Commit | Line | Data |
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d0d638ee | 1 | /* Copyright (c) 1980 Regents of the University of California */ |
31cef89c | 2 | static char sccsid[] = "@(#)asjxxx.c 4.5 8/20/80"; |
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; |
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) |
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*/ |
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; |
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; | |
7a5aec15 RH |
119 | /* |
120 | * Problem with .align | |
121 | * | |
122 | * When the loader constructs an executable file from | |
123 | * a number of objects, it effectively concatnates | |
124 | * together all of the text segments from all objects, | |
125 | * and then all of the data segments. | |
126 | * | |
127 | * If we do an align by a large value, we can align | |
128 | * within the a.out this assembly produces, but | |
129 | * after the loader concatnates, the alignment can't | |
130 | * be guaranteed if the objects preceding this one | |
131 | * in the load are also aligned to the same size. | |
132 | * | |
133 | * Currently, the loader guarantees full word alignment. | |
134 | * So, ridiculous aligns are caught here and converted | |
135 | * to a .align 2, if possible. | |
136 | */ | |
8efb1a2c RH |
137 | if ( (xp->e_xtype != XABS) |
138 | || (xp->e_xvalue < 0) | |
139 | || (xp->e_xvalue > 16) | |
140 | ) { | |
d0d638ee BJ |
141 | yyerror("Illegal `align' argument"); |
142 | return; | |
143 | } | |
7a5aec15 RH |
144 | if (xp->e_xvalue > 2){ |
145 | if (passno == 1){ | |
146 | yywarning(".align %d in any segment is NOT preserved by the loader", | |
147 | xp->e_xvalue); | |
148 | yywarning(".align %d converted to .align 2", | |
149 | xp->e_xvalue); | |
150 | } | |
151 | xp->e_xvalue = 2; | |
8efb1a2c | 152 | } |
d0d638ee BJ |
153 | flushfield(NBPW/4); |
154 | if (passno == 1) { | |
451260e7 RH |
155 | sp->s_tag = JXALIGN; |
156 | sp->s_jxfear = (1 << xp->e_xvalue) - 1; | |
157 | sp->s_type = dotp->e_xtype; | |
158 | sp->s_index = dotp-usedot; | |
d0d638ee BJ |
159 | /* |
160 | * We guess that the align will take up at least one | |
161 | * byte in the code output. We will correct for this | |
162 | * initial high guess when we explode (bump) aligns | |
163 | * when we fix the jxxxes. We must do this guess | |
164 | * so that the symbol table is sorted correctly | |
165 | * and labels declared to fall before the align | |
166 | * really get their, instead of guessing zero size | |
167 | * and have the label (incorrectly) fall after the jxxx. | |
168 | * This is a quirk of our requirement that indices into | |
169 | * the code stream point to the next byte following | |
170 | * the logical entry in the symbol table | |
171 | */ | |
451260e7 RH |
172 | dotp->e_xvalue += 1; |
173 | sp->s_value = dotp->e_xvalue; | |
d0d638ee BJ |
174 | njxxx++; |
175 | } else { | |
451260e7 RH |
176 | mask = (1 << xp->e_xvalue) - 1; |
177 | while (dotp->e_xvalue & mask){ | |
d0d638ee BJ |
178 | #ifdef UNIX |
179 | outb(0); | |
180 | #endif UNIX | |
181 | #ifdef VMS | |
182 | *vms_obj_ptr++ = -1; | |
183 | *vms_obj_ptr++ = 0; | |
451260e7 | 184 | dotp->e_xvalue += 1; |
d0d638ee BJ |
185 | #endif VMS |
186 | } | |
187 | } | |
188 | } | |
189 | ||
190 | /* | |
191 | * Pass 1.5, resolve jxxx instructions and .align in .text | |
192 | */ | |
193 | jxxxfix() | |
194 | { | |
195 | register struct symtab *jumpfrom; | |
196 | struct symtab **cojumpfrom, *ubjumpfrom; | |
197 | register struct symtab *dest; | |
198 | register struct symtab *intdest; /*intermediate dest*/ | |
199 | register struct symtab **cointdest, *ubintdest; | |
200 | ||
201 | register struct symtab *tunnel; | |
202 | int displ,nchange; | |
203 | int badjxalign; /*if jump across an align*/ | |
204 | int stillactives; /*if still active jxxxes*/ | |
205 | int segno; /*current segment number*/ | |
206 | int topono; /*which iteration in the topo sort*/ | |
207 | register unsigned char tag; | |
208 | /* | |
209 | * consider each segment in turn... | |
210 | */ | |
211 | for (segno = 0; segno < NLOC + NLOC; segno++){ | |
212 | badjxalign = 0; /*done on a per segment basis*/ | |
213 | /* | |
214 | * Do a lazy topological sort. | |
215 | */ | |
216 | for (topono = 1, nchange = 1; nchange != 0; topono++){ | |
217 | #ifdef DEBUG | |
218 | if (debug) | |
219 | printf("\nSegment %d, topo iteration %d\n", | |
220 | segno, topono); | |
221 | #endif | |
222 | nchange = 0; | |
223 | stillactives = 0; | |
224 | /* | |
225 | * We keep track of one possible tunnel location. | |
226 | * A tunnel will eventually be an unconditional | |
227 | * branch to the same place that another jxxx | |
228 | * will want to branch to. We will turn a | |
229 | * branch conditional/unconditional (word) that would | |
230 | * have to get bumped because its destination is too | |
231 | * far away, into a branch conditional/unconditional | |
232 | * byte to the tunnel branch conditional/unconditional. | |
233 | * Of course, the tunnel must branch to the same place | |
234 | * as we want to go. | |
235 | */ | |
236 | tunnel = 0; /*initially, no tunnel*/ | |
237 | SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, ubjumpfrom, ++){ | |
451260e7 | 238 | tag = jumpfrom->s_tag; |
d0d638ee BJ |
239 | if (tag <= IGNOREBOUND) |
240 | continue; /*just an ordinary symbol*/ | |
241 | if (tag == JXALIGN){ | |
242 | tunnel = 0; /*avoid tunneling across a flex alocation*/ | |
243 | continue; /*we take care of these later*/ | |
244 | } | |
e5b9ebfb | 245 | if ( jumpfrom->s_jxfear == jbrfsize /*unconditional*/ |
d0d638ee | 246 | || ( tag == JXINACTIVE /*inactive bumped*/ |
451260e7 | 247 | && (jumpfrom->s_jxbump != 0) |
d0d638ee BJ |
248 | ) |
249 | ) tunnel = jumpfrom; | |
250 | if (tag != JXACTIVE) | |
251 | continue; | |
451260e7 RH |
252 | dest = jumpfrom->s_dest; |
253 | if (jumpfrom->s_index != dest->s_index){ | |
d0d638ee BJ |
254 | yyerror("Intersegment jxxx"); |
255 | continue; | |
256 | } | |
451260e7 | 257 | displ = dest->s_value - jumpfrom->s_value; |
d0d638ee BJ |
258 | if (displ < MINBYTE || displ > MAXBYTE) { |
259 | /* | |
260 | * This is an immediate lose! | |
261 | * | |
262 | * We first attempt to tunnel | |
263 | * by finding an intervening jump that | |
264 | * has the same destination. | |
265 | * The tunnel is always the first preceeding | |
266 | * jxxx instruction, so the displacement | |
267 | * to the tunnel is less than zero, and | |
268 | * its relative position will be unaffected | |
269 | * by future jxxx expansions. | |
e5b9ebfb RH |
270 | * |
271 | * No tunnels if doing jumps... | |
d0d638ee | 272 | */ |
e5b9ebfb RH |
273 | if ( (!jxxxJUMP) |
274 | && (jumpfrom->s_jxfear > jbrfsize) | |
d0d638ee | 275 | && (tunnel) |
451260e7 RH |
276 | && (tunnel->s_dest == jumpfrom->s_dest) |
277 | && (tunnel->s_index == jumpfrom->s_index) | |
278 | && (tunnel->s_value - jumpfrom->s_value >= | |
e5b9ebfb | 279 | MINBYTE + jxxxfsize) |
d0d638ee BJ |
280 | ) { |
281 | /* | |
282 | * tunnelling is OK | |
283 | */ | |
451260e7 | 284 | jumpfrom->s_dest = tunnel; |
d0d638ee BJ |
285 | /* |
286 | * no bumping needed, this | |
287 | * is now effectively inactive | |
288 | * but must be remembered | |
289 | */ | |
451260e7 | 290 | jumpfrom->s_tag = JXTUNNEL; |
d0d638ee BJ |
291 | #ifdef DEBUG |
292 | if(debug) | |
293 | printf("Tunnel from %s from line %d\n", | |
451260e7 | 294 | jumpfrom->s_name, lineno); |
d0d638ee BJ |
295 | #endif |
296 | continue; | |
297 | } else { /*tunneling not possible*/ | |
298 | /* | |
299 | * since this will be turned | |
300 | * into a bumped jump, we can | |
301 | * use the unconditional jump | |
302 | * as a tunnel | |
303 | */ | |
304 | tunnel = jumpfrom; | |
451260e7 | 305 | jumpfrom->s_tag = JXNOTYET; |
d0d638ee BJ |
306 | ++nchange; |
307 | continue; | |
308 | } | |
309 | } /*end of immediate lose*/ | |
310 | /* | |
311 | * Do a forward search for an intervening jxxx | |
312 | */ | |
313 | if (displ >= 0) { | |
314 | SEGITERATE(segno, cojumpfrom + 1,0,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){ |
321 | jumpfrom->s_jxoveralign = 1; | |
d0d638ee BJ |
322 | badjxalign++; |
323 | } | |
324 | /* | |
325 | * we assume the worst case | |
326 | * for unfrozen jxxxxes | |
327 | */ | |
451260e7 | 328 | displ += intdest->s_jxfear; |
d0d638ee BJ |
329 | } |
330 | if (displ <= MAXBYTE){ | |
331 | /* | |
332 | * the worst possible conditions | |
333 | * can't hurt us, so forget about | |
334 | * this jump | |
335 | */ | |
451260e7 | 336 | jumpfrom->s_tag = JXINACTIVE; |
d0d638ee BJ |
337 | } else { |
338 | stillactives++; | |
339 | } | |
340 | } else { | |
341 | /* | |
342 | * backward search for intervening jxxx | |
343 | */ | |
344 | SEGITERATE(segno, cojumpfrom - 1,1,cointdest, | |
345 | intdest, ubintdest, --){ | |
451260e7 | 346 | if (intdest->s_value <= dest->s_value) |
d0d638ee | 347 | break; /* beyond destination */ |
451260e7 | 348 | if (intdest->s_tag <= JXQUESTIONABLE) |
d0d638ee | 349 | continue; /*frozen solid*/ |
451260e7 RH |
350 | if (intdest->s_tag == JXALIGN){ |
351 | jumpfrom->s_jxoveralign = 1; | |
d0d638ee BJ |
352 | badjxalign++; |
353 | } | |
451260e7 | 354 | displ -= intdest->s_jxfear; |
d0d638ee BJ |
355 | } |
356 | if (displ >= MINBYTE) { | |
451260e7 | 357 | jumpfrom->s_tag = JXINACTIVE; |
d0d638ee BJ |
358 | } else { |
359 | stillactives++; | |
360 | } | |
361 | } /*end of backwards search*/ | |
362 | } /*end of iterating through all symbols in this seg*/ | |
363 | ||
364 | if (nchange == 0) { | |
365 | /* | |
366 | * Now, if there are still active jxxx entries, | |
367 | * we are partially deadlocked. We can leave | |
368 | * these jxxx entries in their assumed short jump | |
369 | * form, as all initial displacement calcualtions | |
370 | * are hanging on unresolved jxxx instructions | |
371 | * that might explode into a long form, causing | |
372 | * other jxxxes jumping across the first set of | |
373 | * jxxxes to explode, etc. | |
374 | * However, if a jxxx jumps across a .align, | |
375 | * we assume the worst for the deadlock cycle, | |
376 | * and resolve all of them towards the long | |
377 | * jump. | |
378 | * Currently, the C compiler does not produce | |
379 | * jumps across aligns, as aligns are only used | |
380 | * in data segments, or in text segments to align | |
381 | * functions. | |
382 | */ | |
383 | if (stillactives){ | |
384 | SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, | |
385 | ubjumpfrom, ++){ | |
451260e7 RH |
386 | if (jumpfrom->s_tag == JXACTIVE){ |
387 | jumpfrom->s_tag = | |
d0d638ee BJ |
388 | badjxalign?JXNOTYET:JXINACTIVE; |
389 | } | |
390 | } | |
391 | if (badjxalign){ | |
392 | jxxxbump(segno, (struct symtab **)0); | |
393 | } | |
394 | } | |
395 | /* | |
396 | * Handle all of the .align s | |
397 | */ | |
398 | SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, | |
399 | ubjumpfrom, ++){ | |
451260e7 | 400 | if (jumpfrom->s_tag == JXALIGN){ |
d0d638ee BJ |
401 | /* |
402 | * Predict the true displacement | |
403 | * needed, irregardless of the | |
404 | * fact that we guessed 1 | |
405 | */ | |
451260e7 | 406 | displ = (jumpfrom->s_value - 1) & (unsigned)jumpfrom->s_jxfear; |
d0d638ee | 407 | if (displ == 0){ /*no virtual displacement*/ |
451260e7 | 408 | jumpfrom->s_jxfear = -1; |
d0d638ee | 409 | } else { |
451260e7 | 410 | jumpfrom->s_jxfear = (jumpfrom->s_jxfear + 1) - displ; |
d0d638ee | 411 | /* |
451260e7 | 412 | * assert jumpfrom->s_jxfear > 0 |
d0d638ee | 413 | */ |
451260e7 | 414 | if (jumpfrom->s_jxfear == 1){ |
d0d638ee BJ |
415 | /*our prediction was correct*/ |
416 | continue; | |
417 | } | |
418 | /* | |
451260e7 | 419 | * assert jumpfrom->s_jxfear > 1 |
d0d638ee | 420 | */ |
451260e7 | 421 | jumpfrom->s_jxfear -= 1; /*correct guess*/ |
d0d638ee BJ |
422 | } |
423 | /* | |
451260e7 | 424 | * assert jumpfrom->s_jxfear = -1, +1...2**n-1 |
d0d638ee | 425 | */ |
451260e7 | 426 | jumpfrom->s_tag = JXNOTYET; /*signal*/ |
d0d638ee | 427 | jxxxbump(segno, cojumpfrom); |
451260e7 | 428 | jumpfrom->s_tag = JXINACTIVE; |
d0d638ee BJ |
429 | /* |
430 | * Assert jxfrom->jxvalue indexes the first | |
431 | * code byte after the added bytes, and | |
432 | * has n low order zeroes. | |
433 | */ | |
434 | } | |
435 | } /*end of walking through each segment*/ | |
436 | } /*end of no changes */ | |
437 | else { /*changes, and still have to try another pass*/ | |
438 | jxxxbump(segno, (struct symtab **)0); | |
439 | } | |
440 | } /*end of doing the topologic sort*/ | |
441 | } /*end of iterating through all segments*/ | |
442 | } /*end of jxxxfix*/ | |
443 | ||
444 | /* | |
445 | * Go through the symbols in a given segment number, | |
446 | * and see which entries are jxxx entries that have | |
447 | * been logically "exploded" (expanded), but for which | |
448 | * the value of textually following symbols has not been | |
449 | * increased | |
450 | */ | |
451 | ||
452 | jxxxbump(segno, starthint) | |
453 | int segno; | |
454 | struct symtab **starthint; | |
455 | { | |
456 | register struct symtab **cosp, *sp; | |
457 | register struct symtab *ub; | |
458 | register int cum_bump; | |
459 | register unsigned char tag; | |
460 | ||
461 | cum_bump = 0; | |
462 | SEGITERATE(segno, starthint, 0, cosp, sp, ub, ++){ | |
451260e7 | 463 | tag = sp->s_tag; |
d0d638ee BJ |
464 | if (tag == JXNOTYET){ |
465 | #ifdef DEBUG | |
466 | if (debug){ | |
451260e7 | 467 | if (sp->s_dest != 0) |
d0d638ee | 468 | printf("Explode jump to %s on line %d\n", |
451260e7 | 469 | sp->s_dest->s_name, lineno); |
d0d638ee BJ |
470 | else |
471 | printf("Explode an align!\n"); | |
472 | } | |
473 | #endif | |
451260e7 RH |
474 | sp->s_tag = JXINACTIVE; |
475 | sp->s_jxbump = 1; | |
476 | cum_bump += sp->s_jxfear; | |
d0d638ee BJ |
477 | } |
478 | /* | |
479 | * Only bump labels and jxxxes. Ignored entries can | |
480 | * be incremented, as they are thrown away later on. | |
481 | * Stabds are given their final value in the second | |
482 | * pass. | |
483 | */ | |
484 | if (tag >= OKTOBUMP) /*only bump labels and jxxxes and floating stabs*/ | |
451260e7 | 485 | sp->s_value += cum_bump; |
d0d638ee | 486 | } |
451260e7 | 487 | usedot[segno].e_xvalue += cum_bump; |
d0d638ee | 488 | } |