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Have the stack optimization in the code transform only reuse slots that are reachable.

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This commit is contained in:
Daniel Kirchner 2021-04-13 22:25:13 +02:00
parent c9fd97ecae
commit 13401bed87
1 changed files with 16 additions and 8 deletions
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24
libyul/backends/evm/EVMCodeTransform.cpp
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@ -226,16 +226,24 @@ void CodeTransform::operator()(VariableDeclaration const& _varDecl)
else
m_variablesScheduledForDeletion.insert(&var);
}
else if (m_unusedStackSlots.empty())
atTopOfStack = false;
else
{
auto slot = static_cast<size_t>(*m_unusedStackSlots.begin());
m_unusedStackSlots.erase(m_unusedStackSlots.begin());
m_context->variableStackHeights[&var] = slot;
if (size_t heightDiff = variableHeightDiff(var, varName, true))
m_assembly.appendInstruction(evmasm::swapInstruction(static_cast<unsigned>(heightDiff - 1)));
m_assembly.appendInstruction(evmasm::Instruction::POP);
bool foundUnusedSlot = false;
for (auto it = m_unusedStackSlots.begin(); it != m_unusedStackSlots.end(); ++it)
{
if (m_assembly.stackHeight() - *it > 17)
continue;
foundUnusedSlot = true;
m_unusedStackSlots.erase(it);
auto slot = static_cast<size_t>(*it);
m_context->variableStackHeights[&var] = slot;
if (size_t heightDiff = variableHeightDiff(var, varName, true))
m_assembly.appendInstruction(evmasm::swapInstruction(static_cast<unsigned>(heightDiff - 1)));
m_assembly.appendInstruction(evmasm::Instruction::POP);
break;
}
if (!foundUnusedSlot)
atTopOfStack = false;
}
}
}