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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/>.
*/
/**
* Common code generator for translating Yul / inline assembly to EVM and EVM1.5.
*/
#include <libyul/backends/evm/EVMAssembly.h>
#include <libyul/optimiser/ASTWalker.h>
#include <libyul/AsmDataForward.h>
#include <libyul/AsmScope.h>
#include <boost/variant.hpp>
#include <boost/optional.hpp>
namespace langutil
{
class ErrorReporter;
}
namespace yul
{
struct AsmAnalysisInfo;
class EVMAssembly;
struct CodeTransformContext
{
std::map<Scope::Label const*, AbstractAssembly::LabelID> labelIDs;
std::map<Scope::Function const*, AbstractAssembly::LabelID> functionEntryIDs;
std::map<Scope::Variable const*, int> variableStackHeights;
std::map<Scope::Variable const*, unsigned> variableReferences;
};
/**
* Counts the number of references to a variable. This includes actual (read) references
* but also assignments to the variable. It does not include the declaration itself or
* function parameters, but it does include function return parameters.
*
* This component can handle multiple variables of the same name.
*
* Can only be applied to strict assembly.
*/
class VariableReferenceCounter: public yul::ASTWalker
{
public:
explicit VariableReferenceCounter(
CodeTransformContext& _context,
AsmAnalysisInfo const& _assemblyInfo
): m_context(_context), m_info(_assemblyInfo)
{}
public:
void operator()(Identifier const& _identifier);
void operator()(FunctionDefinition const&);
void operator()(ForLoop const&);
void operator()(Block const& _block);
private:
void increaseRefIfFound(YulString _variableName);
CodeTransformContext& m_context;
AsmAnalysisInfo const& m_info;
Scope* m_scope = nullptr;
};
class CodeTransform: public boost::static_visitor<>
{
public:
/// Create the code transformer.
/// @param _identifierAccess used to resolve identifiers external to the inline assembly
CodeTransform(
AbstractAssembly& _assembly,
AsmAnalysisInfo& _analysisInfo,
Block const& _block,
bool _allowStackOpt = false,
bool _yul = false,
bool _evm15 = false,
ExternalIdentifierAccess const& _identifierAccess = ExternalIdentifierAccess(),
bool _useNamedLabelsForFunctions = false
): CodeTransform(
_assembly,
_analysisInfo,
_block,
_allowStackOpt,
_yul,
_evm15,
_identifierAccess,
_useNamedLabelsForFunctions,
_assembly.stackHeight(),
nullptr
)
{
}
protected:
using Context = CodeTransformContext;
CodeTransform(
AbstractAssembly& _assembly,
AsmAnalysisInfo& _analysisInfo,
Block const& _block,
bool _allowStackOpt,
bool _yul,
bool _evm15,
ExternalIdentifierAccess const& _identifierAccess,
bool _useNamedLabelsForFunctions,
int _stackAdjustment,
std::shared_ptr<Context> _context
);
void decreaseReference(YulString _name, Scope::Variable const& _var);
bool unreferenced(Scope::Variable const& _var) const;
/// Marks slots of variables that are not used anymore
/// and were defined in the current scope for reuse.
/// Also POPs unused topmost stack slots.
void freeUnusedVariables();
/// Marks the stack slot of @a _var to be reused.
void deleteVariable(Scope::Variable const& _var);
public:
void operator()(Instruction const& _instruction);
void operator()(Literal const& _literal);
void operator()(Identifier const& _identifier);
void operator()(FunctionalInstruction const& _instr);
void operator()(FunctionCall const&);
void operator()(ExpressionStatement const& _statement);
void operator()(Label const& _label);
void operator()(StackAssignment const& _assignment);
void operator()(Assignment const& _assignment);
void operator()(VariableDeclaration const& _varDecl);
void operator()(If const& _if);
void operator()(Switch const& _switch);
void operator()(FunctionDefinition const&);
void operator()(ForLoop const&);
void operator()(Block const& _block);
private:
AbstractAssembly::LabelID labelFromIdentifier(Identifier const& _identifier);
/// @returns the label ID corresponding to the given label, allocating a new one if
/// necessary.
AbstractAssembly::LabelID labelID(Scope::Label const& _label);
AbstractAssembly::LabelID functionEntryID(YulString _name, Scope::Function const& _function);
/// Generates code for an expression that is supposed to return a single value.
void visitExpression(Expression const& _expression);
void visitStatements(std::vector<Statement> const& _statements);
/// Pops all variables declared in the block and checks that the stack height is equal
/// to @a _blackStartStackHeight.
void finalizeBlock(Block const& _block, int _blockStartStackHeight);
void generateMultiAssignment(std::vector<Identifier> const& _variableNames);
void generateAssignment(Identifier const& _variableName);
/// Determines the stack height difference to the given variables. Throws
/// if it is not yet in scope or the height difference is too large. Returns
/// the (positive) stack height difference otherwise.
int variableHeightDiff(Scope::Variable const& _var, bool _forSwap) const;
void expectDeposit(int _deposit, int _oldHeight) const;
void checkStackHeight(void const* _astElement) const;
AbstractAssembly& m_assembly;
AsmAnalysisInfo& m_info;
Scope* m_scope = nullptr;
bool const m_allowStackOpt = true;
bool m_yul = false;
bool m_evm15 = false;
bool m_useNamedLabelsForFunctions = false;
ExternalIdentifierAccess m_identifierAccess;
/// Adjustment between the stack height as determined during the analysis phase
/// and the stack height in the assembly. This is caused by an initial stack being present
/// for inline assembly and different stack heights depending on the EVM backend used
/// (EVM 1.0 or 1.5).
int m_stackAdjustment = 0;
std::shared_ptr<Context> m_context;
/// Set of variables whose reference counter has reached zero,
/// and whose stack slot will be marked as unused once we reach
/// statement level in the scope where the variable was defined.
std::set<Scope::Variable const*> m_variablesScheduledForDeletion;
std::set<int> m_unusedStackSlots;
};
}
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