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, 6 insertions, 664 deletions

diff --git a/src/cmd/6l/obj.c b/src/cmd/6l/obj.c
index ae649a74b6..ac3273f939 100644
--- a/src/cmd/6l/obj.c
+++ b/src/cmd/6l/obj.c
@@ -30,7 +30,6 @@
 
 // Reading object files.
 
-#define	EXTERN
 #include	"l.h"
 #include	"../ld/lib.h"
 #include	"../ld/elf.h"
@@ -39,104 +38,12 @@
 #include	"../ld/pe.h"
 #include	<ar.h>
 
-char	*noname		= "<none>";
 char*	thestring 	= "amd64";
-char*	paramspace	= "FP";
-
-Header headers[] = {
-	"plan9x32", Hplan9x32,
-	"plan9", Hplan9x64,
-	"elf", Helf,
-	"darwin", Hdarwin,
-	"dragonfly", Hdragonfly,
-	"linux", Hlinux,
-	"freebsd", Hfreebsd,
-	"netbsd", Hnetbsd,
-	"openbsd", Hopenbsd,
-	"windows", Hwindows,
-	"windowsgui", Hwindows,
-	0, 0
-};
-
-/*
- *	-Hplan9x32 -T4128 -R4096	is plan9 32-bit format
- *	-Hplan9 -T0x200028 -R0x200000	is plan9 64-bit format
- *	-Helf -T0x80110000 -R4096	is ELF32
- *	-Hdarwin -Tx -Rx		is apple MH-exec
- *	-Hdragonfly -Tx -Rx		is DragonFly elf-exec
- *	-Hlinux -Tx -Rx			is linux elf-exec
- *	-Hfreebsd -Tx -Rx		is FreeBSD elf-exec
- *	-Hnetbsd -Tx -Rx		is NetBSD elf-exec
- *	-Hopenbsd -Tx -Rx		is OpenBSD elf-exec
- *	-Hwindows -Tx -Rx		is MS Windows PE32+
- */
+LinkArch*	thelinkarch = &linkamd64;
 
 void
-main(int argc, char *argv[])
+archinit(void)
 {
-	Binit(&bso, 1, OWRITE);
-	listinit();
-	memset(debug, 0, sizeof(debug));
-	nerrors = 0;
-	outfile = nil;
-	HEADTYPE = -1;
-	INITTEXT = -1;
-	INITDAT = -1;
-	INITRND = -1;
-	INITENTRY = 0;
-	linkmode = LinkAuto;
-	nuxiinit();
-
-	flagcount("1", "use alternate profiling code", &debug['1']);
-	flagcount("8", "assume 64-bit addresses", &debug['8']);
-	flagfn1("B", "info: define ELF NT_GNU_BUILD_ID note", addbuildinfo);
-	flagint64("D", "addr: data address", &INITDAT);
-	flagstr("E", "sym: entry symbol", &INITENTRY);
-	flagfn1("I", "interp: set ELF interp", setinterp);
-	flagfn1("L", "dir: add dir to library path", Lflag);
-	flagfn1("H", "head: header type", setheadtype);
-	flagcount("K", "add stack underflow checks", &debug['K']);
-	flagcount("O", "print pc-line tables", &debug['O']);
-	flagcount("Q", "debug byte-register code gen", &debug['Q']);
-	flagint32("R", "rnd: address rounding", &INITRND);
-	flagcount("S", "check type signatures", &debug['S']);
-	flagint64("T", "addr: text address", &INITTEXT);
-	flagfn0("V", "print version and exit", doversion);
-	flagcount("W", "disassemble input", &debug['W']);
-	flagfn2("X", "name value: define string data", addstrdata);
-	flagcount("Z", "clear stack frame on entry", &debug['Z']);
-	flagcount("a", "disassemble output", &debug['a']);
-	flagcount("c", "dump call graph", &debug['c']);
-	flagcount("d", "disable dynamic executable", &debug['d']);
-	flagstr("extld", "linker to run in external mode", &extld);
-	flagstr("extldflags", "flags for external linker", &extldflags);
-	flagcount("f", "ignore version mismatch", &debug['f']);
-	flagcount("g", "disable go package data checks", &debug['g']);
-	flagstr("installsuffix", "pkg directory suffix", &flag_installsuffix);
-	flagfn1("linkmode", "mode: set link mode (internal, external, auto)", setlinkmode);
-	flagstr("k", "sym: set field tracking symbol", &tracksym);
-	flagcount("n", "dump symbol table", &debug['n']);
-	flagstr("o", "outfile: set output file", &outfile);
-	flagcount("p", "insert profiling code", &debug['p']);
-	flagstr("r", "dir1:dir2:...: set ELF dynamic linker search path", &rpath);
-	flagcount("race", "enable race detector", &flag_race);
-	flagcount("s", "disable symbol table", &debug['s']);
-	flagcount("shared", "generate shared object (implies -linkmode external)", &flag_shared);
-	flagstr("tmpdir", "leave temporary files in this directory", &tmpdir);
-	flagcount("u", "reject unsafe packages", &debug['u']);
-	flagcount("v", "print link trace", &debug['v']);
-	flagcount("w", "disable DWARF generation", &debug['w']);
-	
-	flagparse(&argc, &argv, usage);
-
-	if(argc != 1)
-		usage();
-
-	mywhatsys();	// get goos
-
-	if(HEADTYPE == -1)
-		HEADTYPE = headtype(goos);
-
 	// getgoextlinkenabled is based on GO_EXTLINK_ENABLED when
 	// Go was built; see ../../make.bash.
 	if(linkmode == LinkAuto && strcmp(getgoextlinkenabled(), "0") == 0)
@@ -160,30 +67,13 @@ main(int argc, char *argv[])
 	case Hopenbsd:
 		break;
 	}
-
-	if(outfile == nil) {
-		if(HEADTYPE == Hwindows)
-			outfile = "6.out.exe";
-		else
-			outfile = "6.out";
-	}
-
-	libinit();
+	ctxt->linkmode = linkmode;
 
 	switch(HEADTYPE) {
 	default:
 		diag("unknown -H option");
 		errorexit();
-	case Hplan9x32:		/* plan 9 */
-		HEADR = 32L;
-		if(INITTEXT == -1)
-			INITTEXT = 4096+HEADR;
-		if(INITDAT == -1)
-			INITDAT = 0;
-		if(INITRND == -1)
-			INITRND = 4096;
-		break;
-	case Hplan9x64:		/* plan 9 */
+	case Hplan9:		/* plan 9 */
 		HEADR = 32L + 8L;
 		if(INITTEXT == -1)
 			INITTEXT = 0x200000+HEADR;
@@ -206,7 +96,7 @@ main(int argc, char *argv[])
 		 * OS X system constant - offset from 0(GS) to our TLS.
 		 * Explained in ../../pkg/runtime/cgo/gcc_darwin_amd64.c.
 		 */
-		tlsoffset = 0x8a0;
+		ctxt->tlsoffset = 0x8a0;
 		machoinit();
 		HEADR = INITIAL_MACHO_HEADR;
 		if(INITRND == -1)
@@ -227,7 +117,7 @@ main(int argc, char *argv[])
 		 * Also known to ../../pkg/runtime/sys_linux_amd64.s
 		 * and ../../pkg/runtime/cgo/gcc_linux_amd64.c.
 		 */
-		tlsoffset = -16;
+		ctxt->tlsoffset = -16;
 		elfinit();
 		HEADR = ELFRESERVE;
 		if(INITTEXT == -1)
@@ -251,552 +141,4 @@ main(int argc, char *argv[])
 	if(INITDAT != 0 && INITRND != 0)
 		print("warning: -D0x%llux is ignored because of -R0x%ux\n",
 			INITDAT, INITRND);
-	if(debug['v'])
-		Bprint(&bso, "HEADER = -H%d -T0x%llux -D0x%llux -R0x%ux\n",
-			HEADTYPE, INITTEXT, INITDAT, INITRND);
-	Bflush(&bso);
-	instinit();
-
-	zprg.link = P;
-	zprg.pcond = P;
-	zprg.back = 2;
-	zprg.as = AGOK;
-	zprg.from.type = D_NONE;
-	zprg.from.index = D_NONE;
-	zprg.from.scale = 1;
-	zprg.to = zprg.from;
-	zprg.mode = 64;
-
-	pcstr = "%.6llux ";
-	histgen = 0;
-	pc = 0;
-	dtype = 4;
-	version = 0;
-	cbp = buf.cbuf;
-	cbc = sizeof(buf.cbuf);
-
-	addlibpath("command line", "command line", argv[0], "main");
-	loadlib();
-	deadcode();
-	patch();
-	follow();
-	doelf();
-	if(HEADTYPE == Hdarwin)
-		domacho();
-	dostkoff();
-	dostkcheck();
-	paramspace = "SP";	/* (FP) now (SP) on output */
-	if(debug['p'])
-		if(debug['1'])
-			doprof1();
-		else
-			doprof2();
-	span();
-	if(HEADTYPE == Hwindows)
-		dope();
-	addexport();
-	textaddress();
-	pclntab();
-	symtab();
-	dodata();
-	address();
-	doweak();
-	reloc();
-	asmb();
-	undef();
-	hostlink();
-	if(debug['v']) {
-		Bprint(&bso, "%5.2f cpu time\n", cputime());
-		Bprint(&bso, "%d symbols\n", nsymbol);
-		Bprint(&bso, "%d sizeof adr\n", sizeof(Adr));
-		Bprint(&bso, "%d sizeof prog\n", sizeof(Prog));
-	}
-	Bflush(&bso);
-
-	errorexit();
-}
-
-static Sym*
-zsym(char *pn, Biobuf *f, Sym *h[])
-{	
-	int o;
-	
-	o = BGETC(f);
-	if(o < 0 || o >= NSYM || h[o] == nil)
-		mangle(pn);
-	return h[o];
-}
-
-static void
-zaddr(char *pn, Biobuf *f, Adr *a, Sym *h[])
-{
-	int t;
-	int32 l;
-	Sym *s;
-	Auto *u;
-
-	t = BGETC(f);
-	a->index = D_NONE;
-	a->scale = 0;
-	if(t & T_INDEX) {
-		a->index = BGETC(f);
-		a->scale = BGETC(f);
-	}
-	a->offset = 0;
-	if(t & T_OFFSET) {
-		a->offset = BGETLE4(f);
-		if(t & T_64) {
-			a->offset &= 0xFFFFFFFFULL;
-			a->offset |= (uvlong)BGETLE4(f) << 32;
-		}
-	}
-	a->sym = S;
-	if(t & T_SYM)
-		a->sym = zsym(pn, f, h);
-	a->type = D_NONE;
-	if(t & T_FCONST) {
-		a->ieee.l = BGETLE4(f);
-		a->ieee.h = BGETLE4(f);
-		a->type = D_FCONST;
-	} else
-	if(t & T_SCONST) {
-		Bread(f, a->scon, NSNAME);
-		a->type = D_SCONST;
-	}
-	if(t & T_TYPE)
-		a->type = BGETC(f);
-	if(a->type < 0 || a->type >= D_SIZE)
-		mangle(pn);
-	adrgotype = S;
-	if(t & T_GOTYPE)
-		adrgotype = zsym(pn, f, h);
-	s = a->sym;
-	t = a->type;
-	if(t == D_INDIR+D_GS || a->index == D_GS)
-		a->offset += tlsoffset;
-	if(t != D_AUTO && t != D_PARAM) {
-		if(s && adrgotype)
-			s->gotype = adrgotype;
-		return;
-	}
-	l = a->offset;
-	for(u=curauto; u; u=u->link) {
-		if(u->asym == s)
-		if(u->type == t) {
-			if(u->aoffset > l)
-				u->aoffset = l;
-			if(adrgotype)
-				u->gotype = adrgotype;
-			return;
-		}
-	}
-	
-	switch(t) {
-	case D_FILE:
-	case D_FILE1:
-	case D_AUTO:
-	case D_PARAM:
-		if(s == S)
-			mangle(pn);
-	}
-
-	u = mal(sizeof(*u));
-	u->link = curauto;
-	curauto = u;
-	u->asym = s;
-	u->aoffset = l;
-	u->type = t;
-	u->gotype = adrgotype;
-}
-
-void
-nopout(Prog *p)
-{
-	p->as = ANOP;
-	p->from.type = D_NONE;
-	p->to.type = D_NONE;
-}
-
-void
-ldobj1(Biobuf *f, char *pkg, int64 len, char *pn)
-{
-	vlong ipc;
-	Prog *p;
-	int v, o, r, skip, mode;
-	Sym *h[NSYM], *s;
-	uint32 sig;
-	char *name, *x;
-	int ntext;
-	vlong eof;
-	char src[1024];
-	Prog *lastp;
-
-	lastp = nil;
-	ntext = 0;
-	eof = Boffset(f) + len;
-	src[0] = 0;
-	pn = estrdup(pn); // we keep it in Sym* references
-
-newloop:
-	memset(h, 0, sizeof(h));
-	version++;
-	histfrogp = 0;
-	ipc = pc;
-	skip = 0;
-	mode = 64;
-
-loop:
-	if(f->state == Bracteof || Boffset(f) >= eof)
-		goto eof;
-	o = BGETC(f);
-	if(o == Beof)
-		goto eof;
-	o |= BGETC(f) << 8;
-	if(o <= AXXX || o >= ALAST) {
-		if(o < 0)
-			goto eof;
-		diag("%s:#%lld: opcode out of range: %#ux", pn, Boffset(f), o);
-		print("	probably not a .6 file\n");
-		errorexit();
-	}
-
-	if(o == ANAME || o == ASIGNAME) {
-		sig = 0;
-		if(o == ASIGNAME)
-			sig = BGETLE4(f);
-		v = BGETC(f);	/* type */
-		o = BGETC(f);	/* sym */
-		r = 0;
-		if(v == D_STATIC)
-			r = version;
-		name = Brdline(f, '\0');
-		if(name == nil) {
-			if(Blinelen(f) > 0) {
-				fprint(2, "%s: name too long\n", pn);
-				errorexit();
-			}
-			goto eof;
-		}
-		x = expandpkg(name, pkg);
-		s = lookup(x, r);
-		if(x != name)
-			free(x);
-
-		if(debug['S'] && r == 0)
-			sig = 1729;
-		if(sig != 0){
-			if(s->sig != 0 && s->sig != sig)
-				diag("incompatible type signatures "
-					"%ux(%s) and %ux(%s) for %s",
-					s->sig, s->file, sig, pn, s->name);
-			s->sig = sig;
-			s->file = pn;
-		}
-
-		if(debug['W'])
-			print("	ANAME	%s\n", s->name);
-		if(o < 0 || o >= nelem(h))
-			mangle(pn);
-		h[o] = s;
-		if((v == D_EXTERN || v == D_STATIC) && s->type == 0)
-			s->type = SXREF;
-		if(v == D_FILE) {
-			if(s->type != SFILE) {
-				histgen++;
-				s->type = SFILE;
-				s->value = histgen;
-			}
-			if(histfrogp < MAXHIST) {
-				histfrog[histfrogp] = s;
-				histfrogp++;
-			} else
-				collapsefrog(s);
-			dwarfaddfrag(s->value, s->name);
-		}
-		goto loop;
-	}
-
-	p = mal(sizeof(*p));
-	p->as = o;
-	p->line = BGETLE4(f);
-	p->back = 2;
-	p->mode = mode;
-	zaddr(pn, f, &p->from, h);
-	fromgotype = adrgotype;
-	zaddr(pn, f, &p->to, h);
-	
-	switch(p->as) {
-	case ATEXT:
-	case ADATA:
-	case AGLOBL:
-		if(p->from.sym == S)
-			mangle(pn);
-		break;
-	}
-
-	if(debug['W'])
-		print("%P\n", p);
-
-	switch(p->as) {
-	case AHISTORY:
-		if(p->to.offset == -1) {
-			addlib(src, pn);
-			histfrogp = 0;
-			goto loop;
-		}
-		if(src[0] == '\0')
-			copyhistfrog(src, sizeof src);
-		addhist(p->line, D_FILE);		/* 'z' */
-		if(p->to.offset)
-			addhist(p->to.offset, D_FILE1);	/* 'Z' */
-		savehist(p->line, p->to.offset);
-		histfrogp = 0;
-		goto loop;
-
-	case AEND:
-		histtoauto();
-		if(cursym != nil && cursym->text)
-			cursym->autom = curauto;
-		curauto = 0;
-		cursym = nil;
-		if(Boffset(f) == eof)
-			return;
-		goto newloop;
-
-	case AGLOBL:
-		s = p->from.sym;
-		if(s->type == 0 || s->type == SXREF) {
-			s->type = SBSS;
-			s->size = 0;
-		}
-		if(s->type != SBSS && s->type != SNOPTRBSS && !s->dupok) {
-			diag("%s: redefinition: %s in %s",
-				pn, s->name, TNAME);
-			s->type = SBSS;
-			s->size = 0;
-		}
-		if(p->to.offset > s->size)
-			s->size = p->to.offset;
-		if(p->from.scale & DUPOK)
-			s->dupok = 1;
-		if(p->from.scale & RODATA)
-			s->type = SRODATA;
-		else if(p->from.scale & NOPTR)
-			s->type = SNOPTRBSS;
-		goto loop;
-
-	case ADATA:
-		// Assume that AGLOBL comes after ADATA.
-		// If we've seen an AGLOBL that said this sym was DUPOK,
-		// ignore any more ADATA we see, which must be
-		// redefinitions.
-		s = p->from.sym;
-		if(s->dupok) {
-//			if(debug['v'])
-//				Bprint(&bso, "skipping %s in %s: dupok\n", s->name, pn);
-			goto loop;
-		}
-		if(s->file == nil)
-			s->file = pn;
-		else if(s->file != pn) {
-			diag("multiple initialization for %s: in both %s and %s", s->name, s->file, pn);
-			errorexit();
-		}
-		savedata(s, p, pn);
-		unmal(p, sizeof *p);
-		goto loop;
-
-	case AGOK:
-		diag("%s: GOK opcode in %s", pn, TNAME);
-		pc++;
-		goto loop;
-
-	case ATYPE:
-		if(skip)
-			goto casdef;
-		pc++;
-		goto loop;
-
-	case ATEXT:
-		s = p->from.sym;
-		if(s->text != nil) {
-			if(p->from.scale & DUPOK) {
-				skip = 1;
-				goto casdef;
-			}
-			diag("%s: %s: redefinition", pn, s->name);
-			return;
-		}
-		if(ntext++ == 0 && s->type != 0 && s->type != SXREF) {
-			/* redefinition, so file has probably been seen before */
-			if(debug['v'])
-				Bprint(&bso, "skipping: %s: redefinition: %s", pn, s->name);
-			return;
-		}
-		if(cursym != nil && cursym->text) {
-			histtoauto();
-			cursym->autom = curauto;
-			curauto = 0;
-		}
-		skip = 0;
-		if(etextp)
-			etextp->next = s;
-		else
-			textp = s;
-		etextp = s;
-		s->text = p;
-		cursym = s;
-		if(s->type != 0 && s->type != SXREF) {
-			if(p->from.scale & DUPOK) {
-				skip = 1;
-				goto casdef;
-			}
-			diag("%s: redefinition: %s\n%P", pn, s->name, p);
-		}
-		if(fromgotype) {
-			if(s->gotype && s->gotype != fromgotype)
-				diag("%s: type mismatch for %s", pn, s->name);
-			s->gotype = fromgotype;
-		}
-		s->type = STEXT;
-		s->hist = gethist();
-		s->value = pc;
-		s->args = p->to.offset >> 32;
-		lastp = p;
-		p->pc = pc++;
-		goto loop;
-
-	case AMODE:
-		if(p->from.type == D_CONST || p->from.type == D_INDIR+D_NONE){
-			switch((int)p->from.offset){
-			case 16: case 32: case 64:
-				mode = p->from.offset;
-				break;
-			}
-		}
-		goto loop;
-
-	case AFMOVF:
-	case AFADDF:
-	case AFSUBF:
-	case AFSUBRF:
-	case AFMULF:
-	case AFDIVF:
-	case AFDIVRF:
-	case AFCOMF:
-	case AFCOMFP:
-	case AMOVSS:
-	case AADDSS:
-	case ASUBSS:
-	case AMULSS:
-	case ADIVSS:
-	case ACOMISS:
-	case AUCOMISS:
-		if(skip)
-			goto casdef;
-		if(p->from.type == D_FCONST) {
-			/* size sb 9 max */
-			sprint(literal, "$%ux", ieeedtof(&p->from.ieee));
-			s = lookup(literal, 0);
-			if(s->type == 0) {
-				s->type = SRODATA;
-				adduint32(s, ieeedtof(&p->from.ieee));
-				s->reachable = 0;
-			}
-			p->from.type = D_EXTERN;
-			p->from.sym = s;
-			p->from.offset = 0;
-		}
-		goto casdef;
-
-	case AFMOVD:
-	case AFADDD:
-	case AFSUBD:
-	case AFSUBRD:
-	case AFMULD:
-	case AFDIVD:
-	case AFDIVRD:
-	case AFCOMD:
-	case AFCOMDP:
-	case AMOVSD:
-	case AADDSD:
-	case ASUBSD:
-	case AMULSD:
-	case ADIVSD:
-	case ACOMISD:
-	case AUCOMISD:
-		if(skip)
-			goto casdef;
-		if(p->from.type == D_FCONST) {
-			/* size sb 18 max */
-			sprint(literal, "$%ux.%ux",
-				p->from.ieee.l, p->from.ieee.h);
-			s = lookup(literal, 0);
-			if(s->type == 0) {
-				s->type = SRODATA;
-				adduint32(s, p->from.ieee.l);
-				adduint32(s, p->from.ieee.h);
-				s->reachable = 0;
-			}
-			p->from.type = D_EXTERN;
-			p->from.sym = s;
-			p->from.offset = 0;
-		}
-		goto casdef;
-
-	casdef:
-	default:
-		if(skip)
-			nopout(p);
-		p->pc = pc;
-		pc++;
-
-		if(p->to.type == D_BRANCH)
-			p->to.offset += ipc;
-		if(lastp == nil) {
-			if(p->as != ANOP)
-				diag("unexpected instruction: %P", p);
-			goto loop;
-		}
-		lastp->link = p;
-		lastp = p;
-		goto loop;
-	}
-
-eof:
-	diag("truncated object file: %s", pn);
-}
-
-Prog*
-prg(void)
-{
-	Prog *p;
-
-	p = mal(sizeof(*p));
-
-	*p = zprg;
-	return p;
-}
-
-Prog*
-copyp(Prog *q)
-{
-	Prog *p;
-
-	p = prg();
-	*p = *q;
-	return p;
-}
-
-Prog*
-appendp(Prog *q)
-{
-	Prog *p;
-
-	p = prg();
-	p->link = q->link;
-	q->link = p;
-	p->line = q->line;
-	p->mode = q->mode;
-	return p;
 }