it is done
      // in a predictable order.
      if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
        MachineModuleInfo &MMI = MF->getMMI();
        if (MMI.hasDebugInfo() &&
            DIVariable(DI->getVariable()).Verify() &&
            !DI->getDebugLoc().isUnknown()) {
          // Don't handle byval struct arguments or VLAs, for example.
          // Non-byval arguments are handled here (they refer to the stack
          // temporary alloca at this point).
          const Value *Address = DI->getAddress();
          if (Address) {
            if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
              Address = BCI->getOperand(0);
            if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
              DenseMap<const AllocaInst *, int>::iterator SI =
                StaticAllocaMap.find(AI);
              if (SI != StaticAllocaMap.end()) { // Check for VLAs.
                int FI = SI->second;
                MMI.setVariableDbgInfo(DI->getVariable(),
                                       FI, DI->getDebugLoc());
              }
            }
          }
        }
      }
    }

  // Create an initial MachineBasicBlock for each LLVM BasicBlock in F.  This
  // also creates the initial PHI MachineInstrs, though none of the input
  // operands are populated.
  for (BB = Fn->begin(); BB != EB; ++BB) {
    MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
    MBBMap[BB] = MBB;
    MF->push_back(MBB);

    // Transfer the address-taken flag. This is necessary because there could
    // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
    // the first one should be marked.
    if (BB->hasAddressTaken())
      MBB->setHasAddressTaken();

    // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
    // appropriate.
    for (BasicBlock::const_iterator I = BB->begin();
         const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
      if (PN->use_empty()) continue;

      // Skip empty types
      if (PN->getType()->isEmptyTy())
        continue;

      DebugLoc DL = PN->getDebugLoc();
      unsigned PHIReg = ValueMap[PN];
      assert(PHIReg && "PHI node does not have an assigned virtual register!");

      SmallVector<EVT, 4> ValueVTs;
      ComputeValueVTs(TLI, PN->getType(), ValueVTs);
      for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
        EVT VT = ValueVTs[vti];
        unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
        const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
        for (unsigned i = 0; i != NumRegisters; ++i)
          BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
        PHIReg += NumRegisters;
      }
    }
  }

  // Mark landing pad blocks.
  for (BB = Fn->begin(); BB != EB; ++BB)
    if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
      MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
}
/// NaClValueEnumerator - Enumerate module-level information.
NaClValueEnumerator::NaClValueEnumerator(const Module *M) {
  // Create map for counting frequency of types, and set field
  // TypeCountMap accordingly.  Note: Pointer field TypeCountMap is
  // used to deal with the fact that types are added through various
  // method calls in this routine. Rather than pass it as an argument,
  // we use a field. The field is a pointer so that the memory
  // footprint of count_map can be garbage collected when this
  // constructor completes.
  TypeCountMapType count_map;
  TypeCountMap = &count_map;
  // Enumerate the global variables.
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    EnumerateValue(I);

  // Enumerate the functions.
  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
    EnumerateValue(I);
    EnumerateAttributes(cast<Function>(I)->getAttributes());
  }

  // Enumerate the aliases.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I);

  // Remember what is the cutoff between globalvalue's and other constants.
  unsigned FirstConstant = Values.size();

  // Enumerate the global variable initializers.
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    if (I->hasInitializer())
      EnumerateValue(I->getInitializer());

  // Enumerate the aliasees.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I->getAliasee());

  // Insert constants and metadata that are named at module level into the slot
  // pool so that the module symbol table can refer to them...
  EnumerateValueSymbolTable(M->getValueSymbolTable());
  EnumerateNamedMetadata(M);

  SmallVector<std::pair<unsigned, MDNode*>, 8> MDs;

  // Enumerate types used by function bodies and argument lists.
  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {

    for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
         I != E; ++I)
      EnumerateType(I->getType());

    for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
      for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
        for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
             OI != E; ++OI) {
          if (MDNode *MD = dyn_cast<MDNode>(*OI))
            if (MD->isFunctionLocal() && MD->getFunction())
              // These will get enumerated during function-incorporation.
              continue;
          EnumerateOperandType(*OI);
        }
        EnumerateType(I->getType());
        if (const CallInst *CI = dyn_cast<CallInst>(I))
          EnumerateAttributes(CI->getAttributes());
        else if (const InvokeInst *II = dyn_cast<InvokeInst>(I))
          EnumerateAttributes(II->getAttributes());

        // Enumerate metadata attached with this instruction.
        MDs.clear();
        I->getAllMetadataOtherThanDebugLoc(MDs);
        for (unsigned i = 0, e = MDs.size(); i != e; ++i)
          EnumerateMetadata(MDs[i].second);

        if (!I->getDebugLoc().isUnknown()) {
          MDNode *Scope, *IA;
          I->getDebugLoc().getScopeAndInlinedAt(Scope, IA, I->getContext());
          if (Scope) EnumerateMetadata(Scope);
          if (IA) EnumerateMetadata(IA);
        }
      }
  }

  // Optimized type indicies to put "common" expected types in with small
  // indices.
  OptimizeTypes(M);
  TypeCountMap = NULL;

  // Optimize constant ordering.
  OptimizeConstants(FirstConstant, Values.size());
}
Example #17
0
/// ValueEnumerator - Enumerate module-level information.
ValueEnumerator::ValueEnumerator(const Module *M) {
  InstructionCount = 0;

  // Enumerate the global variables.
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    EnumerateValue(I);

  // Enumerate the functions.
  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
    EnumerateValue(I);
    EnumerateAttributes(cast<Function>(I)->getAttributes());
  }

  // Enumerate the aliases.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I);

  // Remember what is the cutoff between globalvalue's and other constants.
  unsigned FirstConstant = Values.size();

  // Enumerate the global variable initializers.
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    if (I->hasInitializer())
      EnumerateValue(I->getInitializer());

  // Enumerate the aliasees.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I->getAliasee());

  // Enumerate types used by the type symbol table.
  EnumerateTypeSymbolTable(M->getTypeSymbolTable());

  // Insert constants that are named at module level into the slot pool so that
  // the module symbol table can refer to them...
  EnumerateValueSymbolTable(M->getValueSymbolTable());

  // Enumerate types used by function bodies and argument lists.
  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {

    for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
         I != E; ++I)
      EnumerateType(I->getType());

    MetadataContext &TheMetadata = F->getContext().getMetadata();
    typedef SmallVector<std::pair<unsigned, TrackingVH<MDNode> >, 2> MDMapTy;
    MDMapTy MDs;
    for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
      for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
        for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
             OI != E; ++OI)
          EnumerateOperandType(*OI);
        EnumerateType(I->getType());
        if (const CallInst *CI = dyn_cast<CallInst>(I))
          EnumerateAttributes(CI->getAttributes());
        else if (const InvokeInst *II = dyn_cast<InvokeInst>(I))
          EnumerateAttributes(II->getAttributes());

        // Enumerate metadata attached with this instruction.
        MDs.clear();
        TheMetadata.getMDs(I, MDs);
        for (MDMapTy::const_iterator MI = MDs.begin(), ME = MDs.end(); MI != ME;
             ++MI)
          EnumerateMetadata(MI->second);
      }
  }

  // Optimize constant ordering.
  OptimizeConstants(FirstConstant, Values.size());

  // Sort the type table by frequency so that most commonly used types are early
  // in the table (have low bit-width).
  std::stable_sort(Types.begin(), Types.end(), CompareByFrequency);

  // Partition the Type ID's so that the single-value types occur before the
  // aggregate types.  This allows the aggregate types to be dropped from the
  // type table after parsing the global variable initializers.
  std::partition(Types.begin(), Types.end(), isSingleValueType);

  // Now that we rearranged the type table, rebuild TypeMap.
  for (unsigned i = 0, e = Types.size(); i != e; ++i)
    TypeMap[Types[i].first] = i+1;
}
/// ValueEnumerator - Enumerate module-level information.
ValueEnumerator::ValueEnumerator(const Module *M) {
  // Enumerate the global variables.
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    EnumerateValue(I);

  // Enumerate the functions.
  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
    EnumerateValue(I);
    EnumerateParamAttrs(cast<Function>(I)->getParamAttrs());
  }

  // Enumerate the aliases.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I);
  
  // Remember what is the cutoff between globalvalue's and other constants.
  unsigned FirstConstant = Values.size();
  
  // Enumerate the global variable initializers.
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    if (I->hasInitializer())
      EnumerateValue(I->getInitializer());

  // Enumerate the aliasees.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I->getAliasee());
  
  // Enumerate types used by the type symbol table.
  EnumerateTypeSymbolTable(M->getTypeSymbolTable());

  // Insert constants that are named at module level into the slot pool so that
  // the module symbol table can refer to them...
  EnumerateValueSymbolTable(M->getValueSymbolTable());
  
  // Enumerate types used by function bodies and argument lists.
  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {
    
    for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
         I != E; ++I)
      EnumerateType(I->getType());
    
    for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
      for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
        for (User::const_op_iterator OI = I->op_begin(), E = I->op_end(); 
             OI != E; ++OI)
          EnumerateOperandType(*OI);
        EnumerateType(I->getType());
        if (const CallInst *CI = dyn_cast<CallInst>(I))
          EnumerateParamAttrs(CI->getParamAttrs());
        else if (const InvokeInst *II = dyn_cast<InvokeInst>(I))
          EnumerateParamAttrs(II->getParamAttrs());
      }
  }
  
  // Optimize constant ordering.
  OptimizeConstants(FirstConstant, Values.size());
    
  // Sort the type table by frequency so that most commonly used types are early
  // in the table (have low bit-width).
  std::stable_sort(Types.begin(), Types.end(), CompareByFrequency);
    
  // Partition the Type ID's so that the first-class types occur before the
  // aggregate types.  This allows the aggregate types to be dropped from the
  // type table after parsing the global variable initializers.
  std::partition(Types.begin(), Types.end(), isFirstClassType);

  // Now that we rearranged the type table, rebuild TypeMap.
  for (unsigned i = 0, e = Types.size(); i != e; ++i)
    TypeMap[Types[i].first] = i+1;
}
void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
                               SelectionDAG *DAG) {
  Fn = &fn;
  MF = &mf;
  TLI = MF->getSubtarget().getTargetLowering();
  RegInfo = &MF->getRegInfo();
  MachineModuleInfo &MMI = MF->getMMI();

  // Check whether the function can return without sret-demotion.
  SmallVector<ISD::OutputArg, 4> Outs;
  GetReturnInfo(Fn->getReturnType(), Fn->getAttributes(), Outs, *TLI);
  CanLowerReturn = TLI->CanLowerReturn(Fn->getCallingConv(), *MF,
                                       Fn->isVarArg(), Outs, Fn->getContext());

  // Initialize the mapping of values to registers.  This is only set up for
  // instruction values that are used outside of the block that defines
  // them.
  Function::const_iterator BB = Fn->begin(), EB = Fn->end();
  for (; BB != EB; ++BB)
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
         I != E; ++I) {
      if (const AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
        // Static allocas can be folded into the initial stack frame adjustment.
        if (AI->isStaticAlloca()) {
          const ConstantInt *CUI = cast<ConstantInt>(AI->getArraySize());
          Type *Ty = AI->getAllocatedType();
          uint64_t TySize = TLI->getDataLayout()->getTypeAllocSize(Ty);
          unsigned Align =
              std::max((unsigned)TLI->getDataLayout()->getPrefTypeAlignment(Ty),
                       AI->getAlignment());

          TySize *= CUI->getZExtValue();   // Get total allocated size.
          if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.

          StaticAllocaMap[AI] =
            MF->getFrameInfo()->CreateStackObject(TySize, Align, false, AI);

        } else {
          unsigned Align = std::max(
              (unsigned)TLI->getDataLayout()->getPrefTypeAlignment(
                AI->getAllocatedType()),
              AI->getAlignment());
          unsigned StackAlign =
              MF->getSubtarget().getFrameLowering()->getStackAlignment();
          if (Align <= StackAlign)
            Align = 0;
          // Inform the Frame Information that we have variable-sized objects.
          MF->getFrameInfo()->CreateVariableSizedObject(Align ? Align : 1, AI);
        }
      }

      // Look for inline asm that clobbers the SP register.
      if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
        ImmutableCallSite CS(I);
        if (isa<InlineAsm>(CS.getCalledValue())) {
          unsigned SP = TLI->getStackPointerRegisterToSaveRestore();
          const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
          std::vector<TargetLowering::AsmOperandInfo> Ops =
              TLI->ParseConstraints(TRI, CS);
          for (size_t I = 0, E = Ops.size(); I != E; ++I) {
            TargetLowering::AsmOperandInfo &Op = Ops[I];
            if (Op.Type == InlineAsm::isClobber) {
              // Clobbers don't have SDValue operands, hence SDValue().
              TLI->ComputeConstraintToUse(Op, SDValue(), DAG);
              std::pair<unsigned, const TargetRegisterClass *> PhysReg =
                  TLI->getRegForInlineAsmConstraint(TRI, Op.ConstraintCode,
                                                    Op.ConstraintVT);
              if (PhysReg.first == SP)
                MF->getFrameInfo()->setHasInlineAsmWithSPAdjust(true);
            }
          }
        }
      }

      // Look for calls to the @llvm.va_start intrinsic. We can omit some
      // prologue boilerplate for variadic functions that don't examine their
      // arguments.
      if (const auto *II = dyn_cast<IntrinsicInst>(I)) {
        if (II->getIntrinsicID() == Intrinsic::vastart)
          MF->getFrameInfo()->setHasVAStart(true);
      }

      // If we have a musttail call in a variadic funciton, we need to ensure we
      // forward implicit register parameters.
      if (const auto *CI = dyn_cast<CallInst>(I)) {
        if (CI->isMustTailCall() && Fn->isVarArg())
          MF->getFrameInfo()->setHasMustTailInVarArgFunc(true);
      }

      // Mark values used outside their block as exported, by allocating
      // a virtual register for them.
      if (isUsedOutsideOfDefiningBlock(I))
        if (!isa<AllocaInst>(I) ||
            !StaticAllocaMap.count(cast<AllocaInst>(I)))
          InitializeRegForValue(I);

      // Collect llvm.dbg.declare information. This is done now instead of
      // during the initial isel pass through the IR so that it is done
      // in a predictable order.
      if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
        assert(DI->getVariable() && "Missing variable");
        assert(DI->getDebugLoc() && "Missing location");
        if (MMI.hasDebugInfo()) {
          // Don't handle byval struct arguments or VLAs, for example.
          // Non-byval arguments are handled here (they refer to the stack
          // temporary alloca at this point).
          const Value *Address = DI->getAddress();
          if (Address) {
            if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
              Address = BCI->getOperand(0);
            if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
              DenseMap<const AllocaInst *, int>::iterator SI =
                StaticAllocaMap.find(AI);
              if (SI != StaticAllocaMap.end()) { // Check for VLAs.
                int FI = SI->second;
                MMI.setVariableDbgInfo(DI->getVariable(), DI->getExpression(),
                                       FI, DI->getDebugLoc());
              }
            }
          }
        }
      }

      // Decide the preferred extend type for a value.
      PreferredExtendType[I] = getPreferredExtendForValue(I);
    }

  // Create an initial MachineBasicBlock for each LLVM BasicBlock in F.  This
  // also creates the initial PHI MachineInstrs, though none of the input
  // operands are populated.
  for (BB = Fn->begin(); BB != EB; ++BB) {
    MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
    MBBMap[BB] = MBB;
    MF->push_back(MBB);

    // Transfer the address-taken flag. This is necessary because there could
    // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
    // the first one should be marked.
    if (BB->hasAddressTaken())
      MBB->setHasAddressTaken();

    // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
    // appropriate.
    for (BasicBlock::const_iterator I = BB->begin();
         const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
      if (PN->use_empty()) continue;

      // Skip empty types
      if (PN->getType()->isEmptyTy())
        continue;

      DebugLoc DL = PN->getDebugLoc();
      unsigned PHIReg = ValueMap[PN];
      assert(PHIReg && "PHI node does not have an assigned virtual register!");

      SmallVector<EVT, 4> ValueVTs;
      ComputeValueVTs(*TLI, PN->getType(), ValueVTs);
      for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
        EVT VT = ValueVTs[vti];
        unsigned NumRegisters = TLI->getNumRegisters(Fn->getContext(), VT);
        const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
        for (unsigned i = 0; i != NumRegisters; ++i)
          BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
        PHIReg += NumRegisters;
      }
    }
  }

  // Mark landing pad blocks.
  SmallVector<const LandingPadInst *, 4> LPads;
  for (BB = Fn->begin(); BB != EB; ++BB) {
    if (const auto *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
      MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
    if (BB->isLandingPad())
      LPads.push_back(BB->getLandingPadInst());
  }

  // If this is an MSVC EH personality, we need to do a bit more work.
  EHPersonality Personality = EHPersonality::Unknown;
  if (!LPads.empty())
    Personality = classifyEHPersonality(LPads.back()->getPersonalityFn());
  if (!isMSVCEHPersonality(Personality))
    return;

  if (Personality == EHPersonality::MSVC_Win64SEH ||
      Personality == EHPersonality::MSVC_X86SEH) {
    addSEHHandlersForLPads(LPads);
  }

  WinEHFuncInfo &EHInfo = MMI.getWinEHFuncInfo(&fn);
  if (Personality == EHPersonality::MSVC_CXX) {
    const Function *WinEHParentFn = MMI.getWinEHParent(&fn);
    calculateWinCXXEHStateNumbers(WinEHParentFn, EHInfo);
  }

  // Copy the state numbers to LandingPadInfo for the current function, which
  // could be a handler or the parent. This should happen for 32-bit SEH and
  // C++ EH.
  if (Personality == EHPersonality::MSVC_CXX ||
      Personality == EHPersonality::MSVC_X86SEH) {
    for (const LandingPadInst *LP : LPads) {
      MachineBasicBlock *LPadMBB = MBBMap[LP->getParent()];
      MMI.addWinEHState(LPadMBB, EHInfo.LandingPadStateMap[LP]);
    }
  }
}
Example #20
0
/// analyzeFunction - Fill in the current structure with information gleaned
/// from the specified function.
void InlineCostAnalyzer::FunctionInfo::analyzeFunction(Function *F) {
  unsigned NumInsts = 0, NumBlocks = 0, NumVectorInsts = 0;

  // Look at the size of the callee.  Each basic block counts as 20 units, and
  // each instruction counts as 5.
  for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
    for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
         II != E; ++II) {
      if (isa<PHINode>(II)) continue;           // PHI nodes don't count.

      // Special handling for calls.
      if (isa<CallInst>(II) || isa<InvokeInst>(II)) {
        if (isa<DbgInfoIntrinsic>(II))
          continue;  // Debug intrinsics don't count as size.
        
        CallSite CS = CallSite::get(const_cast<Instruction*>(&*II));
        
        // If this function contains a call to setjmp or _setjmp, never inline
        // it.  This is a hack because we depend on the user marking their local
        // variables as volatile if they are live across a setjmp call, and they
        // probably won't do this in callers.
        if (Function *F = CS.getCalledFunction())
          if (F->isDeclaration() && 
              (F->isName("setjmp") || F->isName("_setjmp"))) {
            NeverInline = true;
            return;
          }

        // Calls often compile into many machine instructions.  Bump up their
        // cost to reflect this.
        if (!isa<IntrinsicInst>(II))
          NumInsts += 5;
      }
      
      if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
        if (!AI->isStaticAlloca())
          this->usesDynamicAlloca = true;
      }

      if (isa<ExtractElementInst>(II) || isa<VectorType>(II->getType()))
        ++NumVectorInsts; 
      
      // Noop casts, including ptr <-> int,  don't count.
      if (const CastInst *CI = dyn_cast<CastInst>(II)) {
        if (CI->isLosslessCast() || isa<IntToPtrInst>(CI) || 
            isa<PtrToIntInst>(CI))
          continue;
      } else if (const GetElementPtrInst *GEPI =
                 dyn_cast<GetElementPtrInst>(II)) {
        // If a GEP has all constant indices, it will probably be folded with
        // a load/store.
        bool AllConstant = true;
        for (unsigned i = 1, e = GEPI->getNumOperands(); i != e; ++i)
          if (!isa<ConstantInt>(GEPI->getOperand(i))) {
            AllConstant = false;
            break;
          }
        if (AllConstant) continue;
      }
      
      ++NumInsts;
    }

    ++NumBlocks;
  }

  this->NumBlocks      = NumBlocks;
  this->NumInsts       = NumInsts;
  this->NumVectorInsts = NumVectorInsts;

  // Check out all of the arguments to the function, figuring out how much
  // code can be eliminated if one of the arguments is a constant.
  for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I)
    ArgumentWeights.push_back(ArgInfo(CountCodeReductionForConstant(I),
                                      CountCodeReductionForAlloca(I)));
}
Example #21
0
/// DebugACrash - Given a predicate that determines whether a component crashes
/// on a program, try to destructively reduce the program while still keeping
/// the predicate true.
static bool DebugACrash(BugDriver &BD,
                        bool (*TestFn)(const BugDriver &, Module *),
                        std::string &Error) {
  // See if we can get away with nuking some of the global variable initializers
  // in the program...
  if (!NoGlobalRM &&
      BD.getProgram()->global_begin() != BD.getProgram()->global_end()) {
    // Now try to reduce the number of global variable initializers in the
    // module to something small.
    Module *M = CloneModule(BD.getProgram());
    bool DeletedInit = false;

    for (Module::global_iterator I = M->global_begin(), E = M->global_end();
         I != E; ++I)
      if (I->hasInitializer()) {
        I->setInitializer(nullptr);
        I->setLinkage(GlobalValue::ExternalLinkage);
        DeletedInit = true;
      }

    if (!DeletedInit) {
      delete M;  // No change made...
    } else {
      // See if the program still causes a crash...
      outs() << "\nChecking to see if we can delete global inits: ";

      if (TestFn(BD, M)) {      // Still crashes?
        BD.setNewProgram(M);
        outs() << "\n*** Able to remove all global initializers!\n";
      } else {                  // No longer crashes?
        outs() << "  - Removing all global inits hides problem!\n";
        delete M;

        std::vector<GlobalVariable*> GVs;

        for (Module::global_iterator I = BD.getProgram()->global_begin(),
               E = BD.getProgram()->global_end(); I != E; ++I)
          if (I->hasInitializer())
            GVs.push_back(&*I);

        if (GVs.size() > 1 && !BugpointIsInterrupted) {
          outs() << "\n*** Attempting to reduce the number of global "
                    << "variables in the testcase\n";

          unsigned OldSize = GVs.size();
          ReduceCrashingGlobalVariables(BD, TestFn).reduceList(GVs, Error);
          if (!Error.empty())
            return true;

          if (GVs.size() < OldSize)
            BD.EmitProgressBitcode(BD.getProgram(), "reduced-global-variables");
        }
      }
    }
  }

  // Now try to reduce the number of functions in the module to something small.
  std::vector<Function*> Functions;
  for (Function &F : *BD.getProgram())
    if (!F.isDeclaration())
      Functions.push_back(&F);

  if (Functions.size() > 1 && !BugpointIsInterrupted) {
    outs() << "\n*** Attempting to reduce the number of functions "
      "in the testcase\n";

    unsigned OldSize = Functions.size();
    ReduceCrashingFunctions(BD, TestFn).reduceList(Functions, Error);

    if (Functions.size() < OldSize)
      BD.EmitProgressBitcode(BD.getProgram(), "reduced-function");
  }

  // Attempt to delete entire basic blocks at a time to speed up
  // convergence... this actually works by setting the terminator of the blocks
  // to a return instruction then running simplifycfg, which can potentially
  // shrinks the code dramatically quickly
  //
  if (!DisableSimplifyCFG && !BugpointIsInterrupted) {
    std::vector<const BasicBlock*> Blocks;
    for (Function &F : *BD.getProgram())
      for (BasicBlock &BB : F)
        Blocks.push_back(&BB);
    unsigned OldSize = Blocks.size();
    ReduceCrashingBlocks(BD, TestFn).reduceList(Blocks, Error);
    if (Blocks.size() < OldSize)
      BD.EmitProgressBitcode(BD.getProgram(), "reduced-blocks");
  }

  // Attempt to delete instructions using bisection. This should help out nasty
  // cases with large basic blocks where the problem is at one end.
  if (!BugpointIsInterrupted) {
    std::vector<const Instruction*> Insts;
    for (const Function &F : *BD.getProgram())
      for (const BasicBlock &BB : F)
        for (const Instruction &I : BB)
          if (!isa<TerminatorInst>(&I))
            Insts.push_back(&I);

    ReduceCrashingInstructions(BD, TestFn).reduceList(Insts, Error);
  }

  // FIXME: This should use the list reducer to converge faster by deleting
  // larger chunks of instructions at a time!
  unsigned Simplification = 2;
  do {
    if (BugpointIsInterrupted) break;
    --Simplification;
    outs() << "\n*** Attempting to reduce testcase by deleting instruc"
           << "tions: Simplification Level #" << Simplification << '\n';

    // Now that we have deleted the functions that are unnecessary for the
    // program, try to remove instructions that are not necessary to cause the
    // crash.  To do this, we loop through all of the instructions in the
    // remaining functions, deleting them (replacing any values produced with
    // nulls), and then running ADCE and SimplifyCFG.  If the transformed input
    // still triggers failure, keep deleting until we cannot trigger failure
    // anymore.
    //
    unsigned InstructionsToSkipBeforeDeleting = 0;
  TryAgain:

    // Loop over all of the (non-terminator) instructions remaining in the
    // function, attempting to delete them.
    unsigned CurInstructionNum = 0;
    for (Module::const_iterator FI = BD.getProgram()->begin(),
           E = BD.getProgram()->end(); FI != E; ++FI)
      if (!FI->isDeclaration())
        for (Function::const_iterator BI = FI->begin(), E = FI->end(); BI != E;
             ++BI)
          for (BasicBlock::const_iterator I = BI->begin(), E = --BI->end();
               I != E; ++I, ++CurInstructionNum) {
            if (InstructionsToSkipBeforeDeleting) {
              --InstructionsToSkipBeforeDeleting;
            } else {
              if (BugpointIsInterrupted) goto ExitLoops;

              if (isa<LandingPadInst>(I))
                continue;

              outs() << "Checking instruction: " << *I;
              std::unique_ptr<Module> M =
                  BD.deleteInstructionFromProgram(&*I, Simplification);

              // Find out if the pass still crashes on this pass...
              if (TestFn(BD, M.get())) {
                // Yup, it does, we delete the old module, and continue trying
                // to reduce the testcase...
                BD.setNewProgram(M.release());
                InstructionsToSkipBeforeDeleting = CurInstructionNum;
                goto TryAgain;  // I wish I had a multi-level break here!
              }
            }
          }

    if (InstructionsToSkipBeforeDeleting) {
      InstructionsToSkipBeforeDeleting = 0;
      goto TryAgain;
    }

  } while (Simplification);
ExitLoops:

  // Try to clean up the testcase by running funcresolve and globaldce...
  if (!BugpointIsInterrupted) {
    outs() << "\n*** Attempting to perform final cleanups: ";
    Module *M = CloneModule(BD.getProgram());
    M = BD.performFinalCleanups(M, true).release();

    // Find out if the pass still crashes on the cleaned up program...
    if (TestFn(BD, M)) {
      BD.setNewProgram(M);     // Yup, it does, keep the reduced version...
    } else {
      delete M;
    }
  }

  BD.EmitProgressBitcode(BD.getProgram(), "reduced-simplified");

  return false;
}
/// NaClValueEnumerator - Enumerate module-level information.
NaClValueEnumerator::NaClValueEnumerator(const Module *M) {
  // Create map for counting frequency of types, and set field
  // TypeCountMap accordingly.  Note: Pointer field TypeCountMap is
  // used to deal with the fact that types are added through various
  // method calls in this routine. Rather than pass it as an argument,
  // we use a field. The field is a pointer so that the memory
  // footprint of count_map can be garbage collected when this
  // constructor completes.
  TypeCountMapType count_map;
  TypeCountMap = &count_map;

  IntPtrType = IntegerType::get(M->getContext(), PNaClIntPtrTypeBitSize);

  // Enumerate the functions. Note: We do this before global
  // variables, so that global variable initializations can refer to
  // the functions without a forward reference.
  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
    EnumerateValue(I);
  }

  // Enumerate the global variables.
  FirstGlobalVarID = Values.size();
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    EnumerateValue(I);
  NumGlobalVarIDs = Values.size() - FirstGlobalVarID;

  // Enumerate the aliases.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I);

  // Remember what is the cutoff between globalvalue's and other constants.
  unsigned FirstConstant = Values.size();

  // Skip global variable initializers since they are handled within
  // WriteGlobalVars of file NaClBitcodeWriter.cpp.

  // Enumerate the aliasees.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I->getAliasee());

  // Insert constants that are named at module level into the slot
  // pool so that the module symbol table can refer to them...
  EnumerateValueSymbolTable(M->getValueSymbolTable());

  // Enumerate types used by function bodies and argument lists.
  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {

    for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
         I != E; ++I)
      EnumerateType(I->getType());

    for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
      for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
        // Don't generate types for elided pointer casts!
        if (IsElidedCast(I))
          continue;

        if (const SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
          // Handle switch instruction specially, so that we don't
          // write out unnecessary vector/array types used to model case
          // selectors.
          EnumerateOperandType(SI->getCondition());
        } else {
          for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
               OI != E; ++OI) {
            EnumerateOperandType(*OI);
          }
        }
        EnumerateType(I->getType());
      }
  }

  // Optimized type indicies to put "common" expected types in with small
  // indices.
  OptimizeTypes(M);
  TypeCountMap = NULL;

  // Optimize constant ordering.
  OptimizeConstants(FirstConstant, Values.size());
}
void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf) {
  Fn = &fn;
  MF = &mf;
  RegInfo = &MF->getRegInfo();

  // Create a vreg for each argument register that is not dead and is used
  // outside of the entry block for the function.
  for (Function::const_arg_iterator AI = Fn->arg_begin(), E = Fn->arg_end();
       AI != E; ++AI)
    if (!isOnlyUsedInEntryBlock(AI, EnableFastISel))
      InitializeRegForValue(AI);

  // Initialize the mapping of values to registers.  This is only set up for
  // instruction values that are used outside of the block that defines
  // them.
  Function::const_iterator BB = Fn->begin(), EB = Fn->end();
  for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
    if (const AllocaInst *AI = dyn_cast<AllocaInst>(I))
      if (const ConstantInt *CUI = dyn_cast<ConstantInt>(AI->getArraySize())) {
        const Type *Ty = AI->getAllocatedType();
        uint64_t TySize = TLI.getTargetData()->getTypeAllocSize(Ty);
        unsigned Align =
          std::max((unsigned)TLI.getTargetData()->getPrefTypeAlignment(Ty),
                   AI->getAlignment());

        TySize *= CUI->getZExtValue();   // Get total allocated size.
        if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
        StaticAllocaMap[AI] =
          MF->getFrameInfo()->CreateStackObject(TySize, Align, false);
      }

  for (; BB != EB; ++BB)
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I)
      if (isUsedOutsideOfDefiningBlock(I))
        if (!isa<AllocaInst>(I) ||
            !StaticAllocaMap.count(cast<AllocaInst>(I)))
          InitializeRegForValue(I);

  // Create an initial MachineBasicBlock for each LLVM BasicBlock in F.  This
  // also creates the initial PHI MachineInstrs, though none of the input
  // operands are populated.
  for (BB = Fn->begin(); BB != EB; ++BB) {
    MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(BB);
    MBBMap[BB] = MBB;
    MF->push_back(MBB);

    // Transfer the address-taken flag. This is necessary because there could
    // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
    // the first one should be marked.
    if (BB->hasAddressTaken())
      MBB->setHasAddressTaken();

    // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
    // appropriate.
    for (BasicBlock::const_iterator I = BB->begin();
         const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
      if (PN->use_empty()) continue;

      DebugLoc DL = PN->getDebugLoc();
      unsigned PHIReg = ValueMap[PN];
      assert(PHIReg && "PHI node does not have an assigned virtual register!");

      SmallVector<EVT, 4> ValueVTs;
      ComputeValueVTs(TLI, PN->getType(), ValueVTs);
      for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
        EVT VT = ValueVTs[vti];
        unsigned NumRegisters = TLI.getNumRegisters(Fn->getContext(), VT);
        const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
        for (unsigned i = 0; i != NumRegisters; ++i)
          BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
        PHIReg += NumRegisters;
      }
    }
  }

  // Mark landing pad blocks.
  for (BB = Fn->begin(); BB != EB; ++BB)
    if (const InvokeInst *Invoke = dyn_cast<InvokeInst>(BB->getTerminator()))
      MBBMap[Invoke->getSuccessor(1)]->setIsLandingPad();
}
Example #24
0
/// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
/// except that it does some simple constant prop and DCE on the fly.  The
/// effect of this is to copy significantly less code in cases where (for
/// example) a function call with constant arguments is inlined, and those
/// constant arguments cause a significant amount of code in the callee to be
/// dead.  Since this doesn't produce an exact copy of the input, it can't be
/// used for things like CloneFunction or CloneModule.
void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
                                     ValueToValueMapTy &VMap,
                                     bool ModuleLevelChanges,
                                     SmallVectorImpl<ReturnInst*> &Returns,
                                     const char *NameSuffix,
                                     ClonedCodeInfo *CodeInfo,
                                     const DataLayout *DL,
                                     Instruction *TheCall) {
  assert(NameSuffix && "NameSuffix cannot be null!");

#ifndef NDEBUG
  for (Function::const_arg_iterator II = OldFunc->arg_begin(),
       E = OldFunc->arg_end(); II != E; ++II)
    assert(VMap.count(II) && "No mapping from source argument specified!");
#endif

  PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
                            NameSuffix, CodeInfo, DL);

  // Clone the entry block, and anything recursively reachable from it.
  std::vector<const BasicBlock*> CloneWorklist;
  CloneWorklist.push_back(&OldFunc->getEntryBlock());
  while (!CloneWorklist.empty()) {
    const BasicBlock *BB = CloneWorklist.back();
    CloneWorklist.pop_back();
    PFC.CloneBlock(BB, CloneWorklist);
  }

  // Loop over all of the basic blocks in the old function.  If the block was
  // reachable, we have cloned it and the old block is now in the value map:
  // insert it into the new function in the right order.  If not, ignore it.
  //
  // Defer PHI resolution until rest of function is resolved.
  SmallVector<const PHINode*, 16> PHIToResolve;
  for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
       BI != BE; ++BI) {
    Value *V = VMap[BI];
    BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
    if (!NewBB) continue;  // Dead block.

    // Add the new block to the new function.
    NewFunc->getBasicBlockList().push_back(NewBB);

    // Handle PHI nodes specially, as we have to remove references to dead
    // blocks.
    for (BasicBlock::const_iterator I = BI->begin(), E = BI->end(); I != E; ++I)
      if (const PHINode *PN = dyn_cast<PHINode>(I))
        PHIToResolve.push_back(PN);
      else
        break;

    // Finally, remap the terminator instructions, as those can't be remapped
    // until all BBs are mapped.
    RemapInstruction(NewBB->getTerminator(), VMap,
                     ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
  }

  // Defer PHI resolution until rest of function is resolved, PHI resolution
  // requires the CFG to be up-to-date.
  for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
    const PHINode *OPN = PHIToResolve[phino];
    unsigned NumPreds = OPN->getNumIncomingValues();
    const BasicBlock *OldBB = OPN->getParent();
    BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);

    // Map operands for blocks that are live and remove operands for blocks
    // that are dead.
    for (; phino != PHIToResolve.size() &&
         PHIToResolve[phino]->getParent() == OldBB; ++phino) {
      OPN = PHIToResolve[phino];
      PHINode *PN = cast<PHINode>(VMap[OPN]);
      for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
        Value *V = VMap[PN->getIncomingBlock(pred)];
        if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
          Value *InVal = MapValue(PN->getIncomingValue(pred),
                                  VMap,
                        ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
          assert(InVal && "Unknown input value?");
          PN->setIncomingValue(pred, InVal);
          PN->setIncomingBlock(pred, MappedBlock);
        } else {
          PN->removeIncomingValue(pred, false);
          --pred, --e;  // Revisit the next entry.
        }
      }
    }

    // The loop above has removed PHI entries for those blocks that are dead
    // and has updated others.  However, if a block is live (i.e. copied over)
    // but its terminator has been changed to not go to this block, then our
    // phi nodes will have invalid entries.  Update the PHI nodes in this
    // case.
    PHINode *PN = cast<PHINode>(NewBB->begin());
    NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
    if (NumPreds != PN->getNumIncomingValues()) {
      assert(NumPreds < PN->getNumIncomingValues());
      // Count how many times each predecessor comes to this block.
      std::map<BasicBlock*, unsigned> PredCount;
      for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
           PI != E; ++PI)
        --PredCount[*PI];

      // Figure out how many entries to remove from each PHI.
      for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
        ++PredCount[PN->getIncomingBlock(i)];

      // At this point, the excess predecessor entries are positive in the
      // map.  Loop over all of the PHIs and remove excess predecessor
      // entries.
      BasicBlock::iterator I = NewBB->begin();
      for (; (PN = dyn_cast<PHINode>(I)); ++I) {
        for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
             E = PredCount.end(); PCI != E; ++PCI) {
          BasicBlock *Pred     = PCI->first;
          for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
            PN->removeIncomingValue(Pred, false);
        }
      }
    }

    // If the loops above have made these phi nodes have 0 or 1 operand,
    // replace them with undef or the input value.  We must do this for
    // correctness, because 0-operand phis are not valid.
    PN = cast<PHINode>(NewBB->begin());
    if (PN->getNumIncomingValues() == 0) {
      BasicBlock::iterator I = NewBB->begin();
      BasicBlock::const_iterator OldI = OldBB->begin();
      while ((PN = dyn_cast<PHINode>(I++))) {
        Value *NV = UndefValue::get(PN->getType());
        PN->replaceAllUsesWith(NV);
        assert(VMap[OldI] == PN && "VMap mismatch");
        VMap[OldI] = NV;
        PN->eraseFromParent();
        ++OldI;
      }
    }
  }

  // Make a second pass over the PHINodes now that all of them have been
  // remapped into the new function, simplifying the PHINode and performing any
  // recursive simplifications exposed. This will transparently update the
  // WeakVH in the VMap. Notably, we rely on that so that if we coalesce
  // two PHINodes, the iteration over the old PHIs remains valid, and the
  // mapping will just map us to the new node (which may not even be a PHI
  // node).
  for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx)
    if (PHINode *PN = dyn_cast<PHINode>(VMap[PHIToResolve[Idx]]))
      recursivelySimplifyInstruction(PN, DL);

  // Now that the inlined function body has been fully constructed, go through
  // and zap unconditional fall-through branches.  This happen all the time when
  // specializing code: code specialization turns conditional branches into
  // uncond branches, and this code folds them.
  Function::iterator Begin = cast<BasicBlock>(VMap[&OldFunc->getEntryBlock()]);
  Function::iterator I = Begin;
  while (I != NewFunc->end()) {
    // Check if this block has become dead during inlining or other
    // simplifications. Note that the first block will appear dead, as it has
    // not yet been wired up properly.
    if (I != Begin && (pred_begin(I) == pred_end(I) ||
                       I->getSinglePredecessor() == I)) {
      BasicBlock *DeadBB = I++;
      DeleteDeadBlock(DeadBB);
      continue;
    }

    // We need to simplify conditional branches and switches with a constant
    // operand. We try to prune these out when cloning, but if the
    // simplification required looking through PHI nodes, those are only
    // available after forming the full basic block. That may leave some here,
    // and we still want to prune the dead code as early as possible.
    ConstantFoldTerminator(I);

    BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
    if (!BI || BI->isConditional()) { ++I; continue; }

    BasicBlock *Dest = BI->getSuccessor(0);
    if (!Dest->getSinglePredecessor()) {
      ++I; continue;
    }

    // We shouldn't be able to get single-entry PHI nodes here, as instsimplify
    // above should have zapped all of them..
    assert(!isa<PHINode>(Dest->begin()));

    // We know all single-entry PHI nodes in the inlined function have been
    // removed, so we just need to splice the blocks.
    BI->eraseFromParent();

    // Make all PHI nodes that referred to Dest now refer to I as their source.
    Dest->replaceAllUsesWith(I);

    // Move all the instructions in the succ to the pred.
    I->getInstList().splice(I->end(), Dest->getInstList());

    // Remove the dest block.
    Dest->eraseFromParent();

    // Do not increment I, iteratively merge all things this block branches to.
  }

  // Make a final pass over the basic blocks from theh old function to gather
  // any return instructions which survived folding. We have to do this here
  // because we can iteratively remove and merge returns above.
  for (Function::iterator I = cast<BasicBlock>(VMap[&OldFunc->getEntryBlock()]),
                          E = NewFunc->end();
       I != E; ++I)
    if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator()))
      Returns.push_back(RI);
}
Example #25
0
/// ValueEnumerator - Enumerate module-level information.
ValueEnumerator::ValueEnumerator(const Module *M) {
  // Enumerate the global variables.
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    EnumerateValue(I);

  // Enumerate the functions.
  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
    EnumerateValue(I);
    EnumerateAttributes(cast<Function>(I)->getAttributes());
  }

  // Enumerate the aliases.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I);

  // Remember what is the cutoff between globalvalue's and other constants.
  unsigned FirstConstant = Values.size();

  // Enumerate the global variable initializers.
  for (Module::const_global_iterator I = M->global_begin(),
         E = M->global_end(); I != E; ++I)
    if (I->hasInitializer())
      EnumerateValue(I->getInitializer());

  // Enumerate the aliasees.
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I)
    EnumerateValue(I->getAliasee());

  // Enumerate types used by the type symbol table.
  EnumerateTypeSymbolTable(M->getTypeSymbolTable());

  // Insert constants and metadata that are named at module level into the slot 
  // pool so that the module symbol table can refer to them...
  EnumerateValueSymbolTable(M->getValueSymbolTable());
  EnumerateNamedMetadata(M);

  SmallVector<std::pair<unsigned, MDNode*>, 8> MDs;

  // Enumerate types used by function bodies and argument lists.
  for (Module::const_iterator F = M->begin(), E = M->end(); F != E; ++F) {

    for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
         I != E; ++I)
      EnumerateType(I->getType());

    for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
      for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I){
        for (User::const_op_iterator OI = I->op_begin(), E = I->op_end();
             OI != E; ++OI) {
          if (MDNode *MD = dyn_cast<MDNode>(*OI))
            if (MD->isFunctionLocal() && MD->getFunction())
              // These will get enumerated during function-incorporation.
              continue;
          EnumerateOperandType(*OI);
        }
        EnumerateType(I->getType());
        if (const CallInst *CI = dyn_cast<CallInst>(I))
          EnumerateAttributes(CI->getAttributes());
        else if (const InvokeInst *II = dyn_cast<InvokeInst>(I))
          EnumerateAttributes(II->getAttributes());

        // Enumerate metadata attached with this instruction.
        MDs.clear();
        I->getAllMetadataOtherThanDebugLoc(MDs);
        for (unsigned i = 0, e = MDs.size(); i != e; ++i)
          EnumerateMetadata(MDs[i].second);
        
        if (!I->getDebugLoc().isUnknown()) {
          MDNode *Scope, *IA;
          I->getDebugLoc().getScopeAndInlinedAt(Scope, IA, I->getContext());
          if (Scope) EnumerateMetadata(Scope);
          if (IA) EnumerateMetadata(IA);
        }
      }
  }

  // Optimize constant ordering.
  OptimizeConstants(FirstConstant, Values.size());

  // Sort the type table by frequency so that most commonly used types are early
  // in the table (have low bit-width).
  std::stable_sort(Types.begin(), Types.end(), CompareByFrequency);

  // Partition the Type ID's so that the single-value types occur before the
  // aggregate types.  This allows the aggregate types to be dropped from the
  // type table after parsing the global variable initializers.
  std::partition(Types.begin(), Types.end(), isSingleValueType);

  // Now that we rearranged the type table, rebuild TypeMap.
  for (unsigned i = 0, e = Types.size(); i != e; ++i)
    TypeMap[Types[i].first] = i+1;
}
Example #26
0
/// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
/// except that it does some simple constant prop and DCE on the fly.  The
/// effect of this is to copy significantly less code in cases where (for
/// example) a function call with constant arguments is inlined, and those
/// constant arguments cause a significant amount of code in the callee to be
/// dead.  Since this doesn't produce an exact copy of the input, it can't be
/// used for things like CloneFunction or CloneModule.
void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
                                     ValueToValueMapTy &VMap,
                                     bool ModuleLevelChanges,
                                     SmallVectorImpl<ReturnInst*> &Returns,
                                     const char *NameSuffix, 
                                     ClonedCodeInfo *CodeInfo,
                                     const TargetData *TD,
                                     Instruction *TheCall) {
  assert(NameSuffix && "NameSuffix cannot be null!");
  
#ifndef NDEBUG
  for (Function::const_arg_iterator II = OldFunc->arg_begin(), 
       E = OldFunc->arg_end(); II != E; ++II)
    assert(VMap.count(II) && "No mapping from source argument specified!");
#endif

  PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
                            Returns, NameSuffix, CodeInfo, TD);

  // Clone the entry block, and anything recursively reachable from it.
  std::vector<const BasicBlock*> CloneWorklist;
  CloneWorklist.push_back(&OldFunc->getEntryBlock());
  while (!CloneWorklist.empty()) {
    const BasicBlock *BB = CloneWorklist.back();
    CloneWorklist.pop_back();
    PFC.CloneBlock(BB, CloneWorklist);
  }
  
  // Loop over all of the basic blocks in the old function.  If the block was
  // reachable, we have cloned it and the old block is now in the value map:
  // insert it into the new function in the right order.  If not, ignore it.
  //
  // Defer PHI resolution until rest of function is resolved.
  SmallVector<const PHINode*, 16> PHIToResolve;
  for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
       BI != BE; ++BI) {
    Value *V = VMap[BI];
    BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
    if (NewBB == 0) continue;  // Dead block.

    // Add the new block to the new function.
    NewFunc->getBasicBlockList().push_back(NewBB);
    
    // Loop over all of the instructions in the block, fixing up operand
    // references as we go.  This uses VMap to do all the hard work.
    //
    BasicBlock::iterator I = NewBB->begin();

    DebugLoc TheCallDL;
    if (TheCall) 
      TheCallDL = TheCall->getDebugLoc();
    
    // Handle PHI nodes specially, as we have to remove references to dead
    // blocks.
    if (PHINode *PN = dyn_cast<PHINode>(I)) {
      // Skip over all PHI nodes, remembering them for later.
      BasicBlock::const_iterator OldI = BI->begin();
      for (; (PN = dyn_cast<PHINode>(I)); ++I, ++OldI)
        PHIToResolve.push_back(cast<PHINode>(OldI));
    }
    
    // Otherwise, remap the rest of the instructions normally.
    for (; I != NewBB->end(); ++I)
      RemapInstruction(I, VMap,
                       ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
  }
  
  // Defer PHI resolution until rest of function is resolved, PHI resolution
  // requires the CFG to be up-to-date.
  for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
    const PHINode *OPN = PHIToResolve[phino];
    unsigned NumPreds = OPN->getNumIncomingValues();
    const BasicBlock *OldBB = OPN->getParent();
    BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);

    // Map operands for blocks that are live and remove operands for blocks
    // that are dead.
    for (; phino != PHIToResolve.size() &&
         PHIToResolve[phino]->getParent() == OldBB; ++phino) {
      OPN = PHIToResolve[phino];
      PHINode *PN = cast<PHINode>(VMap[OPN]);
      for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
        Value *V = VMap[PN->getIncomingBlock(pred)];
        if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
          Value *InVal = MapValue(PN->getIncomingValue(pred),
                                  VMap, 
                        ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
          assert(InVal && "Unknown input value?");
          PN->setIncomingValue(pred, InVal);
          PN->setIncomingBlock(pred, MappedBlock);
        } else {
          PN->removeIncomingValue(pred, false);
          --pred, --e;  // Revisit the next entry.
        }
      } 
    }
    
    // The loop above has removed PHI entries for those blocks that are dead
    // and has updated others.  However, if a block is live (i.e. copied over)
    // but its terminator has been changed to not go to this block, then our
    // phi nodes will have invalid entries.  Update the PHI nodes in this
    // case.
    PHINode *PN = cast<PHINode>(NewBB->begin());
    NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
    if (NumPreds != PN->getNumIncomingValues()) {
      assert(NumPreds < PN->getNumIncomingValues());
      // Count how many times each predecessor comes to this block.
      std::map<BasicBlock*, unsigned> PredCount;
      for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
           PI != E; ++PI)
        --PredCount[*PI];
      
      // Figure out how many entries to remove from each PHI.
      for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
        ++PredCount[PN->getIncomingBlock(i)];
      
      // At this point, the excess predecessor entries are positive in the
      // map.  Loop over all of the PHIs and remove excess predecessor
      // entries.
      BasicBlock::iterator I = NewBB->begin();
      for (; (PN = dyn_cast<PHINode>(I)); ++I) {
        for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
             E = PredCount.end(); PCI != E; ++PCI) {
          BasicBlock *Pred     = PCI->first;
          for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
            PN->removeIncomingValue(Pred, false);
        }
      }
    }
    
    // If the loops above have made these phi nodes have 0 or 1 operand,
    // replace them with undef or the input value.  We must do this for
    // correctness, because 0-operand phis are not valid.
    PN = cast<PHINode>(NewBB->begin());
    if (PN->getNumIncomingValues() == 0) {
      BasicBlock::iterator I = NewBB->begin();
      BasicBlock::const_iterator OldI = OldBB->begin();
      while ((PN = dyn_cast<PHINode>(I++))) {
        Value *NV = UndefValue::get(PN->getType());
        PN->replaceAllUsesWith(NV);
        assert(VMap[OldI] == PN && "VMap mismatch");
        VMap[OldI] = NV;
        PN->eraseFromParent();
        ++OldI;
      }
    }
    // NOTE: We cannot eliminate single entry phi nodes here, because of
    // VMap.  Single entry phi nodes can have multiple VMap entries
    // pointing at them.  Thus, deleting one would require scanning the VMap
    // to update any entries in it that would require that.  This would be
    // really slow.
  }
  
  // Now that the inlined function body has been fully constructed, go through
  // and zap unconditional fall-through branches.  This happen all the time when
  // specializing code: code specialization turns conditional branches into
  // uncond branches, and this code folds them.
  Function::iterator I = cast<BasicBlock>(VMap[&OldFunc->getEntryBlock()]);
  while (I != NewFunc->end()) {
    BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
    if (!BI || BI->isConditional()) { ++I; continue; }
    
    // Note that we can't eliminate uncond branches if the destination has
    // single-entry PHI nodes.  Eliminating the single-entry phi nodes would
    // require scanning the VMap to update any entries that point to the phi
    // node.
    BasicBlock *Dest = BI->getSuccessor(0);
    if (!Dest->getSinglePredecessor() || isa<PHINode>(Dest->begin())) {
      ++I; continue;
    }
    
    // We know all single-entry PHI nodes in the inlined function have been
    // removed, so we just need to splice the blocks.
    BI->eraseFromParent();
    
    // Make all PHI nodes that referred to Dest now refer to I as their source.
    Dest->replaceAllUsesWith(I);

    // Move all the instructions in the succ to the pred.
    I->getInstList().splice(I->end(), Dest->getInstList());
    
    // Remove the dest block.
    Dest->eraseFromParent();
    
    // Do not increment I, iteratively merge all things this block branches to.
  }
}
void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
                               SelectionDAG *DAG) {
  Fn = &fn;
  MF = &mf;
  TLI = MF->getSubtarget().getTargetLowering();
  RegInfo = &MF->getRegInfo();
  MachineModuleInfo &MMI = MF->getMMI();
  const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
  unsigned StackAlign = TFI->getStackAlignment();

  // Check whether the function can return without sret-demotion.
  SmallVector<ISD::OutputArg, 4> Outs;
  GetReturnInfo(Fn->getReturnType(), Fn->getAttributes(), Outs, *TLI,
                mf.getDataLayout());
  CanLowerReturn = TLI->CanLowerReturn(Fn->getCallingConv(), *MF,
                                       Fn->isVarArg(), Outs, Fn->getContext());

  // If this personality uses funclets, we need to do a bit more work.
  DenseMap<const AllocaInst *, int *> CatchObjects;
  EHPersonality Personality = classifyEHPersonality(
      Fn->hasPersonalityFn() ? Fn->getPersonalityFn() : nullptr);
  if (isFuncletEHPersonality(Personality)) {
    // Calculate state numbers if we haven't already.
    WinEHFuncInfo &EHInfo = *MF->getWinEHFuncInfo();
    if (Personality == EHPersonality::MSVC_CXX)
      calculateWinCXXEHStateNumbers(&fn, EHInfo);
    else if (isAsynchronousEHPersonality(Personality))
      calculateSEHStateNumbers(&fn, EHInfo);
    else if (Personality == EHPersonality::CoreCLR)
      calculateClrEHStateNumbers(&fn, EHInfo);

    // Map all BB references in the WinEH data to MBBs.
    for (WinEHTryBlockMapEntry &TBME : EHInfo.TryBlockMap) {
      for (WinEHHandlerType &H : TBME.HandlerArray) {
        if (const AllocaInst *AI = H.CatchObj.Alloca)
          CatchObjects.insert({AI, &H.CatchObj.FrameIndex});
        else
          H.CatchObj.FrameIndex = INT_MAX;
      }
    }
  }

  // Initialize the mapping of values to registers.  This is only set up for
  // instruction values that are used outside of the block that defines
  // them.
  Function::const_iterator BB = Fn->begin(), EB = Fn->end();
  for (; BB != EB; ++BB)
    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end();
         I != E; ++I) {
      if (const AllocaInst *AI = dyn_cast<AllocaInst>(I)) {
        Type *Ty = AI->getAllocatedType();
        unsigned Align =
          std::max((unsigned)MF->getDataLayout().getPrefTypeAlignment(Ty),
                   AI->getAlignment());

        // Static allocas can be folded into the initial stack frame
        // adjustment. For targets that don't realign the stack, don't
        // do this if there is an extra alignment requirement.
        if (AI->isStaticAlloca() && 
            (TFI->isStackRealignable() || (Align <= StackAlign))) {
          const ConstantInt *CUI = cast<ConstantInt>(AI->getArraySize());
          uint64_t TySize = MF->getDataLayout().getTypeAllocSize(Ty);

          TySize *= CUI->getZExtValue();   // Get total allocated size.
          if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
          int FrameIndex = INT_MAX;
          auto Iter = CatchObjects.find(AI);
          if (Iter != CatchObjects.end() && TLI->needsFixedCatchObjects()) {
            FrameIndex = MF->getFrameInfo().CreateFixedObject(
                TySize, 0, /*Immutable=*/false, /*isAliased=*/true);
            MF->getFrameInfo().setObjectAlignment(FrameIndex, Align);
          } else {
            FrameIndex =
                MF->getFrameInfo().CreateStackObject(TySize, Align, false, AI);
          }

          StaticAllocaMap[AI] = FrameIndex;
          // Update the catch handler information.
          if (Iter != CatchObjects.end())
            *Iter->second = FrameIndex;
        } else {
          // FIXME: Overaligned static allocas should be grouped into
          // a single dynamic allocation instead of using a separate
          // stack allocation for each one.
          if (Align <= StackAlign)
            Align = 0;
          // Inform the Frame Information that we have variable-sized objects.
          MF->getFrameInfo().CreateVariableSizedObject(Align ? Align : 1, AI);
        }
      }

      // Look for inline asm that clobbers the SP register.
      if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
        ImmutableCallSite CS(&*I);
        if (isa<InlineAsm>(CS.getCalledValue())) {
          unsigned SP = TLI->getStackPointerRegisterToSaveRestore();
          const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
          std::vector<TargetLowering::AsmOperandInfo> Ops =
              TLI->ParseConstraints(Fn->getParent()->getDataLayout(), TRI, CS);
          for (size_t I = 0, E = Ops.size(); I != E; ++I) {
            TargetLowering::AsmOperandInfo &Op = Ops[I];
            if (Op.Type == InlineAsm::isClobber) {
              // Clobbers don't have SDValue operands, hence SDValue().
              TLI->ComputeConstraintToUse(Op, SDValue(), DAG);
              std::pair<unsigned, const TargetRegisterClass *> PhysReg =
                  TLI->getRegForInlineAsmConstraint(TRI, Op.ConstraintCode,
                                                    Op.ConstraintVT);
              if (PhysReg.first == SP)
                MF->getFrameInfo().setHasOpaqueSPAdjustment(true);
            }
          }
        }
      }

      // Look for calls to the @llvm.va_start intrinsic. We can omit some
      // prologue boilerplate for variadic functions that don't examine their
      // arguments.
      if (const auto *II = dyn_cast<IntrinsicInst>(I)) {
        if (II->getIntrinsicID() == Intrinsic::vastart)
          MF->getFrameInfo().setHasVAStart(true);
      }

      // If we have a musttail call in a variadic function, we need to ensure we
      // forward implicit register parameters.
      if (const auto *CI = dyn_cast<CallInst>(I)) {
        if (CI->isMustTailCall() && Fn->isVarArg())
          MF->getFrameInfo().setHasMustTailInVarArgFunc(true);
      }

      // Mark values used outside their block as exported, by allocating
      // a virtual register for them.
      if (isUsedOutsideOfDefiningBlock(&*I))
        if (!isa<AllocaInst>(I) || !StaticAllocaMap.count(cast<AllocaInst>(I)))
          InitializeRegForValue(&*I);

      // Collect llvm.dbg.declare information. This is done now instead of
      // during the initial isel pass through the IR so that it is done
      // in a predictable order.
      if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
        assert(DI->getVariable() && "Missing variable");
        assert(DI->getDebugLoc() && "Missing location");
        if (MMI.hasDebugInfo()) {
          // Don't handle byval struct arguments or VLAs, for example.
          // Non-byval arguments are handled here (they refer to the stack
          // temporary alloca at this point).
          const Value *Address = DI->getAddress();
          if (Address) {
            if (const BitCastInst *BCI = dyn_cast<BitCastInst>(Address))
              Address = BCI->getOperand(0);
            if (const AllocaInst *AI = dyn_cast<AllocaInst>(Address)) {
              DenseMap<const AllocaInst *, int>::iterator SI =
                StaticAllocaMap.find(AI);
              if (SI != StaticAllocaMap.end()) { // Check for VLAs.
                int FI = SI->second;
                MMI.setVariableDbgInfo(DI->getVariable(), DI->getExpression(),
                                       FI, DI->getDebugLoc());
              }
            }
          }
        }
      }

      // Decide the preferred extend type for a value.
      PreferredExtendType[&*I] = getPreferredExtendForValue(&*I);
    }

  // Create an initial MachineBasicBlock for each LLVM BasicBlock in F.  This
  // also creates the initial PHI MachineInstrs, though none of the input
  // operands are populated.
  for (BB = Fn->begin(); BB != EB; ++BB) {
    // Don't create MachineBasicBlocks for imaginary EH pad blocks. These blocks
    // are really data, and no instructions can live here.
    if (BB->isEHPad()) {
      const Instruction *I = BB->getFirstNonPHI();
      // If this is a non-landingpad EH pad, mark this function as using
      // funclets.
      // FIXME: SEH catchpads do not create funclets, so we could avoid setting
      // this in such cases in order to improve frame layout.
      if (!isa<LandingPadInst>(I)) {
        MMI.setHasEHFunclets(true);
        MF->getFrameInfo().setHasOpaqueSPAdjustment(true);
      }
      if (isa<CatchSwitchInst>(I)) {
        assert(&*BB->begin() == I &&
               "WinEHPrepare failed to remove PHIs from imaginary BBs");
        continue;
      }
      if (isa<FuncletPadInst>(I))
        assert(&*BB->begin() == I && "WinEHPrepare failed to demote PHIs");
    }

    MachineBasicBlock *MBB = mf.CreateMachineBasicBlock(&*BB);
    MBBMap[&*BB] = MBB;
    MF->push_back(MBB);

    // Transfer the address-taken flag. This is necessary because there could
    // be multiple MachineBasicBlocks corresponding to one BasicBlock, and only
    // the first one should be marked.
    if (BB->hasAddressTaken())
      MBB->setHasAddressTaken();

    // Create Machine PHI nodes for LLVM PHI nodes, lowering them as
    // appropriate.
    for (BasicBlock::const_iterator I = BB->begin();
         const PHINode *PN = dyn_cast<PHINode>(I); ++I) {
      if (PN->use_empty()) continue;

      // Skip empty types
      if (PN->getType()->isEmptyTy())
        continue;

      DebugLoc DL = PN->getDebugLoc();
      unsigned PHIReg = ValueMap[PN];
      assert(PHIReg && "PHI node does not have an assigned virtual register!");

      SmallVector<EVT, 4> ValueVTs;
      ComputeValueVTs(*TLI, MF->getDataLayout(), PN->getType(), ValueVTs);
      for (unsigned vti = 0, vte = ValueVTs.size(); vti != vte; ++vti) {
        EVT VT = ValueVTs[vti];
        unsigned NumRegisters = TLI->getNumRegisters(Fn->getContext(), VT);
        const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
        for (unsigned i = 0; i != NumRegisters; ++i)
          BuildMI(MBB, DL, TII->get(TargetOpcode::PHI), PHIReg + i);
        PHIReg += NumRegisters;
      }
    }
  }

  // Mark landing pad blocks.
  SmallVector<const LandingPadInst *, 4> LPads;
  for (BB = Fn->begin(); BB != EB; ++BB) {
    const Instruction *FNP = BB->getFirstNonPHI();
    if (BB->isEHPad() && MBBMap.count(&*BB))
      MBBMap[&*BB]->setIsEHPad();
    if (const auto *LPI = dyn_cast<LandingPadInst>(FNP))
      LPads.push_back(LPI);
  }

  if (!isFuncletEHPersonality(Personality))
    return;

  WinEHFuncInfo &EHInfo = *MF->getWinEHFuncInfo();

  // Map all BB references in the WinEH data to MBBs.
  for (WinEHTryBlockMapEntry &TBME : EHInfo.TryBlockMap) {
    for (WinEHHandlerType &H : TBME.HandlerArray) {
      if (H.Handler)
        H.Handler = MBBMap[H.Handler.get<const BasicBlock *>()];
    }
  }
  for (CxxUnwindMapEntry &UME : EHInfo.CxxUnwindMap)
    if (UME.Cleanup)
      UME.Cleanup = MBBMap[UME.Cleanup.get<const BasicBlock *>()];
  for (SEHUnwindMapEntry &UME : EHInfo.SEHUnwindMap) {
    const BasicBlock *BB = UME.Handler.get<const BasicBlock *>();
    UME.Handler = MBBMap[BB];
  }
  for (ClrEHUnwindMapEntry &CME : EHInfo.ClrEHUnwindMap) {
    const BasicBlock *BB = CME.Handler.get<const BasicBlock *>();
    CME.Handler = MBBMap[BB];
  }
}