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[dev.garbage] runtime: document sysAlloc

In particular, it always returns an aligned pointer.

Change-Id: I763789a539a4bfd8b0efb36a39a80be1a479d3e2
Reviewed-on: https://go-review.googlesource.com/22558
Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Austin Clements 2016-04-28 11:19:53 -04:00
parent 15744c92de
commit 2e8b74b695

View File

@ -387,6 +387,10 @@ func sysReserveHigh(n uintptr, reserved *bool) unsafe.Pointer {
return sysReserve(nil, n, reserved)
}
// sysAlloc allocates the next n bytes from the heap arena. The
// returned pointer is always _PageSize aligned and between
// h.arena_start and h.arena_end. sysAlloc returns nil on failure.
// There is no corresponding free function.
func (h *mheap) sysAlloc(n uintptr) unsafe.Pointer {
if n > h.arena_end-h.arena_used {
// We are in 32-bit mode, maybe we didn't use all possible address space yet.