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runtime: try to determine the actual type during garbage collection

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If the scanned block has no typeinfo the garbage collector will attempt
to get the actual type of the block.

R=golang-dev, bradfitz, rsc
CC=golang-dev
https://golang.org/cl/7093045
This commit is contained in:
Jan Ziak 2013-01-18 16:56:17 -05:00 committed by Russ Cox
parent 09cb91eddc
commit 059fed3dfb
1 changed files with 32 additions and 2 deletions
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34
src/pkg/runtime/mgc0.c
View file

@ -410,7 +410,7 @@ 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;
uintptr n, i, end_b, elemsize, ti, objti, count, type;
uintptr *pc, precise_type, nominal_size;
void *obj;
Type *t;
@ -463,7 +463,6 @@ scanblock(Workbuf *wbuf, Obj *wp, uintptr nobj, bool keepworking)
runtime·printf("scanblock %p %D\n", b, (int64)n);
}
// TODO(atom): to be expanded in a next CL
if(ti != 0) {
pc = (uintptr*)(ti & ~(uintptr)PC_BITS);
precise_type = (ti & PRECISE);
@ -476,6 +475,37 @@ scanblock(Workbuf *wbuf, Obj *wp, uintptr nobj, bool keepworking)
} else {
stack_top.count = 1;
}
} else if(UseSpanType) {
type = runtime·gettype(b);
if(type != 0) {
t = (Type*)(type & ~(uintptr)(PtrSize-1));
switch(type & (PtrSize-1)) {
case TypeInfo_SingleObject:
pc = (uintptr*)t->gc;
precise_type = true; // type information about 'b' is precise
stack_top.count = 1;
stack_top.elemsize = pc[0];
break;
case TypeInfo_Array:
pc = (uintptr*)t->gc;
if(pc[0] == 0)
goto next_block;
precise_type = true; // type information about 'b' is precise
stack_top.count = 0; // 0 means an infinite number of iterations
stack_top.elemsize = pc[0];
stack_top.loop_or_ret = pc+1;
break;
case TypeInfo_Map:
// TODO(atom): to be expanded in a next CL
pc = defaultProg;
break;
default:
runtime·throw("scanblock: invalid type");
return;
}
} else {
pc = defaultProg;
}
} else {
pc = defaultProg;
}