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[dev.garbage] runtime: cleanup and optimize span.base()

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Prior to this CL the base of a span was calculated in various
places using shifts or calls to base(). This CL now
always calls base() which has been optimized to calculate the
base of the span when the span is initialized and store that
value in the span structure.

Change-Id: I661f2bfa21e3748a249cdf049ef9062db6e78100
Reviewed-on: https://go-review.googlesource.com/20703
Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Rick Hudson 2016-03-14 12:02:02 -04:00
parent 8dda1c4c08
commit f8d0d4fd59
6 changed files with 17 additions and 14 deletions
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13
src/runtime/mheap.go
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@ -116,7 +116,8 @@ type mspan struct {
next *mspan // next span in list, or nil if none
prev **mspan // previous span's next field, or list head's first field if none
list *mSpanList // For debugging. TODO: Remove.
//TODO:(rlh) Eliminate start field and use startAddr >> PageShift instead.
startAddr uintptr // uintptr(s.start << _PageShift) aka s.base()
start pageID // starting page number
npages uintptr // number of pages in span
stackfreelist gclinkptr // list of free stacks, avoids overloading freelist
@ -184,7 +185,7 @@ type mspan struct {
}
func (s *mspan) base() uintptr {
return uintptr(s.start << _PageShift)
return s.startAddr
}
func (s *mspan) layout() (size, n, total uintptr) {
@ -300,7 +301,7 @@ func mlookup(v uintptr, base *uintptr, size *uintptr, sp **mspan) int32 {
return 0
}
p := uintptr(s.start) << _PageShift
p := s.base()
if s.sizeclass == 0 {
// Large object.
if base != nil {
@ -542,7 +543,7 @@ func (h *mheap) alloc(npage uintptr, sizeclass int32, large bool, needzero bool)
if s != nil {
if needzero && s.needzero != 0 {
memclr(unsafe.Pointer(s.start<<_PageShift), s.npages<<_PageShift)
memclr(unsafe.Pointer(s.base()), s.npages<<_PageShift)
}
s.needzero = 0
}
@ -610,7 +611,7 @@ HaveSpan:
throw("still in list")
}
if s.npreleased > 0 {
sysUsed(unsafe.Pointer(s.start<<_PageShift), s.npages<<_PageShift)
sysUsed(unsafe.Pointer(s.base()), s.npages<<_PageShift)
memstats.heap_released -= uint64(s.npreleased << _PageShift)
s.npreleased = 0
}
@ -826,6 +827,7 @@ func (h *mheap) freeSpanLocked(s *mspan, acctinuse, acctidle bool, unusedsince i
t := h_spans[p-1]
if t != nil && t.state == _MSpanFree {
s.start = t.start
s.startAddr = uintptr(s.start << _PageShift)
s.npages += t.npages
s.npreleased = t.npreleased // absorb released pages
s.needzero |= t.needzero
@ -925,6 +927,7 @@ func (span *mspan) init(start pageID, npages uintptr) {
span.prev = nil
span.list = nil
span.start = start
span.startAddr = uintptr(start << _PageShift)
span.npages = npages
span.allocCount = 0
span.sizeclass = 0