rustc: Avoid HashStable for DefIndex queries #44584
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I'm not 100% familiar with this trait and this location, but it looks like
there's a default implementation of
DepNodeParams
for anything that implementsHashStable
, but types likeDefId
which have precalculated hashes bypass thisdefault implementation for a speedier one.
This commit applies what I believe is the same optimization to
DefIndex
,looking up the local hash for it rather than going through the full
HashStable
rigamarole
cc #44575