| commit | 987ce938245566f8a8568cb3b7f43ff8442c2353 | [log] [tgz] |
|---|---|---|
| author | Cherry Zhang <cherryyz@google.com> | Fri Jun 26 16:35:49 2020 -0400 |
| committer | Cherry Zhang <cherryyz@google.com> | Sun Jul 05 23:56:19 2020 +0000 |
| tree | 1c12e7a82a56aad78fb4a298dad40e5b6403d178 | |
| parent | 364d3205045b694a6c89a8d9ad932e7c105d0f6c [diff] |
[dev.link] cmd/link: emit ELF relocations in mmap Currently, ELF relocations are generated sequentially in the heap and flushed to output file periodically. In fact, in some cases, the output size of the relocation records can be easily computed, as a relocation entry has fixed size. We only need to count the number of relocation records to compute the size. Once the size is computed, we can mmap the output with the proper size, and directly write relocation records in the mapped memory. It also opens the possibility of writing relocations in parallel (not done in this CL). Note: on some architectures, a Go relocation may turn into multiple ELF relocations, which makes size calculation harder. This CL does not handle those cases, and it still writes sequentially in the heap there. Linking cmd/compile with external linking, name old time/op new time/op delta Asmb2 190ms ± 2% 141ms ± 4% -25.74% (p=0.000 n=10+10) name old alloc/op new alloc/op delta Asmb2_GC 66.8MB ± 0% 8.2MB ± 0% -87.79% (p=0.008 n=5+5) name old live-B new live-B delta Asmb2_GC 66.9M ± 0% 55.2M ± 0% -17.58% (p=0.008 n=5+5) Change-Id: If7056bbe909dc90033eef6b9c4891fcca310602c Reviewed-on: https://go-review.googlesource.com/c/go/+/240399 Run-TryBot: Cherry Zhang <cherryyz@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Than McIntosh <thanm@google.com>
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