diff options
Diffstat (limited to 'libjulia/backends/evm/EVMCodeTransform.cpp')
| -rw-r--r-- | libjulia/backends/evm/EVMCodeTransform.cpp | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/libjulia/backends/evm/EVMCodeTransform.cpp b/libjulia/backends/evm/EVMCodeTransform.cpp index 43bd5a44..2b6a11e0 100644 --- a/libjulia/backends/evm/EVMCodeTransform.cpp +++ b/libjulia/backends/evm/EVMCodeTransform.cpp @@ -262,6 +262,7 @@ void CodeTransform::operator()(Switch const& _switch) m_assembly.setSourceLocation(c.first->location); m_assembly.appendLabel(c.second); (*this)(c.first->body); + // Avoid useless "jump to next" for the last case. if (--numCases > 0) { m_assembly.setSourceLocation(c.first->location); @@ -315,6 +316,7 @@ void CodeTransform::operator()(FunctionDefinition const& _function) auto& var = boost::get<Scope::Variable>(varScope->identifiers.at(v.name)); var.stackHeight = height++; var.active = true; + // Preset stack slots for return variables to zero. m_assembly.appendConstant(u256(0)); } @@ -322,13 +324,20 @@ void CodeTransform::operator()(FunctionDefinition const& _function) .run(_function.body); { - // Stack of target positions of stack elements + // 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) - stackLayout.push_back(i); + 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)) |