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cmd/compile: reduce element size of arrays in sparse{map,set}

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sparseSet and sparseMap only need 32 bit integers in their
arrays, since a sparseEntry key is also limited to 32 bits.
This appears to reduce the space allocated for at least
one pathological compilation by 1%, perhaps more.

Not necessarily for 1.7, but it saves a little and is very
low-risk.

Change-Id: Icf1185859e9f5fe1261a206b441e02c34f7d02fd
Reviewed-on: https://go-review.googlesource.com/22972
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
This commit is contained in:
David Chase 2016-05-09 14:59:25 -04:00 • committed by Russ Cox
parent 2380a039c0
commit d35a4158ab
2 changed files with 15 additions and 15 deletions
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18
src/cmd/compile/internal/ssa/sparsemap.go
View file

@ -14,13 +14,13 @@ type sparseEntry struct {
type sparseMap struct {
dense []sparseEntry
sparse []int
sparse []int32
}
// newSparseMap returns a sparseMap that can map
// integers between 0 and n-1 to int32s.
func newSparseMap(n int) *sparseMap {
return &sparseMap{nil, make([]int, n)}
return &sparseMap{dense: nil, sparse: make([]int32, n)}
}
func (s *sparseMap) size() int {
@ -29,14 +29,14 @@ func (s *sparseMap) size() int {
func (s *sparseMap) contains(k ID) bool {
i := s.sparse[k]
return i < len(s.dense) && s.dense[i].key == k
return i < int32(len(s.dense)) && s.dense[i].key == k
}
// get returns the value for key k, or -1 if k does
// not appear in the map.
func (s *sparseMap) get(k ID) int32 {
i := s.sparse[k]
if i < len(s.dense) && s.dense[i].key == k {
if i < int32(len(s.dense)) && s.dense[i].key == k {
return s.dense[i].val
}
return -1
@ -44,12 +44,12 @@ func (s *sparseMap) get(k ID) int32 {
func (s *sparseMap) set(k ID, v int32) {
i := s.sparse[k]
if i < len(s.dense) && s.dense[i].key == k {
if i < int32(len(s.dense)) && s.dense[i].key == k {
s.dense[i].val = v
return
}
s.dense = append(s.dense, sparseEntry{k, v})
s.sparse[k] = len(s.dense) - 1
s.sparse[k] = int32(len(s.dense)) - 1
}
// setBit sets the v'th bit of k's value, where 0 <= v < 32
@ -58,17 +58,17 @@ func (s *sparseMap) setBit(k ID, v uint) {
panic("bit index too large.")
}
i := s.sparse[k]
if i < len(s.dense) && s.dense[i].key == k {
if i < int32(len(s.dense)) && s.dense[i].key == k {
s.dense[i].val |= 1 << v
return
}
s.dense = append(s.dense, sparseEntry{k, 1 << v})
s.sparse[k] = len(s.dense) - 1
s.sparse[k] = int32(len(s.dense)) - 1
}
func (s *sparseMap) remove(k ID) {
i := s.sparse[k]
if i < len(s.dense) && s.dense[i].key == k {
if i < int32(len(s.dense)) && s.dense[i].key == k {
y := s.dense[len(s.dense)-1]
s.dense[i] = y
s.sparse[y.key] = i