diff --git a/include/llvm/Analysis/CallGraph.h b/include/llvm/Analysis/CallGraph.h index 60649f9ed9d..305d43dd758 100644 --- a/include/llvm/Analysis/CallGraph.h +++ b/include/llvm/Analysis/CallGraph.h @@ -14,17 +14,20 @@ // callgraph node keeps track of which functions the are called by the function // corresponding to the node. // -// A call graph will contain nodes where the function that they correspond to is -// null. This 'external' node is used to represent control flow that is not -// represented (or analyzable) in the module. As such, the external node will -// have edges to functions with the following properties: -// 1. All functions in the module without internal linkage, since they could -// be called by functions outside of the our analysis capability. +// A call graph may contain nodes where the function that they correspond to is +// null. These 'external' nodes are used to represent control flow that is not +// represented (or analyzable) in the module. In particular, this analysis +// builds one external node such that: +// 1. All functions in the module without internal linkage will have edges +// from this external node, indicating that they could be called by +// functions outside of the module. // 2. All functions whose address is used for something more than a direct -// call, for example being stored into a memory location. Since they may -// be called by an unknown caller later, they must be tracked as such. +// call, for example being stored into a memory location will also have an +// edge from this external node. Since they may be called by an unknown +// caller later, they must be tracked as such. // -// Similarly, functions have a call edge to the external node iff: +// There is a second external node added for calls that leave this module. +// Functions have a call edge to the external node iff: // 1. The function is external, reflecting the fact that they could call // anything without internal linkage or that has its address taken. // 2. The function contains an indirect function call. @@ -68,9 +71,18 @@ class CallGraph : public Pass { FunctionMapTy FunctionMap; // Map from a function to its node // Root is root of the call graph, or the external node if a 'main' function - // couldn't be found. ExternalNode is equivalent to (*this)[0]. + // couldn't be found. // - CallGraphNode *Root, *ExternalNode; + CallGraphNode *Root; + + // ExternalCallingNode - This node has edges to all external functions and + // those internal functions that have their address taken. + CallGraphNode *ExternalCallingNode; + + // CallsExternalNode - This node has edges to it from all functions making + // indirect calls or calling an external function. + CallGraphNode *CallsExternalNode; + public: //===--------------------------------------------------------------------- @@ -79,11 +91,8 @@ public: typedef FunctionMapTy::iterator iterator; typedef FunctionMapTy::const_iterator const_iterator; - // getExternalNode - Return the node that points to all functions that are - // accessable from outside of the current program. - // - CallGraphNode *getExternalNode() { return ExternalNode; } - const CallGraphNode *getExternalNode() const { return ExternalNode; } + CallGraphNode *getExternalCallingNode() const { return ExternalCallingNode; } + CallGraphNode *getCallsExternalNode() const { return CallsExternalNode; } // getRoot - Return the root of the call graph, which is either main, or if // main cannot be found, the external node. @@ -215,17 +224,19 @@ public: CalledFunctions.clear(); } -private: // Stuff to construct the node, used by CallGraph - friend class CallGraph; - - // CallGraphNode ctor - Create a node for the specified function... - inline CallGraphNode(Function *f) : F(f) {} - // addCalledFunction add a function to the list of functions called by this // one void addCalledFunction(CallGraphNode *M) { CalledFunctions.push_back(M); } + + void removeCallEdgeTo(CallGraphNode *Callee); + +private: // Stuff to construct the node, used by CallGraph + friend class CallGraph; + + // CallGraphNode ctor - Create a node for the specified function... + inline CallGraphNode(Function *f) : F(f) {} }; @@ -257,7 +268,7 @@ template <> struct GraphTraits { template<> struct GraphTraits : public GraphTraits { static NodeType *getEntryNode(CallGraph *CGN) { - return CGN->getExternalNode(); // Start at the external node! + return CGN->getExternalCallingNode(); // Start at the external node! } typedef std::pair PairTy; typedef std::pointer_to_unary_function DerefFun; @@ -279,7 +290,7 @@ template<> struct GraphTraits : public GraphTraits { template<> struct GraphTraits : public GraphTraits { static NodeType *getEntryNode(const CallGraph *CGN) { - return CGN->getExternalNode(); + return CGN->getExternalCallingNode(); } // nodes_iterator/begin/end - Allow iteration over all nodes in the graph typedef CallGraph::const_iterator nodes_iterator; diff --git a/lib/Analysis/IPA/CallGraph.cpp b/lib/Analysis/IPA/CallGraph.cpp index 506198c4fa2..8d660b99fb3 100644 --- a/lib/Analysis/IPA/CallGraph.cpp +++ b/lib/Analysis/IPA/CallGraph.cpp @@ -7,41 +7,7 @@ // //===----------------------------------------------------------------------===// // -// This interface is used to build and manipulate a call graph, which is a very -// useful tool for interprocedural optimization. -// -// Every function in a module is represented as a node in the call graph. The -// callgraph node keeps track of which functions the are called by the function -// corresponding to the node. -// -// A call graph will contain nodes where the function that they correspond to is -// null. This 'external' node is used to represent control flow that is not -// represented (or analyzable) in the module. As such, the external node will -// have edges to functions with the following properties: -// 1. All functions in the module without internal linkage, since they could -// be called by functions outside of the our analysis capability. -// 2. All functions whose address is used for something more than a direct -// call, for example being stored into a memory location. Since they may -// be called by an unknown caller later, they must be tracked as such. -// -// Similarly, functions have a call edge to the external node iff: -// 1. The function is external, reflecting the fact that they could call -// anything without internal linkage or that has its address taken. -// 2. The function contains an indirect function call. -// -// As an extension in the future, there may be multiple nodes with a null -// function. These will be used when we can prove (through pointer analysis) -// that an indirect call site can call only a specific set of functions. -// -// Because of these properties, the CallGraph captures a conservative superset -// of all of the caller-callee relationships, which is useful for -// transformations. -// -// The CallGraph class also attempts to figure out what the root of the -// CallGraph is, which is currently does by looking for a function named 'main'. -// If no function named 'main' is found, the external node is used as the entry -// node, reflecting the fact that any function without internal linkage could -// be called into (which is common for libraries). +// This file implements the CallGraph class. // //===----------------------------------------------------------------------===// @@ -52,143 +18,10 @@ #include "llvm/iTerminators.h" #include "llvm/Support/CallSite.h" #include "Support/STLExtras.h" - -namespace llvm { +using namespace llvm; static RegisterAnalysis X("callgraph", "Call Graph Construction"); -static const char * const KnownExternalFunctions[] = { - // Low-level system calls - "open", - "read", - "write", - "writev", - "lseek", - "poll", - "ioctl", - - // Low-level stdc library functions - "abort", "exit", - "getenv", "putenv", - - // Standard IO functions - "printf", - "sprintf", - "fopen", - "freopen", - "fclose", - "fwrite", - "puts", - "fputs", - "getc", - "ungetc", - "putc", - "putchar", - "fread", - "fileno", - "ftell", - "fflush", - "fseek", - "fileno", - "ferror", - "feof", - "fdopen", - "__fxstat", - "setbuf", - "setbuffer", - "etlinebuf", - "setvbuf", - - // Memory functions - "malloc", - "free", - "realloc", - "calloc", - "memalign", - - // String functions - "atoi", - "memmove", - "memset", - "memchr", - "memcmp", - "strchr", - "strncpy", - "strncmp", - "strcmp", - "strtok", - "__strcoll_l", - "__strxfrm_l", - "__strftime_l", - "__strtol_l", - "__strtoul_l", - "__strtoll_l", - "__strtoull_l", - "__strtof_l", - "__strtod_l", - "__strtold_l", - "isalpha", - - // Math functions - "exp", "sqrt", "cbrt", "hypot", - "log", "log10", "pow", - "sin", "cos", "tan", - "asin", "acos", "atan", "atan2", - - // Locale functions - "__uselocale", - "__newlocale", - "__freelocale", - "__duplocale", - "__nl_langinfo_l", - - // gettext functions used by libstdc++ - "gettext", - "dgettext", - "dcgettext", - "textdomain", - "bindtextdomain", - - // Random stuff - "__assert_fail", - "__errno_location", - "clock", "time", - "__main", -}; - - -/// ExternalFunctionDoesntCallIntoProgram - This hack is used to indicate to the -/// call graph that the specified external function is _KNOWN_ to not call back -/// into the program. This is important, because otherwise functions which call -/// "printf" for example, end up in a great big SCC that goes from the function -/// through main. -/// -static bool ExternalFunctionDoesntCallIntoProgram(const std::string &Name) { - static std::vector Funcs; - - // First time this is called? - if (Funcs.empty()) { - // Add a whole bunch of functions which are often used... - Funcs.insert(Funcs.end(), KnownExternalFunctions, - KnownExternalFunctions+ - sizeof(KnownExternalFunctions)/sizeof(KnownExternalFunctions[0])); - // Sort the list for efficient access - std::sort(Funcs.begin(), Funcs.end()); - } - - if (Name.size() > 7 && !memcmp("__llvm_", Name.c_str(), 7)) - return true; - - // Binary search for the function name... - std::vector::iterator I = - std::lower_bound(Funcs.begin(), Funcs.end(), Name); - - // Found it? - return I != Funcs.end() && *I == Name; -} - - - // getNodeFor - Return the node for the specified function or create one if it // does not already exist. // @@ -215,12 +48,12 @@ void CallGraph::addToCallGraph(Function *F) { // If this function has external linkage, anything could call it... if (!F->hasInternalLinkage()) { - ExternalNode->addCalledFunction(Node); + ExternalCallingNode->addCalledFunction(Node); // Found the entry point? if (F->getName() == "main") { - if (Root) - Root = ExternalNode; // Found multiple external mains? Don't pick one. + if (Root) // Found multiple external mains? Don't pick one. + Root = ExternalCallingNode; else Root = Node; // Found a main, keep track of it! } @@ -228,9 +61,8 @@ void CallGraph::addToCallGraph(Function *F) { // If this function is not defined in this translation unit, it could call // anything. - if (F->isExternal() && !F->getIntrinsicID() && - !ExternalFunctionDoesntCallIntoProgram(F->getName())) - Node->addCalledFunction(ExternalNode); + if (F->isExternal() && !F->getIntrinsicID()) + Node->addCalledFunction(CallsExternalNode); // Loop over all of the users of the function... looking for callers... // @@ -259,14 +91,14 @@ void CallGraph::addToCallGraph(Function *F) { } } if (isUsedExternally) - ExternalNode->addCalledFunction(Node); + ExternalCallingNode->addCalledFunction(Node); // Look for an indirect function call... for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB) for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE; ++II){ CallSite CS = CallSite::get(II); if (CS.getInstruction() && !CS.getCalledFunction()) - Node->addCalledFunction(ExternalNode); + Node->addCalledFunction(CallsExternalNode); } } @@ -274,7 +106,8 @@ bool CallGraph::run(Module &M) { destroy(); Mod = &M; - ExternalNode = getNodeFor(0); + ExternalCallingNode = getNodeFor(0); + CallsExternalNode = new CallGraphNode(0); Root = 0; // Add every function to the call graph... @@ -282,7 +115,7 @@ bool CallGraph::run(Module &M) { addToCallGraph(I); // If we didn't find a main function, use the external call graph node - if (Root == 0) Root = ExternalNode; + if (Root == 0) Root = ExternalCallingNode; return false; } @@ -328,7 +161,7 @@ void CallGraph::print(std::ostream &o, const Module *M) const { // Functions to keep a call graph up to date with a function that has been // modified // -void CallGraph::addFunctionToModule(Function *Meth) { +void CallGraph::addFunctionToModule(Function *F) { assert(0 && "not implemented"); abort(); } @@ -352,4 +185,12 @@ Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) { void CallGraph::stub() {} -} // End llvm namespace +void CallGraphNode::removeCallEdgeTo(CallGraphNode *Callee) { + for (unsigned i = CalledFunctions.size(); ; --i) { + assert(i && "Cannot find callee to remove!"); + if (CalledFunctions[i-1] == Callee) { + CalledFunctions.erase(CalledFunctions.begin()+i-1); + return; + } + } +}