ld: Fix exported dynamic symbols on Mach-O.

* Avoid confusion between imported and exported symbols.
* Record number of imported and exported symbols correctly.
* Explictly relocate SMACHOSYM section, since it is not in datap.

R=rsc
CC=golang-dev
https://golang.org/cl/3920042

src/cmd/6l/asm.c

@@ -184,7 +184,7 @@ adddynrel(Sym *s, Reloc *r)
 
 	// Handle relocations found in ELF object files.
 	case 256 + R_X86_64_PC32:
-		if(targ->dynimpname)
+		if(targ->dynimpname != nil && !targ->dynexport)
 			diag("unexpected R_X86_64_PC32 relocation for dynamic symbol %s", targ->name);
 		if(targ->type == 0 || targ->type == SXREF)
 			diag("unknown symbol %s in pcrel", targ->name);
@@ -195,7 +195,7 @@ adddynrel(Sym *s, Reloc *r)
 	case 256 + R_X86_64_PLT32:
 		r->type = D_PCREL;
 		r->add += 4;
-		if(targ->dynimpname != nil) {
+		if(targ->dynimpname != nil && !targ->dynexport) {
 			addpltsym(targ);
 			r->sym = lookup(".plt", 0);
 			r->add += targ->plt;
@@ -203,7 +203,7 @@ adddynrel(Sym *s, Reloc *r)
 		return;
 	
 	case 256 + R_X86_64_GOTPCREL:
-		if(targ->dynimpname == nil) {
+		if(targ->dynimpname == nil || targ->dynexport) {
 			// have symbol
 			// turn MOVQ of GOT entry into LEAQ of symbol itself
 			if(r->off < 2 || s->p[r->off-2] != 0x8b) {
@@ -223,7 +223,7 @@ adddynrel(Sym *s, Reloc *r)
 		return;
 	
 	case 256 + R_X86_64_64:
-		if(targ->dynimpname)
+		if(targ->dynimpname != nil && !targ->dynexport)
 			diag("unexpected R_X86_64_64 relocation for dynamic symbol %s", targ->name);
 		r->type = D_ADDR;
 		return;
@@ -234,12 +234,12 @@ adddynrel(Sym *s, Reloc *r)
 	case 512 + MACHO_X86_64_RELOC_BRANCH*2 + 0:
 		// TODO: What is the difference between all these?
 		r->type = D_ADDR;
-		if(targ->dynimpname)
+		if(targ->dynimpname != nil && !targ->dynexport)
 			diag("unexpected reloc for dynamic symbol %s", targ->name);
 		return;
 
 	case 512 + MACHO_X86_64_RELOC_BRANCH*2 + 1:
-		if(targ->dynimpname) {
+		if(targ->dynimpname != nil && !targ->dynexport) {
 			addpltsym(targ);
 			r->sym = lookup(".plt", 0);
 			r->add = targ->plt;
@@ -253,12 +253,12 @@ adddynrel(Sym *s, Reloc *r)
 	case 512 + MACHO_X86_64_RELOC_SIGNED_2*2 + 1:
 	case 512 + MACHO_X86_64_RELOC_SIGNED_4*2 + 1:
 		r->type = D_PCREL;
-		if(targ->dynimpname)
+		if(targ->dynimpname != nil && !targ->dynexport)
 			diag("unexpected pc-relative reloc for dynamic symbol %s", targ->name);
 		return;
 
 	case 512 + MACHO_X86_64_RELOC_GOT_LOAD*2 + 1:
-		if(targ->dynimpname == nil) {
+		if(targ->dynimpname == nil || targ->dynexport) {
 			// have symbol
 			// turn MOVQ of GOT entry into LEAQ of symbol itself
 			if(r->off < 2 || s->p[r->off-2] != 0x8b) {
@@ -271,7 +271,7 @@ adddynrel(Sym *s, Reloc *r)
 		}
 		// fall through
 	case 512 + MACHO_X86_64_RELOC_GOT*2 + 1:
-		if(targ->dynimpname == nil)
+		if(targ->dynimpname == nil || targ->dynexport)
 			diag("unexpected GOT reloc for non-dynamic symbol %s", targ->name);
 		addgotsym(targ);
 		r->type = D_PCREL;
@@ -281,7 +281,7 @@ adddynrel(Sym *s, Reloc *r)
 	}
 	
 	// Handle references to ELF symbols from our own object files.
-	if(targ->dynimpname == nil)
+	if(targ->dynimpname == nil || targ->dynexport)
 		return;
 
 	switch(r->type) {

src/cmd/ld/go.c

@@ -71,7 +71,6 @@ static void loaddynexport(char*, char*, char*, int);
 static int parsemethod(char**, char*, char**);
 static int parsepkgdata(char*, char*, char**, char*, char**, char**, char**);
 
-static int ndynexp;
 static Sym **dynexp;
 
 void

src/cmd/ld/lib.h

@@ -92,6 +92,7 @@ EXTERN	uchar	inuxi8[8];
 EXTERN	char*	outfile;
 EXTERN	int32	nsymbol;
 EXTERN	char*	thestring;
+EXTERN	int	ndynexp;
 
 EXTERN	Segment	segtext;
 EXTERN	Segment	segdata;
@@ -140,6 +141,7 @@ void	codeblk(int32, int32);
 void	datblk(int32, int32);
 Sym*	datsort(Sym*);
 void	reloc(void);
+void	relocsym(Sym*);
 void	savedata(Sym*, Prog*);
 void	symgrow(Sym*, int32);
 vlong	addstring(Sym*, char*);

src/cmd/ld/macho.c

@@ -102,13 +102,6 @@ newMachoDebug(void)
 
 // Generic linking code.
 
-struct	Expsym
-{
-	int	off;
-	Sym*	s;
-} *expsym;
-static int nexpsym;
-
 static char **dylib;
 static int ndylib;
 
@@ -415,9 +408,9 @@ asmbmacho(void)
 		ml->data[0] = 0;	/* ilocalsym */
 		ml->data[1] = 0;	/* nlocalsym */
 		ml->data[2] = 0;	/* iextdefsym */
-		ml->data[3] = 0;	/* nextdefsym */	// TODO nexpsym
-		ml->data[4] = 0;	/* iundefsym */	// TODO nexpsym
-		ml->data[5] = s1->size / (macho64 ? 16 : 12);	/* nundefsym */
+		ml->data[3] = ndynexp;	/* nextdefsym */
+		ml->data[4] = ndynexp;	/* iundefsym */
+		ml->data[5] = (s1->size / (macho64 ? 16 : 12)) - ndynexp;	/* nundefsym */
 		ml->data[6] = 0;	/* tocoffset */
 		ml->data[7] = 0;	/* ntoc */
 		ml->data[8] = 0;	/* modtaboff */
@@ -480,6 +473,7 @@ domacholink(void)
 
 	// write data that will be linkedit section
 	s1 = lookup(".dynsym", 0);
+	relocsym(s1);
 	s2 = lookup(".dynstr", 0);
 	s3 = lookup(".linkedit.plt", 0);
 	s4 = lookup(".linkedit.got", 0);