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| author | Keith Randall <khr@golang.org> | 2014-12-27 19:26:40 -0800 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2015-01-07 21:24:21 +0000 |
| commit | 63116de558b472c437df186d6bf87e163f674ea2 (patch) | |
| tree | b3a997702dd8737db1bbde6408fd1ce6639333ef /src/cmd/ld/lib.h | |
| parent | af7ca8dce4991860263d5e0d0322461cfd00c599 (diff) | |
| download | go-63116de558b472c437df186d6bf87e163f674ea2.tar.xz | |
runtime: faster version of findfunc
Use a lookup table to find the function which contains a pc. It is
faster than the old binary search. findfunc is used primarily for
stack copying and garbage collection.
benchmark old ns/op new ns/op delta
BenchmarkStackCopy 294746596 255400980 -13.35%
(findfunc is one of several tasks done by stack copy, the findfunc
time itself is about 2.5x faster.)
The lookup table is built at link time. The table grows the binary
size by about 0.5% of the text segment.
We impose a lower limit of 16 bytes on any function, which should not
have much of an impact. (The real constraint required is <=256
functions in every 4096 bytes, but 16 bytes/function is easier to
implement.)
Change-Id: Ic315b7a2c83e1f7203cd2a50e5d21a822e18fdca
Reviewed-on: https://go-review.googlesource.com/2097
Reviewed-by: Russ Cox <rsc@golang.org>
Diffstat (limited to 'src/cmd/ld/lib.h')
| -rw-r--r-- | src/cmd/ld/lib.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/src/cmd/ld/lib.h b/src/cmd/ld/lib.h index 17483e0b4c..fd84c8bccb 100644 --- a/src/cmd/ld/lib.h +++ b/src/cmd/ld/lib.h @@ -35,6 +35,7 @@ enum { MAXIO = 8192, + MINFUNC = 16, // minimum size for a function }; typedef struct Segment Segment; @@ -260,6 +261,7 @@ void patch(void); int pathchar(void); void pcln(void); void pclntab(void); +void findfunctab(void); void putelfsectionsym(LSym* s, int shndx); void putelfsymshndx(vlong sympos, int shndx); void putsymb(LSym *s, char *name, int t, vlong v, vlong size, int ver, LSym *typ); |