6l, 8l: emit macho dwarf info before linkedit section

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5272050

src/cmd/6l/asm.c

@@ -703,7 +703,7 @@ asmb(void)
 {
 	int32 magic;
 	int a, dynsym;
-	vlong vl, startva, symo, machlink;
+	vlong vl, startva, symo, dwarfoff, machlink;
 	ElfEhdr *eh;
 	ElfPhdr *ph, *pph;
 	ElfShdr *sh;
@@ -738,8 +738,19 @@ asmb(void)
 	datblk(segdata.vaddr, segdata.filelen);
 
 	machlink = 0;
-	if(HEADTYPE == Hdarwin)
+	if(HEADTYPE == Hdarwin) {
+		if(debug['v'])
+			Bprint(&bso, "%5.2f dwarf\n", cputime());
+
+		dwarfoff = rnd(HEADR+segtext.len, INITRND) + rnd(segdata.filelen, INITRND);
+		cseek(dwarfoff);
+
+		segdwarf.fileoff = cpos();
+		dwarfemitdebugsections();
+		segdwarf.filelen = cpos() - segdwarf.fileoff;
+
 		machlink = domacholink();
+	}
 
 	switch(HEADTYPE) {
 	default:
@@ -811,7 +822,6 @@ asmb(void)
 				dwarfemitdebugsections();
 			}
 			break;
-		case Hdarwin:
 		case Hwindows:
 			if(debug['v'])
 			       Bprint(&bso, "%5.2f dwarf\n", cputime());

src/cmd/8l/asm.c

@@ -660,7 +660,7 @@ asmb(void)
 {
 	int32 v, magic;
 	int a, dynsym;
-	uint32 symo, startva, machlink;
+	uint32 symo, startva, dwarfoff, machlink;
 	ElfEhdr *eh;
 	ElfPhdr *ph, *pph;
 	ElfShdr *sh;
@@ -691,8 +691,19 @@ asmb(void)
 	datblk(segdata.vaddr, segdata.filelen);
 
 	machlink = 0;
-	if(HEADTYPE == Hdarwin)
+	if(HEADTYPE == Hdarwin) {
+		if(debug['v'])
+			Bprint(&bso, "%5.2f dwarf\n", cputime());
+
+		dwarfoff = rnd(HEADR+segtext.len, INITRND) + rnd(segdata.filelen, INITRND);
+		cseek(dwarfoff);
+
+		segdwarf.fileoff = cpos();
+		dwarfemitdebugsections();
+		segdwarf.filelen = cpos() - segdwarf.fileoff;
+
 		machlink = domacholink();
+	}
 
 	if(iself) {
 		/* index of elf text section; needed by asmelfsym, double-checked below */
@@ -772,7 +783,6 @@ asmb(void)
 				cflush();
 			}
 			break;
-		case Hdarwin:
 		case Hwindows:
 			if(debug['v'])
 				Bprint(&bso, "%5.2f dwarf\n", cputime());

src/cmd/ld/lib.h

@@ -129,6 +129,7 @@ EXTERN	int	havedynamic;
 EXTERN	Segment	segtext;
 EXTERN	Segment	segdata;
 EXTERN	Segment	segsym;
+EXTERN	Segment segdwarf;
 
 void	addlib(char *src, char *obj);
 void	addlibpath(char *srcref, char *objref, char *file, char *pkg);

src/cmd/ld/macho.c

@@ -505,7 +505,7 @@ domacholink(void)
 	size = s1->size + s2->size + s3->size + s4->size;
 
 	if(size > 0) {
-		linkoff = rnd(HEADR+segtext.len, INITRND) + rnd(segdata.filelen, INITRND);
+		linkoff = rnd(HEADR+segtext.len, INITRND) + rnd(segdata.filelen, INITRND) + rnd(segdwarf.filelen, INITRND);
 		cseek(linkoff);
 
 		cwrite(s1->p, s1->size);