src/cmd/5l/obj.c - go - Git at Google

 // Inferno utils/5l/obj.c
 // http://code.google.com/p/inferno-os/source/browse/utils/5l/obj.c
 //
 //	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
 //	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
 //	Portions Copyright © 1997-1999 Vita Nuova Limited
 //	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
 //	Portions Copyright © 2004,2006 Bruce Ellis
 //	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
 //	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
 //	Portions Copyright © 2009 The Go Authors.  All rights reserved.
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
 // of this software and associated documentation files (the "Software"), to deal
 // in the Software without restriction, including without limitation the rights
 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 // copies of the Software, and to permit persons to whom the Software is
 // furnished to do so, subject to the following conditions:
 //
 // The above copyright notice and this permission notice shall be included in
 // all copies or substantial portions of the Software.
 //
 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.

 // Reading object files.

 #define	EXTERN
 #include	"l.h"
 #include	"../ld/lib.h"
 #include	"../ld/elf.h"
 #include	"../ld/dwarf.h"
 #include	<ar.h>

 #ifndef	DEFAULT
 #define	DEFAULT	'9'
 #endif

 char	*noname		= "<none>";
 char	*thestring 	= "arm";

 Header headers[] = {
    "noheader", Hnoheader,
    "risc", Hrisc,
    "plan9", Hplan9x32,
    "ixp1200", Hixp1200,
    "ipaq", Hipaq,
    "linux", Hlinux,
    "freebsd", Hfreebsd,
    "netbsd", Hnetbsd,
    0, 0
 };

 /*
  *	-Hrisc -T0x10005000 -R4		is aif for risc os
  *	-Hplan9 -T4128 -R4096		is plan9 format
  *	-Hixp1200			is IXP1200 (raw)
  *	-Hipaq -T0xC0008010 -R1024	is ipaq
  *	-Hlinux -Tx -Rx			is linux elf
  *	-Hfreebsd			is freebsd elf
  *	-Hnetbsd			is netbsd elf
  */

 void
 main(int argc, char *argv[])
 {
 	char *p;
 	Sym *s;

 	Binit(&bso, 1, OWRITE);
 	listinit();
 	nerrors = 0;
 	outfile = "5.out";
 	HEADTYPE = -1;
 	INITTEXT = -1;
 	INITDAT = -1;
 	INITRND = -1;
 	INITENTRY = 0;
 	LIBINITENTRY = 0;
 	linkmode = LinkInternal; // TODO: LinkAuto once everything works.
 	nuxiinit();

 	p = getgoarm();
 	if(p != nil)
 		goarm = atoi(p);
 	else
 		goarm = 6;
 	if(goarm == 5)
 		debug['F'] = 1;

 	flagcount("1", "use alternate profiling code", &debug['1']);
 	flagfn1("B", "info: define ELF NT_GNU_BUILD_ID note", addbuildinfo);
 	flagstr("E", "sym: entry symbol", &INITENTRY);
 	flagint32("D", "addr: data address", &INITDAT);
 	flagcount("G", "debug pseudo-ops", &debug['G']);
 	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("M", "disable software div/mod", &debug['M']);
 	flagcount("O", "print pc-line tables", &debug['O']);
 	flagcount("P", "debug code generation", &debug['P']);
 	flagint32("R", "rnd: address rounding", &INITRND);
 	flagint32("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("k", "sym: set field tracking symbol", &tracksym);
 	flagfn1("linkmode", "mode: set link mode (internal, external, auto)", setlinkmode);
 	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']);
 	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']);
 	flagcount("shared", "generate shared object", &flag_shared);
 	// TODO: link mode flag

 	flagparse(&argc, &argv, usage);

 	if(argc != 1)
 		usage();

 	// getgoextlinkenabled is based on GO_EXTLINK_ENABLED when
 	// Go was built; see ../../make.bash.
 	if(linkmode == LinkAuto && strcmp(getgoextlinkenabled(), "0") == 0)
 		linkmode = LinkInternal;

 	if(linkmode == LinkExternal) {
 		diag("only -linkmode=internal is supported");
 		errorexit();
 	} else if(linkmode == LinkAuto) {
 		linkmode = LinkInternal;
 	}

 	libinit();

 	if(HEADTYPE == -1)
 		HEADTYPE = headtype(goos);
 	switch(HEADTYPE) {
 	default:
 		diag("unknown -H option");
 		errorexit();
 	case Hnoheader:	/* no header */
 		HEADR = 0L;
 		if(INITTEXT == -1)
 			INITTEXT = 0;
 		if(INITDAT == -1)
 			INITDAT = 0;
 		if(INITRND == -1)
 			INITRND = 4;
 		break;
 	case Hrisc:	/* aif for risc os */
 		HEADR = 128L;
 		if(INITTEXT == -1)
 			INITTEXT = 0x10005000 + HEADR;
 		if(INITDAT == -1)
 			INITDAT = 0;
 		if(INITRND == -1)
 			INITRND = 4;
 		break;
 	case Hplan9x32:	/* plan 9 */
 		HEADR = 32L;
 		if(INITTEXT == -1)
 			INITTEXT = 4128;
 		if(INITDAT == -1)
 			INITDAT = 0;
 		if(INITRND == -1)
 			INITRND = 4096;
 		break;
 	case Hixp1200: /* boot for IXP1200 */
 		HEADR = 0L;
 		if(INITTEXT == -1)
 			INITTEXT = 0x0;
 		if(INITDAT == -1)
 			INITDAT = 0;
 		if(INITRND == -1)
 			INITRND = 4;
 		break;
 	case Hipaq: /* boot for ipaq */
 		HEADR = 16L;
 		if(INITTEXT == -1)
 			INITTEXT = 0xC0008010;
 		if(INITDAT == -1)
 			INITDAT = 0;
 		if(INITRND == -1)
 			INITRND = 1024;
 		break;
 	case Hlinux:	/* arm elf */
 	case Hfreebsd:
 	case Hnetbsd:
 		debug['d'] = 0;	// with dynamic linking
 		tlsoffset = -8; // hardcoded number, first 4-byte word for g, and then 4-byte word for m
 		                // this number is known to ../../pkg/runtime/cgo/gcc_linux_arm.c
 		elfinit();
 		HEADR = ELFRESERVE;
 		if(INITTEXT == -1)
 			INITTEXT = 0x10000 + HEADR;
 		if(INITDAT == -1)
 			INITDAT = 0;
 		if(INITRND == -1)
 			INITRND = 4096;
 		break;
 	}
 	if(INITDAT != 0 && INITRND != 0)
 		print("warning: -D0x%ux is ignored because of -R0x%ux\n",
 			INITDAT, INITRND);
 	if(debug['v'])
 		Bprint(&bso, "HEADER = -H0x%d -T0x%ux -D0x%ux -R0x%ux\n",
 			HEADTYPE, INITTEXT, INITDAT, INITRND);
 	Bflush(&bso);
 	zprg.as = AGOK;
 	zprg.scond = 14;
 	zprg.reg = NREG;
 	zprg.from.name = D_NONE;
 	zprg.from.type = D_NONE;
 	zprg.from.reg = NREG;
 	zprg.to = zprg.from;
 	buildop();
 	histgen = 0;
 	pc = 0;
 	dtype = 4;

 	version = 0;
 	cbp = buf.cbuf;
 	cbc = sizeof(buf.cbuf);

 	// embed goarm to runtime.goarm
 	s = lookup("runtime.goarm", 0);
 	s->dupok = 1;
 	adduint8(s, goarm);

 	addlibpath("command line", "command line", argv[0], "main");
 	loadlib();

 	// mark some functions that are only referenced after linker code editing
 	if(debug['F'])
 		mark(rlookup("_sfloat", 0));
 	deadcode();
 	if(textp == nil) {
 		diag("no code");
 		errorexit();
 	}

 	patch();
 	if(debug['p'])
 		if(debug['1'])
 			doprof1();
 		else
 			doprof2();
 	doelf();
 	follow();
 	softfloat();
 	// 5l -Z means zero the stack frame on entry.
 	// This slows down function calls but can help avoid
 	// false positives in garbage collection.
 	if(debug['Z'])
 		dozerostk();
 	noops(); // generate stack split prolog, handle div/mod, etc.
 	dostkcheck();
 	span();
 	addexport();
 	// textaddress() functionality is handled in span()
 	pclntab();
 	symtab();
 	dodata();
 	address();
 	doweak();
 	reloc();
 	asmb();
 	undef();
 	hostlink();

 	if(debug['c'])
 		print("ARM size = %d\n", armsize);
 	if(debug['v']) {
 		Bprint(&bso, "%5.2f cpu time\n", cputime());
 		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)
 		return S;
 	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 i, c;
 	int32 l;
 	Sym *s;
 	Auto *u;

 	a->type = BGETC(f);
 	a->reg = BGETC(f);
 	c = BGETC(f);
 	if(c < 0 || c > NSYM){
 		print("sym out of range: %d\n", c);
 		Bputc(f, ALAST+1);
 		return;
 	}
 	a->sym = h[c];
 	a->name = BGETC(f);
 	adrgotype = zsym(pn, f, h);

 	if((schar)a->reg < 0 || a->reg > NREG) {
 		print("register out of range %d\n", a->reg);
 		Bputc(f, ALAST+1);
 		return;	/*  force real diagnostic */
 	}

 	if(a->type == D_CONST || a->type == D_OCONST) {
 		if(a->name == D_EXTERN || a->name == D_STATIC) {
 			s = a->sym;
 			if(s != S && (s->type == STEXT || s->type == SCONST || s->type == SXREF)) {
 				if(0 && !s->fnptr && s->name[0] != '.')
 					print("%s used as function pointer\n", s->name);
 				s->fnptr = 1;	// over the top cos of SXREF
 			}
 		}
 	}

 	switch(a->type) {
 	default:
 		print("unknown type %d\n", a->type);
 		Bputc(f, ALAST+1);
 		return;	/*  force real diagnostic */

 	case D_NONE:
 	case D_REG:
 	case D_FREG:
 	case D_PSR:
 	case D_FPCR:
 		break;

 	case D_REGREG:
 	case D_REGREG2:
 		a->offset = BGETC(f);
 		break;

 	case D_CONST2:
 		a->offset2 = Bget4(f);	// fall through
 	case D_BRANCH:
 	case D_OREG:
 	case D_CONST:
 	case D_OCONST:
 	case D_SHIFT:
 		a->offset = Bget4(f);
 		break;

 	case D_SCONST:
 		a->sval = mal(NSNAME);
 		Bread(f, a->sval, NSNAME);
 		break;

 	case D_FCONST:
 		a->ieee.l = Bget4(f);
 		a->ieee.h = Bget4(f);
 		break;
 	}
 	s = a->sym;
 	if(s == S)
 		return;
 	i = a->name;
 	if(i != D_AUTO && i != 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 == i) {
 			if(u->aoffset > l)
 				u->aoffset = l;
 			if(adrgotype)
 				u->gotype = adrgotype;
 			return;
 		}

 	u = mal(sizeof(Auto));
 	u->link = curauto;
 	curauto = u;
 	u->asym = s;
 	u->aoffset = l;
 	u->type = i;
 	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)
 {
 	int32 ipc;
 	Prog *p;
 	Sym *h[NSYM], *s;
 	int v, o, r, skip;
 	uint32 sig;
 	char *name;
 	int ntext;
 	int32 eof;
 	char src[1024], *x;
 	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;

 loop:
 	if(f->state == Bracteof || Boffset(f) >= eof)
 		goto eof;
 	o = BGETC(f);
 	if(o == Beof)
 		goto eof;

 	if(o <= AXXX || o >= ALAST) {
 		diag("%s:#%lld: opcode out of range: %#ux", pn, Boffset(f), o);
 		print("	probably not a .5 file\n");
 		errorexit();
 	}
 	if(o == ANAME || o == ASIGNAME) {
 		sig = 0;
 		if(o == ASIGNAME)
 			sig = Bget4(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(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)) {
 			fprint(2, "%s: mangled input file\n", pn);
 			errorexit();
 		}
 		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(Prog));
 	p->as = o;
 	p->scond = BGETC(f);
 	p->reg = BGETC(f);
 	p->line = Bget4(f);

 	zaddr(pn, f, &p->from, h);
 	fromgotype = adrgotype;
 	zaddr(pn, f, &p->to, h);

 	if(p->as != ATEXT && p->as != AGLOBL && p->reg > NREG)
 		diag("register out of range %A %d", p->as, p->reg);

 	p->link = P;
 	p->cond = P;

 	if(debug['W'])
 		print("%P\n", p);

 	switch(o) {
 	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' */
 		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 == S) {
 			diag("GLOBL must have a name\n%P", p);
 			errorexit();
 		}
 		if(s->type == 0 || s->type == SXREF) {
 			s->type = SBSS;
 			s->value = 0;
 		}
 		if(s->type != SBSS && s->type != SNOPTRBSS && !s->dupok) {
 			diag("redefinition: %s\n%P", s->name, p);
 			s->type = SBSS;
 			s->value = 0;
 		}
 		if(p->to.offset > s->size)
 			s->size = p->to.offset;
 		if(p->reg & DUPOK)
 			s->dupok = 1;
 		if(p->reg & RODATA)
 			s->type = SRODATA;
 		else if(p->reg & NOPTR)
 			s->type = SNOPTRBSS;
 		break;

 	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);
 		break;

 	case AGOK:
 		diag("unknown opcode\n%P", p);
 		p->pc = pc;
 		pc++;
 		break;

 	case ALOCALS:
 		if(skip)
 			goto casedef;
 		cursym->locals = p->to.offset;
 		pc++;
 		break;

 	case ATYPE:
 		if(skip)
 			goto casedef;
 		pc++;
 		goto loop;

 	case ATEXT:
 		if(cursym != nil && cursym->text) {
 			histtoauto();
 			cursym->autom = curauto;
 			curauto = 0;
 		}
 		s = p->from.sym;
 		if(s == S) {
 			diag("TEXT must have a name\n%P", p);
 			errorexit();
 		}
 		cursym = s;
 		if(s->type != 0 && s->type != SXREF && (p->reg & DUPOK)) {
 			skip = 1;
 			goto casedef;
 		}
 		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;
 		}
 		skip = 0;
 		if(s->type != 0 && s->type != SXREF)
 			diag("redefinition: %s\n%P", s->name, p);
 		if(etextp)
 			etextp->next = s;
 		else
 			textp = s;
 		if(fromgotype) {
 			if(s->gotype && s->gotype != fromgotype)
 				diag("%s: type mismatch for %s", pn, s->name);
 			s->gotype = fromgotype;
 		}
 		etextp = s;
 		p->align = 4;
 		autosize = (p->to.offset+3L) & ~3L;
 		p->to.offset = autosize;
 		autosize += 4;
 		s->type = STEXT;
 		s->text = p;
 		s->value = pc;
 		s->args = p->to.offset2;
 		lastp = p;
 		p->pc = pc;
 		pc++;
 		break;

 	case ASUB:
 		if(p->from.type == D_CONST)
 		if(p->from.name == D_NONE)
 		if(p->from.offset < 0) {
 			p->from.offset = -p->from.offset;
 			p->as = AADD;
 		}
 		goto casedef;

 	case AADD:
 		if(p->from.type == D_CONST)
 		if(p->from.name == D_NONE)
 		if(p->from.offset < 0) {
 			p->from.offset = -p->from.offset;
 			p->as = ASUB;
 		}
 		goto casedef;

 	case AMOVWD:
 	case AMOVWF:
 	case AMOVDW:
 	case AMOVFW:
 	case AMOVFD:
 	case AMOVDF:
 	// case AMOVF:
 	// case AMOVD:
 	case ACMPF:
 	case ACMPD:
 	case AADDF:
 	case AADDD:
 	case ASUBF:
 	case ASUBD:
 	case AMULF:
 	case AMULD:
 	case ADIVF:
 	case ADIVD:
 		goto casedef;

 	case AMOVF:
 		if(skip)
 			goto casedef;

 		if(p->from.type == D_FCONST && chipfloat(&p->from.ieee) < 0 &&
 		   (chipzero(&p->from.ieee) < 0 || (p->scond & C_SCOND) != C_SCOND_NONE)) {
 			/* 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_OREG;
 			p->from.sym = s;
 			p->from.name = D_EXTERN;
 			p->from.offset = 0;
 		}
 		goto casedef;

 	case AMOVD:
 		if(skip)
 			goto casedef;

 		if(p->from.type == D_FCONST && chipfloat(&p->from.ieee) < 0 &&
 		   (chipzero(&p->from.ieee) < 0 || (p->scond & C_SCOND) != C_SCOND_NONE)) {
 			/* 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_OREG;
 			p->from.sym = s;
 			p->from.name = D_EXTERN;
 			p->from.offset = 0;
 		}
 		goto casedef;

 	default:
 	casedef:
 		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);
 			break;
 		}
 		lastp->link = p;
 		lastp = p;
 		break;
 	}
 	goto loop;

 eof:
 	diag("truncated object file: %s", pn);
 }

 Prog*
 prg(void)
 {
 	Prog *p;

 	p = mal(sizeof(Prog));
 	*p = zprg;
 	return p;
 }

 Prog*
 appendp(Prog *q)
 {
 	Prog *p;

 	p = prg();
 	p->link = q->link;
 	q->link = p;
 	p->line = q->line;
 	return p;
 }
	// Inferno utils/5l/obj.c
	// http://code.google.com/p/inferno-os/source/browse/utils/5l/obj.c
	//
	// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
	// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
	// Portions Copyright © 1997-1999 Vita Nuova Limited
	// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
	// Portions Copyright © 2004,2006 Bruce Ellis
	// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
	// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
	// Portions Copyright © 2009 The Go Authors. All rights reserved.
	//
	// Permission is hereby granted, free of charge, to any person obtaining a copy
	// of this software and associated documentation files (the "Software"), to deal
	// in the Software without restriction, including without limitation the rights
	// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	// copies of the Software, and to permit persons to whom the Software is
	// furnished to do so, subject to the following conditions:
	//
	// The above copyright notice and this permission notice shall be included in
	// all copies or substantial portions of the Software.
	//
	// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	// THE SOFTWARE.

	// Reading object files.

	#define EXTERN
	#include "l.h"
	#include "../ld/lib.h"
	#include "../ld/elf.h"
	#include "../ld/dwarf.h"
	#include <ar.h>

	#ifndef DEFAULT
	#define DEFAULT '9'
	#endif

	char *noname = "<none>";
	char *thestring = "arm";

	Header headers[] = {
	"noheader", Hnoheader,
	"risc", Hrisc,
	"plan9", Hplan9x32,
	"ixp1200", Hixp1200,
	"ipaq", Hipaq,
	"linux", Hlinux,
	"freebsd", Hfreebsd,
	"netbsd", Hnetbsd,
	0, 0
	};

	/*
	* -Hrisc -T0x10005000 -R4 is aif for risc os
	* -Hplan9 -T4128 -R4096 is plan9 format
	* -Hixp1200 is IXP1200 (raw)
	* -Hipaq -T0xC0008010 -R1024 is ipaq
	* -Hlinux -Tx -Rx is linux elf
	* -Hfreebsd is freebsd elf
	* -Hnetbsd is netbsd elf
	*/

	void
	main(int argc, char *argv[])
	{
	char *p;
	Sym *s;

	Binit(&bso, 1, OWRITE);
	listinit();
	nerrors = 0;
	outfile = "5.out";
	HEADTYPE = -1;
	INITTEXT = -1;
	INITDAT = -1;
	INITRND = -1;
	INITENTRY = 0;
	LIBINITENTRY = 0;
	linkmode = LinkInternal; // TODO: LinkAuto once everything works.
	nuxiinit();

	p = getgoarm();
	if(p != nil)
	goarm = atoi(p);
	else
	goarm = 6;
	if(goarm == 5)
	debug['F'] = 1;

	flagcount("1", "use alternate profiling code", &debug['1']);
	flagfn1("B", "info: define ELF NT_GNU_BUILD_ID note", addbuildinfo);
	flagstr("E", "sym: entry symbol", &INITENTRY);
	flagint32("D", "addr: data address", &INITDAT);
	flagcount("G", "debug pseudo-ops", &debug['G']);
	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("M", "disable software div/mod", &debug['M']);
	flagcount("O", "print pc-line tables", &debug['O']);
	flagcount("P", "debug code generation", &debug['P']);
	flagint32("R", "rnd: address rounding", &INITRND);
	flagint32("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("k", "sym: set field tracking symbol", &tracksym);
	flagfn1("linkmode", "mode: set link mode (internal, external, auto)", setlinkmode);
	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']);
	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']);
	flagcount("shared", "generate shared object", &flag_shared);
	// TODO: link mode flag

	flagparse(&argc, &argv, usage);

	if(argc != 1)
	usage();

	// getgoextlinkenabled is based on GO_EXTLINK_ENABLED when
	// Go was built; see ../../make.bash.
	if(linkmode == LinkAuto && strcmp(getgoextlinkenabled(), "0") == 0)
	linkmode = LinkInternal;

	if(linkmode == LinkExternal) {
	diag("only -linkmode=internal is supported");
	errorexit();
	} else if(linkmode == LinkAuto) {
	linkmode = LinkInternal;
	}

	libinit();

	if(HEADTYPE == -1)
	HEADTYPE = headtype(goos);
	switch(HEADTYPE) {
	default:
	diag("unknown -H option");
	errorexit();
	case Hnoheader: /* no header */
	HEADR = 0L;
	if(INITTEXT == -1)
	INITTEXT = 0;
	if(INITDAT == -1)
	INITDAT = 0;
	if(INITRND == -1)
	INITRND = 4;
	break;
	case Hrisc: /* aif for risc os */
	HEADR = 128L;
	if(INITTEXT == -1)
	INITTEXT = 0x10005000 + HEADR;
	if(INITDAT == -1)
	INITDAT = 0;
	if(INITRND == -1)
	INITRND = 4;
	break;
	case Hplan9x32: /* plan 9 */
	HEADR = 32L;
	if(INITTEXT == -1)
	INITTEXT = 4128;
	if(INITDAT == -1)
	INITDAT = 0;
	if(INITRND == -1)
	INITRND = 4096;
	break;
	case Hixp1200: /* boot for IXP1200 */
	HEADR = 0L;
	if(INITTEXT == -1)
	INITTEXT = 0x0;
	if(INITDAT == -1)
	INITDAT = 0;
	if(INITRND == -1)
	INITRND = 4;
	break;
	case Hipaq: /* boot for ipaq */
	HEADR = 16L;
	if(INITTEXT == -1)
	INITTEXT = 0xC0008010;
	if(INITDAT == -1)
	INITDAT = 0;
	if(INITRND == -1)
	INITRND = 1024;
	break;
	case Hlinux: /* arm elf */
	case Hfreebsd:
	case Hnetbsd:
	debug['d'] = 0; // with dynamic linking
	tlsoffset = -8; // hardcoded number, first 4-byte word for g, and then 4-byte word for m
	// this number is known to ../../pkg/runtime/cgo/gcc_linux_arm.c
	elfinit();
	HEADR = ELFRESERVE;
	if(INITTEXT == -1)
	INITTEXT = 0x10000 + HEADR;
	if(INITDAT == -1)
	INITDAT = 0;
	if(INITRND == -1)
	INITRND = 4096;
	break;
	}
	if(INITDAT != 0 && INITRND != 0)
	print("warning: -D0x%ux is ignored because of -R0x%ux\n",
	INITDAT, INITRND);
	if(debug['v'])
	Bprint(&bso, "HEADER = -H0x%d -T0x%ux -D0x%ux -R0x%ux\n",
	HEADTYPE, INITTEXT, INITDAT, INITRND);
	Bflush(&bso);
	zprg.as = AGOK;
	zprg.scond = 14;
	zprg.reg = NREG;
	zprg.from.name = D_NONE;
	zprg.from.type = D_NONE;
	zprg.from.reg = NREG;
	zprg.to = zprg.from;
	buildop();
	histgen = 0;
	pc = 0;
	dtype = 4;

	version = 0;
	cbp = buf.cbuf;
	cbc = sizeof(buf.cbuf);

	// embed goarm to runtime.goarm
	s = lookup("runtime.goarm", 0);
	s->dupok = 1;
	adduint8(s, goarm);

	addlibpath("command line", "command line", argv[0], "main");
	loadlib();

	// mark some functions that are only referenced after linker code editing
	if(debug['F'])
	mark(rlookup("_sfloat", 0));
	deadcode();
	if(textp == nil) {
	diag("no code");
	errorexit();
	}

	patch();
	if(debug['p'])
	if(debug['1'])
	doprof1();
	else
	doprof2();
	doelf();
	follow();
	softfloat();
	// 5l -Z means zero the stack frame on entry.
	// This slows down function calls but can help avoid
	// false positives in garbage collection.
	if(debug['Z'])
	dozerostk();
	noops(); // generate stack split prolog, handle div/mod, etc.
	dostkcheck();
	span();
	addexport();
	// textaddress() functionality is handled in span()
	pclntab();
	symtab();
	dodata();
	address();
	doweak();
	reloc();
	asmb();
	undef();
	hostlink();

	if(debug['c'])
	print("ARM size = %d\n", armsize);
	if(debug['v']) {
	Bprint(&bso, "%5.2f cpu time\n", cputime());
	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)
	return S;
	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 i, c;
	int32 l;
	Sym *s;
	Auto *u;

	a->type = BGETC(f);
	a->reg = BGETC(f);
	c = BGETC(f);
	if(c < 0 \|\| c > NSYM){
	print("sym out of range: %d\n", c);
	Bputc(f, ALAST+1);
	return;
	}
	a->sym = h[c];
	a->name = BGETC(f);
	adrgotype = zsym(pn, f, h);

	if((schar)a->reg < 0 \|\| a->reg > NREG) {
	print("register out of range %d\n", a->reg);
	Bputc(f, ALAST+1);
	return; /* force real diagnostic */
	}

	if(a->type == D_CONST \|\| a->type == D_OCONST) {
	if(a->name == D_EXTERN \|\| a->name == D_STATIC) {
	s = a->sym;
	if(s != S && (s->type == STEXT \|\| s->type == SCONST \|\| s->type == SXREF)) {
	if(0 && !s->fnptr && s->name[0] != '.')
	print("%s used as function pointer\n", s->name);
	s->fnptr = 1; // over the top cos of SXREF
	}
	}
	}

	switch(a->type) {
	default:
	print("unknown type %d\n", a->type);
	Bputc(f, ALAST+1);
	return; /* force real diagnostic */

	case D_NONE:
	case D_REG:
	case D_FREG:
	case D_PSR:
	case D_FPCR:
	break;

	case D_REGREG:
	case D_REGREG2:
	a->offset = BGETC(f);
	break;

	case D_CONST2:
	a->offset2 = Bget4(f); // fall through
	case D_BRANCH:
	case D_OREG:
	case D_CONST:
	case D_OCONST:
	case D_SHIFT:
	a->offset = Bget4(f);
	break;

	case D_SCONST:
	a->sval = mal(NSNAME);
	Bread(f, a->sval, NSNAME);
	break;

	case D_FCONST:
	a->ieee.l = Bget4(f);
	a->ieee.h = Bget4(f);
	break;
	}
	s = a->sym;
	if(s == S)
	return;
	i = a->name;
	if(i != D_AUTO && i != 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 == i) {
	if(u->aoffset > l)
	u->aoffset = l;
	if(adrgotype)
	u->gotype = adrgotype;
	return;
	}

	u = mal(sizeof(Auto));
	u->link = curauto;
	curauto = u;
	u->asym = s;
	u->aoffset = l;
	u->type = i;
	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)
	{
	int32 ipc;
	Prog *p;
	Sym h[NSYM], s;
	int v, o, r, skip;
	uint32 sig;
	char *name;
	int ntext;
	int32 eof;
	char src[1024], *x;
	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;

	loop:
	if(f->state == Bracteof \|\| Boffset(f) >= eof)
	goto eof;
	o = BGETC(f);
	if(o == Beof)
	goto eof;

	if(o <= AXXX \|\| o >= ALAST) {
	diag("%s:#%lld: opcode out of range: %#ux", pn, Boffset(f), o);
	print(" probably not a .5 file\n");
	errorexit();
	}
	if(o == ANAME \|\| o == ASIGNAME) {
	sig = 0;
	if(o == ASIGNAME)
	sig = Bget4(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(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)) {
	fprint(2, "%s: mangled input file\n", pn);
	errorexit();
	}
	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(Prog));
	p->as = o;
	p->scond = BGETC(f);
	p->reg = BGETC(f);
	p->line = Bget4(f);

	zaddr(pn, f, &p->from, h);
	fromgotype = adrgotype;
	zaddr(pn, f, &p->to, h);

	if(p->as != ATEXT && p->as != AGLOBL && p->reg > NREG)
	diag("register out of range %A %d", p->as, p->reg);

	p->link = P;
	p->cond = P;

	if(debug['W'])
	print("%P\n", p);

	switch(o) {
	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' */
	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 == S) {
	diag("GLOBL must have a name\n%P", p);
	errorexit();
	}
	if(s->type == 0 \|\| s->type == SXREF) {
	s->type = SBSS;
	s->value = 0;
	}
	if(s->type != SBSS && s->type != SNOPTRBSS && !s->dupok) {
	diag("redefinition: %s\n%P", s->name, p);
	s->type = SBSS;
	s->value = 0;
	}
	if(p->to.offset > s->size)
	s->size = p->to.offset;
	if(p->reg & DUPOK)
	s->dupok = 1;
	if(p->reg & RODATA)
	s->type = SRODATA;
	else if(p->reg & NOPTR)
	s->type = SNOPTRBSS;
	break;

	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);
	break;

	case AGOK:
	diag("unknown opcode\n%P", p);
	p->pc = pc;
	pc++;
	break;

	case ALOCALS:
	if(skip)
	goto casedef;
	cursym->locals = p->to.offset;
	pc++;
	break;

	case ATYPE:
	if(skip)
	goto casedef;
	pc++;
	goto loop;

	case ATEXT:
	if(cursym != nil && cursym->text) {
	histtoauto();
	cursym->autom = curauto;
	curauto = 0;
	}
	s = p->from.sym;
	if(s == S) {
	diag("TEXT must have a name\n%P", p);
	errorexit();
	}
	cursym = s;
	if(s->type != 0 && s->type != SXREF && (p->reg & DUPOK)) {
	skip = 1;
	goto casedef;
	}
	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;
	}
	skip = 0;
	if(s->type != 0 && s->type != SXREF)
	diag("redefinition: %s\n%P", s->name, p);
	if(etextp)
	etextp->next = s;
	else
	textp = s;
	if(fromgotype) {
	if(s->gotype && s->gotype != fromgotype)
	diag("%s: type mismatch for %s", pn, s->name);
	s->gotype = fromgotype;
	}
	etextp = s;
	p->align = 4;
	autosize = (p->to.offset+3L) & ~3L;
	p->to.offset = autosize;
	autosize += 4;
	s->type = STEXT;
	s->text = p;
	s->value = pc;
	s->args = p->to.offset2;
	lastp = p;
	p->pc = pc;
	pc++;
	break;

	case ASUB:
	if(p->from.type == D_CONST)
	if(p->from.name == D_NONE)
	if(p->from.offset < 0) {
	p->from.offset = -p->from.offset;
	p->as = AADD;
	}
	goto casedef;

	case AADD:
	if(p->from.type == D_CONST)
	if(p->from.name == D_NONE)
	if(p->from.offset < 0) {
	p->from.offset = -p->from.offset;
	p->as = ASUB;
	}
	goto casedef;

	case AMOVWD:
	case AMOVWF:
	case AMOVDW:
	case AMOVFW:
	case AMOVFD:
	case AMOVDF:
	// case AMOVF:
	// case AMOVD:
	case ACMPF:
	case ACMPD:
	case AADDF:
	case AADDD:
	case ASUBF:
	case ASUBD:
	case AMULF:
	case AMULD:
	case ADIVF:
	case ADIVD:
	goto casedef;

	case AMOVF:
	if(skip)
	goto casedef;

	if(p->from.type == D_FCONST && chipfloat(&p->from.ieee) < 0 &&
	(chipzero(&p->from.ieee) < 0 \|\| (p->scond & C_SCOND) != C_SCOND_NONE)) {
	/* 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_OREG;
	p->from.sym = s;
	p->from.name = D_EXTERN;
	p->from.offset = 0;
	}
	goto casedef;

	case AMOVD:
	if(skip)
	goto casedef;

	if(p->from.type == D_FCONST && chipfloat(&p->from.ieee) < 0 &&
	(chipzero(&p->from.ieee) < 0 \|\| (p->scond & C_SCOND) != C_SCOND_NONE)) {
	/* 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_OREG;
	p->from.sym = s;
	p->from.name = D_EXTERN;
	p->from.offset = 0;
	}
	goto casedef;

	default:
	casedef:
	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);
	break;
	}
	lastp->link = p;
	lastp = p;
	break;
	}
	goto loop;

	eof:
	diag("truncated object file: %s", pn);
	}

	Prog*
	prg(void)
	{
	Prog *p;

	p = mal(sizeof(Prog));
	*p = zprg;
	return p;
	}

	Prog*
	appendp(Prog *q)
	{
	Prog *p;

	p = prg();
	p->link = q->link;
	q->link = p;
	p->line = q->line;
	return p;
	}