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cmd/compile/ssa: generate less garbage in schedule

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Passes toolstash -cmp.

name       old alloc/op    new alloc/op    delta
Template      58.5MB ± 0%     57.8MB ± 0%  -1.15%        (p=0.000 n=10+10)
Unicode       41.3MB ± 0%     41.2MB ± 0%  -0.17%        (p=0.000 n=10+10)
GoTypes        196MB ± 0%      193MB ± 0%  -1.26%        (p=0.000 n=10+10)
Compiler       863MB ± 0%      850MB ± 0%  -1.49%        (p=0.000 n=10+10)

name       old allocs/op   new allocs/op   delta
Template        522k ± 0%       507k ± 0%  -2.99%        (p=0.000 n=10+10)
Unicode         403k ± 0%       401k ± 0%  -0.42%        (p=0.000 n=10+10)
GoTypes        1.58M ± 0%      1.52M ± 0%  -3.61%        (p=0.000 n=10+10)
Compiler       6.47M ± 0%      6.17M ± 0%  -4.62%        (p=0.000 n=10+10)

Change-Id: Ia7a6242e8d226b41966c344d253814dcce6424a8
Reviewed-on: https://go-review.googlesource.com/21141
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This commit is contained in:
Josh Bleecher Snyder 2016-03-25 07:33:39 -07:00
parent 967b9940b4
commit 41e176fbe0
1 changed files with 25 additions and 22 deletions
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47
src/cmd/compile/internal/ssa/schedule.go
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@ -16,8 +16,8 @@ const (
)
type ValHeap struct {
a []*Value
less func(a, b *Value) bool
a []*Value
score []int8
}
func (h ValHeap) Len() int { return len(h.a) }
@ -36,7 +36,24 @@ func (h *ValHeap) Pop() interface{} {
h.a = old[0 : n-1]
return x
}
func (h ValHeap) Less(i, j int) bool { return h.less(h.a[i], h.a[j]) }
func (h ValHeap) Less(i, j int) bool {
x := h.a[i]
y := h.a[j]
sx := h.score[x.ID]
sy := h.score[y.ID]
if c := sx - sy; c != 0 {
return c > 0 // higher score comes later.
}
if x.Line != y.Line { // Favor in-order line stepping
return x.Line > y.Line
}
if x.Op != OpPhi {
if c := len(x.Args) - len(y.Args); c != 0 {
return c < 0 // smaller args comes later
}
}
return x.ID > y.ID
}
// Schedule the Values in each Block. After this phase returns, the
// order of b.Values matters and is the order in which those values
@ -48,6 +65,9 @@ func schedule(f *Func) {
// by values that have not been scheduled yet.
uses := make([]int32, f.NumValues())
// reusable priority queue
priq := new(ValHeap)
// "priority" for a value
score := make([]int8, f.NumValues())
@ -156,25 +176,8 @@ func schedule(f *Func) {
// To put things into a priority queue
// The values that should come last are least.
priq := &ValHeap{
a: make([]*Value, 0, 8), // TODO allocate once and reuse.
less: func(x, y *Value) bool {
sx := score[x.ID]
sy := score[y.ID]
if c := sx - sy; c != 0 {
return c > 0 // higher score comes later.
}
if x.Line != y.Line { // Favor in-order line stepping
return x.Line > y.Line
}
if x.Op != OpPhi {
if c := len(x.Args) - len(y.Args); c != 0 {
return c < 0 // smaller args comes later
}
}
return x.ID > y.ID
},
}
priq.score = score
priq.a = priq.a[:0]
// Initialize priority queue with schedulable values.
for _, v := range b.Values {