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gc, ld: tag data as no-pointers and allocate in separate section

Browse Source 
The garbage collector can avoid scanning this section, with
reduces collection time as well as the number of false positives.
Helps a little bit with issue 909, but certainly does not solve it.

R=ken2
CC=golang-dev
https://golang.org/cl/5671099
This commit is contained in:
Russ Cox 2012-02-19 03:19:52 -05:00
parent f7410873ba
commit 4e3f8e915f
12 changed files with 53 additions and 18 deletions
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4
src/cmd/5g/gsubr.c
View File

@ -253,6 +253,10 @@ ggloblnod(Node *nam, int32 width)
p->to.sym = S;
p->to.type = D_CONST;
p->to.offset = width;
if(nam->readonly)
p->from.scale = RODATA;
if(nam->type != T && !haspointers(nam->type))
p->from.scale |= NOPTR;
}
void

3
src/cmd/5l/5.out.h
View File

@ -35,7 +35,8 @@
#define NOPROF (1<<0)
#define DUPOK (1<<1)
#define NOSPLIT (1<<2)
#define ALLTHUMBS (1<<3)
#define RODATA (1<<3)
#define NOPTR (1<<4)
#define REGRET 0
/* -1 disables use of REGARG */

6
src/cmd/5l/obj.c
View File

@ -540,7 +540,7 @@ loop:
s->type = SBSS;
s->value = 0;
}
if(s->type != SBSS && !s->dupok) {
if(s->type != SBSS && s->type != SNOPTRDATA && !s->dupok) {
diag("redefinition: %s\n%P", s->name, p);
s->type = SBSS;
s->value = 0;
@ -549,6 +549,10 @@ loop:
s->size = p->to.offset;
if(p->reg & DUPOK)
s->dupok = 1;
if(p->from.scale & RODATA)
s->type = SRODATA;
else if(p->from.scale & NOPTR)
s->type = SNOPTRDATA;
break;
case ADATA:

2
src/cmd/6g/gsubr.c
View File

@ -231,6 +231,8 @@ ggloblnod(Node *nam, int32 width)
p->to.offset = width;
if(nam->readonly)
p->from.scale = RODATA;
if(nam->type != T && !haspointers(nam->type))
p->from.scale |= NOPTR;
}
void

1
src/cmd/6l/6.out.h
View File

@ -34,6 +34,7 @@
#define DUPOK (1<<1)
#define NOSPLIT (1<<2)
#define RODATA (1<<3)
#define NOPTR (1<<4)
/*
* amd64

4
src/cmd/6l/obj.c
View File

@ -555,7 +555,7 @@ loop:
s->type = SBSS;
s->size = 0;
}
if(s->type != SBSS && !s->dupok) {
if(s->type != SBSS && s->type != SNOPTRDATA && !s->dupok) {
diag("%s: redefinition: %s in %s",
pn, s->name, TNAME);
s->type = SBSS;
@ -567,6 +567,8 @@ loop:
s->dupok = 1;
if(p->from.scale & RODATA)
s->type = SRODATA;
else if(p->from.scale & NOPTR)
s->type = SNOPTRDATA;
goto loop;
case ADATA:

2
src/cmd/8g/gsubr.c
View File

@ -232,6 +232,8 @@ ggloblnod(Node *nam, int32 width)
p->to.offset = width;
if(nam->readonly)
p->from.scale = RODATA;
if(nam->type != T && !haspointers(nam->type))
p->from.scale |= NOPTR;
}
void

1
src/cmd/8l/8.out.h
View File

@ -34,6 +34,7 @@
#define DUPOK (1<<1)
#define NOSPLIT (1<<2)
#define RODATA (1<<3)
#define NOPTR (1<<4)
enum as
{

4
src/cmd/8l/obj.c
View File

@ -563,7 +563,7 @@ loop:
s->type = SBSS;
s->size = 0;
}
if(s->type != SBSS && !s->dupok) {
if(s->type != SBSS && s->type != SNOPTRDATA && !s->dupok) {
diag("%s: redefinition: %s in %s",
pn, s->name, TNAME);
s->type = SBSS;
@ -575,6 +575,8 @@ loop:
s->dupok = 1;
if(p->from.scale & RODATA)
s->type = SRODATA;
else if(p->from.scale & NOPTR)
s->type = SNOPTRDATA;
goto loop;
case ADATA:

41
src/cmd/ld/data.c
View File

@ -615,7 +615,7 @@ addstring(Sym *s, char *str)
int32 r;
if(s->type == 0)
s->type = SDATA;
s->type = SNOPTRDATA;
s->reachable = 1;
r = s->size;
n = strlen(str)+1;
@ -782,7 +782,7 @@ void
dodata(void)
{
int32 t, datsize;
Section *sect;
Section *sect, *noptr;
Sym *s, *last, **l;
if(debug['v'])
@ -887,7 +887,7 @@ dodata(void)
/* writable ELF sections */
datsize = 0;
for(; s != nil && s->type < SDATA; s = s->next) {
for(; s != nil && s->type < SNOPTRDATA; s = s->next) {
sect = addsection(&segdata, s->name, 06);
if(s->align != 0)
datsize = rnd(datsize, s->align);
@ -897,17 +897,26 @@ dodata(void)
datsize += rnd(s->size, PtrSize);
sect->len = datsize - sect->vaddr;
}
/* data */
sect = addsection(&segdata, ".data", 06);
/* pointer-free data, then data */
sect = addsection(&segdata, ".noptrdata", 06);
sect->vaddr = datsize;
for(; s != nil && s->type < SBSS; s = s->next) {
noptr = sect;
for(; ; s = s->next) {
if((s == nil || s->type >= SDATA) && sect == noptr) {
// finish noptrdata, start data
datsize = rnd(datsize, 8);
sect->len = datsize - sect->vaddr;
sect = addsection(&segdata, ".data", 06);
sect->vaddr = datsize;
}
if(s == nil || s->type >= SBSS) {
// finish data
sect->len = datsize - sect->vaddr;
break;
}
s->type = SDATA;
t = s->size;
if(t == 0 && s->name[0] != '.') {
diag("%s: no size", s->name);
t = 1;
}
if(t >= PtrSize)
t = rnd(t, PtrSize);
else if(t > 2)
@ -925,7 +934,6 @@ dodata(void)
s->value = datsize;
datsize += t;
}
sect->len = datsize - sect->vaddr;
/* bss */
sect = addsection(&segdata, ".bss", 06);
@ -996,7 +1004,7 @@ textaddress(void)
void
address(void)
{
Section *s, *text, *data, *rodata, *symtab, *pclntab;
Section *s, *text, *data, *rodata, *symtab, *pclntab, *noptr;
Sym *sym, *sub;
uvlong va;
@ -1022,6 +1030,7 @@ address(void)
if(HEADTYPE == Hplan9x32)
segdata.fileoff = segtext.fileoff + segtext.filelen;
data = nil;
noptr = nil;
for(s=segdata.sect; s != nil; s=s->next) {
s->vaddr = va;
va += s->len;
@ -1029,6 +1038,8 @@ address(void)
segdata.len = va - segdata.vaddr;
if(strcmp(s->name, ".data") == 0)
data = s;
if(strcmp(s->name, ".noptrdata") == 0)
noptr = s;
}
segdata.filelen -= data->next->len; // deduct .bss
@ -1039,7 +1050,7 @@ address(void)
for(sym = datap; sym != nil; sym = sym->next) {
cursym = sym;
if(sym->type < SDATA)
if(sym->type < SNOPTRDATA)
sym->value += rodata->vaddr;
else
sym->value += segdata.sect->vaddr;
@ -1055,6 +1066,8 @@ address(void)
xdefine("esymtab", SRODATA, symtab->vaddr + symtab->len);
xdefine("pclntab", SRODATA, pclntab->vaddr);
xdefine("epclntab", SRODATA, pclntab->vaddr + pclntab->len);
xdefine("noptrdata", SBSS, noptr->vaddr);
xdefine("enoptrdata", SBSS, noptr->vaddr + noptr->len);
xdefine("data", SBSS, data->vaddr);
xdefine("edata", SBSS, data->vaddr + data->len);
xdefine("end", SBSS, segdata.vaddr + segdata.len);

1
src/cmd/ld/lib.h
View File

@ -43,6 +43,7 @@ enum
SPCLNTAB,
SELFROSECT,
SELFSECT,
SNOPTRDATA,
SDATA,
SMACHO, /* Mach-O __nl_symbol_ptr */
SMACHOGOT,

2
src/cmd/ld/symtab.c
View File

@ -330,6 +330,8 @@ symtab(void)
xdefine("etext", STEXT, 0);
xdefine("rodata", SRODATA, 0);
xdefine("erodata", SRODATA, 0);
xdefine("noptrdata", SBSS, 0);
xdefine("enoptrdata", SBSS, 0);
xdefine("data", SBSS, 0);
xdefine("edata", SBSS, 0);
xdefine("end", SBSS, 0);