solidity/libsolidity/codegen/LValue.h

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/*
This file is part of solidity.
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solidity is free software: you can redistribute it and/or modify
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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,
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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/>.
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*/
// SPDX-License-Identifier: GPL-3.0
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/**
* @author Christian <c@ethdev.com>
* @date 2015
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* LValues for use in the expression compiler.
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*/
#pragma once
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#include <libsolidity/codegen/ArrayUtils.h>
#include <libsolutil/Common.h>
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#include <liblangutil/SourceLocation.h>
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#include <memory>
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#include <vector>
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namespace solidity::frontend
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{
class Declaration;
class Type;
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class TupleType;
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class ArrayType;
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class CompilerContext;
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class VariableDeclaration;
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/**
* Abstract class used to retrieve, delete and store data in lvalues/variables.
*/
class LValue
{
protected:
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explicit LValue(CompilerContext& _compilerContext, Type const* _dataType = nullptr):
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m_context(_compilerContext), m_dataType(_dataType) {}
public:
virtual ~LValue() = default;
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/// @returns the number of stack slots occupied by the lvalue reference
virtual unsigned sizeOnStack() const { return 1; }
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/// Copies the value of the current lvalue to the top of the stack and, if @a _remove is true,
/// also removes the reference from the stack.
/// @a _location source location of the current expression, used for error reporting.
virtual void retrieveValue(langutil::SourceLocation const& _location, bool _remove = false) const = 0;
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/// Moves a value from the stack to the lvalue. Removes the value if @a _move is true.
/// @a _location is the source location of the expression that caused this operation.
/// Stack pre: value [lvalue_ref]
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/// Stack post: if !_move: value_of(lvalue_ref)
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virtual void storeValue(Type const& _sourceType,
langutil::SourceLocation const& _location = {}, bool _move = false) const = 0;
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/// Stores zero in the lvalue. Removes the reference from the stack if @a _removeReference is true.
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/// @a _location is the source location of the requested operation
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virtual void setToZero(
langutil::SourceLocation const& _location = {},
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bool _removeReference = true
) const = 0;
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protected:
CompilerContext& m_context;
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Type const* m_dataType;
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};
/**
* Local variable that is completely stored on the stack.
*/
class StackVariable: public LValue
{
public:
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StackVariable(CompilerContext& _compilerContext, VariableDeclaration const& _declaration);
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unsigned sizeOnStack() const override { return 0; }
void retrieveValue(langutil::SourceLocation const& _location, bool _remove = false) const override;
void storeValue(
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Type const& _sourceType,
langutil::SourceLocation const& _location = {},
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bool _move = false
) const override;
void setToZero(
langutil::SourceLocation const& _location = {},
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bool _removeReference = true
) const override;
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private:
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/// Base stack offset (@see CompilerContext::baseStackOffsetOfVariable) of the local variable.
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unsigned m_baseStackOffset;
/// Number of stack elements occupied by the value (not the reference).
unsigned m_size;
};
/**
* Reference to some item in memory.
*/
class MemoryItem: public LValue
{
public:
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MemoryItem(CompilerContext& _compilerContext, Type const& _type, bool _padded = true);
unsigned sizeOnStack() const override { return 1; }
void retrieveValue(langutil::SourceLocation const& _location, bool _remove = false) const override;
void storeValue(
Type const& _sourceType,
langutil::SourceLocation const& _location = {},
bool _move = false
) const override;
void setToZero(
langutil::SourceLocation const& _location = {},
bool _removeReference = true
) const override;
private:
/// Special flag to deal with byte array elements.
bool m_padded = false;
};
/**
* Reference to an immutable variable. During contract creation this refers to a location in memory. At the
* end of contract creation the values from these memory locations are copied into all occurrences of the immutable
* variable in the runtime code.
*/
class ImmutableItem: public LValue
{
public:
ImmutableItem(CompilerContext& _compilerContext, VariableDeclaration const& _variable);
unsigned sizeOnStack() const override { return 0; }
void retrieveValue(langutil::SourceLocation const& _location, bool _remove = false) const override;
void storeValue(
Type const& _sourceType,
langutil::SourceLocation const& _location = {},
bool _move = false
) const override;
void setToZero(
langutil::SourceLocation const& _location = {},
bool _removeReference = true
) const override;
private:
VariableDeclaration const& m_variable;
};
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/**
* Reference to some item in storage. On the stack this is <storage key> <offset_inside_value>,
* where 0 <= offset_inside_value < 32 and an offset of i means that the value is multiplied
* by 2**i before storing it.
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*/
class StorageItem: public LValue
{
public:
/// Constructs the LValue and pushes the location of @a _declaration onto the stack.
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StorageItem(CompilerContext& _compilerContext, VariableDeclaration const& _declaration);
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/// Constructs the LValue and assumes that the storage reference is already on the stack.
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StorageItem(CompilerContext& _compilerContext, Type const& _type);
unsigned sizeOnStack() const override { return 2; }
void retrieveValue(langutil::SourceLocation const& _location, bool _remove = false) const override;
void storeValue(
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Type const& _sourceType,
langutil::SourceLocation const& _location = {},
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bool _move = false
) const override;
void setToZero(
langutil::SourceLocation const& _location = {},
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bool _removeReference = true
) const override;
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};
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/**
* Reference to a single byte inside a storage byte array.
* Stack: <storage_ref> <byte_number>
*/
class StorageByteArrayElement: public LValue
{
public:
/// Constructs the LValue and assumes that the storage reference is already on the stack.
StorageByteArrayElement(CompilerContext& _compilerContext);
unsigned sizeOnStack() const override { return 2; }
void retrieveValue(langutil::SourceLocation const& _location, bool _remove = false) const override;
void storeValue(
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Type const& _sourceType,
langutil::SourceLocation const& _location = {},
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bool _move = false
) const override;
void setToZero(
langutil::SourceLocation const& _location = {},
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bool _removeReference = true
) const override;
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};
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/**
* Tuple object that can itself hold several LValues.
*/
class TupleObject: public LValue
{
public:
/// Constructs the LValue assuming that the other LValues are present on the stack.
/// Empty unique_ptrs are possible if e.g. some values should be ignored during assignment.
TupleObject(CompilerContext& _compilerContext, std::vector<std::unique_ptr<LValue>>&& _lvalues);
unsigned sizeOnStack() const override;
void retrieveValue(langutil::SourceLocation const& _location, bool _remove = false) const override;
void storeValue(
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Type const& _sourceType,
langutil::SourceLocation const& _location = {},
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bool _move = false
) const override;
void setToZero(
langutil::SourceLocation const& _location = {},
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bool _removeReference = true
) const override;
private:
std::vector<std::unique_ptr<LValue>> m_lvalues;
};
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}