Exemple #1
0
// InlineCallIfPossible - If it is possible to inline the specified call site,
// do so and update the CallGraph for this operation.
static bool InlineCallIfPossible(CallSite CS, CallGraph &CG,
                                 const std::set<Function*> &SCCFunctions,
                                 const TargetData &TD) {
    Function *Callee = CS.getCalledFunction();
    Function *Caller = CS.getCaller();

    if (!InlineFunction(CS, &CG, &TD)) return false;

    // If the inlined function had a higher stack protection level than the
    // calling function, then bump up the caller's stack protection level.
    if (Callee->hasFnAttr(Attribute::StackProtectReq))
        Caller->addFnAttr(Attribute::StackProtectReq);
    else if (Callee->hasFnAttr(Attribute::StackProtect) &&
             !Caller->hasFnAttr(Attribute::StackProtectReq))
        Caller->addFnAttr(Attribute::StackProtect);

    // If we inlined the last possible call site to the function, delete the
    // function body now.
    if (Callee->use_empty() && Callee->hasLocalLinkage() &&
            !SCCFunctions.count(Callee)) {
        DOUT << "    -> Deleting dead function: " << Callee->getName() << "\n";
        CallGraphNode *CalleeNode = CG[Callee];

        // Remove any call graph edges from the callee to its callees.
        CalleeNode->removeAllCalledFunctions();

        // Removing the node for callee from the call graph and delete it.
        delete CG.removeFunctionFromModule(CalleeNode);
        ++NumDeleted;
    }
    return true;
}
Exemple #2
0
/// removeDeadFunctions - Remove dead functions that are not included in
/// DNR (Do Not Remove) list.
bool Inliner::removeDeadFunctions(CallGraph &CG, bool AlwaysInlineOnly) {
  SmallVector<CallGraphNode*, 16> FunctionsToRemove;

  // Scan for all of the functions, looking for ones that should now be removed
  // from the program.  Insert the dead ones in the FunctionsToRemove set.
  for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
    CallGraphNode *CGN = I->second;
    Function *F = CGN->getFunction();
    if (!F || F->isDeclaration())
      continue;

    // Handle the case when this function is called and we only want to care
    // about always-inline functions. This is a bit of a hack to share code
    // between here and the InlineAlways pass.
    if (AlwaysInlineOnly &&
        !F->getAttributes().hasAttribute(AttributeSet::FunctionIndex,
                                         Attribute::AlwaysInline))
      continue;

    // If the only remaining users of the function are dead constants, remove
    // them.
    F->removeDeadConstantUsers();

    if (!F->isDefTriviallyDead())
      continue;
    
    // Remove any call graph edges from the function to its callees.
    CGN->removeAllCalledFunctions();

    // Remove any edges from the external node to the function's call graph
    // node.  These edges might have been made irrelegant due to
    // optimization of the program.
    CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);

    // Removing the node for callee from the call graph and delete it.
    FunctionsToRemove.push_back(CGN);
  }
  if (FunctionsToRemove.empty())
    return false;

  // Now that we know which functions to delete, do so.  We didn't want to do
  // this inline, because that would invalidate our CallGraph::iterator
  // objects. :(
  //
  // Note that it doesn't matter that we are iterating over a non-stable order
  // here to do this, it doesn't matter which order the functions are deleted
  // in.
  array_pod_sort(FunctionsToRemove.begin(), FunctionsToRemove.end());
  FunctionsToRemove.erase(std::unique(FunctionsToRemove.begin(),
                                      FunctionsToRemove.end()),
                          FunctionsToRemove.end());
  for (SmallVectorImpl<CallGraphNode *>::iterator I = FunctionsToRemove.begin(),
                                                  E = FunctionsToRemove.end();
       I != E; ++I) {
    delete CG.removeFunctionFromModule(*I);
    ++NumDeleted;
  }
  return true;
}
Exemple #3
0
/// removeDeadFunctions - Remove dead functions that are not included in
/// DNR (Do Not Remove) list.
bool Inliner::removeDeadFunctions(CallGraph &CG, 
                                  SmallPtrSet<const Function *, 16> *DNR) {
  SmallPtrSet<CallGraphNode*, 16> FunctionsToRemove;

  // Scan for all of the functions, looking for ones that should now be removed
  // from the program.  Insert the dead ones in the FunctionsToRemove set.
  for (CallGraph::iterator I = CG.begin(), E = CG.end(); I != E; ++I) {
    CallGraphNode *CGN = I->second;
    if (CGN->getFunction() == 0)
      continue;
    
    Function *F = CGN->getFunction();
    
    // If the only remaining users of the function are dead constants, remove
    // them.
    F->removeDeadConstantUsers();

    if (DNR && DNR->count(F))
      continue;
    if (!F->hasLinkOnceLinkage() && !F->hasLocalLinkage() &&
        !F->hasAvailableExternallyLinkage())
      continue;
    if (!F->use_empty())
      continue;
    
    // Remove any call graph edges from the function to its callees.
    CGN->removeAllCalledFunctions();

    // Remove any edges from the external node to the function's call graph
    // node.  These edges might have been made irrelegant due to
    // optimization of the program.
    CG.getExternalCallingNode()->removeAnyCallEdgeTo(CGN);

    // Removing the node for callee from the call graph and delete it.
    FunctionsToRemove.insert(CGN);
  }

  // Now that we know which functions to delete, do so.  We didn't want to do
  // this inline, because that would invalidate our CallGraph::iterator
  // objects. :(
  //
  // Note that it doesn't matter that we are iterating over a non-stable set
  // here to do this, it doesn't matter which order the functions are deleted
  // in.
  bool Changed = false;
  for (SmallPtrSet<CallGraphNode*, 16>::iterator I = FunctionsToRemove.begin(),
       E = FunctionsToRemove.end(); I != E; ++I) {
    resetCachedCostInfo((*I)->getFunction());
    delete CG.removeFunctionFromModule(*I);
    ++NumDeleted;
    Changed = true;
  }

  return Changed;
}
bool StructuredModuleEditor::removeFunc(Function *FunctionToRemove) {
// Checks to make sure the function we are trying to remove
// actually exists in the CFG
	if (FunctionToRemove == NULL) {
		OS << "Function does not exist in the call graph!\n";
		return false;
	}

	CallGraphNode *NodeToRemove = (*CG)[FunctionToRemove];

	// We cannot remove a node if it has any inteprocedural in-edges
	for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) {
		CallGraphNode *CallingNode = (*CG)[I];
		for (CallGraphNode::iterator CGNI = CallingNode->begin(), CGNE =
				CallingNode->end(); CGNI != CGNE; ++CGNI) {
			Function *Caller = I;
			Function *Callee = CGNI->second->getFunction();
			if (Callee == FunctionToRemove && Caller != Callee) {
				OS << "Cannot remove " << FunctionToRemove->getName()
						<< " because it has at least one interprocedural edge!\n";
				OS << "It is called by " << Caller->getName() << "\n";
				return false;
			}
		}
	}

// Removes all call graph edges from the node we are removing to its callees.
	NodeToRemove->removeAllCalledFunctions();
	CG->getExternalCallingNode()->removeAnyCallEdgeTo(NodeToRemove);

// Removes all call graph edges from callees to the node we are removing
	for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) {
		CallGraphNode *CallingNode = (*CG)[I];
		CallingNode->removeAnyCallEdgeTo(NodeToRemove);
	}
	NodeToRemove->removeAnyCallEdgeTo(CG->getCallsExternalNode());

// Removes the function from the module and the CFG
	FunctionToRemove->dropAllReferences();

	// Remove the function from the module
	CG->removeFunctionFromModule(NodeToRemove);

	return true;
}
Exemple #5
0
bool Inliner::runOnSCC(CallGraphSCC &SCC) {
  CallGraph &CG = getAnalysis<CallGraphWrapperPass>().getCallGraph();
  AssumptionCacheTracker *ACT = &getAnalysis<AssumptionCacheTracker>();
  auto *TLIP = getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
  const TargetLibraryInfo *TLI = TLIP ? &TLIP->getTLI() : nullptr;
  AliasAnalysis *AA = &getAnalysis<AliasAnalysis>();

  SmallPtrSet<Function*, 8> SCCFunctions;
  DEBUG(dbgs() << "Inliner visiting SCC:");
  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
    Function *F = (*I)->getFunction();
    if (F) SCCFunctions.insert(F);
    DEBUG(dbgs() << " " << (F ? F->getName() : "INDIRECTNODE"));
  }

  // Scan through and identify all call sites ahead of time so that we only
  // inline call sites in the original functions, not call sites that result
  // from inlining other functions.
  SmallVector<std::pair<CallSite, int>, 16> CallSites;
  
  // When inlining a callee produces new call sites, we want to keep track of
  // the fact that they were inlined from the callee.  This allows us to avoid
  // infinite inlining in some obscure cases.  To represent this, we use an
  // index into the InlineHistory vector.
  SmallVector<std::pair<Function*, int>, 8> InlineHistory;

  for (CallGraphSCC::iterator I = SCC.begin(), E = SCC.end(); I != E; ++I) {
    Function *F = (*I)->getFunction();
    if (!F) continue;
    
    for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
      for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
        CallSite CS(cast<Value>(I));
        // If this isn't a call, or it is a call to an intrinsic, it can
        // never be inlined.
        if (!CS || isa<IntrinsicInst>(I))
          continue;
        
        // If this is a direct call to an external function, we can never inline
        // it.  If it is an indirect call, inlining may resolve it to be a
        // direct call, so we keep it.
        if (CS.getCalledFunction() && CS.getCalledFunction()->isDeclaration())
          continue;
        
        CallSites.push_back(std::make_pair(CS, -1));
      }
  }

  DEBUG(dbgs() << ": " << CallSites.size() << " call sites.\n");

  // If there are no calls in this function, exit early.
  if (CallSites.empty())
    return false;
  
  // Now that we have all of the call sites, move the ones to functions in the
  // current SCC to the end of the list.
  unsigned FirstCallInSCC = CallSites.size();
  for (unsigned i = 0; i < FirstCallInSCC; ++i)
    if (Function *F = CallSites[i].first.getCalledFunction())
      if (SCCFunctions.count(F))
        std::swap(CallSites[i--], CallSites[--FirstCallInSCC]);

  
  InlinedArrayAllocasTy InlinedArrayAllocas;
  InlineFunctionInfo InlineInfo(&CG, AA, ACT);

  // Now that we have all of the call sites, loop over them and inline them if
  // it looks profitable to do so.
  bool Changed = false;
  bool LocalChange;
  do {
    LocalChange = false;
    // Iterate over the outer loop because inlining functions can cause indirect
    // calls to become direct calls.
    for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi) {
      CallSite CS = CallSites[CSi].first;
      
      Function *Caller = CS.getCaller();
      Function *Callee = CS.getCalledFunction();

      // If this call site is dead and it is to a readonly function, we should
      // just delete the call instead of trying to inline it, regardless of
      // size.  This happens because IPSCCP propagates the result out of the
      // call and then we're left with the dead call.
      if (isInstructionTriviallyDead(CS.getInstruction(), TLI)) {
        DEBUG(dbgs() << "    -> Deleting dead call: "
                     << *CS.getInstruction() << "\n");
        // Update the call graph by deleting the edge from Callee to Caller.
        CG[Caller]->removeCallEdgeFor(CS);
        CS.getInstruction()->eraseFromParent();
        ++NumCallsDeleted;
      } else {
        // We can only inline direct calls to non-declarations.
        if (!Callee || Callee->isDeclaration()) continue;
      
        // If this call site was obtained by inlining another function, verify
        // that the include path for the function did not include the callee
        // itself.  If so, we'd be recursively inlining the same function,
        // which would provide the same callsites, which would cause us to
        // infinitely inline.
        int InlineHistoryID = CallSites[CSi].second;
        if (InlineHistoryID != -1 &&
            InlineHistoryIncludes(Callee, InlineHistoryID, InlineHistory))
          continue;
        
        LLVMContext &CallerCtx = Caller->getContext();

        // Get DebugLoc to report. CS will be invalid after Inliner.
        DebugLoc DLoc = CS.getInstruction()->getDebugLoc();

        // If the policy determines that we should inline this function,
        // try to do so.
        if (!shouldInline(CS)) {
          emitOptimizationRemarkMissed(CallerCtx, DEBUG_TYPE, *Caller, DLoc,
                                       Twine(Callee->getName() +
                                             " will not be inlined into " +
                                             Caller->getName()));
          continue;
        }

        // Attempt to inline the function.
        if (!InlineCallIfPossible(CS, InlineInfo, InlinedArrayAllocas,
                                  InlineHistoryID, InsertLifetime)) {
          emitOptimizationRemarkMissed(CallerCtx, DEBUG_TYPE, *Caller, DLoc,
                                       Twine(Callee->getName() +
                                             " will not be inlined into " +
                                             Caller->getName()));
          continue;
        }
        ++NumInlined;

        // Report the inline decision.
        emitOptimizationRemark(
            CallerCtx, DEBUG_TYPE, *Caller, DLoc,
            Twine(Callee->getName() + " inlined into " + Caller->getName()));

        // If inlining this function gave us any new call sites, throw them
        // onto our worklist to process.  They are useful inline candidates.
        if (!InlineInfo.InlinedCalls.empty()) {
          // Create a new inline history entry for this, so that we remember
          // that these new callsites came about due to inlining Callee.
          int NewHistoryID = InlineHistory.size();
          InlineHistory.push_back(std::make_pair(Callee, InlineHistoryID));

          for (unsigned i = 0, e = InlineInfo.InlinedCalls.size();
               i != e; ++i) {
            Value *Ptr = InlineInfo.InlinedCalls[i];
            CallSites.push_back(std::make_pair(CallSite(Ptr), NewHistoryID));
          }
        }
      }
      
      // If we inlined or deleted the last possible call site to the function,
      // delete the function body now.
      if (Callee && Callee->use_empty() && Callee->hasLocalLinkage() &&
          // TODO: Can remove if in SCC now.
          !SCCFunctions.count(Callee) &&
          
          // The function may be apparently dead, but if there are indirect
          // callgraph references to the node, we cannot delete it yet, this
          // could invalidate the CGSCC iterator.
          CG[Callee]->getNumReferences() == 0) {
        DEBUG(dbgs() << "    -> Deleting dead function: "
              << Callee->getName() << "\n");
        CallGraphNode *CalleeNode = CG[Callee];
        
        // Remove any call graph edges from the callee to its callees.
        CalleeNode->removeAllCalledFunctions();
        
        // Removing the node for callee from the call graph and delete it.
        delete CG.removeFunctionFromModule(CalleeNode);
        ++NumDeleted;
      }

      // Remove this call site from the list.  If possible, use 
      // swap/pop_back for efficiency, but do not use it if doing so would
      // move a call site to a function in this SCC before the
      // 'FirstCallInSCC' barrier.
      if (SCC.isSingular()) {
        CallSites[CSi] = CallSites.back();
        CallSites.pop_back();
      } else {
        CallSites.erase(CallSites.begin()+CSi);
      }
      --CSi;

      Changed = true;
      LocalChange = true;
    }
  } while (LocalChange);

  return Changed;
}
Exemple #6
0
static bool
inlineCallsImpl(CallGraphSCC &SCC, CallGraph &CG,
                std::function<AssumptionCache &(Function &)> GetAssumptionCache,
                ProfileSummaryInfo *PSI, TargetLibraryInfo &TLI,
                bool InsertLifetime,
                function_ref<InlineCost(CallSite CS)> GetInlineCost,
                function_ref<AAResults &(Function &)> AARGetter,
                ImportedFunctionsInliningStatistics &ImportedFunctionsStats) {
  SmallPtrSet<Function *, 8> SCCFunctions;
  LLVM_DEBUG(dbgs() << "Inliner visiting SCC:");
  for (CallGraphNode *Node : SCC) {
    Function *F = Node->getFunction();
    if (F)
      SCCFunctions.insert(F);
    LLVM_DEBUG(dbgs() << " " << (F ? F->getName() : "INDIRECTNODE"));
  }

  // Scan through and identify all call sites ahead of time so that we only
  // inline call sites in the original functions, not call sites that result
  // from inlining other functions.
  SmallVector<std::pair<CallSite, int>, 16> CallSites;

  // When inlining a callee produces new call sites, we want to keep track of
  // the fact that they were inlined from the callee.  This allows us to avoid
  // infinite inlining in some obscure cases.  To represent this, we use an
  // index into the InlineHistory vector.
  SmallVector<std::pair<Function *, int>, 8> InlineHistory;

  for (CallGraphNode *Node : SCC) {
    Function *F = Node->getFunction();
    if (!F || F->isDeclaration())
      continue;

    OptimizationRemarkEmitter ORE(F);
    for (BasicBlock &BB : *F)
      for (Instruction &I : BB) {
        CallSite CS(cast<Value>(&I));
        // If this isn't a call, or it is a call to an intrinsic, it can
        // never be inlined.
        if (!CS || isa<IntrinsicInst>(I))
          continue;

        // If this is a direct call to an external function, we can never inline
        // it.  If it is an indirect call, inlining may resolve it to be a
        // direct call, so we keep it.
        if (Function *Callee = CS.getCalledFunction())
          if (Callee->isDeclaration()) {
            using namespace ore;

            ORE.emit([&]() {
              return OptimizationRemarkMissed(DEBUG_TYPE, "NoDefinition", &I)
                     << NV("Callee", Callee) << " will not be inlined into "
                     << NV("Caller", CS.getCaller())
                     << " because its definition is unavailable"
                     << setIsVerbose();
            });
            continue;
          }

        CallSites.push_back(std::make_pair(CS, -1));
      }
  }

  LLVM_DEBUG(dbgs() << ": " << CallSites.size() << " call sites.\n");

  // If there are no calls in this function, exit early.
  if (CallSites.empty())
    return false;

  // Now that we have all of the call sites, move the ones to functions in the
  // current SCC to the end of the list.
  unsigned FirstCallInSCC = CallSites.size();
  for (unsigned i = 0; i < FirstCallInSCC; ++i)
    if (Function *F = CallSites[i].first.getCalledFunction())
      if (SCCFunctions.count(F))
        std::swap(CallSites[i--], CallSites[--FirstCallInSCC]);

  InlinedArrayAllocasTy InlinedArrayAllocas;
  InlineFunctionInfo InlineInfo(&CG, &GetAssumptionCache, PSI);

  // Now that we have all of the call sites, loop over them and inline them if
  // it looks profitable to do so.
  bool Changed = false;
  bool LocalChange;
  do {
    LocalChange = false;
    // Iterate over the outer loop because inlining functions can cause indirect
    // calls to become direct calls.
    // CallSites may be modified inside so ranged for loop can not be used.
    for (unsigned CSi = 0; CSi != CallSites.size(); ++CSi) {
      CallSite CS = CallSites[CSi].first;

      Function *Caller = CS.getCaller();
      Function *Callee = CS.getCalledFunction();

      // We can only inline direct calls to non-declarations.
      if (!Callee || Callee->isDeclaration())
        continue;

      Instruction *Instr = CS.getInstruction();

      bool IsTriviallyDead = isInstructionTriviallyDead(Instr, &TLI);

      int InlineHistoryID;
      if (!IsTriviallyDead) {
        // If this call site was obtained by inlining another function, verify
        // that the include path for the function did not include the callee
        // itself.  If so, we'd be recursively inlining the same function,
        // which would provide the same callsites, which would cause us to
        // infinitely inline.
        InlineHistoryID = CallSites[CSi].second;
        if (InlineHistoryID != -1 &&
            InlineHistoryIncludes(Callee, InlineHistoryID, InlineHistory))
          continue;
      }

      // FIXME for new PM: because of the old PM we currently generate ORE and
      // in turn BFI on demand.  With the new PM, the ORE dependency should
      // just become a regular analysis dependency.
      OptimizationRemarkEmitter ORE(Caller);

      Optional<InlineCost> OIC = shouldInline(CS, GetInlineCost, ORE);
      // If the policy determines that we should inline this function,
      // delete the call instead.
      if (!OIC)
        continue;

      // If this call site is dead and it is to a readonly function, we should
      // just delete the call instead of trying to inline it, regardless of
      // size.  This happens because IPSCCP propagates the result out of the
      // call and then we're left with the dead call.
      if (IsTriviallyDead) {
        LLVM_DEBUG(dbgs() << "    -> Deleting dead call: " << *Instr << "\n");
        // Update the call graph by deleting the edge from Callee to Caller.
        CG[Caller]->removeCallEdgeFor(CS);
        Instr->eraseFromParent();
        ++NumCallsDeleted;
      } else {
        // Get DebugLoc to report. CS will be invalid after Inliner.
        DebugLoc DLoc = CS->getDebugLoc();
        BasicBlock *Block = CS.getParent();

        // Attempt to inline the function.
        using namespace ore;

        if (!InlineCallIfPossible(CS, InlineInfo, InlinedArrayAllocas,
                                  InlineHistoryID, InsertLifetime, AARGetter,
                                  ImportedFunctionsStats)) {
          ORE.emit([&]() {
            return OptimizationRemarkMissed(DEBUG_TYPE, "NotInlined", DLoc,
                                            Block)
                   << NV("Callee", Callee) << " will not be inlined into "
                   << NV("Caller", Caller);
          });
          continue;
        }
        ++NumInlined;

        ORE.emit([&]() {
          bool AlwaysInline = OIC->isAlways();
          StringRef RemarkName = AlwaysInline ? "AlwaysInline" : "Inlined";
          OptimizationRemark R(DEBUG_TYPE, RemarkName, DLoc, Block);
          R << NV("Callee", Callee) << " inlined into ";
          R << NV("Caller", Caller);
          if (AlwaysInline)
            R << " with cost=always";
          else {
            R << " with cost=" << NV("Cost", OIC->getCost());
            R << " (threshold=" << NV("Threshold", OIC->getThreshold());
            R << ")";
          }
          return R;
        });

        // If inlining this function gave us any new call sites, throw them
        // onto our worklist to process.  They are useful inline candidates.
        if (!InlineInfo.InlinedCalls.empty()) {
          // Create a new inline history entry for this, so that we remember
          // that these new callsites came about due to inlining Callee.
          int NewHistoryID = InlineHistory.size();
          InlineHistory.push_back(std::make_pair(Callee, InlineHistoryID));

          for (Value *Ptr : InlineInfo.InlinedCalls)
            CallSites.push_back(std::make_pair(CallSite(Ptr), NewHistoryID));
        }
      }

      // If we inlined or deleted the last possible call site to the function,
      // delete the function body now.
      if (Callee && Callee->use_empty() && Callee->hasLocalLinkage() &&
          // TODO: Can remove if in SCC now.
          !SCCFunctions.count(Callee) &&
          // The function may be apparently dead, but if there are indirect
          // callgraph references to the node, we cannot delete it yet, this
          // could invalidate the CGSCC iterator.
          CG[Callee]->getNumReferences() == 0) {
        LLVM_DEBUG(dbgs() << "    -> Deleting dead function: "
                          << Callee->getName() << "\n");
        CallGraphNode *CalleeNode = CG[Callee];

        // Remove any call graph edges from the callee to its callees.
        CalleeNode->removeAllCalledFunctions();

        // Removing the node for callee from the call graph and delete it.
        delete CG.removeFunctionFromModule(CalleeNode);
        ++NumDeleted;
      }

      // Remove this call site from the list.  If possible, use
      // swap/pop_back for efficiency, but do not use it if doing so would
      // move a call site to a function in this SCC before the
      // 'FirstCallInSCC' barrier.
      if (SCC.isSingular()) {
        CallSites[CSi] = CallSites.back();
        CallSites.pop_back();
      } else {
        CallSites.erase(CallSites.begin() + CSi);
      }
      --CSi;

      Changed = true;
      LocalChange = true;
    }
  } while (LocalChange);

  return Changed;
}
Exemple #7
0
//Inliner handles erasing functions since it also maintains a copy of the callgraph
//that needs to be kept up to date with the functions in the module
void ManualInliner::eraseFunction(Function * F) {
    CallGraphNode * n = CG->getOrInsertFunction(F);
    n->removeAllCalledFunctions();
    CG->removeFunctionFromModule(n);
    delete F;
}