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cmd/gc, runtime: use type information to scan interface values

Browse Source 
R=golang-dev, rsc, dvyukov
CC=golang-dev
https://golang.org/cl/12785045
This commit is contained in:
Carl Shapiro 2013-08-19 10:19:59 -07:00
parent 2f6e9a1e24
commit 21ea5103a4
2 changed files with 43 additions and 12 deletions
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1
src/cmd/gc/pgen.c
View File

@ -257,7 +257,6 @@ walktype1(Type *t, vlong *xoffset, Bvec *bv)
bvset(bv, ((*xoffset / widthptr) * BitsPerPointer) + 1);
if(isnilinter(t))
bvset(bv, ((*xoffset / widthptr) * BitsPerPointer));
bvset(bv, ((*xoffset + widthptr) / widthptr) * BitsPerPointer);
*xoffset += t->width;
break;

54
src/pkg/runtime/mgc0.c
View File

@ -36,6 +36,10 @@ enum {
// Pointer map
BitsPerPointer = 2,
BitsNoPointer = 0,
BitsPointer = 1,
BitsIface = 2,
BitsEface = 3,
};
// Bits in per-word bitmap.
@ -1398,26 +1402,52 @@ struct BitVector
uint32 data[];
};
// Scans an interface data value when the interface type indicates
// that it is a pointer.
static void
scaninterfacedata(uintptr bits, byte *scanp, bool inprologue)
{
Itab *tab;
Type *type;
if(!inprologue) {
if(bits == BitsIface) {
tab = *(Itab**)scanp;
if(tab->type->size <= sizeof(void*) && (tab->type->kind & KindNoPointers))
return;
} else { // bits == BitsEface
type = *(Type**)scanp;
if(type->size <= sizeof(void*) && (type->kind & KindNoPointers))
return;
}
}
addroot((Obj){scanp+PtrSize, PtrSize, 0});
}
// Starting from scanp, scans words corresponding to set bits.
static void
scanbitvector(byte *scanp, BitVector *bv)
scanbitvector(byte *scanp, BitVector *bv, bool inprologue)
{
uint32 *wp;
uint32 w;
uintptr word, bits;
uint32 *wordp;
int32 i, remptrs;
wp = bv->data;
wordp = bv->data;
for(remptrs = bv->n; remptrs > 0; remptrs -= 32) {
w = *wp++;
word = *wordp++;
if(remptrs < 32)
i = remptrs;
else
i = 32;
i /= BitsPerPointer;
for(; i > 0; i--) {
if(w & 3)
addroot((Obj){scanp, PtrSize, 0});
w >>= BitsPerPointer;
bits = word & 3;
if(bits != BitsNoPointer && *(void**)scanp != nil)
if(bits == BitsPointer)
addroot((Obj){scanp, PtrSize, 0});
else
scaninterfacedata(bits, scanp, inprologue);
word >>= BitsPerPointer;
scanp += PtrSize;
}
}
@ -1430,12 +1460,14 @@ addframeroots(Stkframe *frame, void*)
Func *f;
BitVector *args, *locals;
uintptr size;
bool afterprologue;
f = frame->fn;
// Scan local variables if stack frame has been allocated.
// Use pointer information if known.
if(frame->varp > (byte*)frame->sp) {
afterprologue = (frame->varp > (byte*)frame->sp);
if(afterprologue) {
locals = runtime·funcdata(f, FUNCDATA_GCLocals);
if(locals == nil) {
// No locals information, scan everything.
@ -1450,7 +1482,7 @@ addframeroots(Stkframe *frame, void*)
// Locals bitmap information, scan just the
// pointers in locals.
size = (locals->n*PtrSize) / BitsPerPointer;
scanbitvector(frame->varp - size, locals);
scanbitvector(frame->varp - size, locals, false);
}
}
@ -1458,7 +1490,7 @@ addframeroots(Stkframe *frame, void*)
// Use pointer information if known.
args = runtime·funcdata(f, FUNCDATA_GCArgs);
if(args != nil && args->n > 0)
scanbitvector(frame->argp, args);
scanbitvector(frame->argp, args, !afterprologue);
else
addroot((Obj){frame->argp, frame->arglen, 0});
}