solidity/libsolidity/inlineasm/AsmAnalysis.cpp

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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/>.
*/
/**
* Analyzer part of inline assembly.
*/
#include <libsolidity/inlineasm/AsmAnalysis.h>
#include <libsolidity/inlineasm/AsmData.h>
#include <libsolidity/inlineasm/AsmScopeFiller.h>
#include <libsolidity/inlineasm/AsmScope.h>
#include <libsolidity/inlineasm/AsmAnalysisInfo.h>
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#include <libsolidity/interface/ErrorReporter.h>
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#include <boost/range/adaptor/reversed.hpp>
#include <boost/algorithm/string.hpp>
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#include <memory>
#include <functional>
using namespace std;
using namespace dev;
using namespace dev::solidity;
using namespace dev::solidity::assembly;
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namespace {
set<string> const builtinTypes{"bool", "u8", "s8", "u32", "s32", "u64", "s64", "u128", "s128", "u256", "s256"};
}
bool AsmAnalyzer::analyze(Block const& _block)
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{
if (!(ScopeFiller(m_info, m_errorReporter))(_block))
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return false;
return (*this)(_block);
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}
bool AsmAnalyzer::operator()(Label const& _label)
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{
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solAssert(!m_julia, "");
m_info.stackHeightInfo[&_label] = m_stackHeight;
return true;
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}
bool AsmAnalyzer::operator()(assembly::Instruction const& _instruction)
{
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solAssert(!m_julia, "");
auto const& info = instructionInfo(_instruction.instruction);
m_stackHeight += info.ret - info.args;
m_info.stackHeightInfo[&_instruction] = m_stackHeight;
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warnOnInstructions(_instruction.instruction, _instruction.location);
return true;
}
bool AsmAnalyzer::operator()(assembly::Literal const& _literal)
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{
expectValidType(_literal.type, _literal.location);
++m_stackHeight;
if (_literal.kind == assembly::LiteralKind::String && _literal.value.size() > 32)
{
m_errorReporter.typeError(
_literal.location,
"String literal too long (" + boost::lexical_cast<std::string>(_literal.value.size()) + " > 32)"
);
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return false;
}
m_info.stackHeightInfo[&_literal] = m_stackHeight;
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return true;
}
bool AsmAnalyzer::operator()(assembly::Identifier const& _identifier)
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{
size_t numErrorsBefore = m_errorReporter.errors().size();
bool success = true;
if (m_currentScope->lookup(_identifier.name, Scope::Visitor(
[&](Scope::Variable const& _var)
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{
if (!m_activeVariables.count(&_var))
{
m_errorReporter.declarationError(
_identifier.location,
"Variable " + _identifier.name + " used before it was declared."
);
success = false;
}
++m_stackHeight;
},
[&](Scope::Label const&)
{
++m_stackHeight;
},
[&](Scope::Function const&)
{
m_errorReporter.typeError(
_identifier.location,
"Function " + _identifier.name + " used without being called."
);
success = false;
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}
)))
{
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}
else
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{
size_t stackSize(-1);
if (m_resolver)
{
bool insideFunction = m_currentScope->insideFunction();
stackSize = m_resolver(_identifier, julia::IdentifierContext::RValue, insideFunction);
}
if (stackSize == size_t(-1))
{
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// Only add an error message if the callback did not do it.
if (numErrorsBefore == m_errorReporter.errors().size())
m_errorReporter.declarationError(_identifier.location, "Identifier not found.");
success = false;
}
m_stackHeight += stackSize == size_t(-1) ? 1 : stackSize;
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}
m_info.stackHeightInfo[&_identifier] = m_stackHeight;
return success;
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}
bool AsmAnalyzer::operator()(FunctionalInstruction const& _instr)
{
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solAssert(!m_julia, "");
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bool success = true;
for (auto const& arg: _instr.arguments | boost::adaptors::reversed)
if (!expectExpression(arg))
success = false;
// Parser already checks that the number of arguments is correct.
solAssert(instructionInfo(_instr.instruction.instruction).args == int(_instr.arguments.size()), "");
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if (!(*this)(_instr.instruction))
success = false;
m_info.stackHeightInfo[&_instr] = m_stackHeight;
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return success;
}
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bool AsmAnalyzer::operator()(assembly::StackAssignment const& _assignment)
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{
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solAssert(!m_julia, "");
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bool success = checkAssignment(_assignment.variableName, size_t(-1));
m_info.stackHeightInfo[&_assignment] = m_stackHeight;
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return success;
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}
bool AsmAnalyzer::operator()(assembly::Assignment const& _assignment)
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{
int const expectedItems = _assignment.variableNames.size();
solAssert(expectedItems >= 1, "");
int const stackHeight = m_stackHeight;
bool success = boost::apply_visitor(*this, *_assignment.value);
if ((m_stackHeight - stackHeight) != expectedItems)
{
m_errorReporter.declarationError(
_assignment.location,
"Variable count does not match number of values (" +
to_string(expectedItems) +
" vs. " +
to_string(m_stackHeight - stackHeight) +
")"
);
return false;
}
for (auto const& variableName: _assignment.variableNames)
if (!checkAssignment(variableName, 1))
success = false;
m_info.stackHeightInfo[&_assignment] = m_stackHeight;
return success;
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}
bool AsmAnalyzer::operator()(assembly::VariableDeclaration const& _varDecl)
{
bool success = true;
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int const numVariables = _varDecl.variables.size();
if (_varDecl.value)
{
int const stackHeight = m_stackHeight;
success = boost::apply_visitor(*this, *_varDecl.value);
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if ((m_stackHeight - stackHeight) != numVariables)
{
m_errorReporter.declarationError(_varDecl.location, "Variable count mismatch.");
return false;
}
}
else
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m_stackHeight += numVariables;
for (auto const& variable: _varDecl.variables)
{
expectValidType(variable.type, variable.location);
m_activeVariables.insert(&boost::get<Scope::Variable>(m_currentScope->identifiers.at(variable.name)));
}
m_info.stackHeightInfo[&_varDecl] = m_stackHeight;
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return success;
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}
bool AsmAnalyzer::operator()(assembly::FunctionDefinition const& _funDef)
{
Block const* virtualBlock = m_info.virtualBlocks.at(&_funDef).get();
solAssert(virtualBlock, "");
Scope& varScope = scope(virtualBlock);
for (auto const& var: _funDef.arguments + _funDef.returns)
{
expectValidType(var.type, var.location);
m_activeVariables.insert(&boost::get<Scope::Variable>(varScope.identifiers.at(var.name)));
}
int const stackHeight = m_stackHeight;
m_stackHeight = _funDef.arguments.size() + _funDef.returns.size();
bool success = (*this)(_funDef.body);
m_stackHeight = stackHeight;
m_info.stackHeightInfo[&_funDef] = m_stackHeight;
return success;
}
bool AsmAnalyzer::operator()(assembly::FunctionCall const& _funCall)
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{
bool success = true;
size_t arguments = 0;
size_t returns = 0;
if (!m_currentScope->lookup(_funCall.functionName.name, Scope::Visitor(
[&](Scope::Variable const&)
{
m_errorReporter.typeError(
_funCall.functionName.location,
"Attempt to call variable instead of function."
);
success = false;
},
[&](Scope::Label const&)
{
m_errorReporter.typeError(
_funCall.functionName.location,
"Attempt to call label instead of function."
);
success = false;
},
[&](Scope::Function const& _fun)
{
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/// TODO: compare types too
arguments = _fun.arguments.size();
returns = _fun.returns.size();
}
)))
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{
m_errorReporter.declarationError(_funCall.functionName.location, "Function not found.");
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success = false;
}
if (success)
{
if (_funCall.arguments.size() != arguments)
{
m_errorReporter.typeError(
_funCall.functionName.location,
"Expected " + boost::lexical_cast<string>(arguments) + " arguments but got " +
boost::lexical_cast<string>(_funCall.arguments.size()) + "."
);
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success = false;
}
}
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for (auto const& arg: _funCall.arguments | boost::adaptors::reversed)
if (!expectExpression(arg))
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success = false;
m_stackHeight += int(returns) - int(arguments);
m_info.stackHeightInfo[&_funCall] = m_stackHeight;
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return success;
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}
bool AsmAnalyzer::operator()(If const& _if)
{
bool success = true;
if (!expectExpression(*_if.condition))
success = false;
m_stackHeight--;
if (!(*this)(_if.body))
success = false;
m_info.stackHeightInfo[&_if] = m_stackHeight;
return success;
}
bool AsmAnalyzer::operator()(Switch const& _switch)
{
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bool success = true;
if (!expectExpression(*_switch.expression))
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success = false;
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set<tuple<LiteralKind, string>> cases;
for (auto const& _case: _switch.cases)
{
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if (_case.value)
{
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int const initialStackHeight = m_stackHeight;
// We cannot use "expectExpression" here because *_case.value is not a
// Statement and would be converted to a Statement otherwise.
if (!(*this)(*_case.value))
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success = false;
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expectDeposit(1, initialStackHeight, _case.value->location);
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m_stackHeight--;
/// Note: the parser ensures there is only one default case
auto val = make_tuple(_case.value->kind, _case.value->value);
if (!cases.insert(val).second)
{
m_errorReporter.declarationError(
_case.location,
"Duplicate case defined"
);
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success = false;
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}
}
if (!(*this)(_case.body))
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success = false;
}
m_stackHeight--;
m_info.stackHeightInfo[&_switch] = m_stackHeight;
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return success;
}
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bool AsmAnalyzer::operator()(assembly::ForLoop const& _for)
{
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Scope* originalScope = m_currentScope;
bool success = true;
if (!(*this)(_for.pre))
success = false;
// The block was closed already, but we re-open it again and stuff the
// condition, the body and the post part inside.
m_stackHeight += scope(&_for.pre).numberOfVariables();
m_currentScope = &scope(&_for.pre);
if (!expectExpression(*_for.condition))
success = false;
m_stackHeight--;
if (!(*this)(_for.body))
success = false;
if (!(*this)(_for.post))
success = false;
m_stackHeight -= scope(&_for.pre).numberOfVariables();
m_info.stackHeightInfo[&_for] = m_stackHeight;
m_currentScope = originalScope;
return success;
}
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bool AsmAnalyzer::operator()(Block const& _block)
{
bool success = true;
auto previousScope = m_currentScope;
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m_currentScope = &scope(&_block);
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int const initialStackHeight = m_stackHeight;
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for (auto const& s: _block.statements)
if (!boost::apply_visitor(*this, s))
success = false;
m_stackHeight -= scope(&_block).numberOfVariables();
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int const stackDiff = m_stackHeight - initialStackHeight;
if (stackDiff != 0)
{
m_errorReporter.declarationError(
_block.location,
"Unbalanced stack at the end of a block: " +
(
stackDiff > 0 ?
to_string(stackDiff) + string(" surplus item(s).") :
to_string(-stackDiff) + string(" missing item(s).")
)
);
success = false;
}
m_info.stackHeightInfo[&_block] = m_stackHeight;
m_currentScope = previousScope;
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return success;
}
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bool AsmAnalyzer::expectExpression(Statement const& _statement)
{
bool success = true;
int const initialHeight = m_stackHeight;
if (!boost::apply_visitor(*this, _statement))
success = false;
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if (!expectDeposit(1, initialHeight, locationOf(_statement)))
success = false;
return success;
}
bool AsmAnalyzer::expectDeposit(int _deposit, int _oldHeight, SourceLocation const& _location)
{
if (m_stackHeight - _oldHeight != _deposit)
{
m_errorReporter.typeError(
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_location,
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"Expected expression to return one item to the stack, but did return " +
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boost::lexical_cast<string>(m_stackHeight - _oldHeight) +
" items."
);
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return false;
}
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return true;
}
bool AsmAnalyzer::checkAssignment(assembly::Identifier const& _variable, size_t _valueSize)
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{
bool success = true;
size_t numErrorsBefore = m_errorReporter.errors().size();
size_t variableSize(-1);
if (Scope::Identifier const* var = m_currentScope->lookup(_variable.name))
{
// Check that it is a variable
if (var->type() != typeid(Scope::Variable))
{
m_errorReporter.typeError(_variable.location, "Assignment requires variable.");
success = false;
}
else if (!m_activeVariables.count(&boost::get<Scope::Variable>(*var)))
{
m_errorReporter.declarationError(
_variable.location,
"Variable " + _variable.name + " used before it was declared."
);
success = false;
}
variableSize = 1;
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}
else if (m_resolver)
{
bool insideFunction = m_currentScope->insideFunction();
variableSize = m_resolver(_variable, julia::IdentifierContext::LValue, insideFunction);
}
if (variableSize == size_t(-1))
{
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// Only add message if the callback did not.
if (numErrorsBefore == m_errorReporter.errors().size())
m_errorReporter.declarationError(_variable.location, "Variable not found or variable not lvalue.");
success = false;
}
if (_valueSize == size_t(-1))
_valueSize = variableSize == size_t(-1) ? 1 : variableSize;
m_stackHeight -= _valueSize;
if (_valueSize != variableSize && variableSize != size_t(-1))
{
m_errorReporter.typeError(
_variable.location,
"Variable size (" +
to_string(variableSize) +
") and value size (" +
to_string(_valueSize) +
") do not match."
);
success = false;
}
return success;
}
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Scope& AsmAnalyzer::scope(Block const* _block)
{
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solAssert(m_info.scopes.count(_block) == 1, "Scope requested but not present.");
auto scopePtr = m_info.scopes.at(_block);
solAssert(scopePtr, "Scope requested but not present.");
return *scopePtr;
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}
void AsmAnalyzer::expectValidType(string const& type, SourceLocation const& _location)
{
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if (!m_julia)
return;
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if (!builtinTypes.count(type))
m_errorReporter.typeError(
_location,
"\"" + type + "\" is not a valid type (user defined types are not yet supported)."
);
}
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void AsmAnalyzer::warnOnInstructions(solidity::Instruction _instr, SourceLocation const& _location)
{
static set<solidity::Instruction> futureInstructions{
solidity::Instruction::CREATE2,
solidity::Instruction::RETURNDATACOPY,
solidity::Instruction::RETURNDATASIZE,
solidity::Instruction::STATICCALL
};
if (futureInstructions.count(_instr))
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m_errorReporter.warning(
_location,
"The \"" +
boost::to_lower_copy(instructionInfo(_instr).name)
+ "\" instruction is only available after " +
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"the Metropolis hard fork. Before that it acts as an invalid instruction."
);
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if (_instr == solidity::Instruction::JUMP || _instr == solidity::Instruction::JUMPI)
m_errorReporter.warning(
_location,
"Jump instructions are low-level EVM features that can lead to "
"incorrect stack access. Because of that they are discouraged. "
"Please consider using \"switch\" or \"for\" statements instead."
);
}