avoid loading constructor attributes in AdtDef decoding #54485
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During metadata loading, the AdtDefs for every ADT in the universe need to be loaded (for example, for coherence of builtin traits). For that, the attributes of the AdtDef need to be loaded too. The attributes of a struct are duplicated between 2 def ids - the constructor def-id, and the "type" def id. Loading attributes for both def-ids, which was done in rust-lang#53721, slowed the compilation of small crates by 2-3%. This PR makes sure we only load the attributes for the "type" def-id, avoiding the slowdown.
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Maybe we shouldn't even duplicate the attributes in the first place - but that could have very subtle consequences, so it's probably not worth it. @bors r+ |
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📌 Commit 2c28c4e has been approved by |
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Sep 23, 2018
avoid loading constructor attributes in AdtDef decoding During metadata loading, the AdtDefs for every ADT in the universe need to be loaded (for example, for coherence of builtin traits). For that, the attributes of the AdtDef need to be loaded too. The attributes of a struct are duplicated between 2 def ids - the constructor def-id, and the "type" def id. Loading attributes for both def-ids, which was done in #53721, slowed the compilation of small crates by 2-3%. This PR makes sure we only load the attributes for the "type" def-id, avoiding the slowdown. r? @eddyb & cc @nnethercote
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☀️ Test successful - status-appveyor, status-travis |
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During metadata loading, the AdtDefs for every ADT in the universe need
to be loaded (for example, for coherence of builtin traits). For that,
the attributes of the AdtDef need to be loaded too.
The attributes of a struct are duplicated between 2 def ids - the
constructor def-id, and the "type" def id. Loading attributes for both
def-ids, which was done in #53721, slowed the compilation of small
crates by 2-3%. This PR makes sure we only load the attributes for the
"type" def-id, avoiding the slowdown.
r? @eddyb & cc @nnethercote