| commit | 88382a9f97c96a610df5974cdeb165a6e7237861 | [log] [tgz] |
|---|---|---|
| author | Cherry Zhang <cherryyz@google.com> | Tue Jul 14 14:46:59 2020 -0400 |
| committer | Cherry Zhang <cherryyz@google.com> | Thu Jul 16 20:26:39 2020 +0000 |
| tree | c6860f64c19564a163947fa6d9c478da16870739 | |
| parent | 4f217d5aaa88536f641910e2b97b24489132ee16 [diff] |
[dev.link] cmd/link: stream out external relocations on AMD64 ELF Currently, when external linking, in relocsym (in asmb pass), we convert Go relocations to an in-memory representation of external relocations, and then in asmb2 pass we write them out to the output file. This is not memory efficient. This CL makes it not do the conversion but directly stream out the external relocations based on Go relocations. Currently only do this on AMD64 ELF systems. This reduces memory usage, but makes the asmb2 pass a little slower. Linking cmd/compile with external linking: name old time/op new time/op delta Asmb_GC 83.8ms ± 7% 70.4ms ± 4% -16.03% (p=0.008 n=5+5) Asmb2_GC 95.6ms ± 4% 118.2ms ± 5% +23.65% (p=0.008 n=5+5) TotalTime_GC 1.59s ± 2% 1.62s ± 1% ~ (p=0.151 n=5+5) name old alloc/op new alloc/op delta Asmb_GC 26.0MB ± 0% 4.1MB ± 0% -84.15% (p=0.008 n=5+5) Asmb2_GC 8.19MB ± 0% 8.18MB ± 0% ~ (p=0.222 n=5+5) name old live-B new live-B delta Asmb_GC 49.2M ± 0% 27.4M ± 0% -44.38% (p=0.008 n=5+5) Asmb2_GC 51.5M ± 0% 29.7M ± 0% -42.33% (p=0.008 n=5+5) TODO: figure out what is slow. Possible improvements: - Remove redundant work in relocsym. - Maybe there is a better representation for external relocations now. - Fine-grained parallelism in emitting external relocations. - The old elfrelocsect only iterates over external relocations, now we iterate over all relocations. Is it too many? Change-Id: Ib0a8ee8c88d65864c62b89a8d634614f7f2c813e Reviewed-on: https://go-review.googlesource.com/c/go/+/242603 Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Jeremy Faller <jeremy@golang.org>
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