xref: /openbmc/qemu/target/hexagon/decode.c (revision a6caeee8)
1 /*
2  *  Copyright(c) 2019-2021 Qualcomm Innovation Center, Inc. All Rights Reserved.
3  *
4  *  This program is free software; you can redistribute it and/or modify
5  *  it under the terms of the GNU General Public License as published by
6  *  the Free Software Foundation; either version 2 of the License, or
7  *  (at your option) any later version.
8  *
9  *  This program is distributed in the hope that it will be useful,
10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  *  GNU General Public License for more details.
13  *
14  *  You should have received a copy of the GNU General Public License
15  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
16  */
17 
18 #include "qemu/osdep.h"
19 #include "iclass.h"
20 #include "attribs.h"
21 #include "genptr.h"
22 #include "decode.h"
23 #include "insn.h"
24 #include "printinsn.h"
25 #include "mmvec/decode_ext_mmvec.h"
26 
27 #define fZXTN(N, M, VAL) ((VAL) & ((1LL << (N)) - 1))
28 
29 enum {
30     EXT_IDX_noext = 0,
31     EXT_IDX_noext_AFTER = 4,
32     EXT_IDX_mmvec = 4,
33     EXT_IDX_mmvec_AFTER = 8,
34     XX_LAST_EXT_IDX
35 };
36 
37 /*
38  *  Certain operand types represent a non-contiguous set of values.
39  *  For example, the compound compare-and-jump instruction can only access
40  *  registers R0-R7 and R16-23.
41  *  This table represents the mapping from the encoding to the actual values.
42  */
43 
44 #define DEF_REGMAP(NAME, ELEMENTS, ...) \
45     static const unsigned int DECODE_REGISTER_##NAME[ELEMENTS] = \
46     { __VA_ARGS__ };
47         /* Name   Num Table */
48 DEF_REGMAP(R_16,  16, 0, 1, 2, 3, 4, 5, 6, 7, 16, 17, 18, 19, 20, 21, 22, 23)
49 DEF_REGMAP(R__8,  8,  0, 2, 4, 6, 16, 18, 20, 22)
50 DEF_REGMAP(R_8,   8,  0, 1, 2, 3, 4, 5, 6, 7)
51 
52 #define DECODE_MAPPED_REG(OPNUM, NAME) \
53     insn->regno[OPNUM] = DECODE_REGISTER_##NAME[insn->regno[OPNUM]];
54 
55 typedef struct {
56     const struct DectreeTable *table_link;
57     const struct DectreeTable *table_link_b;
58     Opcode opcode;
59     enum {
60         DECTREE_ENTRY_INVALID,
61         DECTREE_TABLE_LINK,
62         DECTREE_SUBINSNS,
63         DECTREE_EXTSPACE,
64         DECTREE_TERMINAL
65     } type;
66 } DectreeEntry;
67 
68 typedef struct DectreeTable {
69     unsigned int (*lookup_function)(int startbit, int width, uint32_t opcode);
70     unsigned int size;
71     unsigned int startbit;
72     unsigned int width;
73     const DectreeEntry table[];
74 } DectreeTable;
75 
76 #define DECODE_NEW_TABLE(TAG, SIZE, WHATNOT) \
77     static const DectreeTable dectree_table_##TAG;
78 #define TABLE_LINK(TABLE)                     /* NOTHING */
79 #define TERMINAL(TAG, ENC)                    /* NOTHING */
80 #define SUBINSNS(TAG, CLASSA, CLASSB, ENC)    /* NOTHING */
81 #define EXTSPACE(TAG, ENC)                    /* NOTHING */
82 #define INVALID()                             /* NOTHING */
83 #define DECODE_END_TABLE(...)                 /* NOTHING */
84 #define DECODE_MATCH_INFO(...)                /* NOTHING */
85 #define DECODE_LEGACY_MATCH_INFO(...)         /* NOTHING */
86 #define DECODE_OPINFO(...)                    /* NOTHING */
87 
88 #include "dectree_generated.h.inc"
89 
90 #undef DECODE_OPINFO
91 #undef DECODE_MATCH_INFO
92 #undef DECODE_LEGACY_MATCH_INFO
93 #undef DECODE_END_TABLE
94 #undef INVALID
95 #undef TERMINAL
96 #undef SUBINSNS
97 #undef EXTSPACE
98 #undef TABLE_LINK
99 #undef DECODE_NEW_TABLE
100 #undef DECODE_SEPARATOR_BITS
101 
102 #define DECODE_SEPARATOR_BITS(START, WIDTH) NULL, START, WIDTH
103 #define DECODE_NEW_TABLE_HELPER(TAG, SIZE, FN, START, WIDTH) \
104     static const DectreeTable dectree_table_##TAG = { \
105         .size = SIZE, \
106         .lookup_function = FN, \
107         .startbit = START, \
108         .width = WIDTH, \
109         .table = {
110 #define DECODE_NEW_TABLE(TAG, SIZE, WHATNOT) \
111     DECODE_NEW_TABLE_HELPER(TAG, SIZE, WHATNOT)
112 
113 #define TABLE_LINK(TABLE) \
114     { .type = DECTREE_TABLE_LINK, .table_link = &dectree_table_##TABLE },
115 #define TERMINAL(TAG, ENC) \
116     { .type = DECTREE_TERMINAL, .opcode = TAG  },
117 #define SUBINSNS(TAG, CLASSA, CLASSB, ENC) \
118     { \
119         .type = DECTREE_SUBINSNS, \
120         .table_link = &dectree_table_DECODE_SUBINSN_##CLASSA, \
121         .table_link_b = &dectree_table_DECODE_SUBINSN_##CLASSB \
122     },
123 #define EXTSPACE(TAG, ENC) { .type = DECTREE_EXTSPACE },
124 #define INVALID() { .type = DECTREE_ENTRY_INVALID, .opcode = XX_LAST_OPCODE },
125 
126 #define DECODE_END_TABLE(...) } };
127 
128 #define DECODE_MATCH_INFO(...)                /* NOTHING */
129 #define DECODE_LEGACY_MATCH_INFO(...)         /* NOTHING */
130 #define DECODE_OPINFO(...)                    /* NOTHING */
131 
132 #include "dectree_generated.h.inc"
133 
134 #undef DECODE_OPINFO
135 #undef DECODE_MATCH_INFO
136 #undef DECODE_LEGACY_MATCH_INFO
137 #undef DECODE_END_TABLE
138 #undef INVALID
139 #undef TERMINAL
140 #undef SUBINSNS
141 #undef EXTSPACE
142 #undef TABLE_LINK
143 #undef DECODE_NEW_TABLE
144 #undef DECODE_NEW_TABLE_HELPER
145 #undef DECODE_SEPARATOR_BITS
146 
147 static const DectreeTable dectree_table_DECODE_EXT_EXT_noext = {
148     .size = 1, .lookup_function = NULL, .startbit = 0, .width = 0,
149     .table = {
150         { .type = DECTREE_ENTRY_INVALID, .opcode = XX_LAST_OPCODE },
151     }
152 };
153 
154 static const DectreeTable *ext_trees[XX_LAST_EXT_IDX];
155 
156 static void decode_ext_init(void)
157 {
158     int i;
159     for (i = EXT_IDX_noext; i < EXT_IDX_noext_AFTER; i++) {
160         ext_trees[i] = &dectree_table_DECODE_EXT_EXT_noext;
161     }
162     for (i = EXT_IDX_mmvec; i < EXT_IDX_mmvec_AFTER; i++) {
163         ext_trees[i] = &dectree_table_DECODE_EXT_EXT_mmvec;
164     }
165 }
166 
167 typedef struct {
168     uint32_t mask;
169     uint32_t match;
170 } DecodeITableEntry;
171 
172 #define DECODE_NEW_TABLE(TAG, SIZE, WHATNOT)  /* NOTHING */
173 #define TABLE_LINK(TABLE)                     /* NOTHING */
174 #define TERMINAL(TAG, ENC)                    /* NOTHING */
175 #define SUBINSNS(TAG, CLASSA, CLASSB, ENC)    /* NOTHING */
176 #define EXTSPACE(TAG, ENC)                    /* NOTHING */
177 #define INVALID()                             /* NOTHING */
178 #define DECODE_END_TABLE(...)                 /* NOTHING */
179 #define DECODE_OPINFO(...)                    /* NOTHING */
180 
181 #define DECODE_MATCH_INFO_NORMAL(TAG, MASK, MATCH) \
182     [TAG] = { \
183         .mask = MASK, \
184         .match = MATCH, \
185     },
186 
187 #define DECODE_MATCH_INFO_NULL(TAG, MASK, MATCH) \
188     [TAG] = { .match = ~0 },
189 
190 #define DECODE_MATCH_INFO(...) DECODE_MATCH_INFO_NORMAL(__VA_ARGS__)
191 #define DECODE_LEGACY_MATCH_INFO(...) /* NOTHING */
192 
193 static const DecodeITableEntry decode_itable[XX_LAST_OPCODE] = {
194 #include "dectree_generated.h.inc"
195 };
196 
197 #undef DECODE_MATCH_INFO
198 #define DECODE_MATCH_INFO(...) DECODE_MATCH_INFO_NULL(__VA_ARGS__)
199 
200 #undef DECODE_LEGACY_MATCH_INFO
201 #define DECODE_LEGACY_MATCH_INFO(...) DECODE_MATCH_INFO_NORMAL(__VA_ARGS__)
202 
203 static const DecodeITableEntry decode_legacy_itable[XX_LAST_OPCODE] = {
204 #include "dectree_generated.h.inc"
205 };
206 
207 #undef DECODE_OPINFO
208 #undef DECODE_MATCH_INFO
209 #undef DECODE_LEGACY_MATCH_INFO
210 #undef DECODE_END_TABLE
211 #undef INVALID
212 #undef TERMINAL
213 #undef SUBINSNS
214 #undef EXTSPACE
215 #undef TABLE_LINK
216 #undef DECODE_NEW_TABLE
217 #undef DECODE_SEPARATOR_BITS
218 
219 void decode_init(void)
220 {
221     decode_ext_init();
222 }
223 
224 void decode_send_insn_to(Packet *packet, int start, int newloc)
225 {
226     Insn tmpinsn;
227     int direction;
228     int i;
229     if (start == newloc) {
230         return;
231     }
232     if (start < newloc) {
233         /* Move towards end */
234         direction = 1;
235     } else {
236         /* move towards beginning */
237         direction = -1;
238     }
239     for (i = start; i != newloc; i += direction) {
240         tmpinsn = packet->insn[i];
241         packet->insn[i] = packet->insn[i + direction];
242         packet->insn[i + direction] = tmpinsn;
243     }
244 }
245 
246 /* Fill newvalue registers with the correct regno */
247 static void
248 decode_fill_newvalue_regno(Packet *packet)
249 {
250     int i, use_regidx, offset, def_idx, dst_idx;
251     uint16_t def_opcode, use_opcode;
252     char *dststr;
253 
254     for (i = 1; i < packet->num_insns; i++) {
255         if (GET_ATTRIB(packet->insn[i].opcode, A_DOTNEWVALUE) &&
256             !GET_ATTRIB(packet->insn[i].opcode, A_EXTENSION)) {
257             use_opcode = packet->insn[i].opcode;
258 
259             /* It's a store, so we're adjusting the Nt field */
260             if (GET_ATTRIB(use_opcode, A_STORE)) {
261                 use_regidx = strchr(opcode_reginfo[use_opcode], 't') -
262                     opcode_reginfo[use_opcode];
263             } else {    /* It's a Jump, so we're adjusting the Ns field */
264                 use_regidx = strchr(opcode_reginfo[use_opcode], 's') -
265                     opcode_reginfo[use_opcode];
266             }
267 
268             /*
269              * What's encoded at the N-field is the offset to who's producing
270              * the value.  Shift off the LSB which indicates odd/even register,
271              * then walk backwards and skip over the constant extenders.
272              */
273             offset = packet->insn[i].regno[use_regidx] >> 1;
274             def_idx = i - offset;
275             for (int j = 0; j < offset; j++) {
276                 if (GET_ATTRIB(packet->insn[i - j - 1].opcode, A_IT_EXTENDER)) {
277                     def_idx--;
278                 }
279             }
280 
281             /*
282              * Check for a badly encoded N-field which points to an instruction
283              * out-of-range
284              */
285             g_assert(!((def_idx < 0) || (def_idx > (packet->num_insns - 1))));
286 
287             /*
288              * packet->insn[def_idx] is the producer
289              * Figure out which type of destination it produces
290              * and the corresponding index in the reginfo
291              */
292             def_opcode = packet->insn[def_idx].opcode;
293             dststr = strstr(opcode_wregs[def_opcode], "Rd");
294             if (dststr) {
295                 dststr = strchr(opcode_reginfo[def_opcode], 'd');
296             } else {
297                 dststr = strstr(opcode_wregs[def_opcode], "Rx");
298                 if (dststr) {
299                     dststr = strchr(opcode_reginfo[def_opcode], 'x');
300                 } else {
301                     dststr = strstr(opcode_wregs[def_opcode], "Re");
302                     if (dststr) {
303                         dststr = strchr(opcode_reginfo[def_opcode], 'e');
304                     } else {
305                         dststr = strstr(opcode_wregs[def_opcode], "Ry");
306                         if (dststr) {
307                             dststr = strchr(opcode_reginfo[def_opcode], 'y');
308                         } else {
309                             g_assert_not_reached();
310                         }
311                     }
312                 }
313             }
314             g_assert(dststr != NULL);
315 
316             /* Now patch up the consumer with the register number */
317             dst_idx = dststr - opcode_reginfo[def_opcode];
318             packet->insn[i].regno[use_regidx] =
319                 packet->insn[def_idx].regno[dst_idx];
320             /*
321              * We need to remember who produces this value to later
322              * check if it was dynamically cancelled
323              */
324             packet->insn[i].new_value_producer_slot =
325                 packet->insn[def_idx].slot;
326         }
327     }
328 }
329 
330 /* Split CJ into a compare and a jump */
331 static void decode_split_cmpjump(Packet *pkt)
332 {
333     int last, i;
334     int numinsns = pkt->num_insns;
335 
336     /*
337      * First, split all compare-jumps.
338      * The compare is sent to the end as a new instruction.
339      * Do it this way so we don't reorder dual jumps. Those need to stay in
340      * original order.
341      */
342     for (i = 0; i < numinsns; i++) {
343         /* It's a cmp-jump */
344         if (GET_ATTRIB(pkt->insn[i].opcode, A_NEWCMPJUMP)) {
345             last = pkt->num_insns;
346             pkt->insn[last] = pkt->insn[i];    /* copy the instruction */
347             pkt->insn[last].part1 = true;      /* last insn does the CMP */
348             pkt->insn[i].part1 = false;        /* existing insn does the JUMP */
349             pkt->num_insns++;
350         }
351     }
352 
353     /* Now re-shuffle all the compares back to the beginning */
354     for (i = 0; i < pkt->num_insns; i++) {
355         if (pkt->insn[i].part1) {
356             decode_send_insn_to(pkt, i, 0);
357         }
358     }
359 }
360 
361 static bool decode_opcode_can_jump(int opcode)
362 {
363     if ((GET_ATTRIB(opcode, A_JUMP)) ||
364         (GET_ATTRIB(opcode, A_CALL)) ||
365         (opcode == J2_trap0) ||
366         (opcode == J2_pause)) {
367         /* Exception to A_JUMP attribute */
368         if (opcode == J4_hintjumpr) {
369             return false;
370         }
371         return true;
372     }
373 
374     return false;
375 }
376 
377 static bool decode_opcode_ends_loop(int opcode)
378 {
379     return GET_ATTRIB(opcode, A_HWLOOP0_END) ||
380            GET_ATTRIB(opcode, A_HWLOOP1_END);
381 }
382 
383 /* Set the is_* fields in each instruction */
384 static void decode_set_insn_attr_fields(Packet *pkt)
385 {
386     int i;
387     int numinsns = pkt->num_insns;
388     uint16_t opcode;
389 
390     pkt->pkt_has_cof = false;
391     pkt->pkt_has_endloop = false;
392     pkt->pkt_has_dczeroa = false;
393 
394     for (i = 0; i < numinsns; i++) {
395         opcode = pkt->insn[i].opcode;
396         if (pkt->insn[i].part1) {
397             continue;    /* Skip compare of cmp-jumps */
398         }
399 
400         if (GET_ATTRIB(opcode, A_DCZEROA)) {
401             pkt->pkt_has_dczeroa = true;
402         }
403 
404         if (GET_ATTRIB(opcode, A_STORE)) {
405             if (pkt->insn[i].slot == 0) {
406                 pkt->pkt_has_store_s0 = true;
407             } else {
408                 pkt->pkt_has_store_s1 = true;
409             }
410         }
411 
412         pkt->pkt_has_cof |= decode_opcode_can_jump(opcode);
413 
414         pkt->insn[i].is_endloop = decode_opcode_ends_loop(opcode);
415 
416         pkt->pkt_has_endloop |= pkt->insn[i].is_endloop;
417 
418         pkt->pkt_has_cof |= pkt->pkt_has_endloop;
419     }
420 }
421 
422 /*
423  * Shuffle for execution
424  * Move stores to end (in same order as encoding)
425  * Move compares to beginning (for use by .new insns)
426  */
427 static void decode_shuffle_for_execution(Packet *packet)
428 {
429     bool changed = false;
430     int i;
431     bool flag;    /* flag means we've seen a non-memory instruction */
432     int n_mems;
433     int last_insn = packet->num_insns - 1;
434 
435     /*
436      * Skip end loops, somehow an end loop is getting in and messing
437      * up the order
438      */
439     if (decode_opcode_ends_loop(packet->insn[last_insn].opcode)) {
440         last_insn--;
441     }
442 
443     do {
444         changed = false;
445         /*
446          * Stores go last, must not reorder.
447          * Cannot shuffle stores past loads, either.
448          * Iterate backwards.  If we see a non-memory instruction,
449          * then a store, shuffle the store to the front.  Don't shuffle
450          * stores wrt each other or a load.
451          */
452         for (flag = false, n_mems = 0, i = last_insn; i >= 0; i--) {
453             int opcode = packet->insn[i].opcode;
454 
455             if (flag && GET_ATTRIB(opcode, A_STORE)) {
456                 decode_send_insn_to(packet, i, last_insn - n_mems);
457                 n_mems++;
458                 changed = true;
459             } else if (GET_ATTRIB(opcode, A_STORE)) {
460                 n_mems++;
461             } else if (GET_ATTRIB(opcode, A_LOAD)) {
462                 /*
463                  * Don't set flag, since we don't want to shuffle a
464                  * store past a load
465                  */
466                 n_mems++;
467             } else if (GET_ATTRIB(opcode, A_DOTNEWVALUE)) {
468                 /*
469                  * Don't set flag, since we don't want to shuffle past
470                  * a .new value
471                  */
472             } else {
473                 flag = true;
474             }
475         }
476 
477         if (changed) {
478             continue;
479         }
480         /* Compares go first, may be reordered wrt each other */
481         for (flag = false, i = 0; i < last_insn + 1; i++) {
482             int opcode = packet->insn[i].opcode;
483 
484             if ((strstr(opcode_wregs[opcode], "Pd4") ||
485                  strstr(opcode_wregs[opcode], "Pe4")) &&
486                 GET_ATTRIB(opcode, A_STORE) == 0) {
487                 /* This should be a compare (not a store conditional) */
488                 if (flag) {
489                     decode_send_insn_to(packet, i, 0);
490                     changed = true;
491                     continue;
492                 }
493             } else if (GET_ATTRIB(opcode, A_IMPLICIT_WRITES_P3) &&
494                        !decode_opcode_ends_loop(packet->insn[i].opcode)) {
495                 /*
496                  * spNloop instruction
497                  * Don't reorder endloops; they are not valid for .new uses,
498                  * and we want to match HW
499                  */
500                 if (flag) {
501                     decode_send_insn_to(packet, i, 0);
502                     changed = true;
503                     continue;
504                 }
505             } else if (GET_ATTRIB(opcode, A_IMPLICIT_WRITES_P0) &&
506                        !GET_ATTRIB(opcode, A_NEWCMPJUMP)) {
507                 if (flag) {
508                     decode_send_insn_to(packet, i, 0);
509                     changed = true;
510                     continue;
511                 }
512             } else {
513                 flag = true;
514             }
515         }
516         if (changed) {
517             continue;
518         }
519     } while (changed);
520 
521     /*
522      * If we have a .new register compare/branch, move that to the very
523      * very end, past stores
524      */
525     for (i = 0; i < last_insn; i++) {
526         if (GET_ATTRIB(packet->insn[i].opcode, A_DOTNEWVALUE)) {
527             decode_send_insn_to(packet, i, last_insn);
528             break;
529         }
530     }
531 }
532 
533 static void
534 apply_extender(Packet *pkt, int i, uint32_t extender)
535 {
536     int immed_num;
537     uint32_t base_immed;
538 
539     immed_num = opcode_which_immediate_is_extended(pkt->insn[i].opcode);
540     base_immed = pkt->insn[i].immed[immed_num];
541 
542     pkt->insn[i].immed[immed_num] = extender | fZXTN(6, 32, base_immed);
543 }
544 
545 static void decode_apply_extenders(Packet *packet)
546 {
547     int i;
548     for (i = 0; i < packet->num_insns; i++) {
549         if (GET_ATTRIB(packet->insn[i].opcode, A_IT_EXTENDER)) {
550             packet->insn[i + 1].extension_valid = true;
551             apply_extender(packet, i + 1, packet->insn[i].immed[0]);
552         }
553     }
554 }
555 
556 static void decode_remove_extenders(Packet *packet)
557 {
558     int i, j;
559     for (i = 0; i < packet->num_insns; i++) {
560         if (GET_ATTRIB(packet->insn[i].opcode, A_IT_EXTENDER)) {
561             /* Remove this one by moving the remaining instructions down */
562             for (j = i;
563                 (j < packet->num_insns - 1) && (j < INSTRUCTIONS_MAX - 1);
564                 j++) {
565                 packet->insn[j] = packet->insn[j + 1];
566             }
567             packet->num_insns--;
568         }
569     }
570 }
571 
572 static SlotMask get_valid_slots(const Packet *pkt, unsigned int slot)
573 {
574     if (GET_ATTRIB(pkt->insn[slot].opcode, A_EXTENSION)) {
575         return mmvec_ext_decode_find_iclass_slots(pkt->insn[slot].opcode);
576     } else {
577         return find_iclass_slots(pkt->insn[slot].opcode,
578                                  pkt->insn[slot].iclass);
579     }
580 }
581 
582 #define DECODE_NEW_TABLE(TAG, SIZE, WHATNOT)     /* NOTHING */
583 #define TABLE_LINK(TABLE)                        /* NOTHING */
584 #define TERMINAL(TAG, ENC)                       /* NOTHING */
585 #define SUBINSNS(TAG, CLASSA, CLASSB, ENC)       /* NOTHING */
586 #define EXTSPACE(TAG, ENC)                       /* NOTHING */
587 #define INVALID()                                /* NOTHING */
588 #define DECODE_END_TABLE(...)                    /* NOTHING */
589 #define DECODE_MATCH_INFO(...)                   /* NOTHING */
590 #define DECODE_LEGACY_MATCH_INFO(...)            /* NOTHING */
591 
592 #define DECODE_REG(REGNO, WIDTH, STARTBIT) \
593     insn->regno[REGNO] = ((encoding >> STARTBIT) & ((1 << WIDTH) - 1));
594 
595 #define DECODE_IMPL_REG(REGNO, VAL) \
596     insn->regno[REGNO] = VAL;
597 
598 #define DECODE_IMM(IMMNO, WIDTH, STARTBIT, VALSTART) \
599     insn->immed[IMMNO] |= (((encoding >> STARTBIT) & ((1 << WIDTH) - 1))) << \
600                           (VALSTART);
601 
602 #define DECODE_IMM_SXT(IMMNO, WIDTH) \
603     insn->immed[IMMNO] = ((((int32_t)insn->immed[IMMNO]) << (32 - WIDTH)) >> \
604                           (32 - WIDTH));
605 
606 #define DECODE_IMM_NEG(IMMNO, WIDTH) \
607     insn->immed[IMMNO] = -insn->immed[IMMNO];
608 
609 #define DECODE_IMM_SHIFT(IMMNO, SHAMT)                                 \
610     if ((!insn->extension_valid) || \
611         (insn->which_extended != IMMNO)) { \
612         insn->immed[IMMNO] <<= SHAMT; \
613     }
614 
615 #define DECODE_OPINFO(TAG, BEH) \
616     case TAG: \
617         { BEH  } \
618         break; \
619 
620 /*
621  * Fill in the operands of the instruction
622  * dectree_generated.h.inc has a DECODE_OPINFO entry for each opcode
623  * For example,
624  *     DECODE_OPINFO(A2_addi,
625  *          DECODE_REG(0,5,0)
626  *          DECODE_REG(1,5,16)
627  *          DECODE_IMM(0,7,21,9)
628  *          DECODE_IMM(0,9,5,0)
629  *          DECODE_IMM_SXT(0,16)
630  * with the macros defined above, we'll fill in a switch statement
631  * where each case is an opcode tag.
632  */
633 static void
634 decode_op(Insn *insn, Opcode tag, uint32_t encoding)
635 {
636     insn->immed[0] = 0;
637     insn->immed[1] = 0;
638     insn->opcode = tag;
639     if (insn->extension_valid) {
640         insn->which_extended = opcode_which_immediate_is_extended(tag);
641     }
642 
643     switch (tag) {
644 #include "dectree_generated.h.inc"
645     default:
646         break;
647     }
648 
649     insn->generate = opcode_genptr[tag];
650 
651     insn->iclass = iclass_bits(encoding);
652 }
653 
654 #undef DECODE_REG
655 #undef DECODE_IMPL_REG
656 #undef DECODE_IMM
657 #undef DECODE_IMM_SHIFT
658 #undef DECODE_OPINFO
659 #undef DECODE_MATCH_INFO
660 #undef DECODE_LEGACY_MATCH_INFO
661 #undef DECODE_END_TABLE
662 #undef INVALID
663 #undef TERMINAL
664 #undef SUBINSNS
665 #undef EXTSPACE
666 #undef TABLE_LINK
667 #undef DECODE_NEW_TABLE
668 #undef DECODE_SEPARATOR_BITS
669 
670 static unsigned int
671 decode_subinsn_tablewalk(Insn *insn, const DectreeTable *table,
672                          uint32_t encoding)
673 {
674     unsigned int i;
675     Opcode opc;
676     if (table->lookup_function) {
677         i = table->lookup_function(table->startbit, table->width, encoding);
678     } else {
679         i = extract32(encoding, table->startbit, table->width);
680     }
681     if (table->table[i].type == DECTREE_TABLE_LINK) {
682         return decode_subinsn_tablewalk(insn, table->table[i].table_link,
683                                         encoding);
684     } else if (table->table[i].type == DECTREE_TERMINAL) {
685         opc = table->table[i].opcode;
686         if ((encoding & decode_itable[opc].mask) != decode_itable[opc].match) {
687             return 0;
688         }
689         decode_op(insn, opc, encoding);
690         return 1;
691     } else {
692         return 0;
693     }
694 }
695 
696 static unsigned int get_insn_a(uint32_t encoding)
697 {
698     return extract32(encoding, 0, 13);
699 }
700 
701 static unsigned int get_insn_b(uint32_t encoding)
702 {
703     return extract32(encoding, 16, 13);
704 }
705 
706 static unsigned int
707 decode_insns_tablewalk(Insn *insn, const DectreeTable *table,
708                        uint32_t encoding)
709 {
710     unsigned int i;
711     unsigned int a, b;
712     Opcode opc;
713     if (table->lookup_function) {
714         i = table->lookup_function(table->startbit, table->width, encoding);
715     } else {
716         i = extract32(encoding, table->startbit, table->width);
717     }
718     if (table->table[i].type == DECTREE_TABLE_LINK) {
719         return decode_insns_tablewalk(insn, table->table[i].table_link,
720                                       encoding);
721     } else if (table->table[i].type == DECTREE_SUBINSNS) {
722         a = get_insn_a(encoding);
723         b = get_insn_b(encoding);
724         b = decode_subinsn_tablewalk(insn, table->table[i].table_link_b, b);
725         a = decode_subinsn_tablewalk(insn + 1, table->table[i].table_link, a);
726         if ((a == 0) || (b == 0)) {
727             return 0;
728         }
729         return 2;
730     } else if (table->table[i].type == DECTREE_TERMINAL) {
731         opc = table->table[i].opcode;
732         if ((encoding & decode_itable[opc].mask) != decode_itable[opc].match) {
733             if ((encoding & decode_legacy_itable[opc].mask) !=
734                 decode_legacy_itable[opc].match) {
735                 return 0;
736             }
737         }
738         decode_op(insn, opc, encoding);
739         return 1;
740     } else if (table->table[i].type == DECTREE_EXTSPACE) {
741         /*
742          * For now, HVX will be the only coproc
743          */
744         return decode_insns_tablewalk(insn, ext_trees[EXT_IDX_mmvec], encoding);
745     } else {
746         return 0;
747     }
748 }
749 
750 static unsigned int
751 decode_insns(Insn *insn, uint32_t encoding)
752 {
753     const DectreeTable *table;
754     if (parse_bits(encoding) != 0) {
755         /* Start with PP table - 32 bit instructions */
756         table = &dectree_table_DECODE_ROOT_32;
757     } else {
758         /* start with EE table - duplex instructions */
759         table = &dectree_table_DECODE_ROOT_EE;
760     }
761     return decode_insns_tablewalk(insn, table, encoding);
762 }
763 
764 static void decode_add_endloop_insn(Insn *insn, int loopnum)
765 {
766     if (loopnum == 10) {
767         insn->opcode = J2_endloop01;
768         insn->generate = opcode_genptr[J2_endloop01];
769     } else if (loopnum == 1) {
770         insn->opcode = J2_endloop1;
771         insn->generate = opcode_genptr[J2_endloop1];
772     } else if (loopnum == 0) {
773         insn->opcode = J2_endloop0;
774         insn->generate = opcode_genptr[J2_endloop0];
775     } else {
776         g_assert_not_reached();
777     }
778 }
779 
780 static bool decode_parsebits_is_loopend(uint32_t encoding32)
781 {
782     uint32_t bits = parse_bits(encoding32);
783     return bits == 0x2;
784 }
785 
786 static void
787 decode_set_slot_number(Packet *pkt)
788 {
789     int slot;
790     int i;
791     bool hit_mem_insn = false;
792     bool hit_duplex = false;
793     bool slot0_found = false;
794     bool slot1_found = false;
795     int slot1_iidx = 0;
796 
797     /*
798      * The slots are encoded in reverse order
799      * For each instruction, count down until you find a suitable slot
800      */
801     for (i = 0, slot = 3; i < pkt->num_insns; i++) {
802         SlotMask valid_slots = get_valid_slots(pkt, i);
803 
804         while (!(valid_slots & (1 << slot))) {
805             slot--;
806         }
807         pkt->insn[i].slot = slot;
808         if (slot) {
809             /* I've assigned the slot, now decrement it for the next insn */
810             slot--;
811         }
812     }
813 
814     /* Fix the exceptions - mem insns to slot 0,1 */
815     for (i = pkt->num_insns - 1; i >= 0; i--) {
816         /* First memory instruction always goes to slot 0 */
817         if ((GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE) ||
818              GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE_PACKET_RULES)) &&
819             !hit_mem_insn) {
820             hit_mem_insn = true;
821             pkt->insn[i].slot = 0;
822             continue;
823         }
824 
825         /* Next memory instruction always goes to slot 1 */
826         if ((GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE) ||
827              GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE_PACKET_RULES)) &&
828             hit_mem_insn) {
829             pkt->insn[i].slot = 1;
830         }
831     }
832 
833     /* Fix the exceptions - duplex always slot 0,1 */
834     for (i = pkt->num_insns - 1; i >= 0; i--) {
835         /* First subinsn always goes to slot 0 */
836         if (GET_ATTRIB(pkt->insn[i].opcode, A_SUBINSN) && !hit_duplex) {
837             hit_duplex = true;
838             pkt->insn[i].slot = 0;
839             continue;
840         }
841 
842         /* Next subinsn always goes to slot 1 */
843         if (GET_ATTRIB(pkt->insn[i].opcode, A_SUBINSN) && hit_duplex) {
844             pkt->insn[i].slot = 1;
845         }
846     }
847 
848     /* Fix the exceptions - slot 1 is never empty, always aligns to slot 0 */
849     for (i = pkt->num_insns - 1; i >= 0; i--) {
850         /* Is slot0 used? */
851         if (pkt->insn[i].slot == 0) {
852             bool is_endloop = (pkt->insn[i].opcode == J2_endloop01);
853             is_endloop |= (pkt->insn[i].opcode == J2_endloop0);
854             is_endloop |= (pkt->insn[i].opcode == J2_endloop1);
855 
856             /*
857              * Make sure it's not endloop since, we're overloading
858              * slot0 for endloop
859              */
860             if (!is_endloop) {
861                 slot0_found = true;
862             }
863         }
864         /* Is slot1 used? */
865         if (pkt->insn[i].slot == 1) {
866             slot1_found = true;
867             slot1_iidx = i;
868         }
869     }
870     /* Is slot0 empty and slot1 used? */
871     if ((!slot0_found) && slot1_found) {
872         /* Then push it to slot0 */
873         pkt->insn[slot1_iidx].slot = 0;
874     }
875 }
876 
877 /*
878  * decode_packet
879  * Decodes packet with given words
880  * Returns 0 on insufficient words,
881  * or number of words used on success
882  */
883 
884 int decode_packet(int max_words, const uint32_t *words, Packet *pkt,
885                   bool disas_only)
886 {
887     int num_insns = 0;
888     int words_read = 0;
889     bool end_of_packet = false;
890     int new_insns = 0;
891     int i;
892     uint32_t encoding32;
893 
894     /* Initialize */
895     memset(pkt, 0, sizeof(*pkt));
896     /* Try to build packet */
897     while (!end_of_packet && (words_read < max_words)) {
898         encoding32 = words[words_read];
899         end_of_packet = is_packet_end(encoding32);
900         new_insns = decode_insns(&pkt->insn[num_insns], encoding32);
901         g_assert(new_insns > 0);
902         /*
903          * If we saw an extender, mark next word extended so immediate
904          * decode works
905          */
906         if (pkt->insn[num_insns].opcode == A4_ext) {
907             pkt->insn[num_insns + 1].extension_valid = true;
908         }
909         num_insns += new_insns;
910         words_read++;
911     }
912 
913     pkt->num_insns = num_insns;
914     if (!end_of_packet) {
915         /* Ran out of words! */
916         return 0;
917     }
918     pkt->encod_pkt_size_in_bytes = words_read * 4;
919     pkt->pkt_has_hvx = false;
920     for (i = 0; i < num_insns; i++) {
921         pkt->pkt_has_hvx |=
922             GET_ATTRIB(pkt->insn[i].opcode, A_CVI);
923     }
924 
925     /*
926      * Check for :endloop in the parse bits
927      * Section 10.6 of the Programmer's Reference describes the encoding
928      *     The end of hardware loop 0 can be encoded with 2 words
929      *     The end of hardware loop 1 needs 3 words
930      */
931     if ((words_read == 2) && (decode_parsebits_is_loopend(words[0]))) {
932         decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 0);
933     }
934     if (words_read >= 3) {
935         bool has_loop0, has_loop1;
936         has_loop0 = decode_parsebits_is_loopend(words[0]);
937         has_loop1 = decode_parsebits_is_loopend(words[1]);
938         if (has_loop0 && has_loop1) {
939             decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 10);
940         } else if (has_loop1) {
941             decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 1);
942         } else if (has_loop0) {
943             decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 0);
944         }
945     }
946 
947     decode_apply_extenders(pkt);
948     if (!disas_only) {
949         decode_remove_extenders(pkt);
950     }
951     decode_set_slot_number(pkt);
952     decode_fill_newvalue_regno(pkt);
953 
954     if (pkt->pkt_has_hvx) {
955         mmvec_ext_decode_checks(pkt, disas_only);
956     }
957 
958     if (!disas_only) {
959         decode_shuffle_for_execution(pkt);
960         decode_split_cmpjump(pkt);
961         decode_set_insn_attr_fields(pkt);
962     }
963 
964     return words_read;
965 }
966 
967 /* Used for "-d in_asm" logging */
968 int disassemble_hexagon(uint32_t *words, int nwords, bfd_vma pc,
969                         GString *buf)
970 {
971     Packet pkt;
972 
973     if (decode_packet(nwords, words, &pkt, true) > 0) {
974         snprint_a_pkt_disas(buf, &pkt, words, pc);
975         return pkt.encod_pkt_size_in_bytes;
976     } else {
977         g_string_assign(buf, "<invalid>");
978         return 0;
979     }
980 }
981