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/*
This file is part of solidity.
solidity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
solidity is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with solidity. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <libsolidity/ast/AST.h>
#include <libsolidity/ast/ASTVisitor.h>
#include <liblangutil/ErrorReporter.h>
#include <map>
#include <memory>
#include <stack>
#include <vector>
namespace dev
{
namespace solidity
{
/** Basic Control Flow Block.
* Basic block of control flow. Consists of a set of (unordered) AST nodes
* for which control flow is always linear. A basic control flow block
* encompasses at most one scope. Reverts are considered to break the control
* flow.
* @todo Handle function calls correctly. So far function calls are not considered
* to change the control flow.
*/
struct ControlFlowBlock
{
/// All variable declarations inside this control flow block.
std::vector<VariableDeclaration const*> variableDeclarations;
/// All expressions inside this control flow block (this includes all subexpressions!).
std::vector<Expression const*> expressions;
/// All inline assembly statements inside in this control flow block.
std::vector<InlineAssembly const*> inlineAssemblyStatements;
/// If control flow returns in this node, the return statement is stored in returnStatement,
/// otherwise returnStatement is nullptr.
Return const* returnStatement = nullptr;
};
/** Node of the Control Flow Graph.
* The control flow is a directed graph connecting control flow blocks.
* An arc between two nodes indicates that the control flow can possibly
* move from its start node to its end node during execution.
*/
struct CFGNode
{
/// Entry nodes. All CFG nodes from which control flow may move into this node.
std::vector<CFGNode*> entries;
/// Exit nodes. All CFG nodes to which control flow may continue after this node.
std::vector<CFGNode*> exits;
/// Control flow in the node.
ControlFlowBlock block;
};
/** Describes the control flow of a function. */
struct FunctionFlow
{
virtual ~FunctionFlow() {}
/// Entry node. Control flow of the function starts here.
/// This node is empty and does not have any entries.
CFGNode* entry = nullptr;
/// Exit node. All non-reverting control flow of the function ends here.
/// This node is empty and does not have any exits, but may have multiple entries
/// (e.g. all return statements of the function).
CFGNode* exit = nullptr;
/// Revert node. Control flow of the function in case of revert.
/// This node is empty does not have any exits, but may have multiple entries
/// (e.g. all assert, require, revert and throw statements).
CFGNode* revert = nullptr;
};
/** Describes the control flow of a modifier.
* Every placeholder breaks the control flow. The node preceding the
* placeholder is assigned placeholderEntry as exit and the node
* following the placeholder is assigned placeholderExit as entry.
*/
struct ModifierFlow: FunctionFlow
{
/// Control flow leading towards a placeholder exit in placeholderEntry.
CFGNode* placeholderEntry = nullptr;
/// Control flow coming from a placeholder enter from placeholderExit.
CFGNode* placeholderExit = nullptr;
};
class CFG: private ASTConstVisitor
{
public:
explicit CFG(ErrorReporter& _errorReporter): m_errorReporter(_errorReporter) {}
bool constructFlow(ASTNode const& _astRoot);
bool visit(ModifierDefinition const& _modifier) override;
bool visit(FunctionDefinition const& _function) override;
FunctionFlow const& functionFlow(FunctionDefinition const& _function) const;
class NodeContainer
{
public:
CFGNode* newNode();
private:
std::vector<std::unique_ptr<CFGNode>> m_nodes;
};
private:
/// Initially the control flow for all functions *ignoring* modifiers and for
/// all modifiers is constructed. Afterwards the control flow of functions
/// is adjusted by applying all modifiers.
void applyModifiers();
/// Creates a copy of the modifier flow @a _modifierFlow, while replacing the
/// placeholder entry and exit with the function entry and exit, as well as
/// replacing the modifier revert node with the function's revert node.
/// The resulting control flow is the new function flow with the modifier applied.
/// @a _functionFlow is updated in-place.
void applyModifierFlowToFunctionFlow(
ModifierFlow const& _modifierFlow,
FunctionFlow* _functionFlow
);
ErrorReporter& m_errorReporter;
/// Node container.
/// All nodes allocated during the construction of the control flow graph
/// are owned by the CFG class and stored in this container.
NodeContainer m_nodeContainer;
std::map<FunctionDefinition const*, std::unique_ptr<FunctionFlow>> m_functionControlFlow;
std::map<ModifierDefinition const*, std::unique_ptr<ModifierFlow>> m_modifierControlFlow;
};
}
}
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