feat[codegen]: deallocate variables after last use #4219
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deallocate variables after last use, improving memory usage.
charles-cooper
changed the title
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marked this for inclusion in 0.4.1, but depending on when our next audit can be, might push to 0.4.2 |
use_count inside of Expr is dangerous, since Expr() can be called multiple times for a given node. separate the analysis.
| var = self.vars[varname] | ||
| for s in self._scopes: | ||
| if s not in var.blockscopes: | ||
| # defer deallocation until we hit the end of its scope |
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is this accurate? we defer the dealoc until we hit its scope again (not necessarily its end)
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or if "it" refers to the scope then still we might have to wait until multiple scopes finish
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"it" refers to the scope of the variable
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but we sweep after statements, right?
a: uint256 = 0
for i: uint256 in range(1, 3):
a += i # <- can't dealoc, defer
b: uint256 = 0 # a already deallocated, swept after the for
b += 1
return b # actual scope end but a is already deallocated
| @@ -40,6 +40,7 @@ class VariableRecord: | |||
| defined_at: Any = None | |||
| is_internal: bool = False | |||
| alloca: Optional[Alloca] = None | |||
| system: bool = False | |||
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can't we rather modify the analysis than create a new type of variable given it's used only at one place?
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yea, it's a bit of a kludge, until we refactor sqrt to be either pure IR or a library function
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Given that we log write as both write+read, the dealoc won't happen until the last write (although the memory variable might be long dead at that point). So, in this context, the write operation is considered as "use". |
i think a write is a use |
deallocate variables after last use, improving memory usage.
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