Commit 3e246238 authored by Austin Clements's avatar Austin Clements

[dev.garbage] runtime: eliminate mspan.start

This converts all remaining uses of mspan.start to instead use
mspan.base(). In many cases, this actually reduces the complexity of
the code.

Change-Id: If113840e00d3345a6cf979637f6a152e6344aee7
Reviewed-on: https://go-review.googlesource.com/22590Reviewed-by: default avatarRick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
parent b7adc41f
...@@ -170,9 +170,6 @@ const ( ...@@ -170,9 +170,6 @@ const (
_MaxGcproc = 32 _MaxGcproc = 32
) )
// Page number (address>>pageShift)
type pageID uintptr
const _MaxArena32 = 2 << 30 const _MaxArena32 = 2 << 30
// OS-defined helpers: // OS-defined helpers:
......
...@@ -392,9 +392,8 @@ func heapBitsForObject(p, refBase, refOff uintptr) (base uintptr, hbits heapBits ...@@ -392,9 +392,8 @@ func heapBitsForObject(p, refBase, refOff uintptr) (base uintptr, hbits heapBits
idx := off >> _PageShift idx := off >> _PageShift
// p points into the heap, but possibly to the middle of an object. // p points into the heap, but possibly to the middle of an object.
// Consult the span table to find the block beginning. // Consult the span table to find the block beginning.
k := p >> _PageShift
s = h_spans[idx] s = h_spans[idx]
if s == nil || pageID(k) < s.start || p >= s.limit || s.state != mSpanInUse { if s == nil || p < s.base() || p >= s.limit || s.state != mSpanInUse {
if s == nil || s.state == _MSpanStack { if s == nil || s.state == _MSpanStack {
// If s is nil, the virtual address has never been part of the heap. // If s is nil, the virtual address has never been part of the heap.
// This pointer may be to some mmap'd region, so we allow it. // This pointer may be to some mmap'd region, so we allow it.
......
...@@ -116,9 +116,8 @@ type mspan struct { ...@@ -116,9 +116,8 @@ type mspan struct {
next *mspan // next span in list, or nil if none 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 prev **mspan // previous span's next field, or list head's first field if none
list *mSpanList // For debugging. TODO: Remove. 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() startAddr uintptr // address of first byte of span aka s.base()
start pageID // starting page number
npages uintptr // number of pages in span npages uintptr // number of pages in span
stackfreelist gclinkptr // list of free stacks, avoids overloading freelist stackfreelist gclinkptr // list of free stacks, avoids overloading freelist
...@@ -262,11 +261,8 @@ func inheap(b uintptr) bool { ...@@ -262,11 +261,8 @@ func inheap(b uintptr) bool {
return false return false
} }
// Not a beginning of a block, consult span table to find the block beginning. // Not a beginning of a block, consult span table to find the block beginning.
k := b >> _PageShift s := h_spans[(b-mheap_.arena_start)>>_PageShift]
x := k if s == nil || b < s.base() || b >= s.limit || s.state != mSpanInUse {
x -= mheap_.arena_start >> _PageShift
s := h_spans[x]
if s == nil || pageID(k) < s.start || b >= s.limit || s.state != mSpanInUse {
return false return false
} }
return true return true
...@@ -634,10 +630,9 @@ HaveSpan: ...@@ -634,10 +630,9 @@ HaveSpan:
if s.npages > npage { if s.npages > npage {
// Trim extra and put it back in the heap. // Trim extra and put it back in the heap.
t := (*mspan)(h.spanalloc.alloc()) t := (*mspan)(h.spanalloc.alloc())
t.init(s.start+pageID(npage), s.npages-npage) t.init(s.base()+npage<<_PageShift, s.npages-npage)
s.npages = npage s.npages = npage
p := uintptr(t.start) p := (t.base() - h.arena_start) >> _PageShift
p -= (h.arena_start >> _PageShift)
if p > 0 { if p > 0 {
h_spans[p-1] = s h_spans[p-1] = s
} }
...@@ -651,8 +646,7 @@ HaveSpan: ...@@ -651,8 +646,7 @@ HaveSpan:
} }
s.unusedsince = 0 s.unusedsince = 0
p := uintptr(s.start) p := (s.base() - h.arena_start) >> _PageShift
p -= (h.arena_start >> _PageShift)
for n := uintptr(0); n < npage; n++ { for n := uintptr(0); n < npage; n++ {
h_spans[p+n] = s h_spans[p+n] = s
} }
...@@ -680,7 +674,7 @@ func bestFit(list *mSpanList, npage uintptr, best *mspan) *mspan { ...@@ -680,7 +674,7 @@ func bestFit(list *mSpanList, npage uintptr, best *mspan) *mspan {
if s.npages < npage { if s.npages < npage {
continue continue
} }
if best == nil || s.npages < best.npages || (s.npages == best.npages && s.start < best.start) { if best == nil || s.npages < best.npages || (s.npages == best.npages && s.base() < best.base()) {
best = s best = s
} }
} }
...@@ -717,9 +711,8 @@ func (h *mheap) grow(npage uintptr) bool { ...@@ -717,9 +711,8 @@ func (h *mheap) grow(npage uintptr) bool {
// Create a fake "in use" span and free it, so that the // Create a fake "in use" span and free it, so that the
// right coalescing happens. // right coalescing happens.
s := (*mspan)(h.spanalloc.alloc()) s := (*mspan)(h.spanalloc.alloc())
s.init(pageID(uintptr(v)>>_PageShift), ask>>_PageShift) s.init(uintptr(v), ask>>_PageShift)
p := uintptr(s.start) p := (s.base() - h.arena_start) >> _PageShift
p -= (h.arena_start >> _PageShift)
for i := p; i < p+s.npages; i++ { for i := p; i < p+s.npages; i++ {
h_spans[i] = s h_spans[i] = s
} }
...@@ -750,11 +743,8 @@ func (h *mheap) lookupMaybe(v unsafe.Pointer) *mspan { ...@@ -750,11 +743,8 @@ func (h *mheap) lookupMaybe(v unsafe.Pointer) *mspan {
if uintptr(v) < h.arena_start || uintptr(v) >= h.arena_used { if uintptr(v) < h.arena_start || uintptr(v) >= h.arena_used {
return nil return nil
} }
p := uintptr(v) >> _PageShift s := h_spans[(uintptr(v)-h.arena_start)>>_PageShift]
q := p if s == nil || uintptr(v) < s.base() || uintptr(v) >= uintptr(unsafe.Pointer(s.limit)) || s.state != _MSpanInUse {
q -= h.arena_start >> _PageShift
s := h_spans[q]
if s == nil || p < uintptr(s.start) || uintptr(v) >= uintptr(unsafe.Pointer(s.limit)) || s.state != _MSpanInUse {
return nil return nil
} }
return s return s
...@@ -836,13 +826,11 @@ func (h *mheap) freeSpanLocked(s *mspan, acctinuse, acctidle bool, unusedsince i ...@@ -836,13 +826,11 @@ func (h *mheap) freeSpanLocked(s *mspan, acctinuse, acctidle bool, unusedsince i
s.npreleased = 0 s.npreleased = 0
// Coalesce with earlier, later spans. // Coalesce with earlier, later spans.
p := uintptr(s.start) p := (s.base() - h.arena_start) >> _PageShift
p -= h.arena_start >> _PageShift
if p > 0 { if p > 0 {
t := h_spans[p-1] t := h_spans[p-1]
if t != nil && t.state == _MSpanFree { if t != nil && t.state == _MSpanFree {
s.start = t.start s.startAddr = t.startAddr
s.startAddr = uintptr(s.start << _PageShift)
s.npages += t.npages s.npages += t.npages
s.npreleased = t.npreleased // absorb released pages s.npreleased = t.npreleased // absorb released pages
s.needzero |= t.needzero s.needzero |= t.needzero
...@@ -947,12 +935,11 @@ func runtime_debug_freeOSMemory() { ...@@ -947,12 +935,11 @@ func runtime_debug_freeOSMemory() {
} }
// Initialize a new span with the given start and npages. // Initialize a new span with the given start and npages.
func (span *mspan) init(start pageID, npages uintptr) { func (span *mspan) init(base uintptr, npages uintptr) {
span.next = nil span.next = nil
span.prev = nil span.prev = nil
span.list = nil span.list = nil
span.start = start span.startAddr = base
span.startAddr = uintptr(start << _PageShift)
span.npages = npages span.npages = npages
span.allocCount = 0 span.allocCount = 0
span.sizeclass = 0 span.sizeclass = 0
......
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