liblink: create new library based on linker code

There is an enormous amount of code moving around in this CL,
but the code is the same, and it is invoked in the same ways.
This CL is preparation for the new linker structure, not the new
structure itself.

The new library's definition is in include/link.h.

The main change is the use of a Link structure to hold all the
linker-relevant state, replacing the smattering of global variables.
The Link structure should both make it clearer which state must
be carried around and make it possible to parallelize more easily
later.

The main body of the linker has moved into the architecture-independent
cmd/ld directory. That includes the list of known header types, so the
distinction between Hplan9x32 and Hplan9x64 is removed (no other
header type distinguished 32- and 64-bit formats), and code for unused
formats such as ipaq kernels has been deleted.

The code being deleted from 5l, 6l, and 8l reappears in liblink or in ld.
Because multiple files are being merged in the liblink directory,
it is not possible to show the diffs nicely in hg.

The Prog and Addr structures have been unified into an
architecture-independent form and moved to link.h, where they will
be shared by all tools: the assemblers, the compilers, and the linkers.
The unification makes it possible to write architecture-independent
traversal of Prog lists, among other benefits.

The Sym structures cannot be unified: they are too fundamentally
different between the linker and the compilers. Instead, liblink defines
an LSym - a linker Sym - to be used in the Prog and Addr structures,
and the linker now refers exclusively to LSyms. The compilers will
keep using their own syms but will fill out the corresponding LSyms in
the Prog and Addr structures.

Although code from 5l, 6l, and 8l is now in a single library, the
code has been arranged so that only one architecture needs to
be linked into a particular program: 5l will not contain the code
needed for x86 instruction layout, for example.

The object file writing code in liblink/obj.c is from cmd/gc/obj.c.

Preparation for golang.org/s/go13linker work.

This CL does not build by itself. It depends on 35740044
and will be submitted at the same time.

R=iant
CC=golang-dev
https://golang.org/cl/35790044

1 files changed, 100 insertions, 435 deletions

diff --git a/src/cmd/ld/data.c b/src/cmd/ld/data.c
index 30d7c81856..ac28041fbb 100644
--- a/src/cmd/ld/data.c
+++ b/src/cmd/ld/data.c
@@ -38,15 +38,14 @@
 #include	"../../pkg/runtime/mgc0.h"
 
 void	dynreloc(void);
-static vlong addaddrplus4(Sym *s, Sym *t, vlong add);
 
 /*
  * divide-and-conquer list-link
- * sort of Sym* structures.
+ * sort of LSym* structures.
  * Used for the data block.
  */
 int
-datcmp(Sym *s1, Sym *s2)
+datcmp(LSym *s1, LSym *s2)
 {
 	if(s1->type != s2->type)
 		return (int)s1->type - (int)s2->type;
@@ -58,11 +57,11 @@ datcmp(Sym *s1, Sym *s2)
 	return strcmp(s1->name, s2->name);
 }
 
-Sym*
-listsort(Sym *l, int (*cmp)(Sym*, Sym*), int off)
+LSym*
+listsort(LSym *l, int (*cmp)(LSym*, LSym*), int off)
 {
-	Sym *l1, *l2, *le;
-	#define NEXT(l) (*(Sym**)((char*)(l)+off))
+	LSym *l1, *l2, *le;
+	#define NEXT(l) (*(LSym**)((char*)(l)+off))
 
 	if(l == 0 || NEXT(l) == 0)
 		return l;
@@ -128,31 +127,17 @@ listsort(Sym *l, int (*cmp)(Sym*, Sym*), int off)
 	#undef NEXT
 }
 
-Reloc*
-addrel(Sym *s)
-{
-	if(s->nr >= s->maxr) {
-		if(s->maxr == 0)
-			s->maxr = 4;
-		else
-			s->maxr <<= 1;
-		s->r = erealloc(s->r, s->maxr*sizeof s->r[0]);
-		memset(s->r+s->nr, 0, (s->maxr-s->nr)*sizeof s->r[0]);
-	}
-	return &s->r[s->nr++];
-}
-
 void
-relocsym(Sym *s)
+relocsym(LSym *s)
 {
 	Reloc *r;
-	Sym *rs;
+	LSym *rs;
 	Prog p;
 	int32 i, off, siz, fl;
 	vlong o;
 	uchar *cast;
 
-	cursym = s;
+	ctxt->cursym = s;
 	memset(&p, 0, sizeof p);
 	for(r=s->r; r<s->r+s->nr; r++) {
 		r->done = 1;
@@ -218,7 +203,7 @@ relocsym(Sym *s)
 			break;
 		case D_PCREL:
 			// r->sym can be null when CALL $(constant) is transformed from absolute PC to relative PC call.
-			if(linkmode == LinkExternal && r->sym && r->sym->type != SCONST && r->sym->sect != cursym->sect) {
+			if(linkmode == LinkExternal && r->sym && r->sym->type != SCONST && r->sym->sect != ctxt->cursym->sect) {
 				r->done = 0;
 
 				// set up addend for eventual relocation via outer symbol.
@@ -264,7 +249,7 @@ relocsym(Sym *s)
 //print("relocate %s %p %s => %p %p %p %p [%p]\n", s->name, s->value+off, r->sym ? r->sym->name : "<nil>", (void*)symaddr(r->sym), (void*)s->value, (void*)r->off, (void*)r->siz, (void*)o);
 		switch(siz) {
 		default:
-			cursym = s;
+			ctxt->cursym = s;
 			diag("bad reloc size %#ux for %s", siz, r->sym->name);
 		case 4:
 			if(r->type == D_PCREL) {
@@ -291,27 +276,27 @@ relocsym(Sym *s)
 void
 reloc(void)
 {
-	Sym *s;
+	LSym *s;
 
 	if(debug['v'])
 		Bprint(&bso, "%5.2f reloc\n", cputime());
 	Bflush(&bso);
 
-	for(s=textp; s!=S; s=s->next)
+	for(s=ctxt->textp; s!=S; s=s->next)
 		relocsym(s);
 	for(s=datap; s!=S; s=s->next)
 		relocsym(s);
 }
 
 void
-dynrelocsym(Sym *s)
+dynrelocsym(LSym *s)
 {
 	Reloc *r;
 	
 	if(HEADTYPE == Hwindows) {
-		Sym *rel, *targ;
+		LSym *rel, *targ;
 
-		rel = lookup(".rel", 0);
+		rel = linklookup(ctxt, ".rel", 0);
 		if(s == rel)
 			return;
 		for(r=s->r; r<s->r+s->nr; r++) {
@@ -323,17 +308,17 @@ dynrelocsym(Sym *s)
 
 				// jmp *addr
 				if(thechar == '8') {
-					adduint8(rel, 0xff);
-					adduint8(rel, 0x25);
-					addaddr(rel, targ);
-					adduint8(rel, 0x90);
-					adduint8(rel, 0x90);
+					adduint8(ctxt, rel, 0xff);
+					adduint8(ctxt, rel, 0x25);
+					addaddr(ctxt, rel, targ);
+					adduint8(ctxt, rel, 0x90);
+					adduint8(ctxt, rel, 0x90);
 				} else {
-					adduint8(rel, 0xff);
-					adduint8(rel, 0x24);
-					adduint8(rel, 0x25);
-					addaddrplus4(rel, targ, 0);
-					adduint8(rel, 0x90);
+					adduint8(ctxt, rel, 0xff);
+					adduint8(ctxt, rel, 0x24);
+					adduint8(ctxt, rel, 0x25);
+					addaddrplus4(ctxt, rel, targ, 0);
+					adduint8(ctxt, rel, 0x90);
 				}
 			} else if(r->sym->plt >= 0) {
 				r->sym = rel;
@@ -352,7 +337,7 @@ dynrelocsym(Sym *s)
 void
 dynreloc(void)
 {
-	Sym *s;
+	LSym *s;
 
 	// -d suppresses dynamic loader format, so we may as well not
 	// compute these sections or mark their symbols as reachable.
@@ -362,7 +347,7 @@ dynreloc(void)
 		Bprint(&bso, "%5.2f reloc\n", cputime());
 	Bflush(&bso);
 
-	for(s=textp; s!=S; s=s->next)
+	for(s=ctxt->textp; s!=S; s=s->next)
 		dynrelocsym(s);
 	for(s=datap; s!=S; s=s->next)
 		dynrelocsym(s);
@@ -370,118 +355,10 @@ dynreloc(void)
 		elfdynhash();
 }
 
-void
-symgrow(Sym *s, int32 siz)
-{
-	if(s->np >= siz)
-		return;
-
-	if(s->np > s->maxp) {
-		cursym = s;
-		diag("corrupt symbol data: np=%lld > maxp=%lld", (vlong)s->np, (vlong)s->maxp);
-		errorexit();
-	}
-
-	if(s->maxp < siz) {
-		if(s->maxp == 0)
-			s->maxp = 8;
-		while(s->maxp < siz)
-			s->maxp <<= 1;
-		s->p = erealloc(s->p, s->maxp);
-		memset(s->p+s->np, 0, s->maxp-s->np);
-	}
-	s->np = siz;
-}
-
-void
-savedata(Sym *s, Prog *p, char *pn)
-{
-	int32 off, siz, i, fl;
-	uchar *cast;
-	vlong o;
-	Reloc *r;
-
-	off = p->from.offset;
-	siz = p->datasize;
-	if(off < 0 || siz < 0 || off >= 1<<30 || siz >= 100)
-		mangle(pn);
-	symgrow(s, off+siz);
-
-	switch(p->to.type) {
-	default:
-		diag("bad data: %P", p);
-		break;
-
-	case D_FCONST:
-		switch(siz) {
-		default:
-		case 4:
-			fl = ieeedtof(&p->to.ieee);
-			cast = (uchar*)&fl;
-			for(i=0; i<4; i++)
-				s->p[off+i] = cast[fnuxi4[i]];
-			break;
-		case 8:
-			cast = (uchar*)&p->to.ieee;
-			for(i=0; i<8; i++)
-				s->p[off+i] = cast[fnuxi8[i]];
-			break;
-		}
-		break;
-
-	case D_SCONST:
-		for(i=0; i<siz; i++)
-			s->p[off+i] = p->to.scon[i];
-		break;
-
-	case D_CONST:
-		if(p->to.sym)
-			goto Addr;
-		o = p->to.offset;
-		fl = o;
-		cast = (uchar*)&fl;
-		switch(siz) {
-		default:
-			diag("bad nuxi %d\n%P", siz, p);
-			break;
-		case 1:
-			s->p[off] = cast[inuxi1[0]];
-			break;
-		case 2:
-			for(i=0; i<2; i++)
-				s->p[off+i] = cast[inuxi2[i]];
-			break;
-		case 4:
-			for(i=0; i<4; i++)
-				s->p[off+i] = cast[inuxi4[i]];
-			break;
-		case 8:
-			cast = (uchar*)&o;
-			for(i=0; i<8; i++)
-				s->p[off+i] = cast[inuxi8[i]];
-			break;
-		}
-		break;
-
-	case D_ADDR:
-	case D_SIZE:
-	Addr:
-		r = addrel(s);
-		r->off = off;
-		r->siz = siz;
-		r->sym = p->to.sym;
-		r->type = p->to.type;
-		if(r->type != D_SIZE)
-			r->type = D_ADDR;
-		r->add = p->to.offset;
-		break;
-	}
-}
-
 static void
-blk(Sym *start, int32 addr, int32 size)
+blk(LSym *start, int32 addr, int32 size)
 {
-	Sym *sym;
+	LSym *sym;
 	int32 eaddr;
 	uchar *p, *ep;
 
@@ -499,7 +376,7 @@ blk(Sym *start, int32 addr, int32 size)
 			diag("phase error: addr=%#llx but sym=%#llx type=%d", (vlong)addr, (vlong)sym->value, sym->type);
 			errorexit();
 		}
-		cursym = sym;
+		ctxt->cursym = sym;
 		for(; addr < sym->value; addr++)
 			cput(0);
 		p = sym->p;
@@ -523,7 +400,7 @@ blk(Sym *start, int32 addr, int32 size)
 void
 codeblk(int32 addr, int32 size)
 {
-	Sym *sym;
+	LSym *sym;
 	int32 eaddr, n, epc;
 	Prog *p;
 	uchar *q;
@@ -531,13 +408,13 @@ codeblk(int32 addr, int32 size)
 	if(debug['a'])
 		Bprint(&bso, "codeblk [%#x,%#x) at offset %#llx\n", addr, addr+size, cpos());
 
-	blk(textp, addr, size);
+	blk(ctxt->textp, addr, size);
 
 	/* again for printing */
 	if(!debug['a'])
 		return;
 
-	for(sym = textp; sym != nil; sym = sym->next) {
+	for(sym = ctxt->textp; sym != nil; sym = sym->next) {
 		if(!sym->reachable)
 			continue;
 		if(sym->value >= addr)
@@ -600,7 +477,7 @@ codeblk(int32 addr, int32 size)
 void
 datblk(int32 addr, int32 size)
 {
-	Sym *sym;
+	LSym *sym;
 	int32 i, eaddr;
 	uchar *p, *ep;
 	char *typ, *rsname;
@@ -682,28 +559,28 @@ strnput(char *s, int n)
 void
 addstrdata(char *name, char *value)
 {
-	Sym *s, *sp;
+	LSym *s, *sp;
 	char *p;
 
 	p = smprint("%s.str", name);
-	sp = lookup(p, 0);
+	sp = linklookup(ctxt, p, 0);
 	free(p);
 	addstring(sp, value);
 
-	s = lookup(name, 0);
+	s = linklookup(ctxt, name, 0);
 	s->size = 0;
 	s->dupok = 1;
-	addaddr(s, sp);
-	adduint32(s, strlen(value));
+	addaddr(ctxt, s, sp);
+	adduint32(ctxt, s, strlen(value));
 	if(PtrSize == 8)
-		adduint32(s, 0);  // round struct to pointer width
+		adduint32(ctxt, s, 0);  // round struct to pointer width
 
 	// in case reachability has already been computed
 	sp->reachable = s->reachable;
 }
 
 vlong
-addstring(Sym *s, char *str)
+addstring(LSym *s, char *str)
 {
 	int n;
 	int32 r;
@@ -715,230 +592,18 @@ addstring(Sym *s, char *str)
 	n = strlen(str)+1;
 	if(strcmp(s->name, ".shstrtab") == 0)
 		elfsetstring(str, r);
-	symgrow(s, r+n);
+	symgrow(ctxt, s, r+n);
 	memmove(s->p+r, str, n);
 	s->size += n;
 	return r;
 }
 
-vlong
-setuintxx(Sym *s, vlong off, uint64 v, vlong wid)
-{
-	int32 i, fl;
-	vlong o;
-	uchar *cast;
-
-	if(s->type == 0)
-		s->type = SDATA;
-	s->reachable = 1;
-	if(s->size < off+wid) {
-		s->size = off+wid;
-		symgrow(s, s->size);
-	}
-	fl = v;
-	cast = (uchar*)&fl;
-	switch(wid) {
-	case 1:
-		s->p[off] = cast[inuxi1[0]];
-		break;
-	case 2:
-		for(i=0; i<2; i++)
-			s->p[off+i] = cast[inuxi2[i]];
-		break;
-	case 4:
-		for(i=0; i<4; i++)
-			s->p[off+i] = cast[inuxi4[i]];
-		break;
-	case 8:
-		o = v;
-		cast = (uchar*)&o;
-		for(i=0; i<8; i++)
-			s->p[off+i] = cast[inuxi8[i]];
-		break;
-	}
-	return off+wid;
-}
-
-vlong
-adduintxx(Sym *s, uint64 v, int wid)
-{
-	vlong off;
-
-	off = s->size;
-	setuintxx(s, off, v, wid);
-	return off;
-}
-
-vlong
-adduint8(Sym *s, uint8 v)
-{
-	return adduintxx(s, v, 1);
-}
-
-vlong
-adduint16(Sym *s, uint16 v)
-{
-	return adduintxx(s, v, 2);
-}
-
-vlong
-adduint32(Sym *s, uint32 v)
-{
-	return adduintxx(s, v, 4);
-}
-
-vlong
-adduint64(Sym *s, uint64 v)
-{
-	return adduintxx(s, v, 8);
-}
-
-vlong
-setuint8(Sym *s, vlong r, uint8 v)
-{
-	return setuintxx(s, r, v, 1);
-}
-
-vlong
-setuint16(Sym *s, vlong r, uint16 v)
-{
-	return setuintxx(s, r, v, 2);
-}
-
-vlong
-setuint32(Sym *s, vlong r, uint32 v)
-{
-	return setuintxx(s, r, v, 4);
-}
-
-vlong
-setuint64(Sym *s, vlong r, uint64 v)
-{
-	return setuintxx(s, r, v, 8);
-}
-
-vlong
-addaddrplus(Sym *s, Sym *t, vlong add)
-{
-	vlong i;
-	Reloc *r;
-
-	if(s->type == 0)
-		s->type = SDATA;
-	s->reachable = 1;
-	i = s->size;
-	s->size += PtrSize;
-	symgrow(s, s->size);
-	r = addrel(s);
-	r->sym = t;
-	r->off = i;
-	r->siz = PtrSize;
-	r->type = D_ADDR;
-	r->add = add;
-	return i + r->siz;
-}
-
-static vlong
-addaddrplus4(Sym *s, Sym *t, vlong add)
-{
-	vlong i;
-	Reloc *r;
-
-	if(s->type == 0)
-		s->type = SDATA;
-	s->reachable = 1;
-	i = s->size;
-	s->size += 4;
-	symgrow(s, s->size);
-	r = addrel(s);
-	r->sym = t;
-	r->off = i;
-	r->siz = 4;
-	r->type = D_ADDR;
-	r->add = add;
-	return i + r->siz;
-}
-
-vlong
-addpcrelplus(Sym *s, Sym *t, vlong add)
-{
-	vlong i;
-	Reloc *r;
-
-	if(s->type == 0)
-		s->type = SDATA;
-	s->reachable = 1;
-	i = s->size;
-	s->size += 4;
-	symgrow(s, s->size);
-	r = addrel(s);
-	r->sym = t;
-	r->off = i;
-	r->add = add;
-	r->type = D_PCREL;
-	r->siz = 4;
-	return i + r->siz;
-}
-
-vlong
-addaddr(Sym *s, Sym *t)
-{
-	return addaddrplus(s, t, 0);
-}
-
-vlong
-setaddrplus(Sym *s, vlong off, Sym *t, vlong add)
-{
-	Reloc *r;
-
-	if(s->type == 0)
-		s->type = SDATA;
-	s->reachable = 1;
-	if(off+PtrSize > s->size) {
-		s->size = off + PtrSize;
-		symgrow(s, s->size);
-	}
-	r = addrel(s);
-	r->sym = t;
-	r->off = off;
-	r->siz = PtrSize;
-	r->type = D_ADDR;
-	r->add = add;
-	return off + r->siz;
-}
-
-vlong
-setaddr(Sym *s, vlong off, Sym *t)
-{
-	return setaddrplus(s, off, t, 0);
-}
-
-vlong
-addsize(Sym *s, Sym *t)
-{
-	vlong i;
-	Reloc *r;
-
-	if(s->type == 0)
-		s->type = SDATA;
-	s->reachable = 1;
-	i = s->size;
-	s->size += PtrSize;
-	symgrow(s, s->size);
-	r = addrel(s);
-	r->sym = t;
-	r->off = i;
-	r->siz = PtrSize;
-	r->type = D_SIZE;
-	return i + r->siz;
-}
-
 void
 dosymtype(void)
 {
-	Sym *s;
+	LSym *s;
 
-	for(s = allsym; s != nil; s = s->allsym) {
+	for(s = ctxt->allsym; s != nil; s = s->allsym) {
 		if(s->np > 0) {
 			if(s->type == SBSS)
 				s->type = SDATA;
@@ -949,7 +614,7 @@ dosymtype(void)
 }
 
 static int32
-symalign(Sym *s)
+symalign(LSym *s)
 {
 	int32 align;
 
@@ -965,7 +630,7 @@ symalign(Sym *s)
 }
 	
 static vlong
-aligndatsize(vlong datsize, Sym *s)
+aligndatsize(vlong datsize, LSym *s)
 {
 	return rnd(datsize, symalign(s));
 }
@@ -973,7 +638,7 @@ aligndatsize(vlong datsize, Sym *s)
 // maxalign returns the maximum required alignment for
 // the list of symbols s; the list stops when s->type exceeds type.
 static int32
-maxalign(Sym *s, int type)
+maxalign(LSym *s, int type)
 {
 	int32 align, max;
 	
@@ -987,10 +652,10 @@ maxalign(Sym *s, int type)
 }
 
 static void
-gcaddsym(Sym *gc, Sym *s, vlong off)
+gcaddsym(LSym *gc, LSym *s, vlong off)
 {
 	vlong a;
-	Sym *gotype;
+	LSym *gotype;
 
 	if(s->size < PtrSize)
 		return;
@@ -1000,22 +665,22 @@ gcaddsym(Sym *gc, Sym *s, vlong off)
 	gotype = s->gotype;
 	if(gotype != nil) {
 		//print("gcaddsym:    %s    %d    %s\n", s->name, s->size, gotype->name);
-		adduintxx(gc, GC_CALL, PtrSize);
-		adduintxx(gc, off, PtrSize);
-		addpcrelplus(gc, decodetype_gc(gotype), 3*PtrSize+4);
+		adduintxx(ctxt, gc, GC_CALL, PtrSize);
+		adduintxx(ctxt, gc, off, PtrSize);
+		addpcrelplus(ctxt, gc, decodetype_gc(gotype), 3*PtrSize+4);
 		if(PtrSize == 8)
-			adduintxx(gc, 0, 4);
+			adduintxx(ctxt, gc, 0, 4);
 	} else {
 		//print("gcaddsym:    %s    %d    <unknown type>\n", s->name, s->size);
 		for(a = -off&(PtrSize-1); a+PtrSize<=s->size; a+=PtrSize) {
-			adduintxx(gc, GC_APTR, PtrSize);
-			adduintxx(gc, off+a, PtrSize);
+			adduintxx(ctxt, gc, GC_APTR, PtrSize);
+			adduintxx(ctxt, gc, off+a, PtrSize);
 		}
 	}
 }
 
 void
-growdatsize(vlong *datsizep, Sym *s)
+growdatsize(vlong *datsizep, LSym *s)
 {
 	vlong datsize;
 	
@@ -1034,24 +699,24 @@ dodata(void)
 	vlong datsize;
 	Section *sect;
 	Segment *segro;
-	Sym *s, *last, **l;
-	Sym *gcdata1, *gcbss1;
+	LSym *s, *last, **l;
+	LSym *gcdata1, *gcbss1;
 
 	if(debug['v'])
 		Bprint(&bso, "%5.2f dodata\n", cputime());
 	Bflush(&bso);
 
-	gcdata1 = lookup("gcdata", 0);
-	gcbss1 = lookup("gcbss", 0);
+	gcdata1 = linklookup(ctxt, "gcdata", 0);
+	gcbss1 = linklookup(ctxt, "gcbss", 0);
 
 	// size of .data and .bss section. the zero value is later replaced by the actual size of the section.
-	adduintxx(gcdata1, 0, PtrSize);
-	adduintxx(gcbss1, 0, PtrSize);
+	adduintxx(ctxt, gcdata1, 0, PtrSize);
+	adduintxx(ctxt, gcbss1, 0, PtrSize);
 
 	last = nil;
 	datap = nil;
 
-	for(s=allsym; s!=S; s=s->allsym) {
+	for(s=ctxt->allsym; s!=S; s=s->allsym) {
 		if(!s->reachable || s->special)
 			continue;
 		if(STEXT < s->type && s->type < SXREF) {
@@ -1092,7 +757,7 @@ dodata(void)
 	}
 	*l = nil;
 
-	datap = listsort(datap, datcmp, offsetof(Sym, next));
+	datap = listsort(datap, datcmp, offsetof(LSym, next));
 
 	/*
 	 * allocate sections.  list is sorted by type,
@@ -1128,8 +793,8 @@ dodata(void)
 	sect->align = maxalign(s, SINITARR-1);
 	datsize = rnd(datsize, sect->align);
 	sect->vaddr = datsize;
-	lookup("noptrdata", 0)->sect = sect;
-	lookup("enoptrdata", 0)->sect = sect;
+	linklookup(ctxt, "noptrdata", 0)->sect = sect;
+	linklookup(ctxt, "enoptrdata", 0)->sect = sect;
 	for(; s != nil && s->type < SINITARR; s = s->next) {
 		datsize = aligndatsize(datsize, s);
 		s->sect = sect;
@@ -1159,11 +824,11 @@ dodata(void)
 	sect->align = maxalign(s, SBSS-1);
 	datsize = rnd(datsize, sect->align);
 	sect->vaddr = datsize;
-	lookup("data", 0)->sect = sect;
-	lookup("edata", 0)->sect = sect;
+	linklookup(ctxt, "data", 0)->sect = sect;
+	linklookup(ctxt, "edata", 0)->sect = sect;
 	for(; s != nil && s->type < SBSS; s = s->next) {
 		if(s->type == SINITARR) {
-			cursym = s;
+			ctxt->cursym = s;
 			diag("unexpected symbol type %d", s->type);
 		}
 		s->sect = sect;
@@ -1175,16 +840,16 @@ dodata(void)
 	}
 	sect->len = datsize - sect->vaddr;
 
-	adduintxx(gcdata1, GC_END, PtrSize);
-	setuintxx(gcdata1, 0, sect->len, PtrSize);
+	adduintxx(ctxt, gcdata1, GC_END, PtrSize);
+	setuintxx(ctxt, gcdata1, 0, sect->len, PtrSize);
 
 	/* bss */
 	sect = addsection(&segdata, ".bss", 06);
 	sect->align = maxalign(s, SNOPTRBSS-1);
 	datsize = rnd(datsize, sect->align);
 	sect->vaddr = datsize;
-	lookup("bss", 0)->sect = sect;
-	lookup("ebss", 0)->sect = sect;
+	linklookup(ctxt, "bss", 0)->sect = sect;
+	linklookup(ctxt, "ebss", 0)->sect = sect;
 	for(; s != nil && s->type < SNOPTRBSS; s = s->next) {
 		s->sect = sect;
 		datsize = aligndatsize(datsize, s);
@@ -1194,16 +859,16 @@ dodata(void)
 	}
 	sect->len = datsize - sect->vaddr;
 
-	adduintxx(gcbss1, GC_END, PtrSize);
-	setuintxx(gcbss1, 0, sect->len, PtrSize);
+	adduintxx(ctxt, gcbss1, GC_END, PtrSize);
+	setuintxx(ctxt, gcbss1, 0, sect->len, PtrSize);
 
 	/* pointer-free bss */
 	sect = addsection(&segdata, ".noptrbss", 06);
 	sect->align = maxalign(s, SNOPTRBSS);
 	datsize = rnd(datsize, sect->align);
 	sect->vaddr = datsize;
-	lookup("noptrbss", 0)->sect = sect;
-	lookup("enoptrbss", 0)->sect = sect;
+	linklookup(ctxt, "noptrbss", 0)->sect = sect;
+	linklookup(ctxt, "enoptrbss", 0)->sect = sect;
 	for(; s != nil && s->type == SNOPTRBSS; s = s->next) {
 		datsize = aligndatsize(datsize, s);
 		s->sect = sect;
@@ -1211,7 +876,7 @@ dodata(void)
 		growdatsize(&datsize, s);
 	}
 	sect->len = datsize - sect->vaddr;
-	lookup("end", 0)->sect = sect;
+	linklookup(ctxt, "end", 0)->sect = sect;
 
 	// 6g uses 4-byte relocation offsets, so the entire segment must fit in 32 bits.
 	if(datsize != (uint32)datsize) {
@@ -1233,7 +898,7 @@ dodata(void)
 	}
 	
 	if(s != nil) {
-		cursym = nil;
+		ctxt->cursym = nil;
 		diag("unexpected symbol type %d for %s", s->type, s->name);
 	}
 
@@ -1274,8 +939,8 @@ dodata(void)
 	sect->align = maxalign(s, STYPELINK-1);
 	datsize = rnd(datsize, sect->align);
 	sect->vaddr = 0;
-	lookup("rodata", 0)->sect = sect;
-	lookup("erodata", 0)->sect = sect;
+	linklookup(ctxt, "rodata", 0)->sect = sect;
+	linklookup(ctxt, "erodata", 0)->sect = sect;
 	for(; s != nil && s->type < STYPELINK; s = s->next) {
 		datsize = aligndatsize(datsize, s);
 		s->sect = sect;
@@ -1290,8 +955,8 @@ dodata(void)
 	sect->align = maxalign(s, STYPELINK);
 	datsize = rnd(datsize, sect->align);
 	sect->vaddr = datsize;
-	lookup("typelink", 0)->sect = sect;
-	lookup("etypelink", 0)->sect = sect;
+	linklookup(ctxt, "typelink", 0)->sect = sect;
+	linklookup(ctxt, "etypelink", 0)->sect = sect;
 	for(; s != nil && s->type == STYPELINK; s = s->next) {
 		datsize = aligndatsize(datsize, s);
 		s->sect = sect;
@@ -1306,8 +971,8 @@ dodata(void)
 	sect->align = maxalign(s, SPCLNTAB-1);
 	datsize = rnd(datsize, sect->align);
 	sect->vaddr = datsize;
-	lookup("symtab", 0)->sect = sect;
-	lookup("esymtab", 0)->sect = sect;
+	linklookup(ctxt, "symtab", 0)->sect = sect;
+	linklookup(ctxt, "esymtab", 0)->sect = sect;
 	for(; s != nil && s->type < SPCLNTAB; s = s->next) {
 		datsize = aligndatsize(datsize, s);
 		s->sect = sect;
@@ -1322,8 +987,8 @@ dodata(void)
 	sect->align = maxalign(s, SELFROSECT-1);
 	datsize = rnd(datsize, sect->align);
 	sect->vaddr = datsize;
-	lookup("pclntab", 0)->sect = sect;
-	lookup("epclntab", 0)->sect = sect;
+	linklookup(ctxt, "pclntab", 0)->sect = sect;
+	linklookup(ctxt, "epclntab", 0)->sect = sect;
 	for(; s != nil && s->type < SELFROSECT; s = s->next) {
 		datsize = aligndatsize(datsize, s);
 		s->sect = sect;
@@ -1368,7 +1033,7 @@ textaddress(void)
 	uvlong va;
 	Prog *p;
 	Section *sect;
-	Sym *sym, *sub;
+	LSym *sym, *sub;
 
 	addsection(&segtext, ".text", 05);
 
@@ -1377,11 +1042,11 @@ textaddress(void)
 	// and then letting threads copy down, but probably not worth it.
 	sect = segtext.sect;
 	sect->align = FuncAlign;
-	lookup("text", 0)->sect = sect;
-	lookup("etext", 0)->sect = sect;
+	linklookup(ctxt, "text", 0)->sect = sect;
+	linklookup(ctxt, "etext", 0)->sect = sect;
 	va = INITTEXT;
 	sect->vaddr = va;
-	for(sym = textp; sym != nil; sym = sym->next) {
+	for(sym = ctxt->textp; sym != nil; sym = sym->next) {
 		sym->sect = sect;
 		if(sym->type & SSUB)
 			continue;
@@ -1396,7 +1061,7 @@ textaddress(void)
 				p->pc += sub->value;
 		}
 		if(sym->size == 0 && sym->sub != S) {
-			cursym = sym;
+			ctxt->cursym = sym;
 		}
 		va += sym->size;
 	}
@@ -1409,7 +1074,7 @@ address(void)
 {
 	Section *s, *text, *data, *rodata, *symtab, *pclntab, *noptr, *bss, *noptrbss;
 	Section *typelink;
-	Sym *sym, *sub;
+	LSym *sym, *sub;
 	uvlong va;
 	vlong vlen;
 
@@ -1451,7 +1116,7 @@ address(void)
 	segdata.filelen = 0;
 	if(HEADTYPE == Hwindows)
 		segdata.fileoff = segtext.fileoff + rnd(segtext.len, PEFILEALIGN);
-	if(HEADTYPE == Hplan9x64 || HEADTYPE == Hplan9x32)
+	if(HEADTYPE == Hplan9)
 		segdata.fileoff = segtext.fileoff + segtext.filelen;
 	data = nil;
 	noptr = nil;
@@ -1485,7 +1150,7 @@ address(void)
 	pclntab = symtab->next;
 
 	for(sym = datap; sym != nil; sym = sym->next) {
-		cursym = sym;
+		ctxt->cursym = sym;
 		sym->value += sym->sect->vaddr;
 		for(sub = sym->sub; sub != nil; sub = sub->sub)
 			sub->value += sym->value;
@@ -1498,13 +1163,13 @@ address(void)
 	xdefine("typelink", SRODATA, typelink->vaddr);
 	xdefine("etypelink", SRODATA, typelink->vaddr + typelink->len);
 
-	sym = lookup("gcdata", 0);
+	sym = linklookup(ctxt, "gcdata", 0);
 	xdefine("egcdata", SRODATA, symaddr(sym) + sym->size);
-	lookup("egcdata", 0)->sect = sym->sect;
+	linklookup(ctxt, "egcdata", 0)->sect = sym->sect;
 
-	sym = lookup("gcbss", 0);
+	sym = linklookup(ctxt, "gcbss", 0);
 	xdefine("egcbss", SRODATA, symaddr(sym) + sym->size);
-	lookup("egcbss", 0)->sect = sym->sect;
+	linklookup(ctxt, "egcbss", 0)->sect = sym->sect;
 
 	xdefine("symtab", SRODATA, symtab->vaddr);
 	xdefine("esymtab", SRODATA, symtab->vaddr + symtab->len);