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1 | /* |
2 | * Copyright (c) 1982 Regents of the University of California | |
3 | */ | |
4 | #ifndef lint | |
5 | static char sccsid[] = "@(#)asjxxx.c 4.7 6/30/83"; | |
6 | #endif not lint | |
7 | ||
8 | #include <stdio.h> | |
9 | #include "as.h" | |
10 | #include "assyms.h" | |
11 | ||
12 | #define JBR 0x11 | |
13 | #define BRW 0x13 | |
14 | #define JMP 0x71 | |
15 | ||
16 | /* | |
17 | * The number of bytes to add if the jxxx must be "exploded" | |
18 | * into the long form | |
19 | */ | |
20 | #define JBRDELTA 1 /* brb <byte> ==> brw <byte> <byte> */ | |
21 | #define JXXXDELTA 3 /* brb <byte> ==> brb <byte> brw <byte> <byte> */ | |
22 | #define JBRJDELTA d124 /* brb <byte> ==> jmp L^(pc) <byte>*d124 */ | |
23 | #define JXXXJDELTA d124+2 /* brb <byte> ==> brb <byte> jmp L^(pc) <byte>*d124 */ | |
24 | ||
25 | int jbrfsize = JBRDELTA; | |
26 | int jxxxfsize = JXXXDELTA; | |
27 | ||
28 | /* | |
29 | * These variables are filled by asscan.c with the | |
30 | * last name encountered (a pointer buried in the intermediate file), | |
31 | * and the last jxxx symbol table entry encountered. | |
32 | */ | |
33 | struct symtab *lastnam; | |
34 | struct symtab *lastjxxx; | |
35 | ||
36 | initijxxx() | |
37 | { | |
38 | jbrfsize = jxxxJUMP ? JBRJDELTA : JBRDELTA; | |
39 | jxxxfsize = jxxxJUMP ? JXXXJDELTA : JXXXDELTA; | |
40 | /* | |
41 | * Note: ifjxxxJUMP is set, then we do NOT do any tunnelling; | |
42 | * this was too complicated to figure out, and in the first | |
43 | * version of the assembler, tunnelling proved to be the hardest | |
44 | * to get to work! | |
45 | */ | |
46 | } | |
47 | /* | |
48 | * Handle jxxx instructions | |
49 | */ | |
50 | ijxout(opcode, ap, nact) | |
51 | u_char opcode; | |
52 | struct arg *ap; | |
53 | int nact; | |
54 | { | |
55 | if (passno == 1){ | |
56 | /* | |
57 | * READ THIS BEFORE LOOKING AT jxxxfix() | |
58 | * | |
59 | * Record the jxxx in a special symbol table entry | |
60 | */ | |
61 | register struct symtab *jumpfrom; | |
62 | ||
63 | /* | |
64 | * We assume the MINIMAL length | |
65 | */ | |
66 | putins(opcode, ap, nact); | |
67 | jumpfrom = lastjxxx; | |
68 | jumpfrom->s_tag = JXACTIVE; | |
69 | jumpfrom->s_jxbump = 0; | |
70 | if (opcode == JBR) | |
71 | jumpfrom->s_jxfear = jbrfsize; | |
72 | else | |
73 | jumpfrom->s_jxfear = jxxxfsize; | |
74 | if (lastnam == 0) | |
75 | yyerror("jxxx destination not a label"); | |
76 | jumpfrom->s_dest = lastnam; | |
77 | jumpfrom->s_type = dotp->e_xtype; /*only TEXT or DATA*/ | |
78 | jumpfrom->s_index = dotp-usedot; | |
79 | /* | |
80 | * value ALWAYS (ALWAYS!!!) indexes the next instruction | |
81 | * after the jump, even in the jump must be exploded | |
82 | * (bumped) | |
83 | */ | |
84 | jumpfrom->s_value = dotp->e_xvalue; | |
85 | njxxx++; | |
86 | } else {/* pass2, resolve */ | |
87 | /* | |
88 | * READ THIS AFTER LOOKING AT jxxxfix() | |
89 | */ | |
90 | reg long oxvalue; | |
91 | reg struct exp *xp; | |
92 | reg struct symtab *tunnel; | |
93 | reg struct arg *aplast; | |
94 | ||
95 | aplast = ap + nact - 1; | |
96 | xp = aplast->a_xp; | |
97 | if (lastjxxx->s_tag == JXTUNNEL){ | |
98 | lastjxxx->s_tag = JXINACTIVE; | |
99 | tunnel = lastjxxx->s_dest; | |
100 | xp->e_xvalue = tunnel->s_value /*index of instruction following*/ | |
101 | - 3 /* size of brw + word*/ | |
102 | + ( ( (tunnel->s_jxfear == jbrfsize) && | |
103 | (tunnel->s_jxbump == 0))?1:0); | |
104 | /*non bumped branch byteis only 2 back*/ | |
105 | } | |
106 | if (lastjxxx->s_jxbump == 0){ /*wasn't bumped, so is short form*/ | |
107 | putins(opcode, ap, nact); | |
108 | } else { | |
109 | if (opcode != JBR){ | |
110 | /* | |
111 | * branch reverse conditional byte over | |
112 | * branch unconditional word | |
113 | */ | |
114 | oxvalue = xp->e_xvalue; | |
115 | xp->e_xvalue = lastjxxx->s_value; | |
116 | putins(opcode^0x10, ap, nact); | |
117 | xp->e_xvalue = oxvalue; | |
118 | } | |
119 | putins(jxxxJUMP ? JMP : BRW, aplast, 1); | |
120 | } | |
121 | } | |
122 | } | |
123 | ||
124 | jalign(xp, sp) | |
125 | register struct exp *xp; | |
126 | register struct symtab *sp; | |
127 | { | |
128 | register int mask; | |
129 | /* | |
130 | * Problem with .align | |
131 | * | |
132 | * When the loader constructs an executable file from | |
133 | * a number of objects, it effectively concatnates | |
134 | * together all of the text segments from all objects, | |
135 | * and then all of the data segments. | |
136 | * | |
137 | * If we do an align by a large value, we can align | |
138 | * within the a.out this assembly produces, but | |
139 | * after the loader concatnates, the alignment can't | |
140 | * be guaranteed if the objects preceding this one | |
141 | * in the load are also aligned to the same size. | |
142 | * | |
143 | * Currently, the loader guarantees full word alignment. | |
144 | * So, ridiculous aligns are caught here and converted | |
145 | * to a .align 2, if possible. | |
146 | */ | |
147 | if ( ( (xp->e_xtype & XTYPE) != XABS) | |
148 | || (xp->e_xvalue < 0) | |
149 | || (xp->e_xvalue > 16) | |
150 | ) { | |
151 | yyerror("Illegal `align' argument"); | |
152 | return; | |
153 | } | |
154 | if (xp->e_xvalue > 2){ | |
155 | if (passno == 1){ | |
156 | yywarning(".align %d is NOT preserved by the loader", | |
157 | xp->e_xvalue); | |
158 | yywarning(".align %d converted to .align 2", | |
159 | xp->e_xvalue); | |
160 | } | |
161 | xp->e_xvalue = 2; | |
162 | } | |
163 | flushfield(NBPW/4); | |
164 | if (passno == 1) { | |
165 | sp->s_tag = JXALIGN; | |
166 | sp->s_jxfear = (1 << xp->e_xvalue) - 1; | |
167 | sp->s_type = dotp->e_xtype; | |
168 | sp->s_index = dotp-usedot; | |
169 | /* | |
170 | * We guess that the align will take up at least one | |
171 | * byte in the code output. We will correct for this | |
172 | * initial high guess when we explode (bump) aligns | |
173 | * when we fix the jxxxes. We must do this guess | |
174 | * so that the symbol table is sorted correctly | |
175 | * and labels declared to fall before the align | |
176 | * really get their, instead of guessing zero size | |
177 | * and have the label (incorrectly) fall after the jxxx. | |
178 | * This is a quirk of our requirement that indices into | |
179 | * the code stream point to the next byte following | |
180 | * the logical entry in the symbol table | |
181 | */ | |
182 | dotp->e_xvalue += 1; | |
183 | sp->s_value = dotp->e_xvalue; | |
184 | njxxx++; | |
185 | } else { | |
186 | mask = (1 << xp->e_xvalue) - 1; | |
187 | while (dotp->e_xvalue & mask) | |
188 | { | |
189 | Outb(0); | |
190 | if (liston) | |
191 | { | |
192 | *layoutpos++ = '0'; | |
193 | *layoutpos++ = '0'; | |
194 | } | |
195 | } | |
196 | } | |
197 | } | |
198 | ||
199 | djalign(xp, sp) | |
200 | register struct exp *xp; | |
201 | register struct symtab *sp; | |
202 | { | |
203 | register int mask; | |
204 | ||
205 | if ( ( (xp->e_xtype & XTYPE) != XABS) | |
206 | || (xp->e_xvalue < 0) | |
207 | || (xp->e_xvalue > 16) | |
208 | ) { | |
209 | yyerror("Illegal `align' argument"); | |
210 | return; | |
211 | } | |
212 | if (xp->e_xvalue > 2){ | |
213 | if (passno == 1){ | |
214 | yywarning(".align %d is NOT preserved by the loader", | |
215 | xp->e_xvalue); | |
216 | yywarning(".align %d converted to .align 2", | |
217 | xp->e_xvalue); | |
218 | } | |
219 | xp->e_xvalue = 2; | |
220 | } | |
221 | flushfield(NBPW/4); | |
222 | mask = (1 << xp->e_xvalue) - 1; | |
223 | if (passno == 1) { | |
224 | sp->s_tag = JXALIGN; | |
225 | sp->s_jxfear = (1 << xp->e_xvalue) - 1; | |
226 | sp->s_type = dotp->e_xtype; | |
227 | sp->s_index = dotp-usedot; | |
228 | while (dotp->e_xvalue & mask) | |
229 | dotp->e_xvalue ++; | |
230 | sp->s_value = dotp->e_xvalue; | |
231 | njxxx++; | |
232 | } else { | |
233 | while (dotp->e_xvalue & mask) | |
234 | { | |
235 | Outb(0); | |
236 | if (liston) | |
237 | { | |
238 | *layoutpos++ = '0'; | |
239 | *layoutpos++ = '0'; | |
240 | } | |
241 | } | |
242 | } | |
243 | } | |
244 | ||
245 | ||
246 | /* | |
247 | * Pass 1.5, resolve jxxx instructions and .align in .text | |
248 | */ | |
249 | jxxxfix() | |
250 | { | |
251 | register struct symtab *jumpfrom; | |
252 | struct symtab **cojumpfrom, *ubjumpfrom; | |
253 | register struct symtab *dest; | |
254 | register struct symtab *intdest; /*intermediate dest*/ | |
255 | register struct symtab **cointdest, *ubintdest; | |
256 | ||
257 | register struct symtab *tunnel; | |
258 | int displ,nchange; | |
259 | int badjxalign; /*if jump across an align*/ | |
260 | int stillactives; /*if still active jxxxes*/ | |
261 | int segno; /*current segment number*/ | |
262 | int topono; /*which iteration in the topo sort*/ | |
263 | register unsigned char tag; | |
264 | /* | |
265 | * consider each segment in turn... | |
266 | */ | |
267 | for (segno = 0; segno < NLOC + NLOC; segno++){ | |
268 | badjxalign = 0; /*done on a per segment basis*/ | |
269 | /* | |
270 | * Do a lazy topological sort. | |
271 | */ | |
272 | for (topono = 1, nchange = 1; nchange != 0; topono++){ | |
273 | #ifdef lint | |
274 | topno = topno; | |
275 | #endif lint | |
276 | #ifdef DEBUG | |
277 | if (debug) | |
278 | printf("\nSegment %d, topo iteration %d\n", | |
279 | segno, topono); | |
280 | #endif | |
281 | nchange = 0; | |
282 | stillactives = 0; | |
283 | /* | |
284 | * We keep track of one possible tunnel location. | |
285 | * A tunnel will eventually be an unconditional | |
286 | * branch to the same place that another jxxx | |
287 | * will want to branch to. We will turn a | |
288 | * branch conditional/unconditional (word) that would | |
289 | * have to get bumped because its destination is too | |
290 | * far away, into a branch conditional/unconditional | |
291 | * byte to the tunnel branch conditional/unconditional. | |
292 | * Of course, the tunnel must branch to the same place | |
293 | * as we want to go. | |
294 | */ | |
295 | tunnel = 0; /*initially, no tunnel*/ | |
296 | SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, ubjumpfrom, ++){ | |
297 | tag = jumpfrom->s_tag; | |
298 | if (tag <= IGNOREBOUND) | |
299 | continue; /*just an ordinary symbol*/ | |
300 | if (tag == JXALIGN){ | |
301 | tunnel = 0; /*avoid tunneling across a flex alocation*/ | |
302 | continue; /*we take care of these later*/ | |
303 | } | |
304 | if ( jumpfrom->s_jxfear == jbrfsize /*unconditional*/ | |
305 | || ( tag == JXINACTIVE /*inactive bumped*/ | |
306 | && (jumpfrom->s_jxbump != 0) | |
307 | ) | |
308 | ) tunnel = jumpfrom; | |
309 | if (tag != JXACTIVE) | |
310 | continue; | |
311 | dest = jumpfrom->s_dest; | |
312 | if (jumpfrom->s_index != dest->s_index){ | |
313 | yyerror("Intersegment jxxx"); | |
314 | continue; | |
315 | } | |
316 | displ = dest->s_value - jumpfrom->s_value; | |
317 | if (displ < MINBYTE || displ > MAXBYTE) { | |
318 | /* | |
319 | * This is an immediate lose! | |
320 | * | |
321 | * We first attempt to tunnel | |
322 | * by finding an intervening jump that | |
323 | * has the same destination. | |
324 | * The tunnel is always the first preceeding | |
325 | * jxxx instruction, so the displacement | |
326 | * to the tunnel is less than zero, and | |
327 | * its relative position will be unaffected | |
328 | * by future jxxx expansions. | |
329 | * | |
330 | * No tunnels if doing jumps... | |
331 | */ | |
332 | if ( (!jxxxJUMP) | |
333 | && (jumpfrom->s_jxfear > jbrfsize) | |
334 | && (tunnel) | |
335 | && (tunnel->s_dest == jumpfrom->s_dest) | |
336 | && (tunnel->s_index == jumpfrom->s_index) | |
337 | && (tunnel->s_value - jumpfrom->s_value >= | |
338 | MINBYTE + jxxxfsize) | |
339 | ) { | |
340 | /* | |
341 | * tunnelling is OK | |
342 | */ | |
343 | jumpfrom->s_dest = tunnel; | |
344 | /* | |
345 | * no bumping needed, this | |
346 | * is now effectively inactive | |
347 | * but must be remembered | |
348 | */ | |
349 | jumpfrom->s_tag = JXTUNNEL; | |
350 | #ifdef DEBUG | |
351 | if(debug) | |
352 | printf("Tunnel from %s from line %d\n", | |
353 | FETCHNAME(jumpfrom), | |
354 | lineno); | |
355 | #endif | |
356 | continue; | |
357 | } else { /*tunneling not possible*/ | |
358 | /* | |
359 | * since this will be turned | |
360 | * into a bumped jump, we can | |
361 | * use the unconditional jump | |
362 | * as a tunnel | |
363 | */ | |
364 | tunnel = jumpfrom; | |
365 | jumpfrom->s_tag = JXNOTYET; | |
366 | ++nchange; | |
367 | continue; | |
368 | } | |
369 | } /*end of immediate lose*/ | |
370 | /* | |
371 | * Do a forward search for an intervening jxxx | |
372 | */ | |
373 | if (displ >= 0) { | |
374 | SEGITERATE(segno, cojumpfrom + 1,0,cointdest, | |
375 | intdest, ubintdest, ++){ | |
376 | if (intdest->s_value > dest->s_value) | |
377 | break; /* beyond destination */ | |
378 | if (intdest->s_tag <= JXQUESTIONABLE) | |
379 | continue; /*frozen solid*/ | |
380 | if (intdest->s_tag == JXALIGN){ | |
381 | jumpfrom->s_jxoveralign = 1; | |
382 | badjxalign++; | |
383 | } | |
384 | /* | |
385 | * we assume the worst case | |
386 | * for unfrozen jxxxxes | |
387 | */ | |
388 | displ += intdest->s_jxfear; | |
389 | } | |
390 | if (displ <= MAXBYTE){ | |
391 | /* | |
392 | * the worst possible conditions | |
393 | * can't hurt us, so forget about | |
394 | * this jump | |
395 | */ | |
396 | jumpfrom->s_tag = JXINACTIVE; | |
397 | } else { | |
398 | stillactives++; | |
399 | } | |
400 | } else { | |
401 | /* | |
402 | * backward search for intervening jxxx | |
403 | */ | |
404 | SEGITERATE(segno, cojumpfrom - 1,1,cointdest, | |
405 | intdest, ubintdest, --){ | |
406 | if (intdest->s_value <= dest->s_value) | |
407 | break; /* beyond destination */ | |
408 | if (intdest->s_tag <= JXQUESTIONABLE) | |
409 | continue; /*frozen solid*/ | |
410 | if (intdest->s_tag == JXALIGN){ | |
411 | jumpfrom->s_jxoveralign = 1; | |
412 | badjxalign++; | |
413 | } | |
414 | displ -= intdest->s_jxfear; | |
415 | } | |
416 | if (displ >= MINBYTE) { | |
417 | jumpfrom->s_tag = JXINACTIVE; | |
418 | } else { | |
419 | stillactives++; | |
420 | } | |
421 | } /*end of backwards search*/ | |
422 | } /*end of iterating through all symbols in this seg*/ | |
423 | ||
424 | if (nchange == 0) { | |
425 | /* | |
426 | * Now, if there are still active jxxx entries, | |
427 | * we are partially deadlocked. We can leave | |
428 | * these jxxx entries in their assumed short jump | |
429 | * form, as all initial displacement calcualtions | |
430 | * are hanging on unresolved jxxx instructions | |
431 | * that might explode into a long form, causing | |
432 | * other jxxxes jumping across the first set of | |
433 | * jxxxes to explode, etc. | |
434 | * However, if a jxxx jumps across a .align, | |
435 | * we assume the worst for the deadlock cycle, | |
436 | * and resolve all of them towards the long | |
437 | * jump. | |
438 | * Currently, the C compiler does not produce | |
439 | * jumps across aligns, as aligns are only used | |
440 | * in data segments, or in text segments to align | |
441 | * functions. | |
442 | */ | |
443 | if (stillactives){ | |
444 | SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, | |
445 | ubjumpfrom, ++){ | |
446 | if (jumpfrom->s_tag == JXACTIVE){ | |
447 | jumpfrom->s_tag = | |
448 | badjxalign?JXNOTYET:JXINACTIVE; | |
449 | } | |
450 | } | |
451 | if (badjxalign){ | |
452 | jxxxbump(segno, (struct symtab **)0); | |
453 | } | |
454 | } | |
455 | /* | |
456 | * Handle all of the .align s | |
457 | */ | |
458 | SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, | |
459 | ubjumpfrom, ++){ | |
460 | if (jumpfrom->s_tag == JXALIGN){ | |
461 | /* | |
462 | * Predict the true displacement | |
463 | * needed, irregardless of the | |
464 | * fact that we guessed 1 | |
465 | */ | |
466 | displ = (jumpfrom->s_value - 1) & (unsigned)jumpfrom->s_jxfear; | |
467 | if (displ == 0){ /*no virtual displacement*/ | |
468 | jumpfrom->s_jxfear = -1; | |
469 | } else { | |
470 | jumpfrom->s_jxfear = (jumpfrom->s_jxfear + 1) - displ; | |
471 | /* | |
472 | * assert jumpfrom->s_jxfear > 0 | |
473 | */ | |
474 | if (jumpfrom->s_jxfear == 1){ | |
475 | /*our prediction was correct*/ | |
476 | continue; | |
477 | } | |
478 | /* | |
479 | * assert jumpfrom->s_jxfear > 1 | |
480 | */ | |
481 | jumpfrom->s_jxfear -= 1; /*correct guess*/ | |
482 | } | |
483 | /* | |
484 | * assert jumpfrom->s_jxfear = -1, +1...2**n-1 | |
485 | */ | |
486 | jumpfrom->s_tag = JXNOTYET; /*signal*/ | |
487 | jxxxbump(segno, cojumpfrom); | |
488 | jumpfrom->s_tag = JXINACTIVE; | |
489 | /* | |
490 | * Assert jxfrom->jxvalue indexes the first | |
491 | * code byte after the added bytes, and | |
492 | * has n low order zeroes. | |
493 | */ | |
494 | } | |
495 | } /*end of walking through each segment*/ | |
496 | } /*end of no changes */ | |
497 | else { /*changes, and still have to try another pass*/ | |
498 | jxxxbump(segno, (struct symtab **)0); | |
499 | } | |
500 | } /*end of doing the topologic sort*/ | |
501 | } /*end of iterating through all segments*/ | |
502 | } /*end of jxxxfix*/ | |
503 | ||
504 | /* | |
505 | * Go through the symbols in a given segment number, | |
506 | * and see which entries are jxxx entries that have | |
507 | * been logically "exploded" (expanded), but for which | |
508 | * the value of textually following symbols has not been | |
509 | * increased | |
510 | */ | |
511 | ||
512 | jxxxbump(segno, starthint) | |
513 | int segno; | |
514 | struct symtab **starthint; | |
515 | { | |
516 | register struct symtab **cosp, *sp; | |
517 | register struct symtab *ub; | |
518 | register int cum_bump; | |
519 | register unsigned char tag; | |
520 | ||
521 | cum_bump = 0; | |
522 | SEGITERATE(segno, starthint, 0, cosp, sp, ub, ++){ | |
523 | tag = sp->s_tag; | |
524 | if (tag == JXNOTYET){ | |
525 | #ifdef DEBUG | |
526 | if (debug){ | |
527 | if (sp->s_dest != 0) | |
528 | printf("Explode jump to %s on line %d\n", | |
529 | FETCHNAME(sp->s_dest), lineno); | |
530 | else | |
531 | printf("Explode an align!\n"); | |
532 | } | |
533 | #endif | |
534 | sp->s_tag = JXINACTIVE; | |
535 | sp->s_jxbump = 1; | |
536 | cum_bump += sp->s_jxfear; | |
537 | } | |
538 | /* | |
539 | * Only bump labels and jxxxes. Ignored entries can | |
540 | * be incremented, as they are thrown away later on. | |
541 | * Stabds are given their final value in the second | |
542 | * pass. | |
543 | */ | |
544 | if (tag >= OKTOBUMP) /*only bump labels and jxxxes and floating stabs*/ | |
545 | sp->s_value += cum_bump; | |
546 | } | |
547 | usedot[segno].e_xvalue += cum_bump; | |
548 | } |