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| author | Alex Crichton <alex@alexcrichton.com> | 2016-10-12 10:15:27 -0700 |
|---|---|---|
| committer | Alex Crichton <alex@alexcrichton.com> | 2016-10-12 14:07:56 -0700 |
| commit | f05bd1b41ddda779032f4c5c8e30bf640129832f (patch) | |
| tree | 20136a8f6a2215e22703c51ba54c78426c3837fe /src/librustc_metadata | |
| parent | a0ad6616fc2244eea66c6adadd35f899b170505f (diff) | |
| parent | b043e11de2eb2c60f7bfec5e15960f537b229e20 (diff) | |
| download | rust-f05bd1b41ddda779032f4c5c8e30bf640129832f.tar.gz rust-f05bd1b41ddda779032f4c5c8e30bf640129832f.zip | |
Rollup merge of #37064 - nnethercote:read_str, r=eddyb
Avoid allocations in `Decoder::read_str`. `opaque::Decoder::read_str` is very hot within `rustc` due to its use in the reading of crate metadata, and it currently returns a `String`. This commit changes it to instead return a `Cow<str>`, which avoids a heap allocation. This change reduces the number of calls to `malloc` by almost 10% in some benchmarks. This is a [breaking-change] to libserialize.
Diffstat (limited to 'src/librustc_metadata')
| -rw-r--r-- | src/librustc_metadata/decoder.rs | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/src/librustc_metadata/decoder.rs b/src/librustc_metadata/decoder.rs index 579a97138f2..bdb4d383cee 100644 --- a/src/librustc_metadata/decoder.rs +++ b/src/librustc_metadata/decoder.rs @@ -32,6 +32,7 @@ use rustc_const_math::ConstInt; use rustc::mir::repr::Mir; +use std::borrow::Cow; use std::cell::Ref; use std::io; use std::mem; @@ -202,7 +203,7 @@ impl<'doc, 'tcx> Decoder for DecodeContext<'doc, 'tcx> { read_f64 -> f64; read_f32 -> f32; read_char -> char; - read_str -> String; + read_str -> Cow<str>; } fn error(&mut self, err: &str) -> Self::Error { |