solidity/libjulia/backends/evm/EVMCodeTransform.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/>.
*/
/**
* Common code generator for translating Julia / inline assembly to EVM and EVM1.5.
*/
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#include <libjulia/backends/evm/EVMCodeTransform.h>
#include <libsolidity/inlineasm/AsmAnalysisInfo.h>
#include <libsolidity/inlineasm/AsmData.h>
#include <libsolidity/interface/Exceptions.h>
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#include <boost/range/adaptor/reversed.hpp>
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using namespace std;
using namespace dev;
using namespace dev::julia;
using namespace dev::solidity;
using namespace dev::solidity::assembly;
void CodeTransform::operator()(VariableDeclaration const& _varDecl)
{
solAssert(m_scope, "");
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int const numVariables = _varDecl.variables.size();
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int height = m_assembly.stackHeight();
if (_varDecl.value)
{
boost::apply_visitor(*this, *_varDecl.value);
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expectDeposit(numVariables, height);
}
else
{
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int variablesLeft = numVariables;
while (variablesLeft--)
m_assembly.appendConstant(u256(0));
}
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for (auto const& variable: _varDecl.variables)
{
auto& var = boost::get<Scope::Variable>(m_scope->identifiers.at(variable.name));
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m_context->variableStackHeights[&var] = height++;
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}
checkStackHeight(&_varDecl);
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}
void CodeTransform::operator()(Assignment const& _assignment)
{
visitExpression(*_assignment.value);
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m_assembly.setSourceLocation(_assignment.location);
generateAssignment(_assignment.variableName);
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checkStackHeight(&_assignment);
}
void CodeTransform::operator()(StackAssignment const& _assignment)
{
m_assembly.setSourceLocation(_assignment.location);
generateAssignment(_assignment.variableName);
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checkStackHeight(&_assignment);
}
void CodeTransform::operator()(Label const& _label)
{
m_assembly.setSourceLocation(_label.location);
solAssert(m_scope, "");
solAssert(m_scope->identifiers.count(_label.name), "");
Scope::Label& label = boost::get<Scope::Label>(m_scope->identifiers.at(_label.name));
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m_assembly.appendLabel(labelID(label));
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checkStackHeight(&_label);
}
void CodeTransform::operator()(FunctionCall const& _call)
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{
solAssert(m_scope, "");
m_assembly.setSourceLocation(_call.location);
EVMAssembly::LabelID returnLabel(-1); // only used for evm 1.0
if (!m_evm15)
{
returnLabel = m_assembly.newLabelId();
m_assembly.appendLabelReference(returnLabel);
m_stackAdjustment++;
}
Scope::Function* function = nullptr;
solAssert(m_scope->lookup(_call.functionName.name, Scope::NonconstVisitor(
[=](Scope::Variable&) { solAssert(false, "Expected function name."); },
[=](Scope::Label&) { solAssert(false, "Expected function name."); },
[&](Scope::Function& _function) { function = &_function; }
)), "Function name not found.");
solAssert(function, "");
solAssert(function->arguments.size() == _call.arguments.size(), "");
for (auto const& arg: _call.arguments | boost::adaptors::reversed)
visitExpression(arg);
m_assembly.setSourceLocation(_call.location);
if (m_evm15)
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m_assembly.appendJumpsub(functionEntryID(_call.functionName.name, *function), function->arguments.size(), function->returns.size());
else
{
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m_assembly.appendJumpTo(functionEntryID(_call.functionName.name, *function), function->returns.size() - function->arguments.size() - 1);
m_assembly.appendLabel(returnLabel);
m_stackAdjustment--;
}
checkStackHeight(&_call);
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}
void CodeTransform::operator()(FunctionalInstruction const& _instruction)
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{
if (m_evm15 && (
_instruction.instruction.instruction == solidity::Instruction::JUMP ||
_instruction.instruction.instruction == solidity::Instruction::JUMPI
))
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{
bool const isJumpI = _instruction.instruction.instruction == solidity::Instruction::JUMPI;
if (isJumpI)
{
solAssert(_instruction.arguments.size() == 2, "");
visitExpression(_instruction.arguments.at(1));
}
else
{
solAssert(_instruction.arguments.size() == 1, "");
}
m_assembly.setSourceLocation(_instruction.location);
auto label = labelFromIdentifier(boost::get<assembly::Identifier>(_instruction.arguments.at(0)));
if (isJumpI)
m_assembly.appendJumpToIf(label);
else
m_assembly.appendJumpTo(label);
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}
else
{
for (auto const& arg: _instruction.arguments | boost::adaptors::reversed)
visitExpression(arg);
(*this)(_instruction.instruction);
}
checkStackHeight(&_instruction);
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}
void CodeTransform::operator()(assembly::Identifier const& _identifier)
{
m_assembly.setSourceLocation(_identifier.location);
// First search internals, then externals.
solAssert(m_scope, "");
if (m_scope->lookup(_identifier.name, Scope::NonconstVisitor(
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[=](Scope::Variable& _var)
{
if (int heightDiff = variableHeightDiff(_var, false))
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m_assembly.appendInstruction(solidity::dupInstruction(heightDiff));
else
// Store something to balance the stack
m_assembly.appendConstant(u256(0));
},
[=](Scope::Label& _label)
{
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m_assembly.appendLabelReference(labelID(_label));
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},
[=](Scope::Function&)
{
solAssert(false, "Function not removed during desugaring.");
}
)))
{
return;
}
solAssert(
m_identifierAccess.generateCode,
"Identifier not found and no external access available."
);
m_identifierAccess.generateCode(_identifier, IdentifierContext::RValue, m_assembly);
checkStackHeight(&_identifier);
}
void CodeTransform::operator()(assembly::Literal const& _literal)
{
m_assembly.setSourceLocation(_literal.location);
if (_literal.kind == assembly::LiteralKind::Number)
m_assembly.appendConstant(u256(_literal.value));
else if (_literal.kind == assembly::LiteralKind::Boolean)
{
if (_literal.value == "true")
m_assembly.appendConstant(u256(1));
else
m_assembly.appendConstant(u256(0));
}
else
{
solAssert(_literal.value.size() <= 32, "");
m_assembly.appendConstant(u256(h256(_literal.value, h256::FromBinary, h256::AlignLeft)));
}
checkStackHeight(&_literal);
}
void CodeTransform::operator()(assembly::Instruction const& _instruction)
{
solAssert(!m_evm15 || _instruction.instruction != solidity::Instruction::JUMP, "Bare JUMP instruction used for EVM1.5");
solAssert(!m_evm15 || _instruction.instruction != solidity::Instruction::JUMPI, "Bare JUMPI instruction used for EVM1.5");
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m_assembly.setSourceLocation(_instruction.location);
m_assembly.appendInstruction(_instruction.instruction);
checkStackHeight(&_instruction);
}
void CodeTransform::operator()(Switch const& _switch)
{
//@TODO use JUMPV in EVM1.5?
visitExpression(*_switch.expression);
int expressionHeight = m_assembly.stackHeight();
map<Case const*, AbstractAssembly::LabelID> caseBodies;
AbstractAssembly::LabelID end = m_assembly.newLabelId();
for (Case const& c: _switch.cases)
{
if (c.value)
{
(*this)(*c.value);
m_assembly.setSourceLocation(c.location);
AbstractAssembly::LabelID bodyLabel = m_assembly.newLabelId();
caseBodies[&c] = bodyLabel;
solAssert(m_assembly.stackHeight() == expressionHeight + 1, "");
m_assembly.appendInstruction(solidity::dupInstruction(2));
m_assembly.appendInstruction(solidity::Instruction::EQ);
m_assembly.appendJumpToIf(bodyLabel);
}
else
// default case
(*this)(c.body);
}
m_assembly.setSourceLocation(_switch.location);
m_assembly.appendJumpTo(end);
size_t numCases = caseBodies.size();
for (auto const& c: caseBodies)
{
m_assembly.setSourceLocation(c.first->location);
m_assembly.appendLabel(c.second);
(*this)(c.first->body);
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// Avoid useless "jump to next" for the last case.
if (--numCases > 0)
{
m_assembly.setSourceLocation(c.first->location);
m_assembly.appendJumpTo(end);
}
}
m_assembly.setSourceLocation(_switch.location);
m_assembly.appendLabel(end);
m_assembly.appendInstruction(solidity::Instruction::POP);
checkStackHeight(&_switch);
}
void CodeTransform::operator()(FunctionDefinition const& _function)
{
solAssert(m_scope, "");
solAssert(m_scope->identifiers.count(_function.name), "");
Scope::Function& function = boost::get<Scope::Function>(m_scope->identifiers.at(_function.name));
int const localStackAdjustment = m_evm15 ? 0 : 1;
int height = localStackAdjustment;
solAssert(m_info.scopes.at(&_function.body), "");
Scope* varScope = m_info.scopes.at(m_info.virtualBlocks.at(&_function).get()).get();
solAssert(varScope, "");
for (auto const& v: _function.arguments | boost::adaptors::reversed)
{
auto& var = boost::get<Scope::Variable>(varScope->identifiers.at(v.name));
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m_context->variableStackHeights[&var] = height++;
}
m_assembly.setSourceLocation(_function.location);
int stackHeightBefore = m_assembly.stackHeight();
AbstractAssembly::LabelID afterFunction = m_assembly.newLabelId();
if (m_evm15)
{
m_assembly.appendJumpTo(afterFunction, -stackHeightBefore);
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m_assembly.appendBeginsub(functionEntryID(_function.name, function), _function.arguments.size());
}
else
{
m_assembly.appendJumpTo(afterFunction, -stackHeightBefore + height);
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m_assembly.appendLabel(functionEntryID(_function.name, function));
}
m_stackAdjustment += localStackAdjustment;
for (auto const& v: _function.returns)
{
auto& var = boost::get<Scope::Variable>(varScope->identifiers.at(v.name));
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m_context->variableStackHeights[&var] = height++;
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// Preset stack slots for return variables to zero.
m_assembly.appendConstant(u256(0));
}
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CodeTransform(
m_assembly,
m_info,
m_julia,
m_evm15,
m_identifierAccess,
m_useNamedLabelsForFunctions,
localStackAdjustment,
m_context
)(_function.body);
{
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// The stack layout here is:
// <return label>? <arguments...> <return values...>
// But we would like it to be:
// <return values...> <return label>?
// So we have to append some SWAP and POP instructions.
// This vector holds the desired target positions of all stack slots and is
// modified parallel to the actual stack.
vector<int> stackLayout;
if (!m_evm15)
stackLayout.push_back(_function.returns.size()); // Move return label to the top
stackLayout += vector<int>(_function.arguments.size(), -1); // discard all arguments
for (size_t i = 0; i < _function.returns.size(); ++i)
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stackLayout.push_back(i); // Move return values down, but keep order.
solAssert(stackLayout.size() <= 17, "Stack too deep");
while (!stackLayout.empty() && stackLayout.back() != int(stackLayout.size() - 1))
if (stackLayout.back() < 0)
{
m_assembly.appendInstruction(solidity::Instruction::POP);
stackLayout.pop_back();
}
else
{
m_assembly.appendInstruction(swapInstruction(stackLayout.size() - stackLayout.back() - 1));
swap(stackLayout[stackLayout.back()], stackLayout.back());
}
for (int i = 0; size_t(i) < stackLayout.size(); ++i)
solAssert(i == stackLayout[i], "Error reshuffling stack.");
}
if (m_evm15)
m_assembly.appendReturnsub(_function.returns.size(), stackHeightBefore);
else
m_assembly.appendJump(stackHeightBefore - _function.returns.size());
m_stackAdjustment -= localStackAdjustment;
m_assembly.appendLabel(afterFunction);
checkStackHeight(&_function);
}
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void CodeTransform::operator()(ForLoop const& _forLoop)
{
Scope* originalScope = m_scope;
// We start with visiting the block, but not finalizing it.
m_scope = m_info.scopes.at(&_forLoop.pre).get();
int stackStartHeight = m_assembly.stackHeight();
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visitStatements(_forLoop.pre.statements);
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// TODO: When we implement break and continue, the labels and the stack heights at that point
// have to be stored in a stack.
AbstractAssembly::LabelID loopStart = m_assembly.newLabelId();
AbstractAssembly::LabelID loopEnd = m_assembly.newLabelId();
AbstractAssembly::LabelID postPart = m_assembly.newLabelId();
m_assembly.setSourceLocation(_forLoop.location);
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m_assembly.appendLabel(loopStart);
visitExpression(*_forLoop.condition);
m_assembly.setSourceLocation(_forLoop.location);
m_assembly.appendInstruction(solidity::Instruction::ISZERO);
m_assembly.appendJumpToIf(loopEnd);
(*this)(_forLoop.body);
m_assembly.setSourceLocation(_forLoop.location);
m_assembly.appendLabel(postPart);
(*this)(_forLoop.post);
m_assembly.setSourceLocation(_forLoop.location);
m_assembly.appendJumpTo(loopStart);
m_assembly.appendLabel(loopEnd);
finalizeBlock(_forLoop.pre, stackStartHeight);
m_scope = originalScope;
}
void CodeTransform::operator()(Block const& _block)
{
Scope* originalScope = m_scope;
m_scope = m_info.scopes.at(&_block).get();
int blockStartStackHeight = m_assembly.stackHeight();
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visitStatements(_block.statements);
finalizeBlock(_block, blockStartStackHeight);
m_scope = originalScope;
}
AbstractAssembly::LabelID CodeTransform::labelFromIdentifier(Identifier const& _identifier)
{
AbstractAssembly::LabelID label = AbstractAssembly::LabelID(-1);
if (!m_scope->lookup(_identifier.name, Scope::NonconstVisitor(
[=](Scope::Variable&) { solAssert(false, "Expected label"); },
[&](Scope::Label& _label)
{
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label = labelID(_label);
},
[=](Scope::Function&) { solAssert(false, "Expected label"); }
)))
{
solAssert(false, "Identifier not found.");
}
return label;
}
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AbstractAssembly::LabelID CodeTransform::labelID(Scope::Label const& _label)
{
if (!m_context->labelIDs.count(&_label))
m_context->labelIDs[&_label] = m_assembly.newLabelId();
return m_context->labelIDs[&_label];
}
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AbstractAssembly::LabelID CodeTransform::functionEntryID(string const& _name, Scope::Function const& _function)
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{
if (!m_context->functionEntryIDs.count(&_function))
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{
AbstractAssembly::LabelID id =
m_useNamedLabelsForFunctions ?
m_assembly.namedLabel(_name) :
m_assembly.newLabelId();
m_context->functionEntryIDs[&_function] = id;
}
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return m_context->functionEntryIDs[&_function];
}
void CodeTransform::visitExpression(Statement const& _expression)
{
int height = m_assembly.stackHeight();
boost::apply_visitor(*this, _expression);
expectDeposit(1, height);
}
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void CodeTransform::visitStatements(vector<Statement> const& _statements)
{
for (auto const& statement: _statements)
boost::apply_visitor(*this, statement);
}
void CodeTransform::finalizeBlock(Block const& _block, int blockStartStackHeight)
{
m_assembly.setSourceLocation(_block.location);
// pop variables
solAssert(m_info.scopes.at(&_block).get() == m_scope, "");
for (size_t i = 0; i < m_scope->numberOfVariables(); ++i)
m_assembly.appendInstruction(solidity::Instruction::POP);
int deposit = m_assembly.stackHeight() - blockStartStackHeight;
solAssert(deposit == 0, "Invalid stack height at end of block.");
checkStackHeight(&_block);
}
void CodeTransform::generateAssignment(Identifier const& _variableName)
{
solAssert(m_scope, "");
auto var = m_scope->lookup(_variableName.name);
if (var)
{
Scope::Variable const& _var = boost::get<Scope::Variable>(*var);
if (int heightDiff = variableHeightDiff(_var, true))
m_assembly.appendInstruction(solidity::swapInstruction(heightDiff - 1));
m_assembly.appendInstruction(solidity::Instruction::POP);
}
else
{
solAssert(
m_identifierAccess.generateCode,
"Identifier not found and no external access available."
);
m_identifierAccess.generateCode(_variableName, IdentifierContext::LValue, m_assembly);
}
}
int CodeTransform::variableHeightDiff(solidity::assembly::Scope::Variable const& _var, bool _forSwap)
{
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solAssert(m_context->variableStackHeights.count(&_var), "");
int heightDiff = m_assembly.stackHeight() - m_context->variableStackHeights[&_var];
if (heightDiff <= (_forSwap ? 1 : 0) || heightDiff > (_forSwap ? 17 : 16))
{
solUnimplemented(
"Variable inaccessible, too deep inside stack (" + boost::lexical_cast<string>(heightDiff) + ")"
);
return 0;
}
else
return heightDiff;
}
void CodeTransform::expectDeposit(int _deposit, int _oldHeight)
{
solAssert(m_assembly.stackHeight() == _oldHeight + _deposit, "Invalid stack deposit.");
}
void CodeTransform::checkStackHeight(void const* _astElement)
{
solAssert(m_info.stackHeightInfo.count(_astElement), "Stack height for AST element not found.");
solAssert(
m_info.stackHeightInfo.at(_astElement) == m_assembly.stackHeight() - m_stackAdjustment,
"Stack height mismatch between analysis and code generation phase: Analysis: " +
to_string(m_info.stackHeightInfo.at(_astElement)) +
" code gen: " +
to_string(m_assembly.stackHeight() - m_stackAdjustment)
);
}