CompilerContext.cpp

/*
	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.
 */

#include <libsolidity/codegen/CompilerContext.h>

#include <libsolidity/ast/AST.h>
#include <libsolidity/codegen/Compiler.h>
#include <libsolidity/codegen/CompilerUtils.h>
#include <libsolidity/interface/Version.h>

#include <libyul/AsmParser.h>
#include <libyul/AsmAnalysis.h>
#include <libyul/AsmAnalysisInfo.h>
#include <libyul/backends/evm/AsmCodeGen.h>
#include <libyul/backends/evm/EVMDialect.h>
#include <libyul/backends/evm/EVMMetrics.h>
#include <libyul/optimiser/Suite.h>
#include <libyul/Object.h>
#include <libyul/YulString.h>

#include <libsolutil/Whiskers.h>

#include <liblangutil/ErrorReporter.h>
#include <liblangutil/Scanner.h>
#include <liblangutil/SourceReferenceFormatter.h>

#include <boost/algorithm/string/replace.hpp>

#include <utility>
#include <numeric>

// Change to "define" to output all intermediate code
#undef SOL_OUTPUT_ASM
#ifdef SOL_OUTPUT_ASM
#include <libyul/AsmPrinter.h>
#endif


using namespace std;
using namespace solidity;
using namespace solidity::util;
using namespace solidity::evmasm;
using namespace solidity::frontend;
using namespace solidity::langutil;

void CompilerContext::addStateVariable(
	VariableDeclaration const& _declaration,
	u256 const& _storageOffset,
	unsigned _byteOffset
)
{
	m_stateVariables[&_declaration] = make_pair(_storageOffset, _byteOffset);
}

void CompilerContext::startFunction(Declaration const& _function)
{
	m_functionCompilationQueue.startFunction(_function);
	*this << functionEntryLabel(_function);
}

void CompilerContext::callLowLevelFunction(
	string const& _name,
	unsigned _inArgs,
	unsigned _outArgs,
	function<void(CompilerContext&)> const& _generator
)
{
	evmasm::AssemblyItem retTag = pushNewTag();
	CompilerUtils(*this).moveIntoStack(_inArgs);

	*this << lowLevelFunctionTag(_name, _inArgs, _outArgs, _generator);

	appendJump(evmasm::AssemblyItem::JumpType::IntoFunction);
	adjustStackOffset(int(_outArgs) - 1 - _inArgs);
	*this << retTag.tag();
}

evmasm::AssemblyItem CompilerContext::lowLevelFunctionTag(
	string const& _name,
	unsigned _inArgs,
	unsigned _outArgs,
	function<void(CompilerContext&)> const& _generator
)
{
	auto it = m_lowLevelFunctions.find(_name);
	if (it == m_lowLevelFunctions.end())
	{
		evmasm::AssemblyItem tag = newTag().pushTag();
		m_lowLevelFunctions.insert(make_pair(_name, tag));
		m_lowLevelFunctionGenerationQueue.push(make_tuple(_name, _inArgs, _outArgs, _generator));
		return tag;
	}
	else
		return it->second;
}

void CompilerContext::appendMissingLowLevelFunctions()
{
	while (!m_lowLevelFunctionGenerationQueue.empty())
	{
		string name;
		unsigned inArgs;
		unsigned outArgs;
		function<void(CompilerContext&)> generator;
		tie(name, inArgs, outArgs, generator) = m_lowLevelFunctionGenerationQueue.front();
		m_lowLevelFunctionGenerationQueue.pop();

		setStackOffset(inArgs + 1);
		*this << m_lowLevelFunctions.at(name).tag();
		generator(*this);
		CompilerUtils(*this).moveToStackTop(outArgs);
		appendJump(evmasm::AssemblyItem::JumpType::OutOfFunction);
		solAssert(stackHeight() == outArgs, "Invalid stack height in low-level function " + name + ".");
	}
}

void CompilerContext::addVariable(
	VariableDeclaration const& _declaration,
	unsigned _offsetToCurrent
)
{
	solAssert(m_asm->deposit() >= 0 && unsigned(m_asm->deposit()) >= _offsetToCurrent, "");
	unsigned sizeOnStack = _declaration.annotation().type->sizeOnStack();
	// Variables should not have stack size other than [1, 2],
	// but that might change when new types are introduced.
	solAssert(sizeOnStack == 1 || sizeOnStack == 2, "");
	m_localVariables[&_declaration].push_back(unsigned(m_asm->deposit()) - _offsetToCurrent);
}

void CompilerContext::removeVariable(Declaration const& _declaration)
{
	solAssert(m_localVariables.count(&_declaration) && !m_localVariables[&_declaration].empty(), "");
	m_localVariables[&_declaration].pop_back();
	if (m_localVariables[&_declaration].empty())
		m_localVariables.erase(&_declaration);
}

void CompilerContext::removeVariablesAboveStackHeight(unsigned _stackHeight)
{
	vector<Declaration const*> toRemove;
	for (auto _var: m_localVariables)
	{
		solAssert(!_var.second.empty(), "");
		solAssert(_var.second.back() <= stackHeight(), "");
		if (_var.second.back() >= _stackHeight)
			toRemove.push_back(_var.first);
	}
	for (auto _var: toRemove)
		removeVariable(*_var);
}

unsigned CompilerContext::numberOfLocalVariables() const
{
	return m_localVariables.size();
}

shared_ptr<evmasm::Assembly> CompilerContext::compiledContract(ContractDefinition const& _contract) const
{
	auto ret = m_otherCompilers.find(&_contract);
	solAssert(ret != m_otherCompilers.end(), "Compiled contract not found.");
	return ret->second->assemblyPtr();
}

shared_ptr<evmasm::Assembly> CompilerContext::compiledContractRuntime(ContractDefinition const& _contract) const
{
	auto ret = m_otherCompilers.find(&_contract);
	solAssert(ret != m_otherCompilers.end(), "Compiled contract not found.");
	return ret->second->runtimeAssemblyPtr();
}

bool CompilerContext::isLocalVariable(Declaration const* _declaration) const
{
	return !!m_localVariables.count(_declaration);
}

evmasm::AssemblyItem CompilerContext::functionEntryLabel(Declaration const& _declaration)
{
	return m_functionCompilationQueue.entryLabel(_declaration, *this);
}

evmasm::AssemblyItem CompilerContext::functionEntryLabelIfExists(Declaration const& _declaration) const
{
	return m_functionCompilationQueue.entryLabelIfExists(_declaration);
}

FunctionDefinition const& CompilerContext::resolveVirtualFunction(FunctionDefinition const& _function)
{
	// Libraries do not allow inheritance and their functions can be inlined, so we should not
	// search the inheritance hierarchy (which will be the wrong one in case the function
	// is inlined).
	if (auto scope = dynamic_cast<ContractDefinition const*>(_function.scope()))
		if (scope->isLibrary())
			return _function;
	solAssert(!m_inheritanceHierarchy.empty(), "No inheritance hierarchy set.");
	return resolveVirtualFunction(_function, m_inheritanceHierarchy.begin());
}

FunctionDefinition const& CompilerContext::superFunction(FunctionDefinition const& _function, ContractDefinition const& _base)
{
	solAssert(!m_inheritanceHierarchy.empty(), "No inheritance hierarchy set.");
	return resolveVirtualFunction(_function, superContract(_base));
}

FunctionDefinition const* CompilerContext::nextConstructor(ContractDefinition const& _contract) const
{
	vector<ContractDefinition const*>::const_iterator it = superContract(_contract);
	for (; it != m_inheritanceHierarchy.end(); ++it)
		if ((*it)->constructor())
			return (*it)->constructor();

	return nullptr;
}

Declaration const* CompilerContext::nextFunctionToCompile() const
{
	return m_functionCompilationQueue.nextFunctionToCompile();
}

ModifierDefinition const& CompilerContext::resolveVirtualFunctionModifier(
	ModifierDefinition const& _modifier
) const
{
	// Libraries do not allow inheritance and their functions can be inlined, so we should not
	// search the inheritance hierarchy (which will be the wrong one in case the function
	// is inlined).
	if (auto scope = dynamic_cast<ContractDefinition const*>(_modifier.scope()))
		if (scope->isLibrary())
			return _modifier;
	solAssert(!m_inheritanceHierarchy.empty(), "No inheritance hierarchy set.");
	for (ContractDefinition const* contract: m_inheritanceHierarchy)
		for (ModifierDefinition const* modifier: contract->functionModifiers())
			if (modifier->name() == _modifier.name())
				return *modifier;
	solAssert(false, "Function modifier " + _modifier.name() + " not found in inheritance hierarchy.");
}

unsigned CompilerContext::baseStackOffsetOfVariable(Declaration const& _declaration) const
{
	auto res = m_localVariables.find(&_declaration);
	solAssert(res != m_localVariables.end(), "Variable not found on stack.");
	solAssert(!res->second.empty(), "");
	return res->second.back();
}

unsigned CompilerContext::baseToCurrentStackOffset(unsigned _baseOffset) const
{
	return m_asm->deposit() - _baseOffset - 1;
}

unsigned CompilerContext::currentToBaseStackOffset(unsigned _offset) const
{
	return m_asm->deposit() - _offset - 1;
}

pair<u256, unsigned> CompilerContext::storageLocationOfVariable(Declaration const& _declaration) const
{
	auto it = m_stateVariables.find(&_declaration);
	solAssert(it != m_stateVariables.end(), "Variable not found in storage.");
	return it->second;
}

CompilerContext& CompilerContext::appendJump(evmasm::AssemblyItem::JumpType _jumpType)
{
	evmasm::AssemblyItem item(Instruction::JUMP);
	item.setJumpType(_jumpType);
	return *this << item;
}

CompilerContext& CompilerContext::appendInvalid()
{
	return *this << Instruction::INVALID;
}

CompilerContext& CompilerContext::appendConditionalInvalid()
{
	*this << Instruction::ISZERO;
	evmasm::AssemblyItem afterTag = appendConditionalJump();
	*this << Instruction::INVALID;
	*this << afterTag;
	return *this;
}

CompilerContext& CompilerContext::appendRevert(string const& _message)
{
	appendInlineAssembly("{ " + revertReasonIfDebug(_message) + " }");
	return *this;
}

CompilerContext& CompilerContext::appendConditionalRevert(bool _forwardReturnData, string const& _message)
{
	if (_forwardReturnData && m_evmVersion.supportsReturndata())
		appendInlineAssembly(R"({
			if condition {
				returndatacopy(0, 0, returndatasize())
				revert(0, returndatasize())
			}
		})", {"condition"});
	else
		appendInlineAssembly("{ if condition { " + revertReasonIfDebug(_message) + " } }", {"condition"});
	*this << Instruction::POP;
	return *this;
}

void CompilerContext::resetVisitedNodes(ASTNode const* _node)
{
	stack<ASTNode const*> newStack;
	newStack.push(_node);
	std::swap(m_visitedNodes, newStack);
	updateSourceLocation();
}

void CompilerContext::appendInlineAssembly(
	string const& _assembly,
	vector<string> const& _localVariables,
	set<string> const& _externallyUsedFunctions,
	bool _system,
	OptimiserSettings const& _optimiserSettings
)
{
	int startStackHeight = stackHeight();

	set<yul::YulString> externallyUsedIdentifiers;
	for (auto const& fun: _externallyUsedFunctions)
		externallyUsedIdentifiers.insert(yul::YulString(fun));
	for (auto const& var: _localVariables)
		externallyUsedIdentifiers.insert(yul::YulString(var));

	yul::ExternalIdentifierAccess identifierAccess;
	identifierAccess.resolve = [&](
		yul::Identifier const& _identifier,
		yul::IdentifierContext,
		bool _insideFunction
	) -> size_t
	{
		if (_insideFunction)
			return size_t(-1);
		auto it = std::find(_localVariables.begin(), _localVariables.end(), _identifier.name.str());
		return it == _localVariables.end() ? size_t(-1) : 1;
	};
	identifierAccess.generateCode = [&](
		yul::Identifier const& _identifier,
		yul::IdentifierContext _context,
		yul::AbstractAssembly& _assembly
	)
	{
		auto it = std::find(_localVariables.begin(), _localVariables.end(), _identifier.name.str());
		solAssert(it != _localVariables.end(), "");
		int stackDepth = _localVariables.end() - it;
		int stackDiff = _assembly.stackHeight() - startStackHeight + stackDepth;
		if (_context == yul::IdentifierContext::LValue)
			stackDiff -= 1;
		if (stackDiff < 1 || stackDiff > 16)
			BOOST_THROW_EXCEPTION(
				CompilerError() <<
				errinfo_sourceLocation(_identifier.location) <<
				util::errinfo_comment("Stack too deep (" + to_string(stackDiff) + "), try removing local variables.")
			);
		if (_context == yul::IdentifierContext::RValue)
			_assembly.appendInstruction(dupInstruction(stackDiff));
		else
		{
			_assembly.appendInstruction(swapInstruction(stackDiff));
			_assembly.appendInstruction(Instruction::POP);
		}
	};

	ErrorList errors;
	ErrorReporter errorReporter(errors);
	auto scanner = make_shared<langutil::Scanner>(langutil::CharStream(_assembly, "--CODEGEN--"));
	yul::EVMDialect const& dialect = yul::EVMDialect::strictAssemblyForEVM(m_evmVersion);
	shared_ptr<yul::Block> parserResult = yul::Parser(errorReporter, dialect).parse(scanner, false);
#ifdef SOL_OUTPUT_ASM
	cout << yul::AsmPrinter(&dialect)(*parserResult) << endl;
#endif

	auto reportError = [&](string const& _context)
	{
		string message =
			"Error parsing/analyzing inline assembly block:\n" +
			_context + "\n"
			"------------------ Input: -----------------\n" +
			_assembly + "\n"
			"------------------ Errors: ----------------\n";
		for (auto const& error: errorReporter.errors())
			message += SourceReferenceFormatter::formatErrorInformation(*error);
		message += "-------------------------------------------\n";

		solAssert(false, message);
	};

	yul::AsmAnalysisInfo analysisInfo;
	bool analyzerResult = false;
	if (parserResult)
		analyzerResult = yul::AsmAnalyzer(
			analysisInfo,
			errorReporter,
			dialect,
			identifierAccess.resolve
		).analyze(*parserResult);
	if (!parserResult || !errorReporter.errors().empty() || !analyzerResult)
		reportError("Invalid assembly generated by code generator.");

	// Several optimizer steps cannot handle externally supplied stack variables,
	// so we essentially only optimize the ABI functions.
	if (_optimiserSettings.runYulOptimiser && _localVariables.empty())
	{
		yul::Object obj;
		obj.code = parserResult;
		obj.analysisInfo = make_shared<yul::AsmAnalysisInfo>(analysisInfo);

		optimizeYul(obj, dialect, _optimiserSettings, externallyUsedIdentifiers);

		analysisInfo = std::move(*obj.analysisInfo);
		parserResult = std::move(obj.code);

#ifdef SOL_OUTPUT_ASM
		cout << "After optimizer:" << endl;
		cout << yul::AsmPrinter(&dialect)(*parserResult) << endl;
#endif
	}

	if (!errorReporter.errors().empty())
		reportError("Failed to analyze inline assembly block.");

	solAssert(errorReporter.errors().empty(), "Failed to analyze inline assembly block.");
	yul::CodeGenerator::assemble(
		*parserResult,
		analysisInfo,
		*m_asm,
		m_evmVersion,
		identifierAccess,
		_system,
		_optimiserSettings.optimizeStackAllocation
	);

	// Reset the source location to the one of the node (instead of the CODEGEN source location)
	updateSourceLocation();
}


void CompilerContext::optimizeYul(yul::Object& _object, yul::EVMDialect const& _dialect, OptimiserSettings const& _optimiserSettings, std::set<yul::YulString> const& _externalIdentifiers)
{
#ifdef SOL_OUTPUT_ASM
	cout << yul::AsmPrinter(*dialect)(*_object.code) << endl;
#endif

	bool const isCreation = runtimeContext() != nullptr;
	yul::GasMeter meter(_dialect, isCreation, _optimiserSettings.expectedExecutionsPerDeployment);
	yul::OptimiserSuite::run(
		_dialect,
		&meter,
		_object,
		_optimiserSettings.optimizeStackAllocation,
		_externalIdentifiers
	);

#ifdef SOL_OUTPUT_ASM
	cout << "After optimizer:" << endl;
	cout << yul::AsmPrinter(*dialect)(*object.code) << endl;
#endif
}

FunctionDefinition const& CompilerContext::resolveVirtualFunction(
	FunctionDefinition const& _function,
	vector<ContractDefinition const*>::const_iterator _searchStart
)
{
	string name = _function.name();
	FunctionType functionType(_function);
	auto it = _searchStart;
	for (; it != m_inheritanceHierarchy.end(); ++it)
		for (FunctionDefinition const* function: (*it)->definedFunctions())
			if (
				function->name() == name &&
				!function->isConstructor() &&
				FunctionType(*function).asCallableFunction(false)->hasEqualParameterTypes(functionType)
			)
				return *function;
	solAssert(false, "Super function " + name + " not found.");
	return _function; // not reached
}

vector<ContractDefinition const*>::const_iterator CompilerContext::superContract(ContractDefinition const& _contract) const
{
	solAssert(!m_inheritanceHierarchy.empty(), "No inheritance hierarchy set.");
	auto it = find(m_inheritanceHierarchy.begin(), m_inheritanceHierarchy.end(), &_contract);
	solAssert(it != m_inheritanceHierarchy.end(), "Base not found in inheritance hierarchy.");
	return ++it;
}

string CompilerContext::revertReasonIfDebug(string const& _message)
{
	return YulUtilFunctions::revertReasonIfDebug(m_revertStrings, _message);
}

void CompilerContext::updateSourceLocation()
{
	m_asm->setSourceLocation(m_visitedNodes.empty() ? SourceLocation() : m_visitedNodes.top()->location());
}

evmasm::Assembly::OptimiserSettings CompilerContext::translateOptimiserSettings(OptimiserSettings const& _settings)
{
	// Constructing it this way so that we notice changes in the fields.
	evmasm::Assembly::OptimiserSettings asmSettings{false, false, false, false, false, false, m_evmVersion, 0};
	asmSettings.isCreation = true;
	asmSettings.runJumpdestRemover = _settings.runJumpdestRemover;
	asmSettings.runPeephole = _settings.runPeephole;
	asmSettings.runDeduplicate = _settings.runDeduplicate;
	asmSettings.runCSE = _settings.runCSE;
	asmSettings.runConstantOptimiser = _settings.runConstantOptimiser;
	asmSettings.expectedExecutionsPerDeployment = _settings.expectedExecutionsPerDeployment;
	asmSettings.evmVersion = m_evmVersion;
	return asmSettings;
}

evmasm::AssemblyItem CompilerContext::FunctionCompilationQueue::entryLabel(
	Declaration const& _declaration,
	CompilerContext& _context
)
{
	auto res = m_entryLabels.find(&_declaration);
	if (res == m_entryLabels.end())
	{
		evmasm::AssemblyItem tag(_context.newTag());
		m_entryLabels.insert(make_pair(&_declaration, tag));
		m_functionsToCompile.push(&_declaration);
		return tag.tag();
	}
	else
		return res->second.tag();

}

evmasm::AssemblyItem CompilerContext::FunctionCompilationQueue::entryLabelIfExists(Declaration const& _declaration) const
{
	auto res = m_entryLabels.find(&_declaration);
	return res == m_entryLabels.end() ? evmasm::AssemblyItem(evmasm::UndefinedItem) : res->second.tag();
}

Declaration const* CompilerContext::FunctionCompilationQueue::nextFunctionToCompile() const
{
	while (!m_functionsToCompile.empty())
	{
		if (m_alreadyCompiledFunctions.count(m_functionsToCompile.front()))
			m_functionsToCompile.pop();
		else
			return m_functionsToCompile.front();
	}
	return nullptr;
}

void CompilerContext::FunctionCompilationQueue::startFunction(Declaration const& _function)
{
	if (!m_functionsToCompile.empty() && m_functionsToCompile.front() == &_function)
		m_functionsToCompile.pop();
	m_alreadyCompiledFunctions.insert(&_function);
}