1dcf34f2ec
Compiling with -S was not implemented with performance in mind. It allocates profligately. Compiling with -S is ~58% slower, allocates ~47% more memory, and does ~183% more allocations. compilecmp now uses -S to do finer-grained comparisons between compiler versions, so I now care about its performance. This change picks some of the lowest hanging fruit, mostly by modifying printing routines to print directly to a writer, rather than constructing a string first. I have confirmed that compiling std+cmd with "-gcflags=all=-S -p=1" and CGO_ENABLED=0 yields identical results before/after this change. (-p=1 makes package compilation order deterministic. CGO_ENABLED=0 prevents cgo temp workdirs from showing up in filenames.) Using the -S flag, the compiler performance impact is: name old time/op new time/op delta Template 344ms ± 2% 301ms ± 2% -12.45% (p=0.000 n=22+24) Unicode 136ms ± 3% 121ms ± 3% -11.40% (p=0.000 n=24+25) GoTypes 1.24s ± 5% 1.09s ± 3% -12.58% (p=0.000 n=25+25) Compiler 5.66s ± 4% 5.06s ± 2% -10.56% (p=0.000 n=25+20) SSA 19.9s ± 3% 17.2s ± 4% -13.64% (p=0.000 n=25+25) Flate 212ms ± 2% 188ms ± 2% -11.33% (p=0.000 n=25+24) GoParser 278ms ± 3% 242ms ± 1% -12.84% (p=0.000 n=23+24) Reflect 743ms ± 3% 657ms ± 5% -11.56% (p=0.000 n=24+25) Tar 295ms ± 2% 263ms ± 2% -10.78% (p=0.000 n=25+25) XML 409ms ± 2% 360ms ± 3% -12.03% (p=0.000 n=24+25) [Geo mean] 714ms 629ms -11.92% name old user-time/op new user-time/op delta Template 430ms ± 5% 388ms ± 3% -9.76% (p=0.000 n=21+24) Unicode 202ms ±12% 171ms ± 5% -15.21% (p=0.000 n=25+23) GoTypes 1.58s ± 3% 1.42s ± 3% -9.58% (p=0.000 n=24+24) Compiler 7.42s ± 3% 6.68s ± 8% -9.93% (p=0.000 n=25+25) SSA 26.9s ± 3% 22.9s ± 3% -14.85% (p=0.000 n=25+25) Flate 260ms ± 6% 234ms ± 3% -9.69% (p=0.000 n=23+25) GoParser 354ms ± 1% 296ms ± 3% -16.46% (p=0.000 n=23+25) Reflect 953ms ± 2% 865ms ± 4% -9.14% (p=0.000 n=24+24) Tar 380ms ± 2% 348ms ± 2% -8.28% (p=0.000 n=25+22) XML 530ms ± 3% 451ms ± 3% -15.01% (p=0.000 n=24+23) [Geo mean] 929ms 819ms -11.84% name old alloc/op new alloc/op delta Template 54.1MB ± 0% 44.3MB ± 0% -18.24% (p=0.000 n=24+24) Unicode 33.5MB ± 0% 30.6MB ± 0% -8.57% (p=0.000 n=25+25) GoTypes 189MB ± 0% 152MB ± 0% -19.55% (p=0.000 n=25+23) Compiler 875MB ± 0% 703MB ± 0% -19.70% (p=0.000 n=25+25) SSA 3.19GB ± 0% 2.51GB ± 0% -21.50% (p=0.000 n=25+25) Flate 32.9MB ± 0% 27.3MB ± 0% -17.04% (p=0.000 n=25+25) GoParser 43.9MB ± 0% 35.1MB ± 0% -20.19% (p=0.000 n=25+25) Reflect 117MB ± 0% 96MB ± 0% -18.22% (p=0.000 n=24+23) Tar 48.6MB ± 0% 40.6MB ± 0% -16.39% (p=0.000 n=25+24) XML 65.7MB ± 0% 53.9MB ± 0% -17.93% (p=0.000 n=25+23) [Geo mean] 118MB 97MB -17.80% name old allocs/op new allocs/op delta Template 1.07M ± 0% 0.60M ± 0% -43.90% (p=0.000 n=25+24) Unicode 539k ± 0% 398k ± 0% -26.20% (p=0.000 n=23+25) GoTypes 3.97M ± 0% 2.19M ± 0% -44.90% (p=0.000 n=25+24) Compiler 17.6M ± 0% 9.5M ± 0% -46.39% (p=0.000 n=22+23) SSA 66.1M ± 0% 34.1M ± 0% -48.41% (p=0.000 n=25+22) Flate 629k ± 0% 365k ± 0% -41.95% (p=0.000 n=25+25) GoParser 929k ± 0% 500k ± 0% -46.11% (p=0.000 n=25+25) Reflect 2.49M ± 0% 1.47M ± 0% -41.00% (p=0.000 n=24+25) Tar 919k ± 0% 534k ± 0% -41.94% (p=0.000 n=25+24) XML 1.28M ± 0% 0.71M ± 0% -44.72% (p=0.000 n=25+24) [Geo mean] 2.32M 1.33M -42.82% This change also speeds up cmd/objdump a modest amount, ~4%. Change-Id: I7c7aa2b365688bc44b3ef6e1d03bcf934699cabc Reviewed-on: https://go-review.googlesource.com/c/go/+/216857 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> |
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