50688fcb6e
When a map is small, it's not worth putting the contents in an array and then looping over the array. Just generate code instead. This makes smaller binaries. It might also be better for cache lines. It also can avoids adding control flow in the middle of the init function, which can be very large. Eliminating this source of extra blocks makes phi insertion easier for temp-heavy init functions. This reduces the time required for compiler to panic while compiling the code in #19751 from 15 minutes to 45 seconds. The cutoff of 25 was chosen fairly unscientifically by looking at the size of cmd/go. Cutoff of 0: 10689604 Cutoff of 5: 10683572 Cutoff of 15: 10682324 Cutoff of 25: 10681700 Cutoff of 50: 10685476 Cutoff of 100: 10689412 There are probably more sophisticated mechanisms available. For example, the smaller the key/value sizes, the better generated code will be vs a table. Nevertheless this is simple and seems like a good start. Updates #19751 name old time/op new time/op delta Template 204ms ± 6% 202ms ± 5% -0.78% (p=0.027 n=47+45) Unicode 84.8ms ± 6% 85.2ms ± 7% ~ (p=0.146 n=46+45) GoTypes 551ms ± 2% 556ms ± 3% +0.76% (p=0.004 n=43+45) SSA 3.93s ± 3% 3.95s ± 4% ~ (p=0.179 n=50+49) Flate 123ms ± 4% 123ms ± 5% ~ (p=0.201 n=47+49) GoParser 145ms ± 3% 145ms ± 4% ~ (p=0.937 n=50+50) Reflect 356ms ± 3% 354ms ± 5% -0.44% (p=0.048 n=46+50) Tar 107ms ± 6% 106ms ± 6% ~ (p=0.188 n=50+49) XML 201ms ± 4% 200ms ± 4% ~ (p=0.085 n=50+49) name old user-ns/op new user-ns/op delta Template 252M ± 9% 250M ± 7% ~ (p=0.206 n=49+47) Unicode 106M ± 7% 106M ± 9% ~ (p=0.331 n=47+46) GoTypes 724M ± 5% 729M ± 5% ~ (p=0.160 n=47+49) SSA 5.64G ± 2% 5.62G ± 4% ~ (p=0.148 n=47+50) Flate 147M ± 6% 147M ± 5% ~ (p=0.466 n=50+49) GoParser 179M ± 5% 179M ± 6% ~ (p=0.584 n=50+49) Reflect 448M ± 6% 441M ± 8% -1.39% (p=0.027 n=50+49) Tar 124M ± 6% 123M ± 5% ~ (p=0.221 n=50+47) XML 244M ± 5% 243M ± 4% ~ (p=0.275 n=49+49) name old alloc/op new alloc/op delta Template 39.9MB ± 0% 39.4MB ± 0% -1.28% (p=0.008 n=5+5) Unicode 29.8MB ± 0% 29.8MB ± 0% ~ (p=0.310 n=5+5) GoTypes 113MB ± 0% 113MB ± 0% ~ (p=0.421 n=5+5) SSA 854MB ± 0% 854MB ± 0% ~ (p=0.151 n=5+5) Flate 25.3MB ± 0% 25.3MB ± 0% ~ (p=1.000 n=5+5) GoParser 31.8MB ± 0% 31.8MB ± 0% ~ (p=0.222 n=5+5) Reflect 78.2MB ± 0% 78.2MB ± 0% ~ (p=1.000 n=5+5) Tar 26.7MB ± 0% 26.7MB ± 0% ~ (p=0.841 n=5+5) XML 42.3MB ± 0% 42.3MB ± 0% -0.15% (p=0.008 n=5+5) name old allocs/op new allocs/op delta Template 390k ± 1% 386k ± 1% -1.05% (p=0.016 n=5+5) Unicode 319k ± 0% 320k ± 0% ~ (p=0.310 n=5+5) GoTypes 1.14M ± 0% 1.14M ± 0% ~ (p=0.421 n=5+5) SSA 7.60M ± 0% 7.59M ± 0% ~ (p=0.310 n=5+5) Flate 234k ± 0% 235k ± 1% ~ (p=1.000 n=5+5) GoParser 315k ± 1% 317k ± 0% ~ (p=0.151 n=5+5) Reflect 978k ± 0% 978k ± 0% ~ (p=0.841 n=5+5) Tar 251k ± 1% 251k ± 1% ~ (p=0.690 n=5+5) XML 394k ± 0% 392k ± 0% ~ (p=0.056 n=5+5) Change-Id: Ic53a18627082abe075a1cbc33330ce015e50850a Reviewed-on: https://go-review.googlesource.com/39354 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Keith Randall <khr@golang.org> |
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