Avoid allocations in Decoder::read_str
.
#37064
Merged
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opaque::Decoder::read_str
is very hot withinrustc
due to its use inthe reading of crate metadata, and it currently returns a
String
. Thiscommit changes it to instead return a
Cow<str>
, which avoids a heapallocation.
This change reduces the number of calls to
malloc
by almost 10% insome benchmarks.
This is a [breaking-change] to libserialize.