From b374b90e81d0ce6b5d02041ba4f7b15a945b38d8 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Mon, 31 Aug 2009 03:15:49 +0000 Subject: [PATCH] Fix PR4834, a tricky case where the inliner would resolve an indirect function pointer, inline it, then go to delete the body. The problem is that the callgraph had other references to the function, though the inliner had no way to know it, so we got a dangling pointer and an invalid iterator out of the deal. The fix to this is pretty simple: stop the inliner from deleting the function by knowing that there are references to it. Do this by making CallGraphNodes contain a refcount. This requires moving deletion of available_externally functions to the module-level cleanup sweep where it belongs. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80533 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/Analysis/CallGraph.h | 40 +++++++++++++++------- lib/Analysis/IPA/CallGraph.cpp | 37 ++++++++++++-------- lib/Transforms/IPO/Inliner.cpp | 15 ++++---- test/Transforms/Inline/indirect_resolve.ll | 16 +++++++++ 4 files changed, 76 insertions(+), 32 deletions(-) create mode 100644 test/Transforms/Inline/indirect_resolve.ll diff --git a/include/llvm/Analysis/CallGraph.h b/include/llvm/Analysis/CallGraph.h index 59dc3449b76..bc022e3417e 100644 --- a/include/llvm/Analysis/CallGraph.h +++ b/include/llvm/Analysis/CallGraph.h @@ -77,7 +77,7 @@ protected: public: static char ID; // Class identification, replacement for typeinfo //===--------------------------------------------------------------------- - // Accessors... + // Accessors. // typedef FunctionMapTy::iterator iterator; typedef FunctionMapTy::const_iterator const_iterator; @@ -136,7 +136,7 @@ public: CallGraphNode *getOrInsertFunction(const Function *F); //===--------------------------------------------------------------------- - // Pass infrastructure interface glue code... + // Pass infrastructure interface glue code. // protected: CallGraph() {} @@ -163,19 +163,31 @@ class CallGraphNode { Function *F; typedef std::pair CallRecord; std::vector CalledFunctions; + + /// NumReferences - This is the number of times that this CallGraphNode occurs + /// in the CalledFunctions array of this or other CallGraphNodes. + unsigned NumReferences; - CallGraphNode(const CallGraphNode &); // Do not implement + CallGraphNode(const CallGraphNode &); // DO NOT IMPLEMENT + void operator=(const CallGraphNode &); // DO NOT IMPLEMENT + + void DropRef() { --NumReferences; } + void AddRef() { ++NumReferences; } public: typedef std::vector CalledFunctionsVector; + + // CallGraphNode ctor - Create a node for the specified function. + inline CallGraphNode(Function *f) : F(f), NumReferences(0) {} + //===--------------------------------------------------------------------- - // Accessor methods... + // Accessor methods. // typedef std::vector::iterator iterator; typedef std::vector::const_iterator const_iterator; - // getFunction - Return the function that this call graph node represents... + // getFunction - Return the function that this call graph node represents. Function *getFunction() const { return F; } inline iterator begin() { return CalledFunctions.begin(); } @@ -185,9 +197,14 @@ public: inline bool empty() const { return CalledFunctions.empty(); } inline unsigned size() const { return (unsigned)CalledFunctions.size(); } - // Subscripting operator - Return the i'th called function... + /// getNumReferences - Return the number of other CallGraphNodes in this + /// CallGraph that reference this node in their callee list. + unsigned getNumReferences() const { return NumReferences; } + + // Subscripting operator - Return the i'th called function. // CallGraphNode *operator[](unsigned i) const { + assert(i < CalledFunctions.size() && "Invalid index"); return CalledFunctions[i].second; } @@ -204,7 +221,10 @@ public: /// removeAllCalledFunctions - As the name implies, this removes all edges /// from this CallGraphNode to any functions it calls. void removeAllCalledFunctions() { - CalledFunctions.clear(); + while (!CalledFunctions.empty()) { + CalledFunctions.back().second->DropRef(); + CalledFunctions.pop_back(); + } } /// stealCalledFunctionsFrom - Move all the callee information from N to this @@ -220,6 +240,7 @@ public: /// one. void addCalledFunction(CallSite CS, CallGraphNode *M) { CalledFunctions.push_back(std::make_pair(CS, M)); + M->AddRef(); } /// removeCallEdgeFor - This method removes the edge in the node for the @@ -240,11 +261,6 @@ public: /// New CallSite instead. Note that this method takes linear time, so it /// should be used sparingly. void replaceCallSite(CallSite Old, CallSite New, CallGraphNode *NewCallee); - - friend class CallGraph; - - // CallGraphNode ctor - Create a node for the specified function. - inline CallGraphNode(Function *f) : F(f) {} }; //===----------------------------------------------------------------------===// diff --git a/lib/Analysis/IPA/CallGraph.cpp b/lib/Analysis/IPA/CallGraph.cpp index 152add93efe..9711013bea3 100644 --- a/lib/Analysis/IPA/CallGraph.cpp +++ b/lib/Analysis/IPA/CallGraph.cpp @@ -53,7 +53,7 @@ public: CallsExternalNode = new CallGraphNode(0); Root = 0; - // Add every function to the call graph... + // Add every function to the call graph. for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) addToCallGraph(I); @@ -169,12 +169,12 @@ void CallGraph::initialize(Module &M) { } void CallGraph::destroy() { - if (!FunctionMap.empty()) { - for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end(); - I != E; ++I) - delete I->second; - FunctionMap.clear(); - } + if (FunctionMap.empty()) return; + + for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end(); + I != E; ++I) + delete I->second; + FunctionMap.clear(); } void CallGraph::print(raw_ostream &OS, Module*) const { @@ -219,10 +219,11 @@ CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) { void CallGraphNode::print(raw_ostream &OS) const { if (Function *F = getFunction()) - OS << "Call graph node for function: '" << F->getName() - << "'<<0x" << this << ">>\n"; + OS << "Call graph node for function: '" << F->getName() << "'"; else - OS << "Call graph node <>:\n"; + OS << "Call graph node <>"; + + OS << "<<0x" << this << ">> #uses=" << getNumReferences() << '\n'; for (const_iterator I = begin(), E = end(); I != E; ++I) if (Function *FI = I->second->getFunction()) @@ -241,7 +242,9 @@ void CallGraphNode::removeCallEdgeFor(CallSite CS) { for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { assert(I != CalledFunctions.end() && "Cannot find callsite to remove!"); if (I->first == CS) { - CalledFunctions.erase(I); + I->second->DropRef(); + *I = CalledFunctions.back(); + CalledFunctions.pop_back(); return; } } @@ -254,6 +257,7 @@ void CallGraphNode::removeCallEdgeFor(CallSite CS) { void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) { for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i) if (CalledFunctions[i].second == Callee) { + Callee->DropRef(); CalledFunctions[i] = CalledFunctions.back(); CalledFunctions.pop_back(); --i; --e; @@ -266,8 +270,10 @@ void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) { for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { assert(I != CalledFunctions.end() && "Cannot find callee to remove!"); CallRecord &CR = *I; - if (CR.second == Callee && !CR.first.getInstruction()) { - CalledFunctions.erase(I); + if (CR.second == Callee && CR.first.getInstruction() == 0) { + Callee->DropRef(); + *I = CalledFunctions.back(); + CalledFunctions.pop_back(); return; } } @@ -285,8 +291,11 @@ void CallGraphNode::replaceCallSite(CallSite Old, CallSite New, // If the callee is changing, not just the callsite, then update it as // well. - if (NewCallee) + if (NewCallee) { + I->second->DropRef(); I->second = NewCallee; + I->second->AddRef(); + } return; } } diff --git a/lib/Transforms/IPO/Inliner.cpp b/lib/Transforms/IPO/Inliner.cpp index d5967fb11cd..9b8e0a1fc4d 100644 --- a/lib/Transforms/IPO/Inliner.cpp +++ b/lib/Transforms/IPO/Inliner.cpp @@ -293,10 +293,12 @@ bool Inliner::runOnSCC(std::vector &SCC) { // If we inlined the last possible call site to the function, delete the // function body now. - if (Callee->use_empty() && - (Callee->hasLocalLinkage() || - Callee->hasAvailableExternallyLinkage()) && - !SCCFunctions.count(Callee)) { + if (Callee->use_empty() && Callee->hasLocalLinkage() && + !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(errs() << " -> Deleting dead function: " << Callee->getName() << "\n"); CallGraphNode *CalleeNode = CG[Callee]; @@ -353,7 +355,7 @@ bool Inliner::removeDeadFunctions(CallGraph &CG, // 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 == 0 || CGN->getFunction() == 0) + if (CGN->getFunction() == 0) continue; Function *F = CGN->getFunction(); @@ -364,7 +366,8 @@ bool Inliner::removeDeadFunctions(CallGraph &CG, if (DNR && DNR->count(F)) continue; - if (!F->hasLinkOnceLinkage() && !F->hasLocalLinkage()) + if (!F->hasLinkOnceLinkage() && !F->hasLocalLinkage() && + !F->hasAvailableExternallyLinkage()) continue; if (!F->use_empty()) continue; diff --git a/test/Transforms/Inline/indirect_resolve.ll b/test/Transforms/Inline/indirect_resolve.ll new file mode 100644 index 00000000000..4be55d43424 --- /dev/null +++ b/test/Transforms/Inline/indirect_resolve.ll @@ -0,0 +1,16 @@ +; RUN: llvm-as < %s | opt -inline | llvm-dis +; PR4834 + +define i32 @main() { + %funcall1_ = call fastcc i32 ()* ()* @f1() + %executecommandptr1_ = call i32 %funcall1_() + ret i32 %executecommandptr1_ +} + +define internal fastcc i32 ()* @f1() nounwind readnone { + ret i32 ()* @f2 +} + +define internal i32 @f2() nounwind readnone { + ret i32 1 +}