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d0d638ee BJ |
1 | /* Copyright (c) 1980 Regents of the University of California */ |
2 | static char sccsid[] = "@(#)asjxxx.c 4.1 %G%"; | |
3 | #include <stdio.h> | |
4 | #include <sys/types.h> | |
5 | #include "as.h" | |
6 | #include "assyms.h" | |
7 | ||
8 | #define JBR 0x11 | |
9 | #define BRW 0x31 | |
10 | ||
11 | /* | |
12 | * The number of bytes to add if the jxxx must be "exploded" | |
13 | * into the long form | |
14 | */ | |
15 | #define JBRFSIZE 1 /*goes to brw*/ | |
16 | #define JXXXFSIZE 3 /*goes to brb, brw <byte> <byte> */ | |
17 | ||
18 | /* | |
19 | * These variables are filled by asscan.c with the | |
20 | * last name encountered (a pointer buried in the intermediate file), | |
21 | * and the last jxxx symbol table entry encountered. | |
22 | */ | |
23 | struct symtab *lastnam; | |
24 | struct symtab *lastjxxx; | |
25 | ||
26 | /* | |
27 | * Handle jxxx instructions | |
28 | */ | |
29 | ijxout(op,ap,nact) | |
30 | struct arg *ap; | |
31 | { | |
32 | if (passno == 1){ | |
33 | /* | |
34 | * READ THIS BEFORE LOOKING AT jxxxfix() | |
35 | * | |
36 | * Record the jxxx in a special symbol table entry | |
37 | */ | |
38 | register struct symtab *jumpfrom; | |
39 | ||
40 | /* | |
41 | * We assume the MINIMAL length | |
42 | */ | |
43 | putins(op,ap,nact); | |
44 | jumpfrom = lastjxxx; | |
45 | jumpfrom->tag = JXACTIVE; | |
46 | jumpfrom->jxbump = 0; | |
47 | if (op == JBR) | |
48 | jumpfrom->jxfear = JBRFSIZE; | |
49 | else | |
50 | jumpfrom->jxfear = JXXXFSIZE; | |
51 | if (lastnam == 0) | |
52 | yyerror("jxxx destination not a label"); | |
53 | jumpfrom->dest = lastnam; | |
54 | jumpfrom->type = dotp->xtype; /*only TEXT or DATA*/ | |
55 | jumpfrom->index = dotp-usedot; | |
56 | /* | |
57 | * value ALWAYS (ALWAYS!!!) indexes the next instruction | |
58 | * after the jump, even in the jump must be exploded | |
59 | * (bumped) | |
60 | */ | |
61 | jumpfrom->value = dotp->xvalue; | |
62 | njxxx++; | |
63 | } else {/* pass2, resolve */ | |
64 | /* | |
65 | * READ THIS AFTER LOOKING AT jxxxfix() | |
66 | */ | |
67 | register long oxvalue; | |
68 | register struct exp *xp; | |
69 | register struct symtab *tunnel; | |
70 | register struct arg *aplast; | |
71 | ||
72 | aplast = ap + nact - 1; | |
73 | xp = aplast->xp; | |
74 | if (lastjxxx->tag == JXTUNNEL){ | |
75 | lastjxxx->tag = JXINACTIVE; | |
76 | tunnel = lastjxxx->dest; | |
77 | xp->xvalue = tunnel->value /*index of instruction following*/ | |
78 | - 3 /* size of brw + word*/ | |
79 | + ( ( (tunnel->jxfear == JBRFSIZE) && | |
80 | (tunnel->jxbump == 0))?1:0); | |
81 | /*non bumped branch byteis only 2 back*/ | |
82 | } | |
83 | if (lastjxxx->jxbump == 0){ /*wasn't bumped, so is short form*/ | |
84 | putins(op, ap, nact); | |
85 | } else { | |
86 | if (op != JBR){ /*branch reverse conditional byte over | |
87 | branch unconditional word*/ | |
88 | oxvalue = xp->xvalue; | |
89 | xp->xvalue = lastjxxx->value; | |
90 | putins(op^1, ap, nact); | |
91 | xp->xvalue = oxvalue; | |
92 | } | |
93 | putins(BRW, aplast, 1); | |
94 | } | |
95 | } | |
96 | } /*end of ijxout*/ | |
97 | ||
98 | jalign(xp, sp) | |
99 | register struct exp *xp; | |
100 | register struct symtab *sp; | |
101 | { | |
102 | register int mask; | |
103 | if (xp->xtype != XABS || xp->xvalue < 0 || xp->xvalue > 16) { | |
104 | yyerror("Illegal `align' argument"); | |
105 | return; | |
106 | } | |
107 | flushfield(NBPW/4); | |
108 | if (passno == 1) { | |
109 | sp->tag = JXALIGN; | |
110 | sp->jxfear = (1 << xp->xvalue) - 1; | |
111 | sp->type = dotp->xtype; | |
112 | sp->index = dotp-usedot; | |
113 | /* | |
114 | * We guess that the align will take up at least one | |
115 | * byte in the code output. We will correct for this | |
116 | * initial high guess when we explode (bump) aligns | |
117 | * when we fix the jxxxes. We must do this guess | |
118 | * so that the symbol table is sorted correctly | |
119 | * and labels declared to fall before the align | |
120 | * really get their, instead of guessing zero size | |
121 | * and have the label (incorrectly) fall after the jxxx. | |
122 | * This is a quirk of our requirement that indices into | |
123 | * the code stream point to the next byte following | |
124 | * the logical entry in the symbol table | |
125 | */ | |
126 | dotp->xvalue += 1; | |
127 | sp->value = dotp->xvalue; | |
128 | njxxx++; | |
129 | } else { | |
130 | mask = (1 << xp->xvalue) - 1; | |
131 | while (dotp->xvalue & mask){ | |
132 | #ifdef UNIX | |
133 | outb(0); | |
134 | #endif UNIX | |
135 | #ifdef VMS | |
136 | *vms_obj_ptr++ = -1; | |
137 | *vms_obj_ptr++ = 0; | |
138 | dotp->xvalue += 1; | |
139 | #endif VMS | |
140 | } | |
141 | } | |
142 | } | |
143 | ||
144 | /* | |
145 | * Pass 1.5, resolve jxxx instructions and .align in .text | |
146 | */ | |
147 | jxxxfix() | |
148 | { | |
149 | register struct symtab *jumpfrom; | |
150 | struct symtab **cojumpfrom, *ubjumpfrom; | |
151 | register struct symtab *dest; | |
152 | register struct symtab *intdest; /*intermediate dest*/ | |
153 | register struct symtab **cointdest, *ubintdest; | |
154 | ||
155 | register struct symtab *tunnel; | |
156 | int displ,nchange; | |
157 | int badjxalign; /*if jump across an align*/ | |
158 | int stillactives; /*if still active jxxxes*/ | |
159 | int segno; /*current segment number*/ | |
160 | int topono; /*which iteration in the topo sort*/ | |
161 | register unsigned char tag; | |
162 | /* | |
163 | * consider each segment in turn... | |
164 | */ | |
165 | for (segno = 0; segno < NLOC + NLOC; segno++){ | |
166 | badjxalign = 0; /*done on a per segment basis*/ | |
167 | /* | |
168 | * Do a lazy topological sort. | |
169 | */ | |
170 | for (topono = 1, nchange = 1; nchange != 0; topono++){ | |
171 | #ifdef DEBUG | |
172 | if (debug) | |
173 | printf("\nSegment %d, topo iteration %d\n", | |
174 | segno, topono); | |
175 | #endif | |
176 | nchange = 0; | |
177 | stillactives = 0; | |
178 | /* | |
179 | * We keep track of one possible tunnel location. | |
180 | * A tunnel will eventually be an unconditional | |
181 | * branch to the same place that another jxxx | |
182 | * will want to branch to. We will turn a | |
183 | * branch conditional/unconditional (word) that would | |
184 | * have to get bumped because its destination is too | |
185 | * far away, into a branch conditional/unconditional | |
186 | * byte to the tunnel branch conditional/unconditional. | |
187 | * Of course, the tunnel must branch to the same place | |
188 | * as we want to go. | |
189 | */ | |
190 | tunnel = 0; /*initially, no tunnel*/ | |
191 | SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, ubjumpfrom, ++){ | |
192 | tag = jumpfrom->tag; | |
193 | if (tag <= IGNOREBOUND) | |
194 | continue; /*just an ordinary symbol*/ | |
195 | if (tag == JXALIGN){ | |
196 | tunnel = 0; /*avoid tunneling across a flex alocation*/ | |
197 | continue; /*we take care of these later*/ | |
198 | } | |
199 | if ( jumpfrom->jxfear == JBRFSIZE /*unconditional*/ | |
200 | || ( tag == JXINACTIVE /*inactive bumped*/ | |
201 | && (jumpfrom->jxbump != 0) | |
202 | ) | |
203 | ) tunnel = jumpfrom; | |
204 | if (tag != JXACTIVE) | |
205 | continue; | |
206 | dest = jumpfrom->dest; | |
207 | if (jumpfrom->index != dest->index){ | |
208 | yyerror("Intersegment jxxx"); | |
209 | continue; | |
210 | } | |
211 | displ = dest->value - jumpfrom->value; | |
212 | if (displ < MINBYTE || displ > MAXBYTE) { | |
213 | /* | |
214 | * This is an immediate lose! | |
215 | * | |
216 | * We first attempt to tunnel | |
217 | * by finding an intervening jump that | |
218 | * has the same destination. | |
219 | * The tunnel is always the first preceeding | |
220 | * jxxx instruction, so the displacement | |
221 | * to the tunnel is less than zero, and | |
222 | * its relative position will be unaffected | |
223 | * by future jxxx expansions. | |
224 | */ | |
225 | if ( (jumpfrom->jxfear > JBRFSIZE) | |
226 | && (tunnel) | |
227 | && (tunnel->dest == jumpfrom->dest) | |
228 | && (tunnel->index == jumpfrom->index) | |
229 | && (tunnel->value - jumpfrom->value >= | |
230 | MINBYTE + JXXXFSIZE) | |
231 | ) { | |
232 | /* | |
233 | * tunnelling is OK | |
234 | */ | |
235 | jumpfrom->dest = tunnel; | |
236 | /* | |
237 | * no bumping needed, this | |
238 | * is now effectively inactive | |
239 | * but must be remembered | |
240 | */ | |
241 | jumpfrom->tag = JXTUNNEL; | |
242 | #ifdef DEBUG | |
243 | if(debug) | |
244 | printf("Tunnel from %s from line %d\n", | |
245 | jumpfrom->name, lineno); | |
246 | #endif | |
247 | continue; | |
248 | } else { /*tunneling not possible*/ | |
249 | /* | |
250 | * since this will be turned | |
251 | * into a bumped jump, we can | |
252 | * use the unconditional jump | |
253 | * as a tunnel | |
254 | */ | |
255 | tunnel = jumpfrom; | |
256 | jumpfrom->tag = JXNOTYET; | |
257 | ++nchange; | |
258 | continue; | |
259 | } | |
260 | } /*end of immediate lose*/ | |
261 | /* | |
262 | * Do a forward search for an intervening jxxx | |
263 | */ | |
264 | if (displ >= 0) { | |
265 | SEGITERATE(segno, cojumpfrom + 1,0,cointdest, | |
266 | intdest, ubintdest, ++){ | |
267 | if (intdest->value > dest->value) | |
268 | break; /* beyond destination */ | |
269 | if (intdest->tag <= JXQUESTIONABLE) | |
270 | continue; /*frozen solid*/ | |
271 | if (intdest->tag == JXALIGN){ | |
272 | jumpfrom->jxoveralign = 1; | |
273 | badjxalign++; | |
274 | } | |
275 | /* | |
276 | * we assume the worst case | |
277 | * for unfrozen jxxxxes | |
278 | */ | |
279 | displ += intdest->jxfear; | |
280 | } | |
281 | if (displ <= MAXBYTE){ | |
282 | /* | |
283 | * the worst possible conditions | |
284 | * can't hurt us, so forget about | |
285 | * this jump | |
286 | */ | |
287 | jumpfrom->tag = JXINACTIVE; | |
288 | } else { | |
289 | stillactives++; | |
290 | } | |
291 | } else { | |
292 | /* | |
293 | * backward search for intervening jxxx | |
294 | */ | |
295 | SEGITERATE(segno, cojumpfrom - 1,1,cointdest, | |
296 | intdest, ubintdest, --){ | |
297 | if (intdest->value <= dest->value) | |
298 | break; /* beyond destination */ | |
299 | if (intdest->tag <= JXQUESTIONABLE) | |
300 | continue; /*frozen solid*/ | |
301 | if (intdest->tag == JXALIGN){ | |
302 | jumpfrom->jxoveralign = 1; | |
303 | badjxalign++; | |
304 | } | |
305 | displ -= intdest->jxfear; | |
306 | } | |
307 | if (displ >= MINBYTE) { | |
308 | jumpfrom->tag = JXINACTIVE; | |
309 | } else { | |
310 | stillactives++; | |
311 | } | |
312 | } /*end of backwards search*/ | |
313 | } /*end of iterating through all symbols in this seg*/ | |
314 | ||
315 | if (nchange == 0) { | |
316 | /* | |
317 | * Now, if there are still active jxxx entries, | |
318 | * we are partially deadlocked. We can leave | |
319 | * these jxxx entries in their assumed short jump | |
320 | * form, as all initial displacement calcualtions | |
321 | * are hanging on unresolved jxxx instructions | |
322 | * that might explode into a long form, causing | |
323 | * other jxxxes jumping across the first set of | |
324 | * jxxxes to explode, etc. | |
325 | * However, if a jxxx jumps across a .align, | |
326 | * we assume the worst for the deadlock cycle, | |
327 | * and resolve all of them towards the long | |
328 | * jump. | |
329 | * Currently, the C compiler does not produce | |
330 | * jumps across aligns, as aligns are only used | |
331 | * in data segments, or in text segments to align | |
332 | * functions. | |
333 | */ | |
334 | if (stillactives){ | |
335 | SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, | |
336 | ubjumpfrom, ++){ | |
337 | if (jumpfrom->tag == JXACTIVE){ | |
338 | jumpfrom->tag = | |
339 | badjxalign?JXNOTYET:JXINACTIVE; | |
340 | } | |
341 | } | |
342 | if (badjxalign){ | |
343 | jxxxbump(segno, (struct symtab **)0); | |
344 | } | |
345 | } | |
346 | /* | |
347 | * Handle all of the .align s | |
348 | */ | |
349 | SEGITERATE(segno, 0, 0, cojumpfrom, jumpfrom, | |
350 | ubjumpfrom, ++){ | |
351 | if (jumpfrom->tag == JXALIGN){ | |
352 | /* | |
353 | * Predict the true displacement | |
354 | * needed, irregardless of the | |
355 | * fact that we guessed 1 | |
356 | */ | |
357 | displ = (jumpfrom->value - 1) & (unsigned)jumpfrom->jxfear; | |
358 | if (displ == 0){ /*no virtual displacement*/ | |
359 | jumpfrom->jxfear = -1; | |
360 | } else { | |
361 | jumpfrom->jxfear = (jumpfrom->jxfear + 1) - displ; | |
362 | /* | |
363 | * assert jumpfrom->jxfear > 0 | |
364 | */ | |
365 | if (jumpfrom->jxfear == 1){ | |
366 | /*our prediction was correct*/ | |
367 | continue; | |
368 | } | |
369 | /* | |
370 | * assert jumpfrom->jxfear > 1 | |
371 | */ | |
372 | jumpfrom->jxfear -= 1; /*correct guess*/ | |
373 | } | |
374 | /* | |
375 | * assert jumpfrom->jxfear = -1, +1...2**n-1 | |
376 | */ | |
377 | jumpfrom->tag = JXNOTYET; /*signal*/ | |
378 | jxxxbump(segno, cojumpfrom); | |
379 | jumpfrom->tag = JXINACTIVE; | |
380 | /* | |
381 | * Assert jxfrom->jxvalue indexes the first | |
382 | * code byte after the added bytes, and | |
383 | * has n low order zeroes. | |
384 | */ | |
385 | } | |
386 | } /*end of walking through each segment*/ | |
387 | } /*end of no changes */ | |
388 | else { /*changes, and still have to try another pass*/ | |
389 | jxxxbump(segno, (struct symtab **)0); | |
390 | } | |
391 | } /*end of doing the topologic sort*/ | |
392 | } /*end of iterating through all segments*/ | |
393 | } /*end of jxxxfix*/ | |
394 | ||
395 | /* | |
396 | * Go through the symbols in a given segment number, | |
397 | * and see which entries are jxxx entries that have | |
398 | * been logically "exploded" (expanded), but for which | |
399 | * the value of textually following symbols has not been | |
400 | * increased | |
401 | */ | |
402 | ||
403 | jxxxbump(segno, starthint) | |
404 | int segno; | |
405 | struct symtab **starthint; | |
406 | { | |
407 | register struct symtab **cosp, *sp; | |
408 | register struct symtab *ub; | |
409 | register int cum_bump; | |
410 | register unsigned char tag; | |
411 | ||
412 | cum_bump = 0; | |
413 | SEGITERATE(segno, starthint, 0, cosp, sp, ub, ++){ | |
414 | tag = sp->tag; | |
415 | if (tag == JXNOTYET){ | |
416 | #ifdef DEBUG | |
417 | if (debug){ | |
418 | if (sp->dest != 0) | |
419 | printf("Explode jump to %s on line %d\n", | |
420 | sp->dest->name, lineno); | |
421 | else | |
422 | printf("Explode an align!\n"); | |
423 | } | |
424 | #endif | |
425 | sp->tag = JXINACTIVE; | |
426 | sp->jxbump = 1; | |
427 | cum_bump += sp->jxfear; | |
428 | } | |
429 | /* | |
430 | * Only bump labels and jxxxes. Ignored entries can | |
431 | * be incremented, as they are thrown away later on. | |
432 | * Stabds are given their final value in the second | |
433 | * pass. | |
434 | */ | |
435 | if (tag >= OKTOBUMP) /*only bump labels and jxxxes and floating stabs*/ | |
436 | sp->value += cum_bump; | |
437 | } | |
438 | usedot[segno].xvalue += cum_bump; | |
439 | } |