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, 21 insertions, 21 deletions

diff --git a/src/cmd/ld/ldelf.c b/src/cmd/ld/ldelf.c
index 27041bc472..4bc830ef32 100644
--- a/src/cmd/ld/ldelf.c
+++ b/src/cmd/ld/ldelf.c
@@ -258,7 +258,7 @@ struct ElfSect
 	uint64	align;
 	uint64	entsize;
 	uchar	*base;
-	Sym	*sym;
+	LSym	*sym;
 };
 
 struct ElfObj
@@ -301,7 +301,7 @@ struct ElfSym
 	uchar	type;
 	uchar	other;
 	uint16	shndx;
-	Sym*	sym;
+	LSym*	sym;
 };
 
 uchar ElfMagic[4] = { 0x7F, 'E', 'L', 'F' };
@@ -312,7 +312,7 @@ static int	readsym(ElfObj*, int i, ElfSym*, int);
 static int	reltype(char*, int, uchar*);
 
 int
-valuecmp(Sym *a, Sym *b)
+valuecmp(LSym *a, LSym *b)
 {
 	if(a->value < b->value)
 		return -1;
@@ -336,15 +336,15 @@ ldelf(Biobuf *f, char *pkg, int64 len, char *pn)
 	ElfSym sym;
 	Endian *e;
 	Reloc *r, *rp;
-	Sym *s;
-	Sym **symbols;
+	LSym *s;
+	LSym **symbols;
 
 	symbols = nil;
 
 	if(debug['v'])
 		Bprint(&bso, "%5.2f ldelf %s\n", cputime(), pn);
 
-	version++;
+	ctxt->version++;
 	base = Boffset(f);
 
 	if(Bread(f, hdrbuf, sizeof hdrbuf) != sizeof hdrbuf)
@@ -529,7 +529,7 @@ ldelf(Biobuf *f, char *pkg, int64 len, char *pn)
 			goto bad;
 		
 		name = smprint("%s(%s)", pkg, sect->name);
-		s = lookup(name, version);
+		s = linklookup(ctxt, name, ctxt->version);
 		free(name);
 		switch((int)sect->flags&(ElfSectFlagAlloc|ElfSectFlagWrite|ElfSectFlagExec)) {
 		default:
@@ -609,14 +609,14 @@ ldelf(Biobuf *f, char *pkg, int64 len, char *pn)
 			} else {
 				// build a TEXT instruction with a unique pc
 				// just to make the rest of the linker happy.
-				p = prg();
+				p = ctxt->arch->prg();
 				p->as = ATEXT;
 				p->from.type = D_EXTERN;
 				p->from.sym = s;
-				p->textflag = 7;
+				ctxt->arch->settextflag(p, 7);
 				p->to.type = D_CONST;
 				p->link = nil;
-				p->pc = pc++;
+				p->pc = ctxt->pc++;
 				s->text = p;
 			}
 		}
@@ -629,16 +629,16 @@ ldelf(Biobuf *f, char *pkg, int64 len, char *pn)
 		if(s == S)
 			continue;
 		if(s->sub)
-			s->sub = listsort(s->sub, valuecmp, offsetof(Sym, sub));
+			s->sub = listsort(s->sub, valuecmp, offsetof(LSym, sub));
 		if(s->type == STEXT) {
-			if(etextp)
-				etextp->next = s;
+			if(ctxt->etextp)
+				ctxt->etextp->next = s;
 			else
-				textp = s;
-			etextp = s;
+				ctxt->textp = s;
+			ctxt->etextp = s;
 			for(s = s->sub; s != S; s = s->sub) {
-				etextp->next = s;
-				etextp = s;
+				ctxt->etextp->next = s;
+				ctxt->etextp = s;
 			}
 		}
 	}
@@ -761,7 +761,7 @@ map(ElfObj *obj, ElfSect *sect)
 static int
 readsym(ElfObj *obj, int i, ElfSym *sym, int needSym)
 {
-	Sym *s;
+	LSym *s;
 
 	if(i >= obj->nsymtab || i < 0) {
 		werrstr("invalid elf symbol index");
@@ -808,7 +808,7 @@ readsym(ElfObj *obj, int i, ElfSym *sym, int needSym)
 		switch(sym->bind) {
 		case ElfSymBindGlobal:
 			if(needSym) {
-				s = lookup(sym->name, 0);
+				s = linklookup(ctxt, sym->name, 0);
 				// for global scoped hidden symbols we should insert it into
 				// symbol hash table, but mark them as hidden.
 				// __i686.get_pc_thunk.bx is allowed to be duplicated, to
@@ -828,13 +828,13 @@ readsym(ElfObj *obj, int i, ElfSym *sym, int needSym)
 					// local names and hidden visiblity global names are unique
 					// and should only reference by its index, not name, so we
 					// don't bother to add them into hash table
-					s = newsym(sym->name, version);
+					s = linknewsym(ctxt, sym->name, ctxt->version);
 					s->type |= SHIDDEN;
 				}
 			break;
 		case ElfSymBindWeak:
 			if(needSym) {
-				s = newsym(sym->name, 0);
+				s = linknewsym(ctxt, sym->name, 0);
 				if(sym->other == 2)
 					s->type |= SHIDDEN;
 			}