[dev.cc] all: merge dev.power64 (7667e41f3ced) into dev.cc

This is to reduce the delta between dev.cc and dev.garbage to just garbage collector changes.

These are the files that had merge conflicts and have been edited by hand:
        malloc.go
        mem_linux.go
        mgc.go
        os1_linux.go
        proc1.go
        panic1.go
        runtime1.go

LGTM=austin
R=austin
CC=golang-codereviews
https://codereview.appspot.com/174180043

2 files changed, 26 insertions, 12 deletions

diff --git a/src/liblink/asm6.c b/src/liblink/asm6.c
index 428eb9442..7971022b5 100644
--- a/src/liblink/asm6.c
+++ b/src/liblink/asm6.c
@@ -1543,9 +1543,8 @@ static vlong	vaddr(Link*, Addr*, Reloc*);
 static int
 isextern(LSym *s)
 {
-	// All the Solaris dynamic imports from libc.so begin with "libc·", which
-	// the compiler rewrites to "libc." by the time liblink gets it.
-	return strncmp(s->name, "libc.", 5) == 0;
+	// All the Solaris dynamic imports from libc.so begin with "libc_".
+	return strncmp(s->name, "libc_", 5) == 0;
 }
 
 // single-instruction no-ops of various lengths.
diff --git a/src/liblink/objfile.c b/src/liblink/objfile.c
index 6d8694953..aa701f459 100644
--- a/src/liblink/objfile.c
+++ b/src/liblink/objfile.c
@@ -551,9 +551,10 @@ ldobjfile(Link *ctxt, Biobuf *f, char *pkg, int64 len, char *pn)
 static void
 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;
 	char *name;
+	uchar *data;
 	Reloc *r;
 	LSym *s, *dup, *typ;
 	Pcln *pc;
@@ -569,12 +570,24 @@ readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn)
 	dupok = rdint(f);
 	dupok &= 1;
 	size = rdint(f);
+	typ = rdsym(ctxt, f, pkg);
+	rddata(f, &data, &ndata);
+	nreloc = rdint(f);
 	
 	if(v != 0)
 		v = ctxt->version;
 	s = linklookup(ctxt, name, v);
 	dup = nil;
 	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)
 			sysfatal("duplicate symbol %s (types %d and %d) in %s and %s", s->name, s->type, t, s->file, pn);
 		if(s->np > 0) {
@@ -582,28 +595,30 @@ readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn)
 			s = linknewsym(ctxt, ".dup", ndup++); // scratch
 		}
 	}
+overwrite:
 	s->file = pkg;
 	s->dupok = dupok;
 	if(t == SXREF)
 		sysfatal("bad sxref");
 	if(t == 0)
 		sysfatal("missing type for %s in %s", name, pn);
+	if(t == SBSS && (s->type == SRODATA || s->type == SNOPTRBSS))
+		t = s->type;
 	s->type = t;
 	if(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
 		s->gotype = typ;
 	if(dup != nil && typ != nil)
 		dup->gotype = typ;
-	rddata(f, &s->p, &s->np);
+	s->p = data;
+	s->np = ndata;
 	s->maxp = s->np;
-	n = rdint(f);
-	if(n > 0) {
-		s->r = emallocz(n * sizeof s->r[0]);
-		s->nr = n;
-		s->maxr = n;
-		for(i=0; i<n; i++) {
+	if(nreloc > 0) {
+		s->r = emallocz(nreloc * sizeof s->r[0]);
+		s->nr = nreloc;
+		s->maxr = nreloc;
+		for(i=0; i<nreloc; i++) {
 			r = &s->r[i];
 			r->off = rdint(f);
 			r->siz = rdint(f);