runtime: improve precision of GC_REGION

R=rsc
CC=golang-dev
https://golang.org/cl/7383054

diff --git a/src/pkg/runtime/mgc0.c b/src/pkg/runtime/mgc0.c
index e9d5d301b81347aac568ca9fa44722dce2937c27..38ba84df406acb5a5778984349012751ada49a69 100644 (file)
--- a/src/pkg/runtime/mgc0.c
+++ b/src/pkg/runtime/mgc0.c
@@ -546,7 +546,7 @@ static void
 scanblock(Workbuf *wbuf, Obj *wp, uintptr nobj, bool keepworking)
 {
        byte *b, *arena_start, *arena_used;
-       uintptr n, i, end_b, elemsize, ti, objti, count, type;
+       uintptr n, i, end_b, elemsize, size, ti, objti, count, type;
        uintptr *pc, precise_type, nominal_size;
        uintptr *map_ret, mapkey_size, mapval_size, mapkey_ti, mapval_ti;
        void *obj;
@@ -905,9 +905,14 @@ scanblock(Workbuf *wbuf, Obj *wp, uintptr nobj, bool keepworking)
                        continue;
 
                case GC_REGION:
-                       // TODO(atom): to be expanded in a next CL. Same as GC_APTR for now.
                        obj = (void*)(stack_top.b + pc[1]);
+                       size = pc[2];
+                       objti = pc[3];
                        pc += 4;
+
+                       *objbufpos++ = (Obj){obj, size, objti};
+                       if(objbufpos == objbuf_end)
+                               flushobjbuf(objbuf, &objbufpos, &wp, &wbuf, &nobj);
                        break;
 
                case GC_CHAN: