diff options
Diffstat (limited to 'src/runtime/malloc2.go')
| -rw-r--r-- | src/runtime/malloc2.go | 41 |
1 files changed, 32 insertions, 9 deletions
diff --git a/src/runtime/malloc2.go b/src/runtime/malloc2.go index c175c2aec..a9d40de30 100644 --- a/src/runtime/malloc2.go +++ b/src/runtime/malloc2.go @@ -139,10 +139,35 @@ const ( ) // A generic linked list of blocks. (Typically the block is bigger than sizeof(MLink).) +// Since assignments to mlink.next will result in a write barrier being preformed +// this can not be used by some of the internal GC structures. For example when +// the sweeper is placing an unmarked object on the free list it does not want the +// write barrier to be called since that could result in the object being reachable. type mlink struct { next *mlink } +// A gclink is a node in a linked list of blocks, like mlink, +// but it is opaque to the garbage collector. +// The GC does not trace the pointers during collection, +// and the compiler does not emit write barriers for assignments +// of gclinkptr values. Code should store references to gclinks +// as gclinkptr, not as *gclink. +type gclink struct { + next gclinkptr +} + +// A gclinkptr is a pointer to a gclink, but it is opaque +// to the garbage collector. +type gclinkptr uintptr + +// ptr returns the *gclink form of p. +// The result should be used for accessing fields, not stored +// in other data structures. +func (p gclinkptr) ptr() *gclink { + return (*gclink)(unsafe.Pointer(p)) +} + // sysAlloc obtains a large chunk of zeroed memory from the // operating system, typically on the order of a hundred kilobytes // or a megabyte. @@ -275,8 +300,8 @@ type mcachelist struct { } type stackfreelist struct { - list *mlink // linked list of free stacks - size uintptr // total size of stacks in list + list gclinkptr // linked list of free stacks + size uintptr // total size of stacks in list } // Per-thread (in Go, per-P) cache for small objects. @@ -299,8 +324,6 @@ type mcache struct { sudogcache *sudog - gcworkbuf unsafe.Pointer - // Local allocator stats, flushed during GC. local_nlookup uintptr // number of pointer lookups local_largefree uintptr // bytes freed for large objects (>maxsmallsize) @@ -348,11 +371,11 @@ const ( ) type mspan struct { - next *mspan // in a span linked list - prev *mspan // in a span linked list - start pageID // starting page number - npages uintptr // number of pages in span - freelist *mlink // list of free objects + next *mspan // in a span linked list + prev *mspan // in a span linked list + start pageID // starting page number + npages uintptr // number of pages in span + freelist gclinkptr // list of free objects // sweep generation: // if sweepgen == h->sweepgen - 2, the span needs sweeping // if sweepgen == h->sweepgen - 1, the span is currently being swept |