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cmd/compile: reuse []Flow

Browse Source 
Benchmarked using compilebench on a quiet
but rather old OS X laptop.

Benchmarks from others would be welcome,
since the numbers look too good to be true.

name      old time/op    new time/op    delta
Template     331ms ± 9%     303ms ± 4%   -8.25%  (p=0.000 n=24+24)
GoTypes      946ms ± 4%     888ms ± 3%   -6.17%  (p=0.000 n=24+25)
Compiler     3.20s ± 1%     3.10s ± 2%   -3.07%  (p=0.000 n=24+25)

name      old alloc/op   new alloc/op   delta
Template    72.5MB ± 0%    61.8MB ± 0%  -14.76%  (p=0.000 n=25+24)
GoTypes      224MB ± 0%     189MB ± 0%  -15.65%  (p=0.000 n=25+25)
Compiler     695MB ± 0%     561MB ± 0%  -19.26%  (p=0.000 n=25+25)

name      old allocs/op  new allocs/op  delta
Template      498k ± 0%      497k ± 0%   -0.21%  (p=0.000 n=25+23)
GoTypes      1.47M ± 0%     1.47M ± 0%   -0.25%  (p=0.000 n=25+25)
Compiler     4.09M ± 0%     4.08M ± 0%   -0.18%  (p=0.000 n=25+23)

Change-Id: I2394bc748128d721863453257fa5756c410f7898
Reviewed-on: https://go-review.googlesource.com/19771
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2015-06-11 13:56:28 -07:00
parent f28bbb776a
commit 028247d2cd
1 changed files with 20 additions and 1 deletions
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21
src/cmd/compile/internal/gc/popt.go
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@ -241,6 +241,19 @@ var flowmark int
// will not have flow graphs and consequently will not be optimized.
const MaxFlowProg = 50000
var ffcache []Flow // reusable []Flow, to reduce allocation
func growffcache(n int) {
if n > cap(ffcache) {
n = (n * 5) / 4
if n > MaxFlowProg {
n = MaxFlowProg
}
ffcache = make([]Flow, n)
}
ffcache = ffcache[:n]
}
func Flowstart(firstp *obj.Prog, newData func() interface{}) *Graph {
// Count and mark instructions to annotate.
nf := 0
@ -268,7 +281,9 @@ func Flowstart(firstp *obj.Prog, newData func() interface{}) *Graph {
// Allocate annotations and assign to instructions.
graph := new(Graph)
ff := make([]Flow, nf)
growffcache(nf)
ff := ffcache
start := &ff[0]
id := 0
var last *Flow
@ -331,6 +346,10 @@ func Flowend(graph *Graph) {
f.Prog.Info.Flags = 0 // drop cached proginfo
f.Prog.Opt = nil
}
clear := ffcache[:graph.Num]
for i := range clear {
clear[i] = Flow{}
}
}
// find looping structure