Place re-entrancy lock immediately after used storage slots #2308
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fubuloubu
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Feb 16, 2021
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fubuloubu
approved these changes
Feb 16, 2021
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What I did
In storage, place re-entrancy locks immediately after the last used storage slot.
How I did it
Within
parser/global_context.py, storage variables are stored inGlobalContext._globals. The storage slot for each storage variable is determined fromlen(self._globals)prior to adding the variable into the dict. Arrays, mappings, and other multiple-slot types are always assigned exactly one slot, but their actual location is calculated from aSHA3operation (see #769 for more details).Re-entrancy locks start at slot
0xFFFFFFand if more than this many storage variables are defined, a compile-time exception is raised.This PR sets the initial re-entrancy lock to location
len(self._globals)- immediately after the last used storage slot. This works because globals are defined while parsing the module scope, but re-entrancy locks are defined when parsing the local scope of each function. Thus, there is no overlap and by the time we get to the locks we know with certainy the exact size of storage.How to verify it
Run tests.
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