[unix-history] / usr / src / old / as.vax / asjxxx.c

/* Copyright (c) 1980 Regents of the University of California */
static	char sccsid[] = "@(#)asjxxx.c 4.3 %G%";
#include	<stdio.h>
#include	"as.h"
#include	"assyms.h"

#define	JBR	0x11
#define	BRW	0x31
#define	JMP	0x17

/*
 *	The number of bytes to add if the jxxx must be "exploded"
 *	into the long form
 */
#define	JBRDELTA	1	/* brb <byte> ==> brw <byte> <byte> */
#define	JXXXDELTA	3	/* brb <byte> ==> brb <byte> brw <byte> <byte> */
#define	JBRJDELTA	d124	/* brb <byte> ==> jmp L^(pc) <byte>*d124 */
#define	JXXXJDELTA	d124+2	/* brb <byte> ==> brb <byte> jmp L^(pc) <byte>*d124 */

int	jbrfsize = JBRDELTA;
int	jxxxfsize = JXXXDELTA;

/*
 *	These variables are filled by asscan.c with the
 *	last name encountered (a pointer buried in the intermediate file),
 *	and the last jxxx symbol table entry encountered.
 */
struct 	symtab	*lastnam;
struct	symtab	*lastjxxx;

initijxxx()
{
	jbrfsize = jxxxJUMP ? JBRJDELTA : JBRDELTA;
	jxxxfsize = jxxxJUMP ? JXXXJDELTA : JXXXDELTA;
	/*
	 *	Note: ifjxxxJUMP is set, then we do NOT do any tunnelling;
	 *	this was too complicated to figure out, and in the first
	 *	version of the assembler, tunnelling proved to be the hardest
	 *	to get to work!
	 */
}
/*
 *	Handle jxxx instructions
 */
ijxout(op,ap,nact)
	struct arg *ap;
{
	if (passno == 1){
		/*
		 *	READ THIS BEFORE LOOKING AT jxxxfix()
		 *
		 *	Record the jxxx in a special symbol table entry
		 */
		register struct symtab *jumpfrom;

		/*
		 *	We assume the MINIMAL length
		 */
		putins(op,ap,nact); 
		jumpfrom = lastjxxx;
		jumpfrom->s_tag = JXACTIVE;
		jumpfrom->s_jxbump = 0;
		if (op == JBR)
			jumpfrom->s_jxfear = jbrfsize;
		else
			jumpfrom->s_jxfear = jxxxfsize;
		if (lastnam == 0)
			yyerror("jxxx destination not a label");
		jumpfrom->s_dest = lastnam;
		jumpfrom->s_type = dotp->e_xtype;	/*only TEXT or DATA*/
		jumpfrom->s_index = dotp-usedot;
		/*
		 *	value ALWAYS (ALWAYS!!!) indexes the next instruction
		 *	after the jump, even in the jump must be exploded
		 *	(bumped)
		 */
		jumpfrom->s_value = dotp->e_xvalue;
		njxxx++;
	} else {/* pass2, resolve */
		/*
		 *	READ THIS AFTER LOOKING AT jxxxfix()
		 */
		register long		oxvalue;
		register struct	exp 	*xp; 
		register struct symtab	*tunnel;
		register struct arg	*aplast;

		aplast = ap + nact - 1;
		xp = aplast->a_xp;
		if (lastjxxx->s_tag == JXTUNNEL){
			lastjxxx->s_tag = JXINACTIVE;
			tunnel = lastjxxx->s_dest;
			xp->e_xvalue = tunnel->s_value	/*index of instruction following*/
				    - 3			/* size of brw + word*/
				    + ( ( (tunnel->s_jxfear == jbrfsize) &&
					  (tunnel->s_jxbump == 0))?1:0);
							/*non bumped branch byteis only 2 back*/
		}
		if (lastjxxx->s_jxbump == 0){	/*wasn't bumped, so is short form*/
			putins(op, ap, nact);
		} else {
			if (op != JBR){	/*branch reverse conditional byte over 
					  branch unconditional word*/
				oxvalue = xp->e_xvalue;
				xp->e_xvalue = lastjxxx->s_value;
				putins(op^1, ap, nact);
				xp->e_xvalue = oxvalue;
			}
			putins(jxxxJUMP ? JMP : BRW, aplast, 1);
		}
	}
}	/*end of ijxout*/

jalign(xp, sp)
	register struct exp *xp;
	register struct symtab *sp;
{
	register	int	mask;
	if (xp->e_xtype != XABS || xp->e_xvalue < 0 || xp->e_xvalue > 16) {
		yyerror("Illegal `align' argument");
		return;
	}
	flushfield(NBPW/4);
	if (passno == 1) {
		sp->s_tag = JXALIGN;
		sp->s_jxfear = (1 << xp->e_xvalue) - 1;
		sp->s_type = dotp->e_xtype;
		sp->s_index = dotp-usedot;
		/*
		 *	We guess that the align will take up at least one
		 *	byte in the code output.  We will correct for this
		 *	initial high guess when we explode (bump) aligns
		 *	when we fix the jxxxes.  We must do this guess
		 *	so that the symbol table is sorted correctly
		 *	and labels declared to fall before the align
		 *	really get their, instead of guessing zero size
		 *	and have the label (incorrectly) fall after the jxxx.
		 *	This is a quirk of our requirement that indices into
		 *	the code stream point to the next byte following
		 *	the logical entry in the symbol table
		 */
		dotp->e_xvalue += 1;
		sp->s_value = dotp->e_xvalue;
		njxxx++;
	} else {
		mask = (1 << xp->e_xvalue) - 1;
		while (dotp->e_xvalue & mask){
#ifdef UNIX
			outb(0);
#endif UNIX
#ifdef VMS
			*vms_obj_ptr++ = -1;
			*vms_obj_ptr++ = 0;
			dotp->e_xvalue += 1;
#endif VMS
		}
	}
}

/*
 *	Pass 1.5, resolve jxxx instructions and .align in .text
 */
jxxxfix() 
{
	register struct symtab 	*jumpfrom;
		 struct symtab	**cojumpfrom, *ubjumpfrom;
	register struct symtab 	*dest;
	register struct symtab	*intdest;	/*intermediate dest*/
	register struct symtab	**cointdest, *ubintdest;

	register struct symtab 	*tunnel;
	 	 int 		displ,nchange;
		 int		badjxalign;	/*if jump across an align*/
		 int		stillactives;	/*if still active jxxxes*/
		 int		segno;		/*current segment number*/
		 int		topono;		/*which iteration in the topo sort*/
	register unsigned char	tag;
	/*
	 *	consider each segment in turn...
	 */
	for (segno = 0; segno < NLOC + NLOC; segno++){
	    badjxalign = 0;		/*done on a per segment basis*/
	    /*
	     *	Do a lazy topological sort.
	     */
	    for (topono = 1, nchange = 1; nchange != 0; topono++){
#ifdef DEBUG
		if (debug)
			printf("\nSegment %d, topo iteration %d\n",
				segno, topono);
#endif
		nchange = 0;
		stillactives = 0;
		/*
		 *	We keep track of one possible tunnel location.
		 *	A tunnel will eventually be an unconditional
		 *	branch to the same place that another jxxx
		 *	will want to branch to.  We will turn a
		 *	branch conditional/unconditional (word) that would
		 *	have to get bumped because its destination is too
		 *	far away, into a branch conditional/unconditional
		 *	byte to the tunnel branch conditional/unconditional.
		 *	Of course, the tunnel must branch to the same place
		 *	as we want to go.
		 */
		tunnel = 0;	/*initially, no tunnel*/
		SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, ubjumpfrom, ++){
			tag = jumpfrom->s_tag;
			if (tag <= IGNOREBOUND)
				continue;	/*just an ordinary symbol*/
			if (tag == JXALIGN){
				tunnel = 0;	/*avoid tunneling across a flex alocation*/
				continue;	/*we take care of these later*/
			}
			if (   jumpfrom->s_jxfear == jbrfsize	/*unconditional*/
			    || (   tag == JXINACTIVE		/*inactive bumped*/
				&& (jumpfrom->s_jxbump != 0)
			       )
			   ) tunnel = jumpfrom;
			if (tag != JXACTIVE)
				continue;
			dest = jumpfrom->s_dest;
			if (jumpfrom->s_index != dest->s_index){
				yyerror("Intersegment jxxx");
				continue;
			}
			displ = dest->s_value - jumpfrom->s_value;
			if (displ < MINBYTE || displ > MAXBYTE) {
				/*
				 *	This is an immediate lose!
				 *
				 *	We first attempt to tunnel
				 *	by finding an intervening jump that
				 *	has  the same destination.
				 *	The tunnel is always the first preceeding
				 *	jxxx instruction, so the displacement
				 *	to the tunnel is less than zero, and
				 *	its relative position will be unaffected
				 *	by future jxxx expansions.
				 *
				 *	No tunnels if doing jumps...
				 */
				if (    (!jxxxJUMP)
				     && (jumpfrom->s_jxfear > jbrfsize)
				     && (tunnel) 
				     && (tunnel->s_dest == jumpfrom->s_dest)	
				     && (tunnel->s_index == jumpfrom->s_index)
				     && (tunnel->s_value - jumpfrom->s_value >=
						MINBYTE + jxxxfsize)
				   ) {
						/*
						 *	tunnelling is OK
						 */
						jumpfrom->s_dest = tunnel;
						/*
						 * no bumping needed, this
						 * is now effectively inactive
						 * but must be remembered
						 */
						jumpfrom->s_tag = JXTUNNEL;
#ifdef DEBUG
						if(debug)
						printf("Tunnel from %s from line %d\n",
							jumpfrom->s_name, lineno);
#endif
						continue;
				} else {	/*tunneling not possible*/
					/*
					 *	since this will be turned
					 *	into a bumped jump, we can
					 *	use the unconditional jump
					 *	as a tunnel
					 */
					tunnel = jumpfrom;
					jumpfrom->s_tag = JXNOTYET;
					++nchange;
					continue;
				}
			}	/*end of immediate lose*/
			/*
			 *	Do a forward search for an intervening jxxx
			 */
			if (displ >= 0) {
				SEGITERATE(segno, cojumpfrom + 1,0,cointdest,
						intdest, ubintdest, ++){
					if (intdest->s_value > dest->s_value) 
						break; /* beyond destination */
					if (intdest->s_tag <= JXQUESTIONABLE)
						continue;	/*frozen solid*/
					if (intdest->s_tag == JXALIGN){
						jumpfrom->s_jxoveralign = 1;
						badjxalign++;
					}
					/*
					 *	we assume the worst case
					 *	for unfrozen jxxxxes
					 */
					displ += intdest->s_jxfear;
				}
				if (displ <= MAXBYTE){
					/*
					 *	the worst possible conditions
					 *	can't hurt us, so forget about
					 *	this jump
					 */
					jumpfrom->s_tag = JXINACTIVE;
				} else {
					stillactives++;
				}
			} else {
			/*
			 *	backward search for intervening jxxx
			 */
				SEGITERATE(segno, cojumpfrom - 1,1,cointdest,
				  intdest, ubintdest, --){
					if (intdest->s_value <= dest->s_value) 
						break; /* beyond destination */
					if (intdest->s_tag <= JXQUESTIONABLE)
						continue;	/*frozen solid*/
					if (intdest->s_tag == JXALIGN){
						jumpfrom->s_jxoveralign = 1;
						badjxalign++;
					}
					displ -= intdest->s_jxfear; 
				}
				if (displ >= MINBYTE) {
					jumpfrom->s_tag = JXINACTIVE;
				} else {
					stillactives++;
				}
			}	/*end of backwards search*/
		}	/*end of iterating through all symbols in this seg*/

		if (nchange == 0) {
			/*
			 *	Now, if there are still active jxxx entries,
			 *	we are partially deadlocked.  We can leave
			 *	these jxxx entries in their assumed short jump
			 *	form, as all initial displacement calcualtions
			 *	are hanging on unresolved jxxx instructions
			 *	that might explode into a long form, causing
			 *	other jxxxes jumping across the first set of
			 *	jxxxes to explode, etc.
			 *	However, if a jxxx jumps across a .align,
			 *	we assume the worst for the deadlock cycle,
			 *	and resolve all of them towards the long
			 *	jump.
			 *	Currently, the C compiler does not produce
			 *	jumps across aligns, as aligns are only used
			 *	in data segments, or in text segments to align
			 *	functions.
			 */
			if (stillactives){
				SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom,
				    ubjumpfrom, ++){
					if (jumpfrom->s_tag == JXACTIVE){
						jumpfrom->s_tag =
						  badjxalign?JXNOTYET:JXINACTIVE;
					}
				}
				if (badjxalign){
					jxxxbump(segno, (struct symtab **)0);
				}
			}
			/*
			 *	Handle  all of the .align s
			 */
			SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom,
			   ubjumpfrom, ++){
			    if (jumpfrom->s_tag == JXALIGN){
				/*
				 *	Predict the true displacement
				 *	needed, irregardless of the
				 *	fact that we guessed 1
				 */
				displ = (jumpfrom->s_value - 1) & (unsigned)jumpfrom->s_jxfear;
				if (displ == 0){	/*no virtual displacement*/
					jumpfrom->s_jxfear = -1;
				} else {
					jumpfrom->s_jxfear = (jumpfrom->s_jxfear + 1) - displ;
					/*
					 *	assert jumpfrom->s_jxfear > 0
					 */
					if (jumpfrom->s_jxfear == 1){
						/*our prediction was correct*/
						continue;
					}
					/*
					 *	assert jumpfrom->s_jxfear > 1
					 */
					jumpfrom->s_jxfear -= 1;	/*correct guess*/
				}
				/*
				 *	assert jumpfrom->s_jxfear = -1, +1...2**n-1
				 */
				jumpfrom->s_tag = JXNOTYET;	/*signal*/
				jxxxbump(segno, cojumpfrom);
				jumpfrom->s_tag = JXINACTIVE;
				/*
				 *	Assert jxfrom->jxvalue indexes the first
				 *	code byte after the added bytes, and
				 *	has n low order zeroes.
				 */
			  }
			}	/*end of walking through each segment*/
	    	}	/*end of no changes */
		else {	/*changes, and still have to try another pass*/
			jxxxbump(segno, (struct symtab **)0);
		}
	   }	/*end of doing the topologic sort*/
	}	/*end of iterating through all segments*/
}	/*end of jxxxfix*/

/*
 *	Go through the symbols in a given segment number,
 *	and see which entries are jxxx entries that have
 *	been logically "exploded" (expanded), but for which
 *	the value of textually following symbols has not been
 *	increased
 */

jxxxbump(segno, starthint)
	int	segno;
	struct	symtab **starthint;
{
	register	struct	symtab	**cosp, *sp;
	register	struct	symtab		*ub;
	register	int	cum_bump;
	register	unsigned	char	tag;

	cum_bump = 0;
	SEGITERATE(segno, starthint, 0, cosp, sp, ub, ++){
		tag = sp->s_tag;
		if (tag == JXNOTYET){
#ifdef DEBUG
			if (debug){
			if (sp->s_dest != 0)
				printf("Explode jump to %s on line %d\n",
					sp->s_dest->s_name, lineno);
			else
				printf("Explode an align!\n");
			}
#endif
			sp->s_tag = JXINACTIVE;
			sp->s_jxbump = 1;
			cum_bump += sp->s_jxfear;
		}
		/*
		 *	Only bump labels and jxxxes. Ignored entries can
		 *	be incremented, as they are thrown away later on.
		 *	Stabds are given their final value in the second 
		 *	pass.
		 */
		if (tag >= OKTOBUMP)	/*only bump labels and jxxxes and floating stabs*/
			sp->s_value += cum_bump;
	}
	usedot[segno].e_xvalue += cum_bump;
}
Commit	Line	Data
d0d638ee	1	/* Copyright (c) 1980 Regents of the University of California */
e5b9ebfb	2	static char sccsid[] = "@(#)asjxxx.c 4.3 %G%";
d0d638ee	3	#include <stdio.h>
d0d638ee BJ	4	#include "as.h"
	5	#include "assyms.h"
	6
e5b9ebfb RH	7	#define JBR 0x11
	8	#define BRW 0x31
	9	#define JMP 0x17
d0d638ee BJ	10
	11	/*
	12	* The number of bytes to add if the jxxx must be "exploded"
	13	* into the long form
	14	*/
e5b9ebfb RH	15	#define JBRDELTA 1 /* brb <byte> ==> brw <byte> <byte> */
	16	#define JXXXDELTA 3 /* brb <byte> ==> brb <byte> brw <byte> <byte> */
	17	#define JBRJDELTA d124 /* brb <byte> ==> jmp L^(pc) <byte>d124 /
	18	#define JXXXJDELTA d124+2 /* brb <byte> ==> brb <byte> jmp L^(pc) <byte>d124 /
	19
	20	int jbrfsize = JBRDELTA;
	21	int jxxxfsize = JXXXDELTA;
d0d638ee BJ	22
	23	/*
	24	* These variables are filled by asscan.c with the
	25	* last name encountered (a pointer buried in the intermediate file),
	26	* and the last jxxx symbol table entry encountered.
	27	*/
	28	struct symtab *lastnam;
	29	struct symtab *lastjxxx;
	30
e5b9ebfb RH	31	initijxxx()
	32	{
	33	jbrfsize = jxxxJUMP ? JBRJDELTA : JBRDELTA;
	34	jxxxfsize = jxxxJUMP ? JXXXJDELTA : JXXXDELTA;
	35	/*
	36	* Note: ifjxxxJUMP is set, then we do NOT do any tunnelling;
	37	* this was too complicated to figure out, and in the first
	38	* version of the assembler, tunnelling proved to be the hardest
	39	* to get to work!
	40	*/
	41	}
d0d638ee BJ	42	/*
	43	* Handle jxxx instructions
	44	*/
	45	ijxout(op,ap,nact)
	46	struct arg *ap;
	47	{
	48	if (passno == 1){
	49	/*
	50	* READ THIS BEFORE LOOKING AT jxxxfix()
	51	*
	52	* Record the jxxx in a special symbol table entry
	53	*/
	54	register struct symtab *jumpfrom;
	55
	56	/*
	57	* We assume the MINIMAL length
	58	*/
	59	putins(op,ap,nact);
	60	jumpfrom = lastjxxx;
451260e7 RH	61	jumpfrom->s_tag = JXACTIVE;
451260e7 RH	62	jumpfrom->s_jxbump = 0;
d0d638ee	63	if (op == JBR)
e5b9ebfb	64	jumpfrom->s_jxfear = jbrfsize;
d0d638ee	65	else
e5b9ebfb	66	jumpfrom->s_jxfear = jxxxfsize;
d0d638ee BJ	67	if (lastnam == 0)
d0d638ee BJ	68	yyerror("jxxx destination not a label");
451260e7 RH	69	jumpfrom->s_dest = lastnam;
	70	jumpfrom->s_type = dotp->e_xtype; /only TEXT or DATA/
	71	jumpfrom->s_index = dotp-usedot;
d0d638ee BJ	72	/*
	73	* value ALWAYS (ALWAYS!!!) indexes the next instruction
	74	* after the jump, even in the jump must be exploded
	75	* (bumped)
	76	*/
451260e7	77	jumpfrom->s_value = dotp->e_xvalue;
d0d638ee BJ	78	njxxx++;
	79	} else {/* pass2, resolve */
	80	/*
	81	* READ THIS AFTER LOOKING AT jxxxfix()
	82	*/
	83	register long oxvalue;
	84	register struct exp *xp;
	85	register struct symtab *tunnel;
	86	register struct arg *aplast;
	87
	88	aplast = ap + nact - 1;
451260e7 RH	89	xp = aplast->a_xp;
	90	if (lastjxxx->s_tag == JXTUNNEL){
	91	lastjxxx->s_tag = JXINACTIVE;
	92	tunnel = lastjxxx->s_dest;
	93	xp->e_xvalue = tunnel->s_value /index of instruction following/
d0d638ee	94	- 3 /* size of brw + word*/
e5b9ebfb	95	+ ( ( (tunnel->s_jxfear == jbrfsize) &&
451260e7	96	(tunnel->s_jxbump == 0))?1:0);
d0d638ee BJ	97	/non bumped branch byteis only 2 back/
d0d638ee BJ	98	}
451260e7	99	if (lastjxxx->s_jxbump == 0){ /wasn't bumped, so is short form/
d0d638ee BJ	100	putins(op, ap, nact);
	101	} else {
	102	if (op != JBR){ /*branch reverse conditional byte over
	103	branch unconditional word*/
451260e7 RH	104	oxvalue = xp->e_xvalue;
451260e7 RH	105	xp->e_xvalue = lastjxxx->s_value;
d0d638ee	106	putins(op^1, ap, nact);
451260e7	107	xp->e_xvalue = oxvalue;
d0d638ee	108	}
e5b9ebfb	109	putins(jxxxJUMP ? JMP : BRW, aplast, 1);
d0d638ee BJ	110	}
	111	}
	112	} /end of ijxout/
	113
	114	jalign(xp, sp)
	115	register struct exp *xp;
	116	register struct symtab *sp;
	117	{
	118	register int mask;
451260e7	119	if (xp->e_xtype != XABS \|\| xp->e_xvalue < 0 \|\| xp->e_xvalue > 16) {
d0d638ee BJ	120	yyerror("Illegal `align' argument");
	121	return;
	122	}
	123	flushfield(NBPW/4);
	124	if (passno == 1) {
451260e7 RH	125	sp->s_tag = JXALIGN;
	126	sp->s_jxfear = (1 << xp->e_xvalue) - 1;
	127	sp->s_type = dotp->e_xtype;
	128	sp->s_index = dotp-usedot;
d0d638ee BJ	129	/*
	130	* We guess that the align will take up at least one
	131	* byte in the code output. We will correct for this
	132	* initial high guess when we explode (bump) aligns
	133	* when we fix the jxxxes. We must do this guess
	134	* so that the symbol table is sorted correctly
	135	* and labels declared to fall before the align
	136	* really get their, instead of guessing zero size
	137	* and have the label (incorrectly) fall after the jxxx.
	138	* This is a quirk of our requirement that indices into
	139	* the code stream point to the next byte following
	140	* the logical entry in the symbol table
	141	*/
451260e7 RH	142	dotp->e_xvalue += 1;
451260e7 RH	143	sp->s_value = dotp->e_xvalue;
d0d638ee BJ	144	njxxx++;
d0d638ee BJ	145	} else {
451260e7 RH	146	mask = (1 << xp->e_xvalue) - 1;
451260e7 RH	147	while (dotp->e_xvalue & mask){
d0d638ee BJ	148	#ifdef UNIX
	149	outb(0);
	150	#endif UNIX
	151	#ifdef VMS
	152	*vms_obj_ptr++ = -1;
	153	*vms_obj_ptr++ = 0;
451260e7	154	dotp->e_xvalue += 1;
d0d638ee BJ	155	#endif VMS
	156	}
	157	}
	158	}
	159
	160	/*
	161	* Pass 1.5, resolve jxxx instructions and .align in .text
	162	*/
	163	jxxxfix()
	164	{
	165	register struct symtab *jumpfrom;
	166	struct symtab *cojumpfrom, ubjumpfrom;
	167	register struct symtab *dest;
	168	register struct symtab intdest; /intermediate dest*/
	169	register struct symtab *cointdest, ubintdest;
	170
	171	register struct symtab *tunnel;
	172	int displ,nchange;
	173	int badjxalign; /if jump across an align/
	174	int stillactives; /if still active jxxxes/
	175	int segno; /current segment number/
	176	int topono; /which iteration in the topo sort/
	177	register unsigned char tag;
	178	/*
	179	* consider each segment in turn...
	180	*/
	181	for (segno = 0; segno < NLOC + NLOC; segno++){
	182	badjxalign = 0; /done on a per segment basis/
	183	/*
	184	* Do a lazy topological sort.
	185	*/
	186	for (topono = 1, nchange = 1; nchange != 0; topono++){
	187	#ifdef DEBUG
	188	if (debug)
	189	printf("\nSegment %d, topo iteration %d\n",
	190	segno, topono);
	191	#endif
	192	nchange = 0;
	193	stillactives = 0;
	194	/*
	195	* We keep track of one possible tunnel location.
	196	* A tunnel will eventually be an unconditional
	197	* branch to the same place that another jxxx
	198	* will want to branch to. We will turn a
	199	* branch conditional/unconditional (word) that would
	200	* have to get bumped because its destination is too
	201	* far away, into a branch conditional/unconditional
	202	* byte to the tunnel branch conditional/unconditional.
	203	* Of course, the tunnel must branch to the same place
	204	* as we want to go.
	205	*/
	206	tunnel = 0; /initially, no tunnel/
	207	SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, ubjumpfrom, ++){
451260e7	208	tag = jumpfrom->s_tag;
d0d638ee BJ	209	if (tag <= IGNOREBOUND)
	210	continue; /just an ordinary symbol/
	211	if (tag == JXALIGN){
	212	tunnel = 0; /avoid tunneling across a flex alocation/
	213	continue; /we take care of these later/
	214	}
e5b9ebfb	215	if ( jumpfrom->s_jxfear == jbrfsize /unconditional/
d0d638ee	216	\|\| ( tag == JXINACTIVE /inactive bumped/
451260e7	217	&& (jumpfrom->s_jxbump != 0)
d0d638ee BJ	218	)
	219	) tunnel = jumpfrom;
	220	if (tag != JXACTIVE)
	221	continue;
451260e7 RH	222	dest = jumpfrom->s_dest;
451260e7 RH	223	if (jumpfrom->s_index != dest->s_index){
d0d638ee BJ	224	yyerror("Intersegment jxxx");
	225	continue;
	226	}
451260e7	227	displ = dest->s_value - jumpfrom->s_value;
d0d638ee BJ	228	if (displ < MINBYTE \|\| displ > MAXBYTE) {
	229	/*
	230	* This is an immediate lose!
	231	*
	232	* We first attempt to tunnel
	233	* by finding an intervening jump that
	234	* has the same destination.
	235	* The tunnel is always the first preceeding
	236	* jxxx instruction, so the displacement
	237	* to the tunnel is less than zero, and
	238	* its relative position will be unaffected
	239	* by future jxxx expansions.
e5b9ebfb RH	240	*
e5b9ebfb RH	241	* No tunnels if doing jumps...
d0d638ee	242	*/
e5b9ebfb RH	243	if ( (!jxxxJUMP)
e5b9ebfb RH	244	&& (jumpfrom->s_jxfear > jbrfsize)
d0d638ee	245	&& (tunnel)
451260e7 RH	246	&& (tunnel->s_dest == jumpfrom->s_dest)
	247	&& (tunnel->s_index == jumpfrom->s_index)
	248	&& (tunnel->s_value - jumpfrom->s_value >=
e5b9ebfb	249	MINBYTE + jxxxfsize)
d0d638ee BJ	250	) {
	251	/*
	252	* tunnelling is OK
	253	*/
451260e7	254	jumpfrom->s_dest = tunnel;
d0d638ee BJ	255	/*
	256	* no bumping needed, this
	257	* is now effectively inactive
	258	* but must be remembered
	259	*/
451260e7	260	jumpfrom->s_tag = JXTUNNEL;
d0d638ee BJ	261	#ifdef DEBUG
	262	if(debug)
	263	printf("Tunnel from %s from line %d\n",
451260e7	264	jumpfrom->s_name, lineno);
d0d638ee BJ	265	#endif
	266	continue;
	267	} else { /tunneling not possible/
	268	/*
	269	* since this will be turned
	270	* into a bumped jump, we can
	271	* use the unconditional jump
	272	* as a tunnel
	273	*/
	274	tunnel = jumpfrom;
451260e7	275	jumpfrom->s_tag = JXNOTYET;
d0d638ee BJ	276	++nchange;
	277	continue;
	278	}
	279	} /end of immediate lose/
	280	/*
	281	* Do a forward search for an intervening jxxx
	282	*/
	283	if (displ >= 0) {
	284	SEGITERATE(segno, cojumpfrom + 1,0,cointdest,
	285	intdest, ubintdest, ++){
451260e7	286	if (intdest->s_value > dest->s_value)
d0d638ee	287	break; /* beyond destination */
451260e7	288	if (intdest->s_tag <= JXQUESTIONABLE)
d0d638ee	289	continue; /frozen solid/
451260e7 RH	290	if (intdest->s_tag == JXALIGN){
451260e7 RH	291	jumpfrom->s_jxoveralign = 1;
d0d638ee BJ	292	badjxalign++;
	293	}
	294	/*
	295	* we assume the worst case
	296	* for unfrozen jxxxxes
	297	*/
451260e7	298	displ += intdest->s_jxfear;
d0d638ee BJ	299	}
	300	if (displ <= MAXBYTE){
	301	/*
	302	* the worst possible conditions
	303	* can't hurt us, so forget about
	304	* this jump
	305	*/
451260e7	306	jumpfrom->s_tag = JXINACTIVE;
d0d638ee BJ	307	} else {
	308	stillactives++;
	309	}
	310	} else {
	311	/*
	312	* backward search for intervening jxxx
	313	*/
	314	SEGITERATE(segno, cojumpfrom - 1,1,cointdest,
	315	intdest, ubintdest, --){
451260e7	316	if (intdest->s_value <= dest->s_value)
d0d638ee	317	break; /* beyond destination */
451260e7	318	if (intdest->s_tag <= JXQUESTIONABLE)
d0d638ee	319	continue; /frozen solid/
451260e7 RH	320	if (intdest->s_tag == JXALIGN){
451260e7 RH	321	jumpfrom->s_jxoveralign = 1;
d0d638ee BJ	322	badjxalign++;
d0d638ee BJ	323	}
451260e7	324	displ -= intdest->s_jxfear;
d0d638ee BJ	325	}
d0d638ee BJ	326	if (displ >= MINBYTE) {
451260e7	327	jumpfrom->s_tag = JXINACTIVE;
d0d638ee BJ	328	} else {
	329	stillactives++;
	330	}
	331	} /end of backwards search/
	332	} /end of iterating through all symbols in this seg/
	333
	334	if (nchange == 0) {
	335	/*
	336	* Now, if there are still active jxxx entries,
	337	* we are partially deadlocked. We can leave
	338	* these jxxx entries in their assumed short jump
	339	* form, as all initial displacement calcualtions
	340	* are hanging on unresolved jxxx instructions
	341	* that might explode into a long form, causing
	342	* other jxxxes jumping across the first set of
	343	* jxxxes to explode, etc.
	344	* However, if a jxxx jumps across a .align,
	345	* we assume the worst for the deadlock cycle,
	346	* and resolve all of them towards the long
	347	* jump.
	348	* Currently, the C compiler does not produce
	349	* jumps across aligns, as aligns are only used
	350	* in data segments, or in text segments to align
	351	* functions.
	352	*/
	353	if (stillactives){
	354	SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom,
	355	ubjumpfrom, ++){
451260e7 RH	356	if (jumpfrom->s_tag == JXACTIVE){
451260e7 RH	357	jumpfrom->s_tag =
d0d638ee BJ	358	badjxalign?JXNOTYET:JXINACTIVE;
	359	}
	360	}
	361	if (badjxalign){
	362	jxxxbump(segno, (struct symtab **)0);
	363	}
	364	}
	365	/*
	366	* Handle all of the .align s
	367	*/
	368	SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom,
	369	ubjumpfrom, ++){
451260e7	370	if (jumpfrom->s_tag == JXALIGN){
d0d638ee BJ	371	/*
	372	* Predict the true displacement
	373	* needed, irregardless of the
	374	* fact that we guessed 1
	375	*/
451260e7	376	displ = (jumpfrom->s_value - 1) & (unsigned)jumpfrom->s_jxfear;
d0d638ee	377	if (displ == 0){ /no virtual displacement/
451260e7	378	jumpfrom->s_jxfear = -1;
d0d638ee	379	} else {
451260e7	380	jumpfrom->s_jxfear = (jumpfrom->s_jxfear + 1) - displ;
d0d638ee	381	/*
451260e7	382	* assert jumpfrom->s_jxfear > 0
d0d638ee	383	*/
451260e7	384	if (jumpfrom->s_jxfear == 1){
d0d638ee BJ	385	/our prediction was correct/
	386	continue;
	387	}
	388	/*
451260e7	389	* assert jumpfrom->s_jxfear > 1
d0d638ee	390	*/
451260e7	391	jumpfrom->s_jxfear -= 1; /correct guess/
d0d638ee BJ	392	}
d0d638ee BJ	393	/*
451260e7	394	* assert jumpfrom->s_jxfear = -1, +1...2**n-1
d0d638ee	395	*/
451260e7	396	jumpfrom->s_tag = JXNOTYET; /signal/
d0d638ee	397	jxxxbump(segno, cojumpfrom);
451260e7	398	jumpfrom->s_tag = JXINACTIVE;
d0d638ee BJ	399	/*
	400	* Assert jxfrom->jxvalue indexes the first
	401	* code byte after the added bytes, and
	402	* has n low order zeroes.
	403	*/
	404	}
	405	} /end of walking through each segment/
	406	} /end of no changes /
	407	else { /changes, and still have to try another pass/
	408	jxxxbump(segno, (struct symtab **)0);
	409	}
	410	} /end of doing the topologic sort/
	411	} /end of iterating through all segments/
	412	} /end of jxxxfix/
	413
	414	/*
	415	* Go through the symbols in a given segment number,
	416	* and see which entries are jxxx entries that have
	417	* been logically "exploded" (expanded), but for which
	418	* the value of textually following symbols has not been
	419	* increased
	420	*/
	421
	422	jxxxbump(segno, starthint)
	423	int segno;
	424	struct symtab **starthint;
	425	{
	426	register struct symtab *cosp, sp;
	427	register struct symtab *ub;
	428	register int cum_bump;
	429	register unsigned char tag;
	430
	431	cum_bump = 0;
	432	SEGITERATE(segno, starthint, 0, cosp, sp, ub, ++){
451260e7	433	tag = sp->s_tag;
d0d638ee BJ	434	if (tag == JXNOTYET){
	435	#ifdef DEBUG
	436	if (debug){
451260e7	437	if (sp->s_dest != 0)
d0d638ee	438	printf("Explode jump to %s on line %d\n",
451260e7	439	sp->s_dest->s_name, lineno);
d0d638ee BJ	440	else
	441	printf("Explode an align!\n");
	442	}
	443	#endif
451260e7 RH	444	sp->s_tag = JXINACTIVE;
	445	sp->s_jxbump = 1;
	446	cum_bump += sp->s_jxfear;
d0d638ee BJ	447	}
	448	/*
	449	* Only bump labels and jxxxes. Ignored entries can
	450	* be incremented, as they are thrown away later on.
	451	* Stabds are given their final value in the second
	452	* pass.
	453	*/
	454	if (tag >= OKTOBUMP) /only bump labels and jxxxes and floating stabs/
451260e7	455	sp->s_value += cum_bump;
d0d638ee	456	}
451260e7	457	usedot[segno].e_xvalue += cum_bump;
d0d638ee	458	}