From 1f77deada1abc9ca1e635ab13d45707e852a5628 Mon Sep 17 00:00:00 2001 From: Leonardo Alt Date: Thu, 3 May 2018 16:40:33 +0200 Subject: [050] Reserving and popping local vars in their scope --- libsolidity/codegen/ContractCompiler.cpp | 104 +++++++++++++++++++++---------- 1 file changed, 70 insertions(+), 34 deletions(-) (limited to 'libsolidity/codegen/ContractCompiler.cpp') diff --git a/libsolidity/codegen/ContractCompiler.cpp b/libsolidity/codegen/ContractCompiler.cpp index 81aba21e..def4a878 100644 --- a/libsolidity/codegen/ContractCompiler.cpp +++ b/libsolidity/codegen/ContractCompiler.cpp @@ -427,7 +427,7 @@ bool ContractCompiler::visit(FunctionDefinition const& _function) m_context.startFunction(_function); // stack upon entry: [return address] [arg0] [arg1] ... [argn] - // reserve additional slots: [retarg0] ... [retargm] [localvar0] ... [localvarp] + // reserve additional slots: [retarg0] ... [retargm] unsigned parametersSize = CompilerUtils::sizeOnStack(_function.parameters()); if (!_function.isConstructor()) @@ -441,22 +441,18 @@ bool ContractCompiler::visit(FunctionDefinition const& _function) for (ASTPointer const& variable: _function.returnParameters()) appendStackVariableInitialisation(*variable); - for (VariableDeclaration const* localVariable: _function.localVariables()) - appendStackVariableInitialisation(*localVariable); if (_function.isConstructor()) if (auto c = m_context.nextConstructor(dynamic_cast(*_function.scope()))) appendBaseConstructor(*c); - solAssert(m_returnTags.empty(), ""); m_breakTags.clear(); m_continueTags.clear(); - m_stackCleanupForReturn = 0; m_currentFunction = &_function; m_modifierDepth = -1; + m_scopeStackHeight.clear(); appendModifierOrFunctionCode(); - solAssert(m_returnTags.empty(), ""); // Now we need to re-shuffle the stack. For this we keep a record of the stack layout @@ -467,14 +463,12 @@ bool ContractCompiler::visit(FunctionDefinition const& _function) unsigned const c_argumentsSize = CompilerUtils::sizeOnStack(_function.parameters()); unsigned const c_returnValuesSize = CompilerUtils::sizeOnStack(_function.returnParameters()); - unsigned const c_localVariablesSize = CompilerUtils::sizeOnStack(_function.localVariables()); vector stackLayout; stackLayout.push_back(c_returnValuesSize); // target of return address stackLayout += vector(c_argumentsSize, -1); // discard all arguments for (unsigned i = 0; i < c_returnValuesSize; ++i) stackLayout.push_back(i); - stackLayout += vector(c_localVariablesSize, -1); if (stackLayout.size() > 17) BOOST_THROW_EXCEPTION( @@ -493,18 +487,19 @@ bool ContractCompiler::visit(FunctionDefinition const& _function) m_context << swapInstruction(stackLayout.size() - stackLayout.back() - 1); swap(stackLayout[stackLayout.back()], stackLayout.back()); } - //@todo assert that everything is in place now + for (int i = 0; i < int(stackLayout.size()); ++i) + if (stackLayout[i] != i) + solAssert(false, "Invalid stack layout on cleanup."); for (ASTPointer const& variable: _function.parameters() + _function.returnParameters()) m_context.removeVariable(*variable); - for (VariableDeclaration const* localVariable: _function.localVariables()) - m_context.removeVariable(*localVariable); m_context.adjustStackOffset(-(int)c_returnValuesSize); /// The constructor and the fallback function doesn't to jump out. if (!_function.isConstructor() && !_function.isFallback()) m_context.appendJump(eth::AssemblyItem::JumpType::OutOfFunction); + return false; } @@ -669,14 +664,16 @@ bool ContractCompiler::visit(WhileStatement const& _whileStatement) eth::AssemblyItem loopStart = m_context.newTag(); eth::AssemblyItem loopEnd = m_context.newTag(); - m_breakTags.push_back(loopEnd); + m_breakTags.push_back({loopEnd, m_context.stackHeight()}); + + visitLoop(&_whileStatement); m_context << loopStart; if (_whileStatement.isDoWhile()) { eth::AssemblyItem condition = m_context.newTag(); - m_continueTags.push_back(condition); + m_continueTags.push_back({condition, m_context.stackHeight()}); _whileStatement.body().accept(*this); @@ -687,7 +684,7 @@ bool ContractCompiler::visit(WhileStatement const& _whileStatement) } else { - m_continueTags.push_back(loopStart); + m_continueTags.push_back({loopStart, m_context.stackHeight()}); compileExpression(_whileStatement.condition()); m_context << Instruction::ISZERO; m_context.appendConditionalJumpTo(loopEnd); @@ -712,12 +709,14 @@ bool ContractCompiler::visit(ForStatement const& _forStatement) eth::AssemblyItem loopStart = m_context.newTag(); eth::AssemblyItem loopEnd = m_context.newTag(); eth::AssemblyItem loopNext = m_context.newTag(); - m_continueTags.push_back(loopNext); - m_breakTags.push_back(loopEnd); + + visitLoop(&_forStatement); if (_forStatement.initializationExpression()) _forStatement.initializationExpression()->accept(*this); + m_breakTags.push_back({loopEnd, m_context.stackHeight()}); + m_continueTags.push_back({loopNext, m_context.stackHeight()}); m_context << loopStart; // if there is no terminating condition in for, default is to always be true @@ -737,11 +736,16 @@ bool ContractCompiler::visit(ForStatement const& _forStatement) _forStatement.loopExpression()->accept(*this); m_context.appendJumpTo(loopStart); + m_context << loopEnd; m_continueTags.pop_back(); m_breakTags.pop_back(); + // For the case where no break/return is executed: + // loop initialization variables have to be freed + popScopedVariables(&_forStatement); + checker.check(); return false; } @@ -750,7 +754,7 @@ bool ContractCompiler::visit(Continue const& _continueStatement) { CompilerContext::LocationSetter locationSetter(m_context, _continueStatement); solAssert(!m_continueTags.empty(), ""); - m_context.appendJumpTo(m_continueTags.back()); + popAndJump(m_context.stackHeight() - m_continueTags.back().second, m_continueTags.back().first); return false; } @@ -758,7 +762,7 @@ bool ContractCompiler::visit(Break const& _breakStatement) { CompilerContext::LocationSetter locationSetter(m_context, _breakStatement); solAssert(!m_breakTags.empty(), ""); - m_context.appendJumpTo(m_breakTags.back()); + popAndJump(m_context.stackHeight() - m_breakTags.back().second, m_breakTags.back().first); return false; } @@ -784,10 +788,8 @@ bool ContractCompiler::visit(Return const& _return) for (auto const& retVariable: boost::adaptors::reverse(returnParameters)) CompilerUtils(m_context).moveToStackVariable(*retVariable); } - for (unsigned i = 0; i < m_stackCleanupForReturn; ++i) - m_context << Instruction::POP; - m_context.appendJumpTo(m_returnTags.back()); - m_context.adjustStackOffset(m_stackCleanupForReturn); + + popAndJump(m_context.stackHeight() - m_returnTags.back().second, m_returnTags.back().first); return false; } @@ -810,8 +812,15 @@ bool ContractCompiler::visit(EmitStatement const& _emit) bool ContractCompiler::visit(VariableDeclarationStatement const& _variableDeclarationStatement) { - StackHeightChecker checker(m_context); CompilerContext::LocationSetter locationSetter(m_context, _variableDeclarationStatement); + + // Local variable slots are reserved when their declaration is visited, + // and freed in the end of their scope. + for (auto _decl: _variableDeclarationStatement.declarations()) + if (_decl) + appendStackVariableInitialisation(*_decl); + + StackHeightChecker checker(m_context); if (Expression const* expression = _variableDeclarationStatement.initialValue()) { CompilerUtils utils(m_context); @@ -861,6 +870,18 @@ bool ContractCompiler::visit(PlaceholderStatement const& _placeholderStatement) return true; } +bool ContractCompiler::visit(Block const& _block) +{ + m_scopeStackHeight[m_modifierDepth][&_block] = m_context.stackHeight(); + return true; +} + +void ContractCompiler::endVisit(Block const& _block) +{ + // Frees local variables declared in the scope of this block. + popScopedVariables(&_block); +} + void ContractCompiler::appendMissingFunctions() { while (Declaration const* function = m_context.nextFunctionToCompile()) @@ -916,27 +937,19 @@ void ContractCompiler::appendModifierOrFunctionCode() modifier.parameters()[i]->annotation().type ); } - for (VariableDeclaration const* localVariable: modifier.localVariables()) - { - addedVariables.push_back(localVariable); - appendStackVariableInitialisation(*localVariable); - } - stackSurplus = - CompilerUtils::sizeOnStack(modifier.parameters()) + - CompilerUtils::sizeOnStack(modifier.localVariables()); + stackSurplus = CompilerUtils::sizeOnStack(modifier.parameters()); codeBlock = &modifier.body(); } } if (codeBlock) { - m_returnTags.push_back(m_context.newTag()); - + m_returnTags.push_back({m_context.newTag(), m_context.stackHeight()}); codeBlock->accept(*this); solAssert(!m_returnTags.empty(), ""); - m_context << m_returnTags.back(); + m_context << m_returnTags.back().first; m_returnTags.pop_back(); CompilerUtils(m_context).popStackSlots(stackSurplus); @@ -983,3 +996,26 @@ eth::AssemblyPointer ContractCompiler::cloneRuntime() const a << u256(0x20) << u256(0) << Instruction::RETURN; return make_shared(a); } + +void ContractCompiler::popScopedVariables(ASTNode const* _node) +{ + unsigned blockHeight = m_scopeStackHeight[m_modifierDepth][_node]; + unsigned stackDiff = m_context.stackHeight() - blockHeight; + CompilerUtils(m_context).popStackSlots(stackDiff); + m_context.removeVariablesAboveStackHeight(blockHeight); + m_scopeStackHeight[m_modifierDepth].erase(_node); + if (m_scopeStackHeight[m_modifierDepth].size() == 0) + m_scopeStackHeight.erase(m_modifierDepth); +} + +void ContractCompiler::visitLoop(BreakableStatement const* _loop) +{ + m_scopeStackHeight[m_modifierDepth][_loop] = m_context.stackHeight(); +} + +void ContractCompiler::popAndJump(unsigned _amount, eth::AssemblyItem const& _jumpTo) +{ + CompilerUtils(m_context).popStackSlots(_amount); + m_context.appendJumpTo(_jumpTo); + m_context.adjustStackOffset(_amount); +} -- cgit