cmd/compilebench: add object file size to package benchmarks

Protected by flag -obj.

Sample relevant output from compilecmp using this commit.

name       old obj-bytes     new obj-bytes     delta
Template          382k ± 0%         381k ± 0%   -0.23%  (p=0.002 n=6+6)
Unicode           203k ± 0%         203k ± 0%   -0.00%  (p=0.002 n=6+6)
GoTypes          1.18M ± 0%        1.17M ± 0%   -0.08%  (p=0.002 n=6+6)
Compiler         3.99M ± 0%        3.99M ± 0%   -0.08%  (p=0.002 n=6+6)
SSA              8.28M ± 0%        8.28M ± 0%   -0.02%  (p=0.002 n=6+6)
Flate             230k ± 0%         230k ± 0%   -0.05%  (p=0.002 n=6+6)
GoParser          287k ± 0%         287k ± 0%   -0.16%  (p=0.002 n=6+6)
Reflect          1.00M ± 0%        1.00M ± 0%   -0.01%  (p=0.002 n=6+6)
Tar               190k ± 0%         189k ± 0%   -0.24%  (p=0.002 n=6+6)
XML               416k ± 0%         415k ± 0%   -0.16%  (p=0.002 n=6+6)

name       old export-bytes  new export-bytes  delta
Template         19.0k ± 0%        18.2k ± 0%   -4.55%  (p=0.002 n=6+6)
Unicode          4.45k ± 0%        4.44k ± 0%   -0.11%  (p=0.002 n=6+6)
GoTypes          29.7k ± 0%        28.8k ± 0%   -3.12%  (p=0.002 n=6+6)
Compiler         75.6k ± 0%        72.5k ± 0%   -4.03%  (p=0.002 n=6+6)
SSA              76.2k ± 0%        74.8k ± 0%   -1.72%  (p=0.002 n=6+6)
Flate            4.98k ± 0%        4.87k ± 0%   -2.29%  (p=0.002 n=6+6)
GoParser         8.81k ± 0%        8.34k ± 0%   -5.30%  (p=0.002 n=6+6)
Reflect          6.25k ± 0%        6.16k ± 0%   -1.49%  (p=0.002 n=6+6)
Tar              9.49k ± 0%        9.03k ± 0%   -4.82%  (p=0.002 n=6+6)
XML              16.0k ± 0%        15.4k ± 0%   -4.03%  (p=0.002 n=6+6)


Change-Id: I3f5e6ec022cb02ad6937f7859c573ca1edc39fb7
Reviewed-on: https://go-review.googlesource.com/41053
Reviewed-by: Robert Griesemer <gri@golang.org>
1 file changed