Commit 0185ba76 authored by Russ Cox's avatar Russ Cox

[dev.cc] liblink: resolve bss vs other conflict regardless of order found

If the linker finds the same name given a BSS and a non-BSS
symbol, the assumption is that the non-BSS symbol is the
true one, and the BSS symbol is just the best Go can do toward
an "extern" declaration. This has always been the case,
as long as the object files were read in the right order.

The old code worked when the BSS symbol is found before
the non-BSS symbol. This CL adds equivalent logic for when
the non-BSS symbol is found before the BSS symbol.
This comes up when Go must refer to symbols defined in
host object files.

LGTM=r
R=r
CC=austin, golang-codereviews, iant, khr
https://golang.org/cl/171480043
parent 729847cf
...@@ -546,9 +546,10 @@ ldobjfile(Link *ctxt, Biobuf *f, char *pkg, int64 len, char *pn) ...@@ -546,9 +546,10 @@ ldobjfile(Link *ctxt, Biobuf *f, char *pkg, int64 len, char *pn)
static void static void
readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn) readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn)
{ {
int i, j, c, t, v, n, size, dupok; int i, j, c, t, v, n, ndata, nreloc, size, dupok;
static int ndup; static int ndup;
char *name; char *name;
uchar *data;
Reloc *r; Reloc *r;
LSym *s, *dup, *typ; LSym *s, *dup, *typ;
Pcln *pc; Pcln *pc;
...@@ -564,12 +565,24 @@ readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn) ...@@ -564,12 +565,24 @@ readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn)
dupok = rdint(f); dupok = rdint(f);
dupok &= 1; dupok &= 1;
size = rdint(f); size = rdint(f);
typ = rdsym(ctxt, f, pkg);
rddata(f, &data, &ndata);
nreloc = rdint(f);
if(v != 0) if(v != 0)
v = ctxt->version; v = ctxt->version;
s = linklookup(ctxt, name, v); s = linklookup(ctxt, name, v);
dup = nil; dup = nil;
if(s->type != 0 && s->type != SXREF) { if(s->type != 0 && s->type != SXREF) {
if((t == SDATA || t == SBSS || t == SNOPTRBSS) && ndata == 0 && nreloc == 0) {
if(s->size < size)
s->size = size;
if(typ != nil && s->gotype == nil)
s->gotype = typ;
return;
}
if((s->type == SDATA || s->type == SBSS || s->type == SNOPTRBSS) && s->np == 0 && s->nr == 0)
goto overwrite;
if(s->type != SBSS && s->type != SNOPTRBSS && !dupok && !s->dupok) if(s->type != SBSS && s->type != SNOPTRBSS && !dupok && !s->dupok)
sysfatal("duplicate symbol %s (types %d and %d) in %s and %s", s->name, s->type, t, s->file, pn); sysfatal("duplicate symbol %s (types %d and %d) in %s and %s", s->name, s->type, t, s->file, pn);
if(s->np > 0) { if(s->np > 0) {
...@@ -577,28 +590,30 @@ readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn) ...@@ -577,28 +590,30 @@ readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn)
s = linknewsym(ctxt, ".dup", ndup++); // scratch s = linknewsym(ctxt, ".dup", ndup++); // scratch
} }
} }
overwrite:
s->file = pkg; s->file = pkg;
s->dupok = dupok; s->dupok = dupok;
if(t == SXREF) if(t == SXREF)
sysfatal("bad sxref"); sysfatal("bad sxref");
if(t == 0) if(t == 0)
sysfatal("missing type for %s in %s", name, pn); sysfatal("missing type for %s in %s", name, pn);
if(t == SBSS && (s->type == SRODATA || s->type == SNOPTRBSS))
t = s->type;
s->type = t; s->type = t;
if(s->size < size) if(s->size < size)
s->size = size; s->size = size;
typ = rdsym(ctxt, f, pkg);
if(typ != nil) // if bss sym defined multiple times, take type from any one def if(typ != nil) // if bss sym defined multiple times, take type from any one def
s->gotype = typ; s->gotype = typ;
if(dup != nil && typ != nil) if(dup != nil && typ != nil)
dup->gotype = typ; dup->gotype = typ;
rddata(f, &s->p, &s->np); s->p = data;
s->np = ndata;
s->maxp = s->np; s->maxp = s->np;
n = rdint(f); if(nreloc > 0) {
if(n > 0) { s->r = emallocz(nreloc * sizeof s->r[0]);
s->r = emallocz(n * sizeof s->r[0]); s->nr = nreloc;
s->nr = n; s->maxr = nreloc;
s->maxr = n; for(i=0; i<nreloc; i++) {
for(i=0; i<n; i++) {
r = &s->r[i]; r = &s->r[i];
r->off = rdint(f); r->off = rdint(f);
r->siz = rdint(f); r->siz = rdint(f);
......
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