Commit 08a3a7c0 authored by Ian Lance Taylor's avatar Ian Lance Taylor

cmd/compile: update maxPtrmaskBytes comment for larger value

The comment for maxPtrmaskBytes implied that the value was still 16,
but that changed in CL 10815.

Change-Id: I86e304bc7d9d1a0a6b22b600fefcc1325e4372d9
Reviewed-on: https://go-review.googlesource.com/36120Reviewed-by: default avatarDavid Crawshaw <crawshaw@golang.org>
Reviewed-by: default avatarAustin Clements <austin@google.com>
parent 4aa7b142
......@@ -1572,14 +1572,13 @@ func dalgsym(t *Type) *Sym {
// maxPtrmaskBytes is the maximum length of a GC ptrmask bitmap,
// which holds 1-bit entries describing where pointers are in a given type.
// 16 bytes is enough to describe 128 pointer-sized words, 512 or 1024 bytes
// depending on the system. Above this length, the GC information is
// recorded as a GC program, which can express repetition compactly.
// In either form, the information is used by the runtime to initialize the
// heap bitmap, and for large types (like 128 or more words), they are
// roughly the same speed. GC programs are never much larger and often
// more compact. (If large arrays are involved, they can be arbitrarily more
// compact.)
// Above this length, the GC information is recorded as a GC program,
// which can express repetition compactly. In either form, the
// information is used by the runtime to initialize the heap bitmap,
// and for large types (like 128 or more words), they are roughly the
// same speed. GC programs are never much larger and often more
// compact. (If large arrays are involved, they can be arbitrarily
// more compact.)
//
// The cutoff must be large enough that any allocation large enough to
// use a GC program is large enough that it does not share heap bitmap
......
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