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, 92 insertions, 92 deletions

diff --git a/src/cmd/ld/elf.c b/src/cmd/ld/elf.c
index 6b3638ec56..8c7ca86097 100644
--- a/src/cmd/ld/elf.c
+++ b/src/cmd/ld/elf.c
@@ -287,35 +287,35 @@ elfhash(uchar *name)
 }
 
 void
-elfwritedynent(Sym *s, int tag, uint64 val)
+elfwritedynent(LSym *s, int tag, uint64 val)
 {
 	if(elf64) {
-		adduint64(s, tag);
-		adduint64(s, val);
+		adduint64(ctxt, s, tag);
+		adduint64(ctxt, s, val);
 	} else {
-		adduint32(s, tag);
-		adduint32(s, val);
+		adduint32(ctxt, s, tag);
+		adduint32(ctxt, s, val);
 	}
 }
 
 void
-elfwritedynentsym(Sym *s, int tag, Sym *t)
+elfwritedynentsym(LSym *s, int tag, LSym *t)
 {
 	if(elf64)
-		adduint64(s, tag);
+		adduint64(ctxt, s, tag);
 	else
-		adduint32(s, tag);
-	addaddr(s, t);
+		adduint32(ctxt, s, tag);
+	addaddr(ctxt, s, t);
 }
 
 void
-elfwritedynentsymsize(Sym *s, int tag, Sym *t)
+elfwritedynentsymsize(LSym *s, int tag, LSym *t)
 {
 	if(elf64)
-		adduint64(s, tag);
+		adduint64(ctxt, s, tag);
 	else
-		adduint32(s, tag);
-	addsize(s, t);
+		adduint32(ctxt, s, tag);
+	addsize(ctxt, s, t);
 }
 
 int
@@ -561,7 +561,7 @@ haveaux:
 void
 elfdynhash(void)
 {
-	Sym *s, *sy, *dynstr;
+	LSym *s, *sy, *dynstr;
 	int i, j, nbucket, b, nfile;
 	uint32 hc, *chain, *buckets;
 	int nsym;
@@ -575,7 +575,7 @@ elfdynhash(void)
 		return;
 
 	nsym = nelfsym;
-	s = lookup(".hash", 0);
+	s = linklookup(ctxt, ".hash", 0);
 	s->type = SELFROSECT;
 	s->reachable = 1;
 
@@ -591,14 +591,14 @@ elfdynhash(void)
 	chain = malloc(nsym * sizeof chain[0]);
 	buckets = malloc(nbucket * sizeof buckets[0]);
 	if(need == nil || chain == nil || buckets == nil) {
-		cursym = nil;
+		ctxt->cursym = nil;
 		diag("out of memory");
 		errorexit();
 	}
 	memset(need, 0, nsym * sizeof need[0]);
 	memset(chain, 0, nsym * sizeof chain[0]);
 	memset(buckets, 0, nbucket * sizeof buckets[0]);
-	for(sy=allsym; sy!=S; sy=sy->allsym) {
+	for(sy=ctxt->allsym; sy!=S; sy=sy->allsym) {
 		if (sy->dynid <= 0)
 			continue;
 
@@ -613,69 +613,69 @@ elfdynhash(void)
 		buckets[b] = sy->dynid;
 	}
 
-	adduint32(s, nbucket);
-	adduint32(s, nsym);
+	adduint32(ctxt, s, nbucket);
+	adduint32(ctxt, s, nsym);
 	for(i = 0; i<nbucket; i++)
-		adduint32(s, buckets[i]);
+		adduint32(ctxt, s, buckets[i]);
 	for(i = 0; i<nsym; i++)
-		adduint32(s, chain[i]);
+		adduint32(ctxt, s, chain[i]);
 
 	free(chain);
 	free(buckets);
 	
 	// version symbols
-	dynstr = lookup(".dynstr", 0);
-	s = lookup(".gnu.version_r", 0);
+	dynstr = linklookup(ctxt, ".dynstr", 0);
+	s = linklookup(ctxt, ".gnu.version_r", 0);
 	i = 2;
 	nfile = 0;
 	for(l=needlib; l; l=l->next) {
 		nfile++;
 		// header
-		adduint16(s, 1);  // table version
+		adduint16(ctxt, s, 1);  // table version
 		j = 0;
 		for(x=l->aux; x; x=x->next)
 			j++;
-		adduint16(s, j);	// aux count
-		adduint32(s, addstring(dynstr, l->file));  // file string offset
-		adduint32(s, 16);  // offset from header to first aux
+		adduint16(ctxt, s, j);	// aux count
+		adduint32(ctxt, s, addstring(dynstr, l->file));  // file string offset
+		adduint32(ctxt, s, 16);  // offset from header to first aux
 		if(l->next)
-			adduint32(s, 16+j*16);  // offset from this header to next
+			adduint32(ctxt, s, 16+j*16);  // offset from this header to next
 		else
-			adduint32(s, 0);
+			adduint32(ctxt, s, 0);
 		
 		for(x=l->aux; x; x=x->next) {
 			x->num = i++;
 			// aux struct
-			adduint32(s, elfhash((uchar*)x->vers));  // hash
-			adduint16(s, 0);  // flags
-			adduint16(s, x->num);  // other - index we refer to this by
-			adduint32(s, addstring(dynstr, x->vers));  // version string offset
+			adduint32(ctxt, s, elfhash((uchar*)x->vers));  // hash
+			adduint16(ctxt, s, 0);  // flags
+			adduint16(ctxt, s, x->num);  // other - index we refer to this by
+			adduint32(ctxt, s, addstring(dynstr, x->vers));  // version string offset
 			if(x->next)
-				adduint32(s, 16);  // offset from this aux to next
+				adduint32(ctxt, s, 16);  // offset from this aux to next
 			else
-				adduint32(s, 0);
+				adduint32(ctxt, s, 0);
 		}
 	}
 
 	// version references
-	s = lookup(".gnu.version", 0);
+	s = linklookup(ctxt, ".gnu.version", 0);
 	for(i=0; i<nsym; i++) {
 		if(i == 0)
-			adduint16(s, 0); // first entry - no symbol
+			adduint16(ctxt, s, 0); // first entry - no symbol
 		else if(need[i] == nil)
-			adduint16(s, 1); // global
+			adduint16(ctxt, s, 1); // global
 		else
-			adduint16(s, need[i]->num);
+			adduint16(ctxt, s, need[i]->num);
 	}
 
 	free(need);
 
-	s = lookup(".dynamic", 0);
+	s = linklookup(ctxt, ".dynamic", 0);
 	elfverneed = nfile;
 	if(elfverneed) {
-		elfwritedynentsym(s, DT_VERNEED, lookup(".gnu.version_r", 0));
+		elfwritedynentsym(s, DT_VERNEED, linklookup(ctxt, ".gnu.version_r", 0));
 		elfwritedynent(s, DT_VERNEEDNUM, nfile);
-		elfwritedynentsym(s, DT_VERSYM, lookup(".gnu.version", 0));
+		elfwritedynentsym(s, DT_VERSYM, linklookup(ctxt, ".gnu.version", 0));
 	}
 	elfwritedynent(s, DT_NULL, 0);
 }
@@ -807,9 +807,9 @@ elfshreloc(Section *sect)
 }
 
 void
-elfrelocsect(Section *sect, Sym *first)
+elfrelocsect(Section *sect, LSym *first)
 {
-	Sym *sym;
+	LSym *sym;
 	int32 eaddr;
 	Reloc *r;
 
@@ -834,7 +834,7 @@ elfrelocsect(Section *sect, Sym *first)
 			continue;
 		if(sym->value >= eaddr)
 			break;
-		cursym = sym;
+		ctxt->cursym = sym;
 		
 		for(r = sym->r; r < sym->r+sym->nr; r++) {
 			if(r->done)
@@ -861,7 +861,7 @@ elfemitreloc(void)
 	while(cpos()&7)
 		cput(0);
 
-	elfrelocsect(segtext.sect, textp);
+	elfrelocsect(segtext.sect, ctxt->textp);
 	for(sect=segtext.sect->next; sect!=nil; sect=sect->next)
 		elfrelocsect(sect, datap);	
 	for(sect=segrodata.sect; sect!=nil; sect=sect->next)
@@ -873,13 +873,13 @@ elfemitreloc(void)
 void
 doelf(void)
 {
-	Sym *s, *shstrtab, *dynstr;
+	LSym *s, *shstrtab, *dynstr;
 
 	if(!iself)
 		return;
 
 	/* predefine strings we need for section headers */
-	shstrtab = lookup(".shstrtab", 0);
+	shstrtab = linklookup(ctxt, ".shstrtab", 0);
 	shstrtab->type = SELFROSECT;
 	shstrtab->reachable = 1;
 
@@ -969,7 +969,7 @@ doelf(void)
 		addstring(shstrtab, ".gnu.version_r");
 
 		/* dynamic symbol table - first entry all zeros */
-		s = lookup(".dynsym", 0);
+		s = linklookup(ctxt, ".dynsym", 0);
 		s->type = SELFROSECT;
 		s->reachable = 1;
 		if(thechar == '6')
@@ -978,7 +978,7 @@ doelf(void)
 			s->size += ELF32SYMSIZE;
 
 		/* dynamic string table */
-		s = lookup(".dynstr", 0);
+		s = linklookup(ctxt, ".dynstr", 0);
 		s->type = SELFROSECT;
 		s->reachable = 1;
 		if(s->size == 0)
@@ -987,85 +987,85 @@ doelf(void)
 
 		/* relocation table */
 		if(thechar == '6')
-			s = lookup(".rela", 0);
+			s = linklookup(ctxt, ".rela", 0);
 		else
-			s = lookup(".rel", 0);
+			s = linklookup(ctxt, ".rel", 0);
 		s->reachable = 1;
 		s->type = SELFROSECT;
 
 		/* global offset table */
-		s = lookup(".got", 0);
+		s = linklookup(ctxt, ".got", 0);
 		s->reachable = 1;
 		s->type = SELFSECT; // writable
 
 		/* hash */
-		s = lookup(".hash", 0);
+		s = linklookup(ctxt, ".hash", 0);
 		s->reachable = 1;
 		s->type = SELFROSECT;
 
-		s = lookup(".got.plt", 0);
+		s = linklookup(ctxt, ".got.plt", 0);
 		s->reachable = 1;
 		s->type = SELFSECT; // writable
 
-		s = lookup(".plt", 0);
+		s = linklookup(ctxt, ".plt", 0);
 		s->reachable = 1;
 		s->type = SELFRXSECT;
 		
 		elfsetupplt();
 		
 		if(thechar == '6')
-			s = lookup(".rela.plt", 0);
+			s = linklookup(ctxt, ".rela.plt", 0);
 		else
-			s = lookup(".rel.plt", 0);
+			s = linklookup(ctxt, ".rel.plt", 0);
 		s->reachable = 1;
 		s->type = SELFROSECT;
 		
-		s = lookup(".gnu.version", 0);
+		s = linklookup(ctxt, ".gnu.version", 0);
 		s->reachable = 1;
 		s->type = SELFROSECT;
 		
-		s = lookup(".gnu.version_r", 0);
+		s = linklookup(ctxt, ".gnu.version_r", 0);
 		s->reachable = 1;
 		s->type = SELFROSECT;
 
 		/* define dynamic elf table */
-		s = lookup(".dynamic", 0);
+		s = linklookup(ctxt, ".dynamic", 0);
 		s->reachable = 1;
 		s->type = SELFSECT; // writable
 
 		/*
 		 * .dynamic table
 		 */
-		elfwritedynentsym(s, DT_HASH, lookup(".hash", 0));
-		elfwritedynentsym(s, DT_SYMTAB, lookup(".dynsym", 0));
+		elfwritedynentsym(s, DT_HASH, linklookup(ctxt, ".hash", 0));
+		elfwritedynentsym(s, DT_SYMTAB, linklookup(ctxt, ".dynsym", 0));
 		if(thechar == '6')
 			elfwritedynent(s, DT_SYMENT, ELF64SYMSIZE);
 		else
 			elfwritedynent(s, DT_SYMENT, ELF32SYMSIZE);
-		elfwritedynentsym(s, DT_STRTAB, lookup(".dynstr", 0));
-		elfwritedynentsymsize(s, DT_STRSZ, lookup(".dynstr", 0));
+		elfwritedynentsym(s, DT_STRTAB, linklookup(ctxt, ".dynstr", 0));
+		elfwritedynentsymsize(s, DT_STRSZ, linklookup(ctxt, ".dynstr", 0));
 		if(thechar == '6') {
-			elfwritedynentsym(s, DT_RELA, lookup(".rela", 0));
-			elfwritedynentsymsize(s, DT_RELASZ, lookup(".rela", 0));
+			elfwritedynentsym(s, DT_RELA, linklookup(ctxt, ".rela", 0));
+			elfwritedynentsymsize(s, DT_RELASZ, linklookup(ctxt, ".rela", 0));
 			elfwritedynent(s, DT_RELAENT, ELF64RELASIZE);
 		} else {
-			elfwritedynentsym(s, DT_REL, lookup(".rel", 0));
-			elfwritedynentsymsize(s, DT_RELSZ, lookup(".rel", 0));
+			elfwritedynentsym(s, DT_REL, linklookup(ctxt, ".rel", 0));
+			elfwritedynentsymsize(s, DT_RELSZ, linklookup(ctxt, ".rel", 0));
 			elfwritedynent(s, DT_RELENT, ELF32RELSIZE);
 		}
 		if(rpath)
 			elfwritedynent(s, DT_RUNPATH, addstring(dynstr, rpath));
 		
-		elfwritedynentsym(s, DT_PLTGOT, lookup(".got.plt", 0));
+		elfwritedynentsym(s, DT_PLTGOT, linklookup(ctxt, ".got.plt", 0));
 
 		if(thechar == '6') {
 			elfwritedynent(s, DT_PLTREL, DT_RELA);
-			elfwritedynentsymsize(s, DT_PLTRELSZ, lookup(".rela.plt", 0));
-			elfwritedynentsym(s, DT_JMPREL, lookup(".rela.plt", 0));
+			elfwritedynentsymsize(s, DT_PLTRELSZ, linklookup(ctxt, ".rela.plt", 0));
+			elfwritedynentsym(s, DT_JMPREL, linklookup(ctxt, ".rela.plt", 0));
 		} else {
 			elfwritedynent(s, DT_PLTREL, DT_REL);
-			elfwritedynentsymsize(s, DT_PLTRELSZ, lookup(".rel.plt", 0));
-			elfwritedynentsym(s, DT_JMPREL, lookup(".rel.plt", 0));
+			elfwritedynentsymsize(s, DT_PLTRELSZ, linklookup(ctxt, ".rel.plt", 0));
+			elfwritedynentsym(s, DT_JMPREL, linklookup(ctxt, ".rel.plt", 0));
 		}
 		
 		elfwritedynent(s, DT_DEBUG, 0);
@@ -1075,7 +1075,7 @@ doelf(void)
 }
 
 void
-shsym(ElfShdr *sh, Sym *s)
+shsym(ElfShdr *sh, LSym *s)
 {
 	vlong addr;
 	addr = symaddr(s);
@@ -1254,13 +1254,13 @@ asmbelf(vlong symo)
 		sh->addralign = PtrSize;
 		sh->link = elfshname(".dynstr")->shnum;
 		// sh->info = index of first non-local symbol (number of local symbols)
-		shsym(sh, lookup(".dynsym", 0));
+		shsym(sh, linklookup(ctxt, ".dynsym", 0));
 
 		sh = elfshname(".dynstr");
 		sh->type = SHT_STRTAB;
 		sh->flags = SHF_ALLOC;
 		sh->addralign = 1;
-		shsym(sh, lookup(".dynstr", 0));
+		shsym(sh, linklookup(ctxt, ".dynstr", 0));
 
 		if(elfverneed) {
 			sh = elfshname(".gnu.version");
@@ -1269,7 +1269,7 @@ asmbelf(vlong symo)
 			sh->addralign = 2;
 			sh->link = elfshname(".dynsym")->shnum;
 			sh->entsize = 2;
-			shsym(sh, lookup(".gnu.version", 0));
+			shsym(sh, linklookup(ctxt, ".gnu.version", 0));
 			
 			sh = elfshname(".gnu.version_r");
 			sh->type = SHT_GNU_VERNEED;
@@ -1277,7 +1277,7 @@ asmbelf(vlong symo)
 			sh->addralign = PtrSize;
 			sh->info = elfverneed;
 			sh->link = elfshname(".dynstr")->shnum;
-			shsym(sh, lookup(".gnu.version_r", 0));
+			shsym(sh, linklookup(ctxt, ".gnu.version_r", 0));
 		}
 
 		switch(eh->machine) {
@@ -1289,7 +1289,7 @@ asmbelf(vlong symo)
 			sh->addralign = PtrSize;
 			sh->link = elfshname(".dynsym")->shnum;
 			sh->info = elfshname(".plt")->shnum;
-			shsym(sh, lookup(".rela.plt", 0));
+			shsym(sh, linklookup(ctxt, ".rela.plt", 0));
 
 			sh = elfshname(".rela");
 			sh->type = SHT_RELA;
@@ -1297,7 +1297,7 @@ asmbelf(vlong symo)
 			sh->entsize = ELF64RELASIZE;
 			sh->addralign = 8;
 			sh->link = elfshname(".dynsym")->shnum;
-			shsym(sh, lookup(".rela", 0));
+			shsym(sh, linklookup(ctxt, ".rela", 0));
 			break;
 		
 		default:
@@ -1306,7 +1306,7 @@ asmbelf(vlong symo)
 			sh->flags = SHF_ALLOC;
 			sh->entsize = ELF32RELSIZE;
 			sh->link = elfshname(".dynsym")->shnum;
-			shsym(sh, lookup(".rel.plt", 0));
+			shsym(sh, linklookup(ctxt, ".rel.plt", 0));
 
 			sh = elfshname(".rel");
 			sh->type = SHT_REL;
@@ -1314,7 +1314,7 @@ asmbelf(vlong symo)
 			sh->entsize = ELF32RELSIZE;
 			sh->addralign = 4;
 			sh->link = elfshname(".dynsym")->shnum;
-			shsym(sh, lookup(".rel", 0));
+			shsym(sh, linklookup(ctxt, ".rel", 0));
 			break;
 		}
 
@@ -1326,21 +1326,21 @@ asmbelf(vlong symo)
 		else
 			sh->entsize = 4;
 		sh->addralign = 4;
-		shsym(sh, lookup(".plt", 0));
+		shsym(sh, linklookup(ctxt, ".plt", 0));
 
 		sh = elfshname(".got");
 		sh->type = SHT_PROGBITS;
 		sh->flags = SHF_ALLOC+SHF_WRITE;
 		sh->entsize = PtrSize;
 		sh->addralign = PtrSize;
-		shsym(sh, lookup(".got", 0));
+		shsym(sh, linklookup(ctxt, ".got", 0));
 
 		sh = elfshname(".got.plt");
 		sh->type = SHT_PROGBITS;
 		sh->flags = SHF_ALLOC+SHF_WRITE;
 		sh->entsize = PtrSize;
 		sh->addralign = PtrSize;
-		shsym(sh, lookup(".got.plt", 0));
+		shsym(sh, linklookup(ctxt, ".got.plt", 0));
 		
 		sh = elfshname(".hash");
 		sh->type = SHT_HASH;
@@ -1348,7 +1348,7 @@ asmbelf(vlong symo)
 		sh->entsize = 4;
 		sh->addralign = PtrSize;
 		sh->link = elfshname(".dynsym")->shnum;
-		shsym(sh, lookup(".hash", 0));
+		shsym(sh, linklookup(ctxt, ".hash", 0));
 
 		/* sh and PT_DYNAMIC for .dynamic section */
 		sh = elfshname(".dynamic");
@@ -1357,7 +1357,7 @@ asmbelf(vlong symo)
 		sh->entsize = 2*PtrSize;
 		sh->addralign = PtrSize;
 		sh->link = elfshname(".dynstr")->shnum;
-		shsym(sh, lookup(".dynamic", 0));
+		shsym(sh, linklookup(ctxt, ".dynamic", 0));
 		ph = newElfPhdr();
 		ph->type = PT_DYNAMIC;
 		ph->flags = PF_R + PF_W;
@@ -1369,11 +1369,11 @@ asmbelf(vlong symo)
 		// Do not emit PT_TLS for OpenBSD since ld.so(1) does
 		// not currently support it. This is handled
 		// appropriately in runtime/cgo.
-		if(tlsoffset != 0 && HEADTYPE != Hopenbsd) {
+		if(ctxt->tlsoffset != 0 && HEADTYPE != Hopenbsd) {
 			ph = newElfPhdr();
 			ph->type = PT_TLS;
 			ph->flags = PF_R;
-			ph->memsz = -tlsoffset;
+			ph->memsz = -ctxt->tlsoffset;
 			ph->align = PtrSize;
 		}
 	}
@@ -1394,7 +1394,7 @@ elfobj:
 	sh = elfshname(".shstrtab");
 	sh->type = SHT_STRTAB;
 	sh->addralign = 1;
-	shsym(sh, lookup(".shstrtab", 0));
+	shsym(sh, linklookup(ctxt, ".shstrtab", 0));
 	eh->shstrndx = sh->shnum;
 
 	// put these sections early in the list
@@ -1430,7 +1430,7 @@ elfobj:
 		sh = elfshname(".tbss");
 		sh->type = SHT_NOBITS;
 		sh->addralign = PtrSize;
-		sh->size = -tlsoffset;
+		sh->size = -ctxt->tlsoffset;
 		sh->flags = SHF_ALLOC | SHF_TLS | SHF_WRITE;
 	}