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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/>.
*/
/**
* @date 2017
* Abstract assembly interface, subclasses of which are to be used with the generic
* bytecode generator.
*/
#pragma once
#include <libdevcore/Common.h>
#include <libdevcore/CommonData.h>
#include <functional>
#include <memory>
namespace langutil
{
struct SourceLocation;
}
namespace dev
{
namespace solidity
{
enum class Instruction: uint8_t;
}
}
namespace yul
{
struct Instruction;
struct Identifier;
///
/// Assembly class that abstracts both the libevmasm assembly and the new Yul assembly.
///
class AbstractAssembly
{
public:
using LabelID = size_t;
using SubID = size_t;
virtual ~AbstractAssembly() = default;
/// Set a new source location valid starting from the next instruction.
virtual void setSourceLocation(langutil::SourceLocation const& _location) = 0;
/// Retrieve the current height of the stack. This does not have to be zero
/// at the beginning.
virtual int stackHeight() const = 0;
/// Append an EVM instruction.
virtual void appendInstruction(dev::solidity::Instruction _instruction) = 0;
/// Append a constant.
virtual void appendConstant(dev::u256 const& _constant) = 0;
/// Append a label.
virtual void appendLabel(LabelID _labelId) = 0;
/// Append a label reference.
virtual void appendLabelReference(LabelID _labelId) = 0;
/// Generate a new unique label.
virtual LabelID newLabelId() = 0;
/// Returns a label identified by the given name. Creates it if it does not yet exist.
virtual LabelID namedLabel(std::string const& _name) = 0;
/// Append a reference to a to-be-linked symbol.
/// Currently, we assume that the value is always a 20 byte number.
virtual void appendLinkerSymbol(std::string const& _name) = 0;
/// Append a jump instruction.
/// @param _stackDiffAfter the stack adjustment after this instruction.
/// This is helpful to stack height analysis if there is no continuing control flow.
virtual void appendJump(int _stackDiffAfter) = 0;
/// Append a jump-to-immediate operation.
/// @param _stackDiffAfter the stack adjustment after this instruction.
virtual void appendJumpTo(LabelID _labelId, int _stackDiffAfter = 0) = 0;
/// Append a jump-to-if-immediate operation.
virtual void appendJumpToIf(LabelID _labelId) = 0;
/// Start a subroutine identified by @a _labelId that takes @a _arguments
/// stack slots as arguments.
virtual void appendBeginsub(LabelID _labelId, int _arguments) = 0;
/// Call a subroutine identified by @a _labelId, taking @a _arguments from the
/// stack upon call and putting @a _returns arguments onto the stack upon return.
virtual void appendJumpsub(LabelID _labelId, int _arguments, int _returns) = 0;
/// Return from a subroutine.
/// @param _stackDiffAfter the stack adjustment after this instruction.
virtual void appendReturnsub(int _returns, int _stackDiffAfter = 0) = 0;
/// Append the assembled size as a constant.
virtual void appendAssemblySize() = 0;
/// Creates a new sub-assembly, which can be referenced using dataSize and dataOffset.
virtual std::pair<std::shared_ptr<AbstractAssembly>, SubID> createSubAssembly() = 0;
/// Appends the offset of the given sub-assembly or data.
virtual void appendDataOffset(SubID _sub) = 0;
/// Appends the size of the given sub-assembly or data.
virtual void appendDataSize(SubID _sub) = 0;
/// Appends the given data to the assembly and returns its ID.
virtual SubID appendData(dev::bytes const& _data) = 0;
};
enum class IdentifierContext { LValue, RValue };
/// Object that is used to resolve references and generate code for access to identifiers external
/// to inline assembly (not used in standalone assembly mode).
struct ExternalIdentifierAccess
{
using Resolver = std::function<size_t(Identifier const&, IdentifierContext, bool /*_crossesFunctionBoundary*/)>;
/// Resolve an external reference given by the identifier in the given context.
/// @returns the size of the value (number of stack slots) or size_t(-1) if not found.
Resolver resolve;
using CodeGenerator = std::function<void(Identifier const&, IdentifierContext, yul::AbstractAssembly&)>;
/// Generate code for retrieving the value (rvalue context) or storing the value (lvalue context)
/// of an identifier. The code should be appended to the assembly. In rvalue context, the value is supposed
/// to be put onto the stack, in lvalue context, the value is assumed to be at the top of the stack.
CodeGenerator generateCode;
};
}
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