//===- CallGraph.h - AST-based Call graph -----------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file declares the AST-based CallGraph.
//
// A call graph for functions whose definitions/bodies are available in the
// current translation unit. The graph has a "virtual" root node that contains
// edges to all externally available functions.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_ANALYSIS_CALLGRAPH_H
#define LLVM_CLANG_ANALYSIS_CALLGRAPH_H
#include "clang/AST/Decl.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/iterator_range.h"
#include <memory>
namespace clang {
class CallGraphNode;
class Decl;
class DeclContext;
class Stmt;
/// The AST-based call graph.
///
/// The call graph extends itself with the given declarations by implementing
/// the recursive AST visitor, which constructs the graph by visiting the given
/// declarations.
class CallGraph : public RecursiveASTVisitor<CallGraph> {
friend class CallGraphNode;
using FunctionMapTy =
llvm::DenseMap<const Decl *, std::unique_ptr<CallGraphNode>>;
/// FunctionMap owns all CallGraphNodes.
FunctionMapTy FunctionMap;
/// This is a virtual root node that has edges to all the functions.
CallGraphNode *Root;
public:
CallGraph();
~CallGraph();
/// Populate the call graph with the functions in the given
/// declaration.
///
/// Recursively walks the declaration to find all the dependent Decls as well.
void addToCallGraph(Decl *D) {
TraverseDecl(D);
}
/// Determine if a declaration should be included in the graph.
static bool includeInGraph(const Decl *D);
/// Determine if a declaration should be included in the graph for the
/// purposes of being a callee. This is similar to includeInGraph except
/// it permits declarations, not just definitions.
static bool includeCalleeInGraph(const Decl *D);
/// Lookup the node for the given declaration.
CallGraphNode *getNode(const Decl *) const;
/// Lookup the node for the given declaration. If none found, insert
/// one into the graph.
CallGraphNode *getOrInsertNode(Decl *);
using iterator = FunctionMapTy::iterator;
using const_iterator = FunctionMapTy::const_iterator;
/// Iterators through all the elements in the graph. Note, this gives
/// non-deterministic order.
iterator begin() { return FunctionMap.begin(); }
iterator end() { return FunctionMap.end(); }
const_iterator begin() const { return FunctionMap.begin(); }
const_iterator end() const { return FunctionMap.end(); }
/// Get the number of nodes in the graph.
unsigned size() const { return FunctionMap.size(); }
/// Get the virtual root of the graph, all the functions available externally
/// are represented as callees of the node.
CallGraphNode *getRoot() const { return Root; }
/// Iterators through all the nodes of the graph that have no parent. These
/// are the unreachable nodes, which are either unused or are due to us
/// failing to add a call edge due to the analysis imprecision.
using nodes_iterator = llvm::SetVector<CallGraphNode *>::iterator;
using const_nodes_iterator = llvm::SetVector<CallGraphNode *>::const_iterator;
void print(raw_ostream &os) const;
void dump() const;
void viewGraph() const;
void addNodesForBlocks(DeclContext *D);
/// Part of recursive declaration visitation. We recursively visit all the
/// declarations to collect the root functions.
bool VisitFunctionDecl(FunctionDecl *FD) {
// We skip function template definitions, as their semantics is
// only determined when they are instantiated.
if (includeInGraph(FD) && FD->isThisDeclarationADefinition()) {
// Add all blocks declared inside this function to the graph.
addNodesForBlocks(FD);
// If this function has external linkage, anything could call it.
// Note, we are not precise here. For example, the function could have
// its address taken.
addNodeForDecl(FD, FD->isGlobal());
}
return true;
}
/// Part of recursive declaration visitation.
bool VisitObjCMethodDecl(ObjCMethodDecl *MD) {
if (includeInGraph(MD)) {
addNodesForBlocks(MD);
addNodeForDecl(MD, true);
}
return true;
}
// We are only collecting the declarations, so do not step into the bodies.
bool TraverseStmt(Stmt *S) { return true; }
bool shouldWalkTypesOfTypeLocs() const { return false; }
bool shouldVisitTemplateInstantiations() const { return true; }
bool shouldVisitImplicitCode() const { return true; }
private:
/// Add the given declaration to the call graph.
void addNodeForDecl(Decl *D, bool IsGlobal);
};
class CallGraphNode {
public:
struct CallRecord {
CallGraphNode *Callee;
Expr *CallExpr;
CallRecord() = default;
CallRecord(CallGraphNode *Callee_, Expr *CallExpr_)
: Callee(Callee_), CallExpr(CallExpr_) {}
// The call destination is the only important data here,
// allow to transparently unwrap into it.
operator CallGraphNode *() const { return Callee; }
};
private:
/// The function/method declaration.
Decl *FD;
/// The list of functions called from this node.
SmallVector<CallRecord, 5> CalledFunctions;
public:
CallGraphNode(Decl *D) : FD(D) {}
using iterator = SmallVectorImpl<CallRecord>::iterator;
using const_iterator = SmallVectorImpl<CallRecord>::const_iterator;
/// Iterators through all the callees/children of the node.
iterator begin() { return CalledFunctions.begin(); }
iterator end() { return CalledFunctions.end(); }
const_iterator begin() const { return CalledFunctions.begin(); }
const_iterator end() const { return CalledFunctions.end(); }
/// Iterator access to callees/children of the node.
llvm::iterator_range<iterator> callees() {
return llvm::make_range(begin(), end());
}
llvm::iterator_range<const_iterator> callees() const {
return llvm::make_range(begin(), end());
}
bool empty() const { return CalledFunctions.empty(); }
unsigned size() const { return CalledFunctions.size(); }
void addCallee(CallRecord Call) { CalledFunctions.push_back(Call); }
Decl *getDecl() const { return FD; }
FunctionDecl *getDefinition() const {
return getDecl()->getAsFunction()->getDefinition();
}
void print(raw_ostream &os) const;
void dump() const;
};
// NOTE: we are comparing based on the callee only. So different call records
// (with different call expressions) to the same callee will compare equal!
inline bool operator==(const CallGraphNode::CallRecord &LHS,
const CallGraphNode::CallRecord &RHS) {
return LHS.Callee == RHS.Callee;
}
} // namespace clang
namespace llvm {
// Specialize DenseMapInfo for clang::CallGraphNode::CallRecord.
template <> struct DenseMapInfo<clang::CallGraphNode::CallRecord> {
static inline clang::CallGraphNode::CallRecord getEmptyKey() {
return clang::CallGraphNode::CallRecord(
DenseMapInfo<clang::CallGraphNode *>::getEmptyKey(),
DenseMapInfo<clang::Expr *>::getEmptyKey());
}
static inline clang::CallGraphNode::CallRecord getTombstoneKey() {
return clang::CallGraphNode::CallRecord(
DenseMapInfo<clang::CallGraphNode *>::getTombstoneKey(),
DenseMapInfo<clang::Expr *>::getTombstoneKey());
}
static unsigned getHashValue(const clang::CallGraphNode::CallRecord &Val) {
// NOTE: we are comparing based on the callee only.
// Different call records with the same callee will compare equal!
return DenseMapInfo<clang::CallGraphNode *>::getHashValue(Val.Callee);
}
static bool isEqual(const clang::CallGraphNode::CallRecord &LHS,
const clang::CallGraphNode::CallRecord &RHS) {
return LHS == RHS;
}
};
// Graph traits for iteration, viewing.
template <> struct GraphTraits<clang::CallGraphNode*> {
using NodeType = clang::CallGraphNode;
using NodeRef = clang::CallGraphNode *;
using ChildIteratorType = NodeType::iterator;
static NodeType *getEntryNode(clang::CallGraphNode *CGN) { return CGN; }
static ChildIteratorType child_begin(NodeType *N) { return N->begin(); }
static ChildIteratorType child_end(NodeType *N) { return N->end(); }
};
template <> struct GraphTraits<const clang::CallGraphNode*> {
using NodeType = const clang::CallGraphNode;
using NodeRef = const clang::CallGraphNode *;
using ChildIteratorType = NodeType::const_iterator;
static NodeType *getEntryNode(const clang::CallGraphNode *CGN) { return CGN; }
static ChildIteratorType child_begin(NodeType *N) { return N->begin();}
static ChildIteratorType child_end(NodeType *N) { return N->end(); }
};
template <> struct GraphTraits<clang::CallGraph*>
: public GraphTraits<clang::CallGraphNode*> {
static NodeType *getEntryNode(clang::CallGraph *CGN) {
return CGN->getRoot(); // Start at the external node!
}
static clang::CallGraphNode *
CGGetValue(clang::CallGraph::const_iterator::value_type &P) {
return P.second.get();
}
// nodes_iterator/begin/end - Allow iteration over all nodes in the graph
using nodes_iterator =
mapped_iterator<clang::CallGraph::iterator, decltype(&CGGetValue)>;
static nodes_iterator nodes_begin(clang::CallGraph *CG) {
return nodes_iterator(CG->begin(), &CGGetValue);
}
static nodes_iterator nodes_end (clang::CallGraph *CG) {
return nodes_iterator(CG->end(), &CGGetValue);
}
static unsigned size(clang::CallGraph *CG) { return CG->size(); }
};
template <> struct GraphTraits<const clang::CallGraph*> :
public GraphTraits<const clang::CallGraphNode*> {
static NodeType *getEntryNode(const clang::CallGraph *CGN) {
return CGN->getRoot();
}
static clang::CallGraphNode *
CGGetValue(clang::CallGraph::const_iterator::value_type &P) {
return P.second.get();
}
// nodes_iterator/begin/end - Allow iteration over all nodes in the graph
using nodes_iterator =
mapped_iterator<clang::CallGraph::const_iterator, decltype(&CGGetValue)>;
static nodes_iterator nodes_begin(const clang::CallGraph *CG) {
return nodes_iterator(CG->begin(), &CGGetValue);
}
static nodes_iterator nodes_end(const clang::CallGraph *CG) {
return nodes_iterator(CG->end(), &CGGetValue);
}
static unsigned size(const clang::CallGraph *CG) { return CG->size(); }
};
} // namespace llvm
#endif // LLVM_CLANG_ANALYSIS_CALLGRAPH_H