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Detect loops in call graph generator.

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This commit is contained in:
chriseth
2019-12-03 21:38:20 +01:00
parent 287b9be7af
commit bbeb093abf
13 changed files with 169 additions and 29 deletions
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libyul/optimiser/Semantics.cpp
+41 -4
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@@ -108,11 +108,44 @@ void MSizeFinder::operator()(FunctionCall const& _functionCall)
map<YulString, SideEffects> SideEffectsPropagator::sideEffects(
Dialect const& _dialect,
map<YulString, std::set<YulString>> const& _directCallGraph
CallGraph const& _directCallGraph
)
{
// Any loop currently makes a function non-movable, because
// it could be a non-terminating loop.
// The same is true for any function part of a call cycle.
// In the future, we should refine that, because the property
// is actually a bit different from "not movable".
map<YulString, SideEffects> ret;
for (auto const& call: _directCallGraph)
for (auto const& function: _directCallGraph.functionsWithLoops)
{
ret[function].movable = false;
ret[function].sideEffectFree = false;
ret[function].sideEffectFreeIfNoMSize = false;
}
// Detect recursive functions.
for (auto const& call: _directCallGraph.functionCalls)
{
// TODO we could shortcut the search as soon as we find a
// function that has as bad side-effects as we can
// ever achieve via recursion.
auto search = [&](YulString const& _functionName, CycleDetector<YulString>& _cycleDetector, size_t) {
for (auto const& callee: _directCallGraph.functionCalls.at(_functionName))
if (!_dialect.builtin(callee))
if (_cycleDetector.run(callee))
return;
};
if (CycleDetector<YulString>(search).run(call.first))
{
ret[call.first].movable = false;
ret[call.first].sideEffectFree = false;
ret[call.first].sideEffectFreeIfNoMSize = false;
}
}
for (auto const& call: _directCallGraph.functionCalls)
{
YulString funName = call.first;
SideEffects sideEffects;
@@ -123,11 +156,15 @@ map<YulString, SideEffects> SideEffectsPropagator::sideEffects(
if (BuiltinFunction const* f = _dialect.builtin(_function))
sideEffects += f->sideEffects;
else
for (YulString callee: _directCallGraph.at(_function))
{
if (ret.count(_function))
sideEffects += ret[_function];
for (YulString callee: _directCallGraph.functionCalls.at(_function))
_addChild(callee);
}
}
);
ret[funName] = sideEffects;
ret[funName] += sideEffects;
}
return ret;
}