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+//===--- CFG.h - Classes for representing and building CFGs------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the CFG and CFGBuilder classes for representing and
+// building Control-Flow Graphs (CFGs) from ASTs.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_CFG_H
+#define LLVM_CLANG_CFG_H
+
+#include "llvm/ADT/GraphTraits.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/raw_ostream.h"
+#include <list>
+#include <vector>
+#include <cassert>
+
+namespace clang {
+ class Stmt;
+ class Expr;
+ class CFG;
+ class PrinterHelper;
+ class BlockEdge;
+
+/// CFGBlock - Represents a single basic block in a source-level CFG.
+/// It consists of:
+///
+/// (1) A set of statements/expressions (which may contain subexpressions).
+/// (2) A "terminator" statement (not in the set of statements).
+/// (3) A list of successors and predecessors.
+///
+/// Terminator: The terminator represents the type of control-flow that occurs
+/// at the end of the basic block. The terminator is a Stmt* referring to an
+/// AST node that has control-flow: if-statements, breaks, loops, etc.
+/// If the control-flow is conditional, the condition expression will appear
+/// within the set of statements in the block (usually the last statement).
+///
+/// Predecessors: the order in the set of predecessors is arbitrary.
+///
+/// Successors: the order in the set of successors is NOT arbitrary. We
+/// currently have the following orderings based on the terminator:
+///
+/// Terminator Successor Ordering
+/// -----------------------------------------------------
+/// if Then Block; Else Block
+/// ? operator LHS expression; RHS expression
+/// &&, || expression that uses result of && or ||, RHS
+///
+class CFGBlock {
+ typedef std::vector<Stmt*> StatementListTy;
+ /// Stmts - The set of statements in the basic block.
+ StatementListTy Stmts;
+
+ /// Label - An (optional) label that prefixes the executable
+ /// statements in the block. When this variable is non-NULL, it is
+ /// either an instance of LabelStmt or SwitchCase.
+ Stmt *Label;
+
+ /// Terminator - The terminator for a basic block that
+ /// indicates the type of control-flow that occurs between a block
+ /// and its successors.
+ Stmt *Terminator;
+
+ /// LoopTarget - Some blocks are used to represent the "loop edge" to
+ /// the start of a loop from within the loop body. This Stmt* will be
+ /// refer to the loop statement for such blocks (and be null otherwise).
+ const Stmt *LoopTarget;
+
+ /// BlockID - A numerical ID assigned to a CFGBlock during construction
+ /// of the CFG.
+ unsigned BlockID;
+
+ /// Predecessors/Successors - Keep track of the predecessor / successor
+ /// CFG blocks.
+ typedef std::vector<CFGBlock*> AdjacentBlocks;
+ AdjacentBlocks Preds;
+ AdjacentBlocks Succs;
+
+public:
+ explicit CFGBlock(unsigned blockid) : Label(NULL), Terminator(NULL),
+ LoopTarget(NULL), BlockID(blockid) {}
+ ~CFGBlock() {};
+
+ // Statement iterators
+ typedef StatementListTy::iterator iterator;
+ typedef StatementListTy::const_iterator const_iterator;
+ typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+ typedef std::reverse_iterator<iterator> reverse_iterator;
+
+ Stmt* front() const { return Stmts.front(); }
+ Stmt* back() const { return Stmts.back(); }
+
+ iterator begin() { return Stmts.begin(); }
+ iterator end() { return Stmts.end(); }
+ const_iterator begin() const { return Stmts.begin(); }
+ const_iterator end() const { return Stmts.end(); }
+
+ reverse_iterator rbegin() { return Stmts.rbegin(); }
+ reverse_iterator rend() { return Stmts.rend(); }
+ const_reverse_iterator rbegin() const { return Stmts.rbegin(); }
+ const_reverse_iterator rend() const { return Stmts.rend(); }
+
+ unsigned size() const { return Stmts.size(); }
+ bool empty() const { return Stmts.empty(); }
+
+ Stmt* operator[](size_t i) const { assert (i < size()); return Stmts[i]; }
+
+ // CFG iterators
+ typedef AdjacentBlocks::iterator pred_iterator;
+ typedef AdjacentBlocks::const_iterator const_pred_iterator;
+ typedef AdjacentBlocks::reverse_iterator pred_reverse_iterator;
+ typedef AdjacentBlocks::const_reverse_iterator const_pred_reverse_iterator;
+
+ typedef AdjacentBlocks::iterator succ_iterator;
+ typedef AdjacentBlocks::const_iterator const_succ_iterator;
+ typedef AdjacentBlocks::reverse_iterator succ_reverse_iterator;
+ typedef AdjacentBlocks::const_reverse_iterator const_succ_reverse_iterator;
+
+ pred_iterator pred_begin() { return Preds.begin(); }
+ pred_iterator pred_end() { return Preds.end(); }
+ const_pred_iterator pred_begin() const { return Preds.begin(); }
+ const_pred_iterator pred_end() const { return Preds.end(); }
+
+ pred_reverse_iterator pred_rbegin() { return Preds.rbegin(); }
+ pred_reverse_iterator pred_rend() { return Preds.rend(); }
+ const_pred_reverse_iterator pred_rbegin() const { return Preds.rbegin(); }
+ const_pred_reverse_iterator pred_rend() const { return Preds.rend(); }
+
+ succ_iterator succ_begin() { return Succs.begin(); }
+ succ_iterator succ_end() { return Succs.end(); }
+ const_succ_iterator succ_begin() const { return Succs.begin(); }
+ const_succ_iterator succ_end() const { return Succs.end(); }
+
+ succ_reverse_iterator succ_rbegin() { return Succs.rbegin(); }
+ succ_reverse_iterator succ_rend() { return Succs.rend(); }
+ const_succ_reverse_iterator succ_rbegin() const { return Succs.rbegin(); }
+ const_succ_reverse_iterator succ_rend() const { return Succs.rend(); }
+
+ unsigned succ_size() const { return Succs.size(); }
+ bool succ_empty() const { return Succs.empty(); }
+
+ unsigned pred_size() const { return Preds.size(); }
+ bool pred_empty() const { return Preds.empty(); }
+
+ // Manipulation of block contents
+
+ void appendStmt(Stmt* Statement) { Stmts.push_back(Statement); }
+ void setTerminator(Stmt* Statement) { Terminator = Statement; }
+ void setLabel(Stmt* Statement) { Label = Statement; }
+ void setLoopTarget(const Stmt *loopTarget) { LoopTarget = loopTarget; }
+
+ Stmt* getTerminator() { return Terminator; }
+ const Stmt* getTerminator() const { return Terminator; }
+
+ Stmt* getTerminatorCondition();
+
+ const Stmt* getTerminatorCondition() const {
+ return const_cast<CFGBlock*>(this)->getTerminatorCondition();
+ }
+
+ const Stmt *getLoopTarget() const { return LoopTarget; }
+
+ bool hasBinaryBranchTerminator() const;
+
+ Stmt* getLabel() { return Label; }
+ const Stmt* getLabel() const { return Label; }
+
+ void reverseStmts();
+
+ void addSuccessor(CFGBlock* Block) {
+ Block->Preds.push_back(this);
+ Succs.push_back(Block);
+ }
+
+ unsigned getBlockID() const { return BlockID; }
+
+ void dump(const CFG* cfg) const;
+ void print(llvm::raw_ostream& OS, const CFG* cfg) const;
+ void printTerminator(llvm::raw_ostream& OS) const;
+};
+
+
+/// CFG - Represents a source-level, intra-procedural CFG that represents the
+/// control-flow of a Stmt. The Stmt can represent an entire function body,
+/// or a single expression. A CFG will always contain one empty block that
+/// represents the Exit point of the CFG. A CFG will also contain a designated
+/// Entry block. The CFG solely represents control-flow; it consists of
+/// CFGBlocks which are simply containers of Stmt*'s in the AST the CFG
+/// was constructed from.
+class CFG {
+public:
+ //===--------------------------------------------------------------------===//
+ // CFG Construction & Manipulation.
+ //===--------------------------------------------------------------------===//
+
+ /// buildCFG - Builds a CFG from an AST. The responsibility to free the
+ /// constructed CFG belongs to the caller.
+ static CFG* buildCFG(Stmt* AST);
+
+ /// createBlock - Create a new block in the CFG. The CFG owns the block;
+ /// the caller should not directly free it.
+ CFGBlock* createBlock();
+
+ /// setEntry - Set the entry block of the CFG. This is typically used
+ /// only during CFG construction. Most CFG clients expect that the
+ /// entry block has no predecessors and contains no statements.
+ void setEntry(CFGBlock *B) { Entry = B; }
+
+ /// setExit - Set the exit block of the CFG. This is typically used
+ /// only during CFG construction. Most CFG clients expect that the
+ /// exit block has no successors and contains no statements.
+ void setIndirectGotoBlock(CFGBlock* B) { IndirectGotoBlock = B; }
+
+ //===--------------------------------------------------------------------===//
+ // Block Iterators
+ //===--------------------------------------------------------------------===//
+
+ typedef std::list<CFGBlock> CFGBlockListTy;
+
+ typedef CFGBlockListTy::iterator iterator;
+ typedef CFGBlockListTy::const_iterator const_iterator;
+ typedef std::reverse_iterator<iterator> reverse_iterator;
+ typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
+
+ CFGBlock& front() { return Blocks.front(); }
+ CFGBlock& back() { return Blocks.back(); }
+
+ iterator begin() { return Blocks.begin(); }
+ iterator end() { return Blocks.end(); }
+ const_iterator begin() const { return Blocks.begin(); }
+ const_iterator end() const { return Blocks.end(); }
+
+ reverse_iterator rbegin() { return Blocks.rbegin(); }
+ reverse_iterator rend() { return Blocks.rend(); }
+ const_reverse_iterator rbegin() const { return Blocks.rbegin(); }
+ const_reverse_iterator rend() const { return Blocks.rend(); }
+
+ CFGBlock& getEntry() { return *Entry; }
+ const CFGBlock& getEntry() const { return *Entry; }
+ CFGBlock& getExit() { return *Exit; }
+ const CFGBlock& getExit() const { return *Exit; }
+
+ CFGBlock* getIndirectGotoBlock() { return IndirectGotoBlock; }
+ const CFGBlock* getIndirectGotoBlock() const { return IndirectGotoBlock; }
+
+ //===--------------------------------------------------------------------===//
+ // Member templates useful for various batch operations over CFGs.
+ //===--------------------------------------------------------------------===//
+
+ template <typename CALLBACK>
+ void VisitBlockStmts(CALLBACK& O) const {
+ for (const_iterator I=begin(), E=end(); I != E; ++I)
+ for (CFGBlock::const_iterator BI=I->begin(), BE=I->end(); BI != BE; ++BI)
+ O(*BI);
+ }
+
+ //===--------------------------------------------------------------------===//
+ // CFG Introspection.
+ //===--------------------------------------------------------------------===//
+
+ struct BlkExprNumTy {
+ const signed Idx;
+ explicit BlkExprNumTy(signed idx) : Idx(idx) {}
+ explicit BlkExprNumTy() : Idx(-1) {}
+ operator bool() const { return Idx >= 0; }
+ operator unsigned() const { assert(Idx >=0); return (unsigned) Idx; }
+ };
+
+ bool isBlkExpr(const Stmt* S) { return getBlkExprNum(S); }
+ BlkExprNumTy getBlkExprNum(const Stmt* S);
+ unsigned getNumBlkExprs();
+
+ unsigned getNumBlockIDs() const { return NumBlockIDs; }
+
+ //===--------------------------------------------------------------------===//
+ // CFG Debugging: Pretty-Printing and Visualization.
+ //===--------------------------------------------------------------------===//
+
+ void viewCFG() const;
+ void print(llvm::raw_ostream& OS) const;
+ void dump() const;
+
+ //===--------------------------------------------------------------------===//
+ // Internal: constructors and data.
+ //===--------------------------------------------------------------------===//
+
+ CFG() : Entry(NULL), Exit(NULL), IndirectGotoBlock(NULL), NumBlockIDs(0),
+ BlkExprMap(NULL) {};
+
+ ~CFG();
+
+ llvm::BumpPtrAllocator& getAllocator() {
+ return Alloc;
+ }
+
+private:
+ CFGBlock* Entry;
+ CFGBlock* Exit;
+ CFGBlock* IndirectGotoBlock; // Special block to contain collective dispatch
+ // for indirect gotos
+ CFGBlockListTy Blocks;
+ unsigned NumBlockIDs;
+
+ // BlkExprMap - An opaque pointer to prevent inclusion of DenseMap.h.
+ // It represents a map from Expr* to integers to record the set of
+ // block-level expressions and their "statement number" in the CFG.
+ void* BlkExprMap;
+
+ /// Alloc - An internal allocator.
+ llvm::BumpPtrAllocator Alloc;
+};
+} // end namespace clang
+
+//===----------------------------------------------------------------------===//
+// GraphTraits specializations for CFG basic block graphs (source-level CFGs)
+//===----------------------------------------------------------------------===//
+
+namespace llvm {
+
+// Traits for: CFGBlock
+
+template <> struct GraphTraits<clang::CFGBlock* > {
+ typedef clang::CFGBlock NodeType;
+ typedef clang::CFGBlock::succ_iterator ChildIteratorType;
+
+ static NodeType* getEntryNode(clang::CFGBlock* BB)
+ { return BB; }
+
+ static inline ChildIteratorType child_begin(NodeType* N)
+ { return N->succ_begin(); }
+
+ static inline ChildIteratorType child_end(NodeType* N)
+ { return N->succ_end(); }
+};
+
+template <> struct GraphTraits<const clang::CFGBlock* > {
+ typedef const clang::CFGBlock NodeType;
+ typedef clang::CFGBlock::const_succ_iterator ChildIteratorType;
+
+ static NodeType* getEntryNode(const clang::CFGBlock* BB)
+ { return BB; }
+
+ static inline ChildIteratorType child_begin(NodeType* N)
+ { return N->succ_begin(); }
+
+ static inline ChildIteratorType child_end(NodeType* N)
+ { return N->succ_end(); }
+};
+
+template <> struct GraphTraits<Inverse<const clang::CFGBlock*> > {
+ typedef const clang::CFGBlock NodeType;
+ typedef clang::CFGBlock::const_pred_iterator ChildIteratorType;
+
+ static NodeType *getEntryNode(Inverse<const clang::CFGBlock*> G)
+ { return G.Graph; }
+
+ static inline ChildIteratorType child_begin(NodeType* N)
+ { return N->pred_begin(); }
+
+ static inline ChildIteratorType child_end(NodeType* N)
+ { return N->pred_end(); }
+};
+
+// Traits for: CFG
+
+template <> struct GraphTraits<clang::CFG* >
+ : public GraphTraits<clang::CFGBlock* > {
+
+ typedef clang::CFG::iterator nodes_iterator;
+
+ static NodeType *getEntryNode(clang::CFG* F) { return &F->getEntry(); }
+ static nodes_iterator nodes_begin(clang::CFG* F) { return F->begin(); }
+ static nodes_iterator nodes_end(clang::CFG* F) { return F->end(); }
+};
+
+template <> struct GraphTraits< const clang::CFG* >
+ : public GraphTraits< const clang::CFGBlock* > {
+
+ typedef clang::CFG::const_iterator nodes_iterator;
+
+ static NodeType *getEntryNode( const clang::CFG* F) { return &F->getEntry(); }
+ static nodes_iterator nodes_begin( const clang::CFG* F) { return F->begin(); }
+ static nodes_iterator nodes_end( const clang::CFG* F) { return F->end(); }
+};
+
+template <> struct GraphTraits<Inverse<const clang::CFG*> >
+ : public GraphTraits<Inverse<const clang::CFGBlock*> > {
+
+ typedef clang::CFG::const_iterator nodes_iterator;
+
+ static NodeType *getEntryNode(const clang::CFG* F) { return &F->getExit(); }
+ static nodes_iterator nodes_begin(const clang::CFG* F) { return F->begin();}
+ static nodes_iterator nodes_end(const clang::CFG* F) { return F->end(); }
+};
+
+} // end llvm namespace
+
+#endif
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