path: root/libsolidity/codegen/CompilerContext.h

/*
    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/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2014
 * Utilities for the solidity compiler.
 */

#pragma once

#include <libsolidity/ast/ASTAnnotations.h>
#include <libsolidity/ast/ASTForward.h>
#include <libsolidity/ast/Types.h>
#include <libsolidity/codegen/ABIFunctions.h>

#include <libevmasm/Assembly.h>
#include <libevmasm/Instruction.h>
#include <liblangutil/EVMVersion.h>
#include <libdevcore/Common.h>

#include <functional>
#include <ostream>
#include <stack>
#include <queue>
#include <utility>

namespace dev {
namespace solidity {


/**
 * Context to be shared by all units that compile the same contract.
 * It stores the generated bytecode and the position of identifiers in memory and on the stack.
 */
class CompilerContext
{
public:
    explicit CompilerContext(EVMVersion _evmVersion = EVMVersion{}, CompilerContext* _runtimeContext = nullptr):
        m_asm(std::make_shared<eth::Assembly>()),
        m_evmVersion(_evmVersion),
        m_runtimeContext(_runtimeContext),
        m_abiFunctions(m_evmVersion)
    {
        if (m_runtimeContext)
            m_runtimeSub = size_t(m_asm->newSub(m_runtimeContext->m_asm).data());
    }

    EVMVersion const& evmVersion() const { return m_evmVersion; }

    /// Update currently enabled set of experimental features.
    void setExperimentalFeatures(std::set<ExperimentalFeature> const& _features) { m_experimentalFeatures = _features; }
    /// @returns true if the given feature is enabled.
    bool experimentalFeatureActive(ExperimentalFeature _feature) const { return m_experimentalFeatures.count(_feature); }

    void addStateVariable(VariableDeclaration const& _declaration, u256 const& _storageOffset, unsigned _byteOffset);
    void addVariable(VariableDeclaration const& _declaration, unsigned _offsetToCurrent = 0);
    void removeVariable(Declaration const& _declaration);
    /// Removes all local variables currently allocated above _stackHeight.
    void removeVariablesAboveStackHeight(unsigned _stackHeight);
    /// Returns the number of currently allocated local variables.
    unsigned numberOfLocalVariables() const;

    void setCompiledContracts(std::map<ContractDefinition const*, eth::Assembly const*> const& _contracts) { m_compiledContracts = _contracts; }
    eth::Assembly const& compiledContract(ContractDefinition const& _contract) const;

    void setStackOffset(int _offset) { m_asm->setDeposit(_offset); }
    void adjustStackOffset(int _adjustment) { m_asm->adjustDeposit(_adjustment); }
    unsigned stackHeight() const { solAssert(m_asm->deposit() >= 0, ""); return unsigned(m_asm->deposit()); }

    bool isLocalVariable(Declaration const* _declaration) const;
    bool isStateVariable(Declaration const* _declaration) const { return m_stateVariables.count(_declaration) != 0; }

    /// @returns the entry label of the given function and creates it if it does not exist yet.
    eth::AssemblyItem functionEntryLabel(Declaration const& _declaration);
    /// @returns the entry label of the given function. Might return an AssemblyItem of type
    /// UndefinedItem if it does not exist yet.
    eth::AssemblyItem functionEntryLabelIfExists(Declaration const& _declaration) const;
    /// @returns the entry label of the given function and takes overrides into account.
    FunctionDefinition const& resolveVirtualFunction(FunctionDefinition const& _function);
    /// @returns the function that overrides the given declaration from the most derived class just
    /// above _base in the current inheritance hierarchy.
    FunctionDefinition const& superFunction(FunctionDefinition const& _function, ContractDefinition const& _base);
    /// @returns the next constructor in the inheritance hierarchy.
    FunctionDefinition const* nextConstructor(ContractDefinition const& _contract) const;
    /// Sets the current inheritance hierarchy from derived to base.
    void setInheritanceHierarchy(std::vector<ContractDefinition const*> const& _hierarchy) { m_inheritanceHierarchy = _hierarchy; }

    /// @returns the next function in the queue of functions that are still to be compiled
    /// (i.e. that were referenced during compilation but where we did not yet generate code for).
    /// Returns nullptr if the queue is empty. Does not remove the function from the queue,
    /// that will only be done by startFunction below.
    Declaration const* nextFunctionToCompile() const;
    /// Resets function specific members, inserts the function entry label and marks the function
    /// as "having code".
    void startFunction(Declaration const& _function);

    /// Appends a call to the named low-level function and inserts the generator into the
    /// list of low-level-functions to be generated, unless it already exists.
    /// Note that the generator should not assume that objects are still alive when it is called,
    /// unless they are guaranteed to be alive for the whole run of the compiler (AST nodes, for example).
    void callLowLevelFunction(
        std::string const& _name,
        unsigned _inArgs,
        unsigned _outArgs,
        std::function<void(CompilerContext&)> const& _generator
    );
    /// Returns the tag of the named low-level function and inserts the generator into the
    /// list of low-level-functions to be generated, unless it already exists.
    /// Note that the generator should not assume that objects are still alive when it is called,
    /// unless they are guaranteed to be alive for the whole run of the compiler (AST nodes, for example).
    eth::AssemblyItem lowLevelFunctionTag(
        std::string const& _name,
        unsigned _inArgs,
        unsigned _outArgs,
        std::function<void(CompilerContext&)> const& _generator
    );
    /// Generates the code for missing low-level functions, i.e. calls the generators passed above.
    void appendMissingLowLevelFunctions();
    ABIFunctions& abiFunctions() { return m_abiFunctions; }

    ModifierDefinition const& resolveVirtualFunctionModifier(ModifierDefinition const& _modifier) const;
    /// Returns the distance of the given local variable from the bottom of the stack (of the current function).
    unsigned baseStackOffsetOfVariable(Declaration const& _declaration) const;
    /// If supplied by a value returned by @ref baseStackOffsetOfVariable(variable), returns
    /// the distance of that variable from the current top of the stack.
    unsigned baseToCurrentStackOffset(unsigned _baseOffset) const;
    /// Converts an offset relative to the current stack height to a value that can be used later
    /// with baseToCurrentStackOffset to point to the same stack element.
    unsigned currentToBaseStackOffset(unsigned _offset) const;
    /// @returns pair of slot and byte offset of the value inside this slot.
    std::pair<u256, unsigned> storageLocationOfVariable(Declaration const& _declaration) const;

    /// Appends a JUMPI instruction to a new tag and @returns the tag
    eth::AssemblyItem appendConditionalJump() { return m_asm->appendJumpI().tag(); }
    /// Appends a JUMPI instruction to @a _tag
    CompilerContext& appendConditionalJumpTo(eth::AssemblyItem const& _tag) { m_asm->appendJumpI(_tag); return *this; }
    /// Appends a JUMP to a new tag and @returns the tag
    eth::AssemblyItem appendJumpToNew() { return m_asm->appendJump().tag(); }
    /// Appends a JUMP to a tag already on the stack
    CompilerContext& appendJump(eth::AssemblyItem::JumpType _jumpType = eth::AssemblyItem::JumpType::Ordinary);
    /// Appends an INVALID instruction
    CompilerContext& appendInvalid();
    /// Appends a conditional INVALID instruction
    CompilerContext& appendConditionalInvalid();
    /// Appends a REVERT(0, 0) call
    CompilerContext& appendRevert();
    /// Appends a conditional REVERT-call, either forwarding the RETURNDATA or providing the
    /// empty string. Consumes the condition.
    /// If the current EVM version does not support RETURNDATA, uses REVERT but does not forward
    /// the data.
    CompilerContext& appendConditionalRevert(bool _forwardReturnData = false);
    /// Appends a JUMP to a specific tag
    CompilerContext& appendJumpTo(
        eth::AssemblyItem const& _tag,
        eth::AssemblyItem::JumpType _jumpType = eth::AssemblyItem::JumpType::Ordinary
    ) { *m_asm << _tag.pushTag(); return appendJump(_jumpType); }
    /// Appends pushing of a new tag and @returns the new tag.
    eth::AssemblyItem pushNewTag() { return m_asm->append(m_asm->newPushTag()).tag(); }
    /// @returns a new tag without pushing any opcodes or data
    eth::AssemblyItem newTag() { return m_asm->newTag(); }
    /// @returns a new tag identified by name.
    eth::AssemblyItem namedTag(std::string const& _name) { return m_asm->namedTag(_name); }
    /// Adds a subroutine to the code (in the data section) and pushes its size (via a tag)
    /// on the stack. @returns the pushsub assembly item.
    eth::AssemblyItem addSubroutine(eth::AssemblyPointer const& _assembly) { return m_asm->appendSubroutine(_assembly); }
    /// Pushes the size of the subroutine.
    void pushSubroutineSize(size_t _subRoutine) { m_asm->pushSubroutineSize(_subRoutine); }
    /// Pushes the offset of the subroutine.
    void pushSubroutineOffset(size_t _subRoutine) { m_asm->pushSubroutineOffset(_subRoutine); }
    /// Pushes the size of the final program
    void appendProgramSize() { m_asm->appendProgramSize(); }
    /// Adds data to the data section, pushes a reference to the stack
    eth::AssemblyItem appendData(bytes const& _data) { return m_asm->append(_data); }
    /// Appends the address (virtual, will be filled in by linker) of a library.
    void appendLibraryAddress(std::string const& _identifier) { m_asm->appendLibraryAddress(_identifier); }
    /// Appends a zero-address that can be replaced by something else at deploy time (if the
    /// position in bytecode is known).
    void appendDeployTimeAddress() { m_asm->append(eth::PushDeployTimeAddress); }
    /// Resets the stack of visited nodes with a new stack having only @c _node
    void resetVisitedNodes(ASTNode const* _node);
    /// Pops the stack of visited nodes
    void popVisitedNodes() { m_visitedNodes.pop(); updateSourceLocation(); }
    /// Pushes an ASTNode to the stack of visited nodes
    void pushVisitedNodes(ASTNode const* _node) { m_visitedNodes.push(_node); updateSourceLocation(); }

    /// Append elements to the current instruction list and adjust @a m_stackOffset.
    CompilerContext& operator<<(eth::AssemblyItem const& _item) { m_asm->append(_item); return *this; }
    CompilerContext& operator<<(Instruction _instruction) { m_asm->append(_instruction); return *this; }
    CompilerContext& operator<<(u256 const& _value) { m_asm->append(_value); return *this; }
    CompilerContext& operator<<(bytes const& _data) { m_asm->append(_data); return *this; }

    /// Appends inline assembly (strict mode).
    /// @a _replacements are string-matching replacements that are performed prior to parsing the inline assembly.
    /// @param _localVariables assigns stack positions to variables with the last one being the stack top
    /// @param _externallyUsedFunctions a set of function names that are not to be renamed or removed.
    /// @param _system if true, this is a "system-level" assembly where all functions use named labels.
    void appendInlineAssembly(
        std::string const& _assembly,
        std::vector<std::string> const& _localVariables = std::vector<std::string>(),
        std::set<std::string> const& _externallyUsedFunctions = std::set<std::string>(),
        bool _system = false
    );

    /// Appends arbitrary data to the end of the bytecode.
    void appendAuxiliaryData(bytes const& _data) { m_asm->appendAuxiliaryDataToEnd(_data); }

    /// Run optimisation step.
    void optimise(bool _fullOptimsation, unsigned _runs = 200) { m_asm->optimise(_fullOptimsation, m_evmVersion, true, _runs); }

    /// @returns the runtime context if in creation mode and runtime context is set, nullptr otherwise.
    CompilerContext* runtimeContext() { return m_runtimeContext; }
    /// @returns the identifier of the runtime subroutine.
    size_t runtimeSub() const { return m_runtimeSub; }

    /// @returns a const reference to the underlying assembly.
    eth::Assembly const& assembly() const { return *m_asm; }
    /// @returns non-const reference to the underlying assembly. Should be avoided in favour of
    /// wrappers in this class.
    eth::Assembly& nonConstAssembly() { return *m_asm; }

    /// @arg _sourceCodes is the map of input files to source code strings
    std::string assemblyString(StringMap const& _sourceCodes = StringMap()) const
    {
        return m_asm->assemblyString(_sourceCodes);
    }

    /// @arg _sourceCodes is the map of input files to source code strings
    Json::Value assemblyJSON(StringMap const& _sourceCodes = StringMap()) const
    {
        return m_asm->assemblyJSON(_sourceCodes);
    }

    eth::LinkerObject const& assembledObject() const { return m_asm->assemble(); }
    eth::LinkerObject const& assembledRuntimeObject(size_t _subIndex) const { return m_asm->sub(_subIndex).assemble(); }

    /**
     * Helper class to pop the visited nodes stack when a scope closes
     */
    class LocationSetter: public ScopeGuard
    {
    public:
        LocationSetter(CompilerContext& _compilerContext, ASTNode const& _node):
            ScopeGuard([&]{ _compilerContext.popVisitedNodes(); }) { _compilerContext.pushVisitedNodes(&_node); }
    };

private:
    /// Searches the inheritance hierarchy towards the base starting from @a _searchStart and returns
    /// the first function definition that is overwritten by _function.
    FunctionDefinition const& resolveVirtualFunction(
        FunctionDefinition const& _function,
        std::vector<ContractDefinition const*>::const_iterator _searchStart
    );
    /// @returns an iterator to the contract directly above the given contract.
    std::vector<ContractDefinition const*>::const_iterator superContract(const ContractDefinition &_contract) const;
    /// Updates source location set in the assembly.
    void updateSourceLocation();

    /**
     * Helper class that manages function labels and ensures that referenced functions are
     * compiled in a specific order.
     */
    struct FunctionCompilationQueue
    {
        /// @returns the entry label of the given function and creates it if it does not exist yet.
        /// @param _context compiler context used to create a new tag if needed
        eth::AssemblyItem entryLabel(Declaration const& _declaration, CompilerContext& _context);
        /// @returns the entry label of the given function. Might return an AssemblyItem of type
        /// UndefinedItem if it does not exist yet.
        eth::AssemblyItem entryLabelIfExists(Declaration const& _declaration) const;

        /// @returns the next function in the queue of functions that are still to be compiled
        /// (i.e. that were referenced during compilation but where we did not yet generate code for).
        /// Returns nullptr if the queue is empty. Does not remove the function from the queue,
        /// that will only be done by startFunction below.
        Declaration const* nextFunctionToCompile() const;
        /// Informs the queue that we are about to compile the given function, i.e. removes
        /// the function from the queue of functions to compile.
        void startFunction(const Declaration &_function);

        /// Labels pointing to the entry points of functions.
        std::map<Declaration const*, eth::AssemblyItem> m_entryLabels;
        /// Set of functions for which we did not yet generate code.
        std::set<Declaration const*> m_alreadyCompiledFunctions;
        /// Queue of functions that still need to be compiled (important to be a queue to maintain
        /// determinism even in the presence of a non-deterministic allocator).
        /// Mutable because we will throw out some functions earlier than needed.
        mutable std::queue<Declaration const*> m_functionsToCompile;
    } m_functionCompilationQueue;

    eth::AssemblyPointer m_asm;
    /// Version of the EVM to compile against.
    EVMVersion m_evmVersion;
    /// Activated experimental features.
    std::set<ExperimentalFeature> m_experimentalFeatures;
    /// Other already compiled contracts to be used in contract creation calls.
    std::map<ContractDefinition const*, eth::Assembly const*> m_compiledContracts;
    /// Storage offsets of state variables
    std::map<Declaration const*, std::pair<u256, unsigned>> m_stateVariables;
    /// Offsets of local variables on the stack (relative to stack base).
    /// This needs to be a stack because if a modifier contains a local variable and this
    /// modifier is applied twice, the position of the variable needs to be restored
    /// after the nested modifier is left.
    std::map<Declaration const*, std::vector<unsigned>> m_localVariables;
    /// List of current inheritance hierarchy from derived to base.
    std::vector<ContractDefinition const*> m_inheritanceHierarchy;
    /// Stack of current visited AST nodes, used for location attachment
    std::stack<ASTNode const*> m_visitedNodes;
    /// The runtime context if in Creation mode, this is used for generating tags that would be stored into the storage and then used at runtime.
    CompilerContext *m_runtimeContext;
    /// The index of the runtime subroutine.
    size_t m_runtimeSub = -1;
    /// An index of low-level function labels by name.
    std::map<std::string, eth::AssemblyItem> m_lowLevelFunctions;
    /// Container for ABI functions to be generated.
    ABIFunctions m_abiFunctions;
    /// The queue of low-level functions to generate.
    std::queue<std::tuple<std::string, unsigned, unsigned, std::function<void(CompilerContext&)>>> m_lowLevelFunctionGenerationQueue;
};

}
}