src/cmd/5l/span.c

// Inferno utils/5l/span.c
// http://code.google.com/p/inferno-os/source/browse/utils/5l/span.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.

#include	"l.h"
#include	"../ld/lib.h"

static struct {
	uint32	start;
	uint32	size;
	uint32	extra;
} pool;

int	checkpool(Prog*, int);
int 	flushpool(Prog*, int, int);

int
isbranch(Prog *p)
{
	int as = p->as;
	return (as >= ABEQ && as <= ABLE) || as == AB || as == ABL || as == ABX;
}

static int
ispad(Prog *p)
{
	if(p->as != AMOVW)
		return 0;
	if(p->from.type != D_REG || p->from.reg != REGSB)
		return 0;
	if(p->to.type != D_REG || p->to.reg != REGSB)
		return 0;
	return 1;
}

int
fninc(Sym *s)
{
	if(thumb){
		if(s->thumb){
			if(s->foreign)
				return 8;
			else
				return 0;
		}
		else{
			if(s->foreign)
				return 0;
			else
				diag("T A !foreign in fninc");
		}
	}
	else{
		if(s->thumb){
			if(s->foreign)
				return 0;
			else
				diag("A T !foreign in fninc");
		}
		else{
			if(s->foreign)
				return 4;
			else
				return 0;
		}
	}
	return 0;
}

int
fnpinc(Sym *s)
{
	if(!s->fnptr){	// a simplified case BX O(R) -> BL O(R)
		if(!debug['f'])
			diag("fnptr == 0 in fnpinc");
		if(s->foreign)
			diag("bad usage in fnpinc %s %d %d %d", s->name, s->used, s->foreign, s->thumb);
		return 0;
	}
	/* 0, 1, 2, 3 squared */
	if(s->thumb)
		return s->foreign ? 9 : 1;
	else
		return s->foreign ? 4 : 0;
}

static Prog *
pad(Prog *p, int pc)
{
	Prog *q;

	q = prg();
	q->as = AMOVW;
	q->line = p->line;
	q->from.type = D_REG;
	q->from.reg = REGSB;
	q->to.type = D_REG;
	q->to.reg = REGSB;
	q->pc = pc;
	q->link = p->link;
	return q;
}

static int
scan(Prog *op, Prog *p, int c)
{
	Prog *q;

	for(q = op->link; q != p; q = q->link){
		q->pc = c;
		c += oplook(q)->size;
		nocache(q);
	}
	return c;
}

/* size of a case statement including jump table */
static int32
casesz(Prog *p)
{
	int jt = 0;
	int32 n = 0;
	Optab *o;

	for( ; p != P; p = p->link){
		if(p->as == ABCASE)
			jt = 1;
		else if(jt)
			break;
		o = oplook(p);
		n += o->size;
	}
	return n;
}

void
span(void)
{
	Prog *p, *op;
	Sym *setext, *s;
	Optab *o;
	int m, bflag, i;
	int32 c, otxt, v;
	int lastthumb = -1;

	if(debug['v'])
		Bprint(&bso, "%5.2f span\n", cputime());
	Bflush(&bso);

	bflag = 0;
	c = INITTEXT;
	op = nil;
	otxt = c;
	for(p = firstp; p != P; op = p, p = p->link) {
		setarch(p);
		p->pc = c;
		o = oplook(p);
		m = o->size;
		// must check literal pool here in case p generates many instructions
		if(blitrl){
			if(thumb && isbranch(p))
				pool.extra += brextra(p);
			if(checkpool(op, p->as == ACASE ? casesz(p) : m))
				c = p->pc = scan(op, p, c);
		}
		if(m == 0) {
			if(p->as == ATEXT) {
				if(blitrl && lastthumb != -1 && lastthumb != thumb){	// flush literal pool
					if(flushpool(op, 0, 1))
						c = p->pc = scan(op, p, c);
				}
				lastthumb = thumb;
				curtext = p;
				autosize = p->to.offset + 4;
				if(p->from.sym != S)
					p->from.sym->value = c;
				/* need passes to resolve branches */
				if(c-otxt >= 1L<<17)
					bflag = 1;
				otxt = c;
				if(thumb && blitrl)
					pool.extra += brextra(p);
				continue;
			}
			diag("zero-width instruction\n%P", p);
			continue;
		}
		switch(o->flag & (LFROM|LTO|LPOOL)) {
		case LFROM:
			addpool(p, &p->from);
			break;
		case LTO:
			addpool(p, &p->to);
			break;
		case LPOOL:
			if ((p->scond&C_SCOND) == 14)
				flushpool(p, 0, 0);
			break;
		}
		if(p->as==AMOVW && p->to.type==D_REG && p->to.reg==REGPC && (p->scond&C_SCOND) == 14)
			flushpool(p, 0, 0);
		c += m;
		if(blitrl && p->link == P){
			if(thumb && isbranch(p))
				pool.extra += brextra(p);
			checkpool(p, 0);
		}
	}

	/*
	 * if any procedure is large enough to
	 * generate a large SBRA branch, then
	 * generate extra passes putting branches
	 * around jmps to fix. this is rare.
	 */
	while(bflag) {
		if(debug['v'])
			Bprint(&bso, "%5.2f span1\n", cputime());
		bflag = 0;
		c = INITTEXT;
		for(p = firstp; p != P; p = p->link) {
			setarch(p);
			p->pc = c;
			if(thumb && isbranch(p))
				nocache(p);
			o = oplook(p);
/* very larg branches
			if(o->type == 6 && p->cond) {
				otxt = p->cond->pc - c;
				if(otxt < 0)
					otxt = -otxt;
				if(otxt >= (1L<<17) - 10) {
					q = prg();
					q->link = p->link;
					p->link = q;
					q->as = AB;
					q->to.type = D_BRANCH;
					q->cond = p->cond;
					p->cond = q;
					q = prg();
					q->link = p->link;
					p->link = q;
					q->as = AB;
					q->to.type = D_BRANCH;
					q->cond = q->link->link;
					bflag = 1;
				}
			}
 */
			m = o->size;
			if(m == 0) {
				if(p->as == ATEXT) {
					curtext = p;
					autosize = p->to.offset + 4;
					if(p->from.sym != S)
						p->from.sym->value = c;
					continue;
				}
				diag("zero-width instruction\n%P", p);
				continue;
			}
			c += m;
		}
	}

	if(seenthumb){		// branch resolution
		int passes = 0;
		int lastc = 0;
		int again;
		Prog *oop;

	loop:
		passes++;
		if(passes > 100){
			diag("span looping !");
			errorexit();
		}
		c = INITTEXT;
		oop = op = nil;
		again = 0;
		for(p = firstp; p != P; oop = op, op = p, p = p->link){
			setarch(p);
			if(p->pc != c)
				again = 1;
			p->pc = c;
			if(thumb && isbranch(p))
				nocache(p);
			o = oplook(p);
			m = o->size;
			if(passes == 1 && thumb && isbranch(p)){	// start conservative so unneeded alignment is not added
				if(p->as == ABL)
					m = 4;
				else
					m = 2;
				p->align = 0;
			}
			if(p->align){
				if((p->align == 4 && (c&3)) || (p->align == 2 && !(c&3))){
					if(ispad(op)){
						oop->link = p;
						op = oop;
						c -= 2;
						p->pc = c;
					}
					else{
						op->link = pad(op, c);
						op = op->link;
						c += 2;
						p->pc = c;
					}
					again = 1;
				}
			}
			if(m == 0) {
				if(p->as == ATEXT) {
					curtext = p;
					autosize = p->to.offset + 4;
					if(p->from.sym != S)
						p->from.sym->value = c;
					continue;
				}
			}
			c += m;
		}
		if(c != lastc || again){
			lastc = c;
			goto loop;
		}
	}

	if(0 && seenthumb){		// rm redundant padding - obsolete
		int d;

		op = nil;
		d = 0;
		for(p = firstp; p != P; op = p, p = p->link){
			p->pc -= d;
			if(p->as == ATEXT){
				if(p->from.sym != S)
					p->from.sym->value -= d;
// if(p->from.sym != S) print("%s %ux %d %d %d\n", p->from.sym->name ? p->from.sym->name : "?", p->from.sym->value, p->from.sym->thumb, p->from.sym->foreign, p->from.sym->fnptr);
			}
			if(ispad(p) && p->link != P && ispad(p->link)){
				op->link = p->link->link;
				d += 4;
				p = op;
			}
		}
		// print("%d bytes removed (padding)\n", d);
		c -= d;
	}

	if(debug['t']) {
		/*
		 * add strings to text segment
		 */
		c = rnd(c, 8);
		for(i=0; i<NHASH; i++)
		for(s = hash[i]; s != S; s = s->link) {
			if(s->type != SSTRING)
				continue;
			v = s->value;
			while(v & 3)
				v++;
			s->value = c;
			c += v;
		}
	}

	c = rnd(c, 8);

	setext = lookup("etext", 0);
	if(setext != S) {
		setext->value = c;
		textsize = c - INITTEXT;
	}
	if(INITRND)
		INITDAT = rnd(c, INITRND);
	if(debug['v'])
		Bprint(&bso, "tsize = %lux\n", textsize);
	Bflush(&bso);
}

/*
 * when the first reference to the literal pool threatens
 * to go out of range of a 12-bit PC-relative offset,
 * drop the pool now, and branch round it.
 * this happens only in extended basic blocks that exceed 4k.
 */
int
checkpool(Prog *p, int sz)
{
	if(thumb){
		if(pool.size >= 0x3fc || (p->pc+sz+pool.extra+2+2)+(pool.size-4)-pool.start-4 >= 0x3fc)
			return flushpool(p, 1, 0);
		else if(p->link == P)
			return flushpool(p, 2, 0);
		return 0;
	}
	if(pool.size >= 0xffc || immaddr((p->pc+sz+4)+4+pool.size - pool.start+8) == 0)
		return flushpool(p, 1, 0);
	else if(p->link == P)
		return flushpool(p, 2, 0);
	return 0;
}

int
flushpool(Prog *p, int skip, int force)
{
	Prog *q;

	if(blitrl) {
		if(skip){
			if(0 && skip==1)print("note: flush literal pool at %lux: len=%lud ref=%lux\n", p->pc+4, pool.size, pool.start);
			q = prg();
			q->as = AB;
			q->to.type = D_BRANCH;
			q->cond = p->link;
			q->link = blitrl;
			blitrl = q;
		}
		else if(!force && (p->pc+pool.size-pool.start < (thumb ? 0x3fc+4-pool.extra : 2048)))
			return 0;
		elitrl->link = p->link;
		p->link = blitrl;
		blitrl = 0;	/* BUG: should refer back to values until out-of-range */
		elitrl = 0;
		pool.size = 0;
		pool.start = 0;
		pool.extra = 0;
		return 1;
	}
	return 0;
}

void
addpool(Prog *p, Adr *a)
{
	Prog *q, t;
	int c;

	if(thumb)
		c = thumbaclass(a, p);
	else
		c = aclass(a);

	t = zprg;
	t.as = AWORD;

	switch(c) {
	default:
		t.to = *a;
		break;

	case	C_SROREG:
	case C_LOREG:
	case C_ROREG:
	case C_FOREG:
	case C_SOREG:
	case C_HOREG:
	case C_GOREG:
	case C_FAUTO:
	case C_SAUTO:
	case C_LAUTO:
	case C_LACON:
	case C_GACON:
		t.to.type = D_CONST;
		t.to.offset = instoffset;
		break;
	}

	for(q = blitrl; q != P; q = q->link)	/* could hash on t.t0.offset */
		if(memcmp(&q->to, &t.to, sizeof(t.to)) == 0) {
			p->cond = q;
			return;
		}

	q = prg();
	*q = t;
	q->pc = pool.size;

	if(blitrl == P) {
		blitrl = q;
		pool.start = p->pc;
		q->align = 4;
	} else
		elitrl->link = q;
	elitrl = q;
	pool.size += 4;

	p->cond = q;
}

void
xdefine(char *p, int t, int32 v)
{
	Sym *s;

	s = lookup(p, 0);
	if(s->type == 0 || s->type == SXREF) {
		s->type = t;
		s->value = v;
	}
}

int32
regoff(Adr *a)
{

	instoffset = 0;
	aclass(a);
	return instoffset;
}

int32
immrot(uint32 v)
{
	int i;

	for(i=0; i<16; i++) {
		if((v & ~0xff) == 0)
			return (i<<8) | v | (1<<25);
		v = (v<<2) | (v>>30);
	}
	return 0;
}

int32
immaddr(int32 v)
{
	if(v >= 0 && v <= 0xfff)
		return (v & 0xfff) |
			(1<<24) |	/* pre indexing */
			(1<<23);	/* pre indexing, up */
	if(v >= -0xfff && v < 0)
		return (-v & 0xfff) |
			(1<<24);	/* pre indexing */
	return 0;
}

int
immfloat(int32 v)
{
	return (v & 0xC03) == 0;	/* offset will fit in floating-point load/store */
}

int
immhalf(int32 v)
{
	if(v >= 0 && v <= 0xff)
		return v|
			(1<<24)|	/* pre indexing */
			(1<<23);	/* pre indexing, up */
	if(v >= -0xff && v < 0)
		return (-v & 0xff)|
			(1<<24);	/* pre indexing */
	return 0;
}

int
aclass(Adr *a)
{
	Sym *s;
	int t;

	switch(a->type) {
	case D_NONE:
		return C_NONE;

	case D_REG:
		return C_REG;

	case D_REGREG:
		return C_REGREG;

	case D_SHIFT:
		return C_SHIFT;

	case D_FREG:
		return C_FREG;

	case D_FPCR:
		return C_FCR;

	case D_OREG:
		switch(a->name) {
		case D_EXTERN:
		case D_STATIC:
			if(a->sym == 0 || a->sym->name == 0) {
				print("null sym external\n");
				print("%D\n", a);
				return C_GOK;
			}
			s = a->sym;
			t = s->type;
			if(t == 0 || t == SXREF) {
				diag("undefined external: %s in %s",
					s->name, TNAME);
				s->type = SDATA;
			}
			if(dlm) {
				switch(t) {
				default:
					instoffset = s->value + a->offset + INITDAT;
					break;
				case SUNDEF:
				case STEXT:
				case SCONST:
				case SLEAF:
				case SSTRING:
					instoffset = s->value + a->offset;
					break;
				}
				return C_ADDR;
			}
			instoffset = s->value + a->offset - BIG;
			t = immaddr(instoffset);
			if(t) {
				if(immhalf(instoffset))
					return immfloat(t) ? C_HFEXT : C_HEXT;
				if(immfloat(t))
					return C_FEXT;
				return C_SEXT;
			}
			return C_LEXT;
		case D_AUTO:
			instoffset = autosize + a->offset;
			t = immaddr(instoffset);
			if(t){
				if(immhalf(instoffset))
					return immfloat(t) ? C_HFAUTO : C_HAUTO;
				if(immfloat(t))
					return C_FAUTO;
				return C_SAUTO;
			}
			return C_LAUTO;

		case D_PARAM:
			instoffset = autosize + a->offset + 4L;
			t = immaddr(instoffset);
			if(t){
				if(immhalf(instoffset))
					return immfloat(t) ? C_HFAUTO : C_HAUTO;
				if(immfloat(t))
					return C_FAUTO;
				return C_SAUTO;
			}
			return C_LAUTO;
		case D_NONE:
			instoffset = a->offset;
			t = immaddr(instoffset);
			if(t) {
				if(immhalf(instoffset))		 /* n.b. that it will also satisfy immrot */
					return immfloat(t) ? C_HFOREG : C_HOREG;
				if(immfloat(t))
					return C_FOREG; /* n.b. that it will also satisfy immrot */
				t = immrot(instoffset);
				if(t)
					return C_SROREG;
				if(immhalf(instoffset))
					return C_HOREG;
				return C_SOREG;
			}
			t = immrot(instoffset);
			if(t)
				return C_ROREG;
			return C_LOREG;
		}
		return C_GOK;

	case D_PSR:
		return C_PSR;

	case D_OCONST:
		switch(a->name) {
		case D_EXTERN:
		case D_STATIC:
			s = a->sym;
			t = s->type;
			if(t == 0 || t == SXREF) {
				diag("undefined external: %s in %s",
					s->name, TNAME);
				s->type = SDATA;
			}
			if(s->type == SFIXED) {
				instoffset = s->value + a->offset;
				return C_LCON;
			}
			instoffset = s->value + a->offset + INITDAT;
			if(s->type == STEXT || s->type == SLEAF || s->type == SUNDEF) {
				instoffset = s->value + a->offset;
#ifdef CALLEEBX
				instoffset += fnpinc(s);
#else
				if(s->thumb)
					instoffset++;	// T bit
#endif
				return C_LCON;
			}
			return C_LCON;
		}
		return C_GOK;

	case D_FCONST:
		return C_FCON;

	case D_CONST:
	case D_CONST2:
		switch(a->name) {

		case D_NONE:
			instoffset = a->offset;
			if(a->reg != NREG)
				goto aconsize;

			t = immrot(instoffset);
			if(t)
				return C_RCON;
			t = immrot(~instoffset);
			if(t)
				return C_NCON;
			return C_LCON;

		case D_EXTERN:
		case D_STATIC:
			s = a->sym;
			if(s == S)
				break;
			t = s->type;
			switch(t) {
			case 0:
			case SXREF:
				diag("undefined external: %s in %s",
					s->name, TNAME);
				s->type = SDATA;
				break;
			case SFIXED:
				instoffset = s->value + a->offset;
				return C_LCON;
			case SUNDEF:
			case STEXT:
			case SSTRING:
			case SCONST:
			case SLEAF:
				instoffset = s->value + a->offset;
#ifdef CALLEEBX
				instoffset += fnpinc(s);
#else
				if(s->thumb)
					instoffset++;	// T bit
#endif
				return C_LCON;
			}
			if(!dlm) {
				instoffset = s->value + a->offset - BIG;
				t = immrot(instoffset);
				if(t && instoffset != 0)
					return C_RECON;
			}
			instoffset = s->value + a->offset + INITDAT;
			return C_LCON;

		case D_AUTO:
			instoffset = autosize + a->offset;
			goto aconsize;

		case D_PARAM:
			instoffset = autosize + a->offset + 4L;
		aconsize:
			t = immrot(instoffset);
			if(t)
				return C_RACON;
			return C_LACON;
		}
		return C_GOK;

	case D_BRANCH:
		return C_SBRA;
	}
	return C_GOK;
}

Optab*
oplook(Prog *p)
{
	int a1, a2, a3, r;
	char *c1, *c3;
	Optab *o, *e;
	Optab *otab;
	Oprang *orange;

	if(thumb){
		otab = thumboptab;
		orange = thumboprange;
	}
	else{
		otab = optab;
		orange = oprange;
	}
	a1 = p->optab;
	if(a1)
		return otab+(a1-1);
	a1 = p->from.class;
	if(a1 == 0) {
		if(thumb)
			a1 = thumbaclass(&p->from, p) + 1;
		else
			a1 = aclass(&p->from) + 1;
		p->from.class = a1;
	}
	a1--;
	a3 = p->to.class;
	if(a3 == 0) {
		if(thumb)
			a3 = thumbaclass(&p->to, p) + 1;
		else
			a3 = aclass(&p->to) + 1;
		p->to.class = a3;
	}
	a3--;
	a2 = C_NONE;
	if(p->reg != NREG)
		a2 = C_REG;
	r = p->as;
	o = orange[r].start;
	if(o == 0) {
		a1 = opcross[repop[r]][a1][a2][a3];
		if(a1) {
			p->optab = a1+1;
			return otab+a1;
		}
		o = orange[r].stop; /* just generate an error */
	}
	if(debug['O']) {
		print("oplook %A %O %O %O\n",
			(int)p->as, a1, a2, a3);
		print("		%d %d\n", p->from.type, p->to.type);
	}
	e = orange[r].stop;
	c1 = xcmp[a1];
	c3 = xcmp[a3];
	for(; o<e; o++)
		if(o->a2 == a2)
		if(c1[o->a1])
		if(c3[o->a3]) {
			p->optab = (o-otab)+1;
			return o;
		}
	diag("illegal combination %A %O %O %O, %d %d",
		p->as, a1, a2, a3, p->from.type, p->to.type);
	prasm(p);
	if(o == 0)
		o = otab;
	return o;
}

int
cmp(int a, int b)
{

	if(a == b)
		return 1;
	switch(a) {
	case C_LCON:
		if(b == C_RCON || b == C_NCON)
			return 1;
		break;
	case C_LACON:
		if(b == C_RACON)
			return 1;
		break;
	case C_LECON:
		if(b == C_RECON)
			return 1;
		break;

	case C_HFEXT:
		return b == C_HEXT || b == C_FEXT;
	case C_FEXT:
	case C_HEXT:
		return b == C_HFEXT;
	case C_SEXT:
		return cmp(C_HFEXT, b);
	case C_LEXT:
		return cmp(C_SEXT, b);

	case C_HFAUTO:
		return b == C_HAUTO || b == C_FAUTO;
	case C_FAUTO:
	case C_HAUTO:
		return b == C_HFAUTO;
	case C_SAUTO:
		return cmp(C_HFAUTO, b);
	case C_LAUTO:
		return cmp(C_SAUTO, b);

	case C_HFOREG:
		return b == C_HOREG || b == C_FOREG;
	case C_FOREG:
	case C_HOREG:
		return b == C_HFOREG;
	case C_SROREG:
		return cmp(C_SOREG, b) || cmp(C_ROREG, b);
	case C_SOREG:
	case C_ROREG:
		return b == C_SROREG || cmp(C_HFOREG, b);
	case C_LOREG:
		return cmp(C_SROREG, b);

	case C_LBRA:
		if(b == C_SBRA)
			return 1;
		break;
	case C_GBRA:
		if(b == C_SBRA || b == C_LBRA)
			return 1;

	case C_HREG:
		return cmp(C_SP, b) || cmp(C_PC, b);

	}
	return 0;
}

int
ocmp(const void *a1, const void *a2)
{
	Optab *p1, *p2;
	int n;

	p1 = (Optab*)a1;
	p2 = (Optab*)a2;
	n = p1->as - p2->as;
	if(n)
		return n;
	n = (p2->flag&V4) - (p1->flag&V4);	/* architecture version */
	if(n)
		return n;
	n = p1->a1 - p2->a1;
	if(n)
		return n;
	n = p1->a2 - p2->a2;
	if(n)
		return n;
	n = p1->a3 - p2->a3;
	if(n)
		return n;
	return 0;
}

void
buildop(void)
{
	int i, n, r;

	armv4 = !debug['h'];
	for(i=0; i<C_GOK; i++)
		for(n=0; n<C_GOK; n++)
			xcmp[i][n] = cmp(n, i);
	for(n=0; optab[n].as != AXXX; n++)
		if((optab[n].flag & V4) && !armv4) {
			optab[n].as = AXXX;
			break;
		}
	qsort(optab, n, sizeof(optab[0]), ocmp);
	for(i=0; i<n; i++) {
		r = optab[i].as;
		oprange[r].start = optab+i;
		while(optab[i].as == r)
			i++;
		oprange[r].stop = optab+i;
		i--;

		switch(r)
		{
		default:
			diag("unknown op in build: %A", r);
			errorexit();
		case AADD:
			oprange[AAND] = oprange[r];
			oprange[AEOR] = oprange[r];
			oprange[ASUB] = oprange[r];
			oprange[ARSB] = oprange[r];
			oprange[AADC] = oprange[r];
			oprange[ASBC] = oprange[r];
			oprange[ARSC] = oprange[r];
			oprange[AORR] = oprange[r];
			oprange[ABIC] = oprange[r];
			break;
		case ACMP:
			oprange[ATST] = oprange[r];
			oprange[ATEQ] = oprange[r];
			oprange[ACMN] = oprange[r];
			break;
		case AMVN:
			break;
		case ABEQ:
			oprange[ABNE] = oprange[r];
			oprange[ABCS] = oprange[r];
			oprange[ABHS] = oprange[r];
			oprange[ABCC] = oprange[r];
			oprange[ABLO] = oprange[r];
			oprange[ABMI] = oprange[r];
			oprange[ABPL] = oprange[r];
			oprange[ABVS] = oprange[r];
			oprange[ABVC] = oprange[r];
			oprange[ABHI] = oprange[r];
			oprange[ABLS] = oprange[r];
			oprange[ABGE] = oprange[r];
			oprange[ABLT] = oprange[r];
			oprange[ABGT] = oprange[r];
			oprange[ABLE] = oprange[r];
			break;
		case ASLL:
			oprange[ASRL] = oprange[r];
			oprange[ASRA] = oprange[r];
			break;
		case AMUL:
			oprange[AMULU] = oprange[r];
			break;
		case ADIV:
			oprange[AMOD] = oprange[r];
			oprange[AMODU] = oprange[r];
			oprange[ADIVU] = oprange[r];
			break;
		case AMOVW:
		case AMOVB:
		case AMOVBU:
		case AMOVH:
		case AMOVHU:
			break;
		case ASWPW:
			oprange[ASWPBU] = oprange[r];
			break;
		case AB:
		case ABL:
		case ABX:
		case ABXRET:
		case ASWI:
		case AWORD:
		case AMOVM:
		case ARFE:
		case ATEXT:
		case ACASE:
		case ABCASE:
			break;
		case AADDF:
			oprange[AADDD] = oprange[r];
			oprange[ASUBF] = oprange[r];
			oprange[ASUBD] = oprange[r];
			oprange[AMULF] = oprange[r];
			oprange[AMULD] = oprange[r];
			oprange[ADIVF] = oprange[r];
			oprange[ADIVD] = oprange[r];
			oprange[AMOVFD] = oprange[r];
			oprange[AMOVDF] = oprange[r];
			break;

		case ACMPF:
			oprange[ACMPD] = oprange[r];
			break;

		case AMOVF:
			oprange[AMOVD] = oprange[r];
			break;

		case AMOVFW:
			oprange[AMOVWF] = oprange[r];
			oprange[AMOVWD] = oprange[r];
			oprange[AMOVDW] = oprange[r];
			break;

		case AMULL:
			oprange[AMULA] = oprange[r];
			oprange[AMULAL] = oprange[r];
			oprange[AMULLU] = oprange[r];
			oprange[AMULALU] = oprange[r];
			break;
		case ALDREX:
		case ASTREX:
			break;
		}
	}
}

/*
void
buildrep(int x, int as)
{
	Opcross *p;
	Optab *e, *s, *o;
	int a1, a2, a3, n;

	if(C_NONE != 0 || C_REG != 1 || C_GOK >= 32 || x >= nelem(opcross)) {
		diag("assumptions fail in buildrep");
		errorexit();
	}
	repop[as] = x;
	p = (opcross + x);
	s = oprange[as].start;
	e = oprange[as].stop;
	for(o=e-1; o>=s; o--) {
		n = o-optab;
		for(a2=0; a2<2; a2++) {
			if(a2) {
				if(o->a2 == C_NONE)
					continue;
			} else
				if(o->a2 != C_NONE)
					continue;
			for(a1=0; a1<32; a1++) {
				if(!xcmp[a1][o->a1])
					continue;
				for(a3=0; a3<32; a3++)
					if(xcmp[a3][o->a3])
						(*p)[a1][a2][a3] = n;
			}
		}
	}
	oprange[as].start = 0;
}
*/

enum{
	ABSD = 0,
	ABSU = 1,
	RELD = 2,
	RELU = 3,
};

int modemap[4] = { 0, 1, -1, 2, };

typedef struct Reloc Reloc;

struct Reloc
{
	int n;
	int t;
	uchar *m;
	uint32 *a;
};

Reloc rels;

static void
grow(Reloc *r)
{
	int t;
	uchar *m, *nm;
	uint32 *a, *na;

	t = r->t;
	r->t += 64;
	m = r->m;
	a = r->a;
	r->m = nm = malloc(r->t*sizeof(uchar));
	r->a = na = malloc(r->t*sizeof(uint32));
	memmove(nm, m, t*sizeof(uchar));
	memmove(na, a, t*sizeof(uint32));
	free(m);
	free(a);
}

void
dynreloc(Sym *s, int32 v, int abs)
{
	int i, k, n;
	uchar *m;
	uint32 *a;
	Reloc *r;

	if(v&3)
		diag("bad relocation address");
	v >>= 2;
	if(s != S && s->type == SUNDEF)
		k = abs ? ABSU : RELU;
	else
		k = abs ? ABSD : RELD;
	/* Bprint(&bso, "R %s a=%ld(%lx) %d\n", s->name, a, a, k); */
	k = modemap[k];
	r = &rels;
	n = r->n;
	if(n >= r->t)
		grow(r);
	m = r->m;
	a = r->a;
	for(i = n; i > 0; i--){
		if(v < a[i-1]){	/* happens occasionally for data */
			m[i] = m[i-1];
			a[i] = a[i-1];
		}
		else
			break;
	}
	m[i] = k;
	a[i] = v;
	r->n++;
}

static int
sput(char *s)
{
	char *p;

	p = s;
	while(*s)
		cput(*s++);
	cput(0);
	return  s-p+1;
}

void
asmdyn()
{
	int i, n, t, c;
	Sym *s;
	uint32 la, ra, *a;
	vlong off;
	uchar *m;
	Reloc *r;

	cflush();
	off = seek(cout, 0, 1);
	lput(0);
	t = 0;
	lput(imports);
	t += 4;
	for(i = 0; i < NHASH; i++)
		for(s = hash[i]; s != S; s = s->link)
			if(s->type == SUNDEF){
				lput(s->sig);
				t += 4;
				t += sput(s->name);
			}

	la = 0;
	r = &rels;
	n = r->n;
	m = r->m;
	a = r->a;
	lput(n);
	t += 4;
	for(i = 0; i < n; i++){
		ra = *a-la;
		if(*a < la)
			diag("bad relocation order");
		if(ra < 256)
			c = 0;
		else if(ra < 65536)
			c = 1;
		else
			c = 2;
		cput((c<<6)|*m++);
		t++;
		if(c == 0){
			cput(ra);
			t++;
		}
		else if(c == 1){
			wput(ra);
			t += 2;
		}
		else{
			lput(ra);
			t += 4;
		}
		la = *a++;
	}

	cflush();
	seek(cout, off, 0);
	lput(t);

	if(debug['v']){
		Bprint(&bso, "import table entries = %d\n", imports);
		Bprint(&bso, "export table entries = %d\n", exports);
	}
}