diff options
| author | Russ Cox <rsc@golang.org> | 2014-10-07 11:06:51 -0400 |
|---|---|---|
| committer | Russ Cox <rsc@golang.org> | 2014-10-07 11:06:51 -0400 |
| commit | 18172c42ff48611df564e5af8bf00515bbac612a (patch) | |
| tree | ef248fd6221698fa640c525d68be3afa0583b31b /src/runtime | |
| parent | f739b7750853f2d620c78eca9fc14c32e48a14d5 (diff) | |
| download | go-18172c42ff48611df564e5af8bf00515bbac612a.tar.xz | |
runtime: remove type-punning for Type.gc[0], gc[1]
Depending on flags&KindGCProg,
gc[0] and gc[1] are either pointers or inlined bitmap bits.
That's not compatible with a precise garbage collector:
it needs to be always pointers or never pointers.
Change the inlined bitmap case to store a pointer to an
out-of-line bitmap in gc[0]. The out-of-line bitmaps are
dedup'ed, so that for example all pointer types share the
same out-of-line bitmap.
Fixes #8864.
LGTM=r
R=golang-codereviews, dvyukov, r
CC=golang-codereviews, iant, khr, rlh
https://golang.org/cl/155820043
Diffstat (limited to 'src/runtime')
| -rw-r--r-- | src/runtime/malloc.go | 2 | ||||
| -rw-r--r-- | src/runtime/type.h | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/src/runtime/malloc.go b/src/runtime/malloc.go index 99d14e3145..9b4264f2b3 100644 --- a/src/runtime/malloc.go +++ b/src/runtime/malloc.go @@ -270,7 +270,7 @@ func mallocgc(size uintptr, typ *_type, flags int) unsafe.Pointer { } ptrmask = (*uint8)(add(unsafe.Pointer(ptrmask), 1)) // skip the unroll flag byte } else { - ptrmask = (*uint8)(unsafe.Pointer(&typ.gc[0])) // embed mask + ptrmask = (*uint8)(unsafe.Pointer(typ.gc[0])) // pointer to unrolled mask } if size == 2*ptrSize { *xbits = *ptrmask | bitBoundary diff --git a/src/runtime/type.h b/src/runtime/type.h index de82e886f2..f5b4f9d13f 100644 --- a/src/runtime/type.h +++ b/src/runtime/type.h @@ -23,7 +23,7 @@ struct Type uint8 kind; void* alg; // gc stores type info required for garbage collector. - // If (kind&KindGCProg)==0, then gc directly contains sparse GC bitmap + // If (kind&KindGCProg)==0, then gc[0] points at sparse GC bitmap // (no indirection), 4 bits per word. // If (kind&KindGCProg)!=0, then gc[1] points to a compiler-generated // read-only GC program; and gc[0] points to BSS space for sparse GC bitmap. |