xref: /openbmc/qemu/target/hexagon/decode.c (revision ac12b601)
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 
26 #define fZXTN(N, M, VAL) ((VAL) & ((1LL << (N)) - 1))
27 
28 enum {
29     EXT_IDX_noext = 0,
30     EXT_IDX_noext_AFTER = 4,
31     EXT_IDX_mmvec = 4,
32     EXT_IDX_mmvec_AFTER = 8,
33     XX_LAST_EXT_IDX
34 };
35 
36 /*
37  *  Certain operand types represent a non-contiguous set of values.
38  *  For example, the compound compare-and-jump instruction can only access
39  *  registers R0-R7 and R16-23.
40  *  This table represents the mapping from the encoding to the actual values.
41  */
42 
43 #define DEF_REGMAP(NAME, ELEMENTS, ...) \
44     static const unsigned int DECODE_REGISTER_##NAME[ELEMENTS] = \
45     { __VA_ARGS__ };
46         /* Name   Num Table */
47 DEF_REGMAP(R_16,  16, 0, 1, 2, 3, 4, 5, 6, 7, 16, 17, 18, 19, 20, 21, 22, 23)
48 DEF_REGMAP(R__8,  8,  0, 2, 4, 6, 16, 18, 20, 22)
49 
50 #define DECODE_MAPPED_REG(OPNUM, NAME) \
51     insn->regno[OPNUM] = DECODE_REGISTER_##NAME[insn->regno[OPNUM]];
52 
53 typedef struct {
54     const struct DectreeTable *table_link;
55     const struct DectreeTable *table_link_b;
56     Opcode opcode;
57     enum {
58         DECTREE_ENTRY_INVALID,
59         DECTREE_TABLE_LINK,
60         DECTREE_SUBINSNS,
61         DECTREE_EXTSPACE,
62         DECTREE_TERMINAL
63     } type;
64 } DectreeEntry;
65 
66 typedef struct DectreeTable {
67     unsigned int (*lookup_function)(int startbit, int width, uint32_t opcode);
68     unsigned int size;
69     unsigned int startbit;
70     unsigned int width;
71     const DectreeEntry table[];
72 } DectreeTable;
73 
74 #define DECODE_NEW_TABLE(TAG, SIZE, WHATNOT) \
75     static const DectreeTable dectree_table_##TAG;
76 #define TABLE_LINK(TABLE)                     /* NOTHING */
77 #define TERMINAL(TAG, ENC)                    /* NOTHING */
78 #define SUBINSNS(TAG, CLASSA, CLASSB, ENC)    /* NOTHING */
79 #define EXTSPACE(TAG, ENC)                    /* NOTHING */
80 #define INVALID()                             /* NOTHING */
81 #define DECODE_END_TABLE(...)                 /* NOTHING */
82 #define DECODE_MATCH_INFO(...)                /* NOTHING */
83 #define DECODE_LEGACY_MATCH_INFO(...)         /* NOTHING */
84 #define DECODE_OPINFO(...)                    /* NOTHING */
85 
86 #include "dectree_generated.h.inc"
87 
88 #undef DECODE_OPINFO
89 #undef DECODE_MATCH_INFO
90 #undef DECODE_LEGACY_MATCH_INFO
91 #undef DECODE_END_TABLE
92 #undef INVALID
93 #undef TERMINAL
94 #undef SUBINSNS
95 #undef EXTSPACE
96 #undef TABLE_LINK
97 #undef DECODE_NEW_TABLE
98 #undef DECODE_SEPARATOR_BITS
99 
100 #define DECODE_SEPARATOR_BITS(START, WIDTH) NULL, START, WIDTH
101 #define DECODE_NEW_TABLE_HELPER(TAG, SIZE, FN, START, WIDTH) \
102     static const DectreeTable dectree_table_##TAG = { \
103         .size = SIZE, \
104         .lookup_function = FN, \
105         .startbit = START, \
106         .width = WIDTH, \
107         .table = {
108 #define DECODE_NEW_TABLE(TAG, SIZE, WHATNOT) \
109     DECODE_NEW_TABLE_HELPER(TAG, SIZE, WHATNOT)
110 
111 #define TABLE_LINK(TABLE) \
112     { .type = DECTREE_TABLE_LINK, .table_link = &dectree_table_##TABLE },
113 #define TERMINAL(TAG, ENC) \
114     { .type = DECTREE_TERMINAL, .opcode = TAG  },
115 #define SUBINSNS(TAG, CLASSA, CLASSB, ENC) \
116     { \
117         .type = DECTREE_SUBINSNS, \
118         .table_link = &dectree_table_DECODE_SUBINSN_##CLASSA, \
119         .table_link_b = &dectree_table_DECODE_SUBINSN_##CLASSB \
120     },
121 #define EXTSPACE(TAG, ENC) { .type = DECTREE_EXTSPACE },
122 #define INVALID() { .type = DECTREE_ENTRY_INVALID, .opcode = XX_LAST_OPCODE },
123 
124 #define DECODE_END_TABLE(...) } };
125 
126 #define DECODE_MATCH_INFO(...)                /* NOTHING */
127 #define DECODE_LEGACY_MATCH_INFO(...)         /* NOTHING */
128 #define DECODE_OPINFO(...)                    /* NOTHING */
129 
130 #include "dectree_generated.h.inc"
131 
132 #undef DECODE_OPINFO
133 #undef DECODE_MATCH_INFO
134 #undef DECODE_LEGACY_MATCH_INFO
135 #undef DECODE_END_TABLE
136 #undef INVALID
137 #undef TERMINAL
138 #undef SUBINSNS
139 #undef EXTSPACE
140 #undef TABLE_LINK
141 #undef DECODE_NEW_TABLE
142 #undef DECODE_NEW_TABLE_HELPER
143 #undef DECODE_SEPARATOR_BITS
144 
145 static const DectreeTable dectree_table_DECODE_EXT_EXT_noext = {
146     .size = 1, .lookup_function = NULL, .startbit = 0, .width = 0,
147     .table = {
148         { .type = DECTREE_ENTRY_INVALID, .opcode = XX_LAST_OPCODE },
149     }
150 };
151 
152 static const DectreeTable *ext_trees[XX_LAST_EXT_IDX];
153 
154 static void decode_ext_init(void)
155 {
156     int i;
157     for (i = EXT_IDX_noext; i < EXT_IDX_noext_AFTER; i++) {
158         ext_trees[i] = &dectree_table_DECODE_EXT_EXT_noext;
159     }
160 }
161 
162 typedef struct {
163     uint32_t mask;
164     uint32_t match;
165 } DecodeITableEntry;
166 
167 #define DECODE_NEW_TABLE(TAG, SIZE, WHATNOT)  /* NOTHING */
168 #define TABLE_LINK(TABLE)                     /* NOTHING */
169 #define TERMINAL(TAG, ENC)                    /* NOTHING */
170 #define SUBINSNS(TAG, CLASSA, CLASSB, ENC)    /* NOTHING */
171 #define EXTSPACE(TAG, ENC)                    /* NOTHING */
172 #define INVALID()                             /* NOTHING */
173 #define DECODE_END_TABLE(...)                 /* NOTHING */
174 #define DECODE_OPINFO(...)                    /* NOTHING */
175 
176 #define DECODE_MATCH_INFO_NORMAL(TAG, MASK, MATCH) \
177     [TAG] = { \
178         .mask = MASK, \
179         .match = MATCH, \
180     },
181 
182 #define DECODE_MATCH_INFO_NULL(TAG, MASK, MATCH) \
183     [TAG] = { .match = ~0 },
184 
185 #define DECODE_MATCH_INFO(...) DECODE_MATCH_INFO_NORMAL(__VA_ARGS__)
186 #define DECODE_LEGACY_MATCH_INFO(...) /* NOTHING */
187 
188 static const DecodeITableEntry decode_itable[XX_LAST_OPCODE] = {
189 #include "dectree_generated.h.inc"
190 };
191 
192 #undef DECODE_MATCH_INFO
193 #define DECODE_MATCH_INFO(...) DECODE_MATCH_INFO_NULL(__VA_ARGS__)
194 
195 #undef DECODE_LEGACY_MATCH_INFO
196 #define DECODE_LEGACY_MATCH_INFO(...) DECODE_MATCH_INFO_NORMAL(__VA_ARGS__)
197 
198 static const DecodeITableEntry decode_legacy_itable[XX_LAST_OPCODE] = {
199 #include "dectree_generated.h.inc"
200 };
201 
202 #undef DECODE_OPINFO
203 #undef DECODE_MATCH_INFO
204 #undef DECODE_LEGACY_MATCH_INFO
205 #undef DECODE_END_TABLE
206 #undef INVALID
207 #undef TERMINAL
208 #undef SUBINSNS
209 #undef EXTSPACE
210 #undef TABLE_LINK
211 #undef DECODE_NEW_TABLE
212 #undef DECODE_SEPARATOR_BITS
213 
214 void decode_init(void)
215 {
216     decode_ext_init();
217 }
218 
219 void decode_send_insn_to(Packet *packet, int start, int newloc)
220 {
221     Insn tmpinsn;
222     int direction;
223     int i;
224     if (start == newloc) {
225         return;
226     }
227     if (start < newloc) {
228         /* Move towards end */
229         direction = 1;
230     } else {
231         /* move towards beginning */
232         direction = -1;
233     }
234     for (i = start; i != newloc; i += direction) {
235         tmpinsn = packet->insn[i];
236         packet->insn[i] = packet->insn[i + direction];
237         packet->insn[i + direction] = tmpinsn;
238     }
239 }
240 
241 /* Fill newvalue registers with the correct regno */
242 static void
243 decode_fill_newvalue_regno(Packet *packet)
244 {
245     int i, use_regidx, offset, def_idx, dst_idx;
246     uint16_t def_opcode, use_opcode;
247     char *dststr;
248 
249     for (i = 1; i < packet->num_insns; i++) {
250         if (GET_ATTRIB(packet->insn[i].opcode, A_DOTNEWVALUE) &&
251             !GET_ATTRIB(packet->insn[i].opcode, A_EXTENSION)) {
252             use_opcode = packet->insn[i].opcode;
253 
254             /* It's a store, so we're adjusting the Nt field */
255             if (GET_ATTRIB(use_opcode, A_STORE)) {
256                 use_regidx = strchr(opcode_reginfo[use_opcode], 't') -
257                     opcode_reginfo[use_opcode];
258             } else {    /* It's a Jump, so we're adjusting the Ns field */
259                 use_regidx = strchr(opcode_reginfo[use_opcode], 's') -
260                     opcode_reginfo[use_opcode];
261             }
262 
263             /*
264              * What's encoded at the N-field is the offset to who's producing
265              * the value.  Shift off the LSB which indicates odd/even register,
266              * then walk backwards and skip over the constant extenders.
267              */
268             offset = packet->insn[i].regno[use_regidx] >> 1;
269             def_idx = i - offset;
270             for (int j = 0; j < offset; j++) {
271                 if (GET_ATTRIB(packet->insn[i - j - 1].opcode, A_IT_EXTENDER)) {
272                     def_idx--;
273                 }
274             }
275 
276             /*
277              * Check for a badly encoded N-field which points to an instruction
278              * out-of-range
279              */
280             g_assert(!((def_idx < 0) || (def_idx > (packet->num_insns - 1))));
281 
282             /*
283              * packet->insn[def_idx] is the producer
284              * Figure out which type of destination it produces
285              * and the corresponding index in the reginfo
286              */
287             def_opcode = packet->insn[def_idx].opcode;
288             dststr = strstr(opcode_wregs[def_opcode], "Rd");
289             if (dststr) {
290                 dststr = strchr(opcode_reginfo[def_opcode], 'd');
291             } else {
292                 dststr = strstr(opcode_wregs[def_opcode], "Rx");
293                 if (dststr) {
294                     dststr = strchr(opcode_reginfo[def_opcode], 'x');
295                 } else {
296                     dststr = strstr(opcode_wregs[def_opcode], "Re");
297                     if (dststr) {
298                         dststr = strchr(opcode_reginfo[def_opcode], 'e');
299                     } else {
300                         dststr = strstr(opcode_wregs[def_opcode], "Ry");
301                         if (dststr) {
302                             dststr = strchr(opcode_reginfo[def_opcode], 'y');
303                         } else {
304                             g_assert_not_reached();
305                         }
306                     }
307                 }
308             }
309             g_assert(dststr != NULL);
310 
311             /* Now patch up the consumer with the register number */
312             dst_idx = dststr - opcode_reginfo[def_opcode];
313             packet->insn[i].regno[use_regidx] =
314                 packet->insn[def_idx].regno[dst_idx];
315             /*
316              * We need to remember who produces this value to later
317              * check if it was dynamically cancelled
318              */
319             packet->insn[i].new_value_producer_slot =
320                 packet->insn[def_idx].slot;
321         }
322     }
323 }
324 
325 /* Split CJ into a compare and a jump */
326 static void decode_split_cmpjump(Packet *pkt)
327 {
328     int last, i;
329     int numinsns = pkt->num_insns;
330 
331     /*
332      * First, split all compare-jumps.
333      * The compare is sent to the end as a new instruction.
334      * Do it this way so we don't reorder dual jumps. Those need to stay in
335      * original order.
336      */
337     for (i = 0; i < numinsns; i++) {
338         /* It's a cmp-jump */
339         if (GET_ATTRIB(pkt->insn[i].opcode, A_NEWCMPJUMP)) {
340             last = pkt->num_insns;
341             pkt->insn[last] = pkt->insn[i];    /* copy the instruction */
342             pkt->insn[last].part1 = true;      /* last insn does the CMP */
343             pkt->insn[i].part1 = false;        /* existing insn does the JUMP */
344             pkt->num_insns++;
345         }
346     }
347 
348     /* Now re-shuffle all the compares back to the beginning */
349     for (i = 0; i < pkt->num_insns; i++) {
350         if (pkt->insn[i].part1) {
351             decode_send_insn_to(pkt, i, 0);
352         }
353     }
354 }
355 
356 static bool decode_opcode_can_jump(int opcode)
357 {
358     if ((GET_ATTRIB(opcode, A_JUMP)) ||
359         (GET_ATTRIB(opcode, A_CALL)) ||
360         (opcode == J2_trap0) ||
361         (opcode == J2_pause)) {
362         /* Exception to A_JUMP attribute */
363         if (opcode == J4_hintjumpr) {
364             return false;
365         }
366         return true;
367     }
368 
369     return false;
370 }
371 
372 static bool decode_opcode_ends_loop(int opcode)
373 {
374     return GET_ATTRIB(opcode, A_HWLOOP0_END) ||
375            GET_ATTRIB(opcode, A_HWLOOP1_END);
376 }
377 
378 /* Set the is_* fields in each instruction */
379 static void decode_set_insn_attr_fields(Packet *pkt)
380 {
381     int i;
382     int numinsns = pkt->num_insns;
383     uint16_t opcode;
384 
385     pkt->pkt_has_cof = false;
386     pkt->pkt_has_endloop = false;
387     pkt->pkt_has_dczeroa = false;
388 
389     for (i = 0; i < numinsns; i++) {
390         opcode = pkt->insn[i].opcode;
391         if (pkt->insn[i].part1) {
392             continue;    /* Skip compare of cmp-jumps */
393         }
394 
395         if (GET_ATTRIB(opcode, A_DCZEROA)) {
396             pkt->pkt_has_dczeroa = true;
397         }
398 
399         if (GET_ATTRIB(opcode, A_STORE)) {
400             if (pkt->insn[i].slot == 0) {
401                 pkt->pkt_has_store_s0 = true;
402             } else {
403                 pkt->pkt_has_store_s1 = true;
404             }
405         }
406 
407         pkt->pkt_has_cof |= decode_opcode_can_jump(opcode);
408 
409         pkt->insn[i].is_endloop = decode_opcode_ends_loop(opcode);
410 
411         pkt->pkt_has_endloop |= pkt->insn[i].is_endloop;
412 
413         pkt->pkt_has_cof |= pkt->pkt_has_endloop;
414     }
415 }
416 
417 /*
418  * Shuffle for execution
419  * Move stores to end (in same order as encoding)
420  * Move compares to beginning (for use by .new insns)
421  */
422 static void decode_shuffle_for_execution(Packet *packet)
423 {
424     bool changed = false;
425     int i;
426     bool flag;    /* flag means we've seen a non-memory instruction */
427     int n_mems;
428     int last_insn = packet->num_insns - 1;
429 
430     /*
431      * Skip end loops, somehow an end loop is getting in and messing
432      * up the order
433      */
434     if (decode_opcode_ends_loop(packet->insn[last_insn].opcode)) {
435         last_insn--;
436     }
437 
438     do {
439         changed = false;
440         /*
441          * Stores go last, must not reorder.
442          * Cannot shuffle stores past loads, either.
443          * Iterate backwards.  If we see a non-memory instruction,
444          * then a store, shuffle the store to the front.  Don't shuffle
445          * stores wrt each other or a load.
446          */
447         for (flag = false, n_mems = 0, i = last_insn; i >= 0; i--) {
448             int opcode = packet->insn[i].opcode;
449 
450             if (flag && GET_ATTRIB(opcode, A_STORE)) {
451                 decode_send_insn_to(packet, i, last_insn - n_mems);
452                 n_mems++;
453                 changed = true;
454             } else if (GET_ATTRIB(opcode, A_STORE)) {
455                 n_mems++;
456             } else if (GET_ATTRIB(opcode, A_LOAD)) {
457                 /*
458                  * Don't set flag, since we don't want to shuffle a
459                  * store past a load
460                  */
461                 n_mems++;
462             } else if (GET_ATTRIB(opcode, A_DOTNEWVALUE)) {
463                 /*
464                  * Don't set flag, since we don't want to shuffle past
465                  * a .new value
466                  */
467             } else {
468                 flag = true;
469             }
470         }
471 
472         if (changed) {
473             continue;
474         }
475         /* Compares go first, may be reordered wrt each other */
476         for (flag = false, i = 0; i < last_insn + 1; i++) {
477             int opcode = packet->insn[i].opcode;
478 
479             if ((strstr(opcode_wregs[opcode], "Pd4") ||
480                  strstr(opcode_wregs[opcode], "Pe4")) &&
481                 GET_ATTRIB(opcode, A_STORE) == 0) {
482                 /* This should be a compare (not a store conditional) */
483                 if (flag) {
484                     decode_send_insn_to(packet, i, 0);
485                     changed = true;
486                     continue;
487                 }
488             } else if (GET_ATTRIB(opcode, A_IMPLICIT_WRITES_P3) &&
489                        !decode_opcode_ends_loop(packet->insn[i].opcode)) {
490                 /*
491                  * spNloop instruction
492                  * Don't reorder endloops; they are not valid for .new uses,
493                  * and we want to match HW
494                  */
495                 if (flag) {
496                     decode_send_insn_to(packet, i, 0);
497                     changed = true;
498                     continue;
499                 }
500             } else if (GET_ATTRIB(opcode, A_IMPLICIT_WRITES_P0) &&
501                        !GET_ATTRIB(opcode, A_NEWCMPJUMP)) {
502                 if (flag) {
503                     decode_send_insn_to(packet, i, 0);
504                     changed = true;
505                     continue;
506                 }
507             } else {
508                 flag = true;
509             }
510         }
511         if (changed) {
512             continue;
513         }
514     } while (changed);
515 
516     /*
517      * If we have a .new register compare/branch, move that to the very
518      * very end, past stores
519      */
520     for (i = 0; i < last_insn; i++) {
521         if (GET_ATTRIB(packet->insn[i].opcode, A_DOTNEWVALUE)) {
522             decode_send_insn_to(packet, i, last_insn);
523             break;
524         }
525     }
526 }
527 
528 static void
529 apply_extender(Packet *pkt, int i, uint32_t extender)
530 {
531     int immed_num;
532     uint32_t base_immed;
533 
534     immed_num = opcode_which_immediate_is_extended(pkt->insn[i].opcode);
535     base_immed = pkt->insn[i].immed[immed_num];
536 
537     pkt->insn[i].immed[immed_num] = extender | fZXTN(6, 32, base_immed);
538 }
539 
540 static void decode_apply_extenders(Packet *packet)
541 {
542     int i;
543     for (i = 0; i < packet->num_insns; i++) {
544         if (GET_ATTRIB(packet->insn[i].opcode, A_IT_EXTENDER)) {
545             packet->insn[i + 1].extension_valid = true;
546             apply_extender(packet, i + 1, packet->insn[i].immed[0]);
547         }
548     }
549 }
550 
551 static void decode_remove_extenders(Packet *packet)
552 {
553     int i, j;
554     for (i = 0; i < packet->num_insns; i++) {
555         if (GET_ATTRIB(packet->insn[i].opcode, A_IT_EXTENDER)) {
556             /* Remove this one by moving the remaining instructions down */
557             for (j = i;
558                 (j < packet->num_insns - 1) && (j < INSTRUCTIONS_MAX - 1);
559                 j++) {
560                 packet->insn[j] = packet->insn[j + 1];
561             }
562             packet->num_insns--;
563         }
564     }
565 }
566 
567 static SlotMask get_valid_slots(const Packet *pkt, unsigned int slot)
568 {
569     return find_iclass_slots(pkt->insn[slot].opcode,
570                              pkt->insn[slot].iclass);
571 }
572 
573 #define DECODE_NEW_TABLE(TAG, SIZE, WHATNOT)     /* NOTHING */
574 #define TABLE_LINK(TABLE)                        /* NOTHING */
575 #define TERMINAL(TAG, ENC)                       /* NOTHING */
576 #define SUBINSNS(TAG, CLASSA, CLASSB, ENC)       /* NOTHING */
577 #define EXTSPACE(TAG, ENC)                       /* NOTHING */
578 #define INVALID()                                /* NOTHING */
579 #define DECODE_END_TABLE(...)                    /* NOTHING */
580 #define DECODE_MATCH_INFO(...)                   /* NOTHING */
581 #define DECODE_LEGACY_MATCH_INFO(...)            /* NOTHING */
582 
583 #define DECODE_REG(REGNO, WIDTH, STARTBIT) \
584     insn->regno[REGNO] = ((encoding >> STARTBIT) & ((1 << WIDTH) - 1));
585 
586 #define DECODE_IMPL_REG(REGNO, VAL) \
587     insn->regno[REGNO] = VAL;
588 
589 #define DECODE_IMM(IMMNO, WIDTH, STARTBIT, VALSTART) \
590     insn->immed[IMMNO] |= (((encoding >> STARTBIT) & ((1 << WIDTH) - 1))) << \
591                           (VALSTART);
592 
593 #define DECODE_IMM_SXT(IMMNO, WIDTH) \
594     insn->immed[IMMNO] = ((((int32_t)insn->immed[IMMNO]) << (32 - WIDTH)) >> \
595                           (32 - WIDTH));
596 
597 #define DECODE_IMM_NEG(IMMNO, WIDTH) \
598     insn->immed[IMMNO] = -insn->immed[IMMNO];
599 
600 #define DECODE_IMM_SHIFT(IMMNO, SHAMT)                                 \
601     if ((!insn->extension_valid) || \
602         (insn->which_extended != IMMNO)) { \
603         insn->immed[IMMNO] <<= SHAMT; \
604     }
605 
606 #define DECODE_OPINFO(TAG, BEH) \
607     case TAG: \
608         { BEH  } \
609         break; \
610 
611 /*
612  * Fill in the operands of the instruction
613  * dectree_generated.h.inc has a DECODE_OPINFO entry for each opcode
614  * For example,
615  *     DECODE_OPINFO(A2_addi,
616  *          DECODE_REG(0,5,0)
617  *          DECODE_REG(1,5,16)
618  *          DECODE_IMM(0,7,21,9)
619  *          DECODE_IMM(0,9,5,0)
620  *          DECODE_IMM_SXT(0,16)
621  * with the macros defined above, we'll fill in a switch statement
622  * where each case is an opcode tag.
623  */
624 static void
625 decode_op(Insn *insn, Opcode tag, uint32_t encoding)
626 {
627     insn->immed[0] = 0;
628     insn->immed[1] = 0;
629     insn->opcode = tag;
630     if (insn->extension_valid) {
631         insn->which_extended = opcode_which_immediate_is_extended(tag);
632     }
633 
634     switch (tag) {
635 #include "dectree_generated.h.inc"
636     default:
637         break;
638     }
639 
640     insn->generate = opcode_genptr[tag];
641 
642     insn->iclass = iclass_bits(encoding);
643 }
644 
645 #undef DECODE_REG
646 #undef DECODE_IMPL_REG
647 #undef DECODE_IMM
648 #undef DECODE_IMM_SHIFT
649 #undef DECODE_OPINFO
650 #undef DECODE_MATCH_INFO
651 #undef DECODE_LEGACY_MATCH_INFO
652 #undef DECODE_END_TABLE
653 #undef INVALID
654 #undef TERMINAL
655 #undef SUBINSNS
656 #undef EXTSPACE
657 #undef TABLE_LINK
658 #undef DECODE_NEW_TABLE
659 #undef DECODE_SEPARATOR_BITS
660 
661 static unsigned int
662 decode_subinsn_tablewalk(Insn *insn, const DectreeTable *table,
663                          uint32_t encoding)
664 {
665     unsigned int i;
666     Opcode opc;
667     if (table->lookup_function) {
668         i = table->lookup_function(table->startbit, table->width, encoding);
669     } else {
670         i = extract32(encoding, table->startbit, table->width);
671     }
672     if (table->table[i].type == DECTREE_TABLE_LINK) {
673         return decode_subinsn_tablewalk(insn, table->table[i].table_link,
674                                         encoding);
675     } else if (table->table[i].type == DECTREE_TERMINAL) {
676         opc = table->table[i].opcode;
677         if ((encoding & decode_itable[opc].mask) != decode_itable[opc].match) {
678             return 0;
679         }
680         decode_op(insn, opc, encoding);
681         return 1;
682     } else {
683         return 0;
684     }
685 }
686 
687 static unsigned int get_insn_a(uint32_t encoding)
688 {
689     return extract32(encoding, 0, 13);
690 }
691 
692 static unsigned int get_insn_b(uint32_t encoding)
693 {
694     return extract32(encoding, 16, 13);
695 }
696 
697 static unsigned int
698 decode_insns_tablewalk(Insn *insn, const DectreeTable *table,
699                        uint32_t encoding)
700 {
701     unsigned int i;
702     unsigned int a, b;
703     Opcode opc;
704     if (table->lookup_function) {
705         i = table->lookup_function(table->startbit, table->width, encoding);
706     } else {
707         i = extract32(encoding, table->startbit, table->width);
708     }
709     if (table->table[i].type == DECTREE_TABLE_LINK) {
710         return decode_insns_tablewalk(insn, table->table[i].table_link,
711                                       encoding);
712     } else if (table->table[i].type == DECTREE_SUBINSNS) {
713         a = get_insn_a(encoding);
714         b = get_insn_b(encoding);
715         b = decode_subinsn_tablewalk(insn, table->table[i].table_link_b, b);
716         a = decode_subinsn_tablewalk(insn + 1, table->table[i].table_link, a);
717         if ((a == 0) || (b == 0)) {
718             return 0;
719         }
720         return 2;
721     } else if (table->table[i].type == DECTREE_TERMINAL) {
722         opc = table->table[i].opcode;
723         if ((encoding & decode_itable[opc].mask) != decode_itable[opc].match) {
724             if ((encoding & decode_legacy_itable[opc].mask) !=
725                 decode_legacy_itable[opc].match) {
726                 return 0;
727             }
728         }
729         decode_op(insn, opc, encoding);
730         return 1;
731     } else {
732         return 0;
733     }
734 }
735 
736 static unsigned int
737 decode_insns(Insn *insn, uint32_t encoding)
738 {
739     const DectreeTable *table;
740     if (parse_bits(encoding) != 0) {
741         /* Start with PP table - 32 bit instructions */
742         table = &dectree_table_DECODE_ROOT_32;
743     } else {
744         /* start with EE table - duplex instructions */
745         table = &dectree_table_DECODE_ROOT_EE;
746     }
747     return decode_insns_tablewalk(insn, table, encoding);
748 }
749 
750 static void decode_add_endloop_insn(Insn *insn, int loopnum)
751 {
752     if (loopnum == 10) {
753         insn->opcode = J2_endloop01;
754         insn->generate = opcode_genptr[J2_endloop01];
755     } else if (loopnum == 1) {
756         insn->opcode = J2_endloop1;
757         insn->generate = opcode_genptr[J2_endloop1];
758     } else if (loopnum == 0) {
759         insn->opcode = J2_endloop0;
760         insn->generate = opcode_genptr[J2_endloop0];
761     } else {
762         g_assert_not_reached();
763     }
764 }
765 
766 static bool decode_parsebits_is_loopend(uint32_t encoding32)
767 {
768     uint32_t bits = parse_bits(encoding32);
769     return bits == 0x2;
770 }
771 
772 static void
773 decode_set_slot_number(Packet *pkt)
774 {
775     int slot;
776     int i;
777     bool hit_mem_insn = false;
778     bool hit_duplex = false;
779     bool slot0_found = false;
780     bool slot1_found = false;
781     int slot1_iidx = 0;
782 
783     /*
784      * The slots are encoded in reverse order
785      * For each instruction, count down until you find a suitable slot
786      */
787     for (i = 0, slot = 3; i < pkt->num_insns; i++) {
788         SlotMask valid_slots = get_valid_slots(pkt, i);
789 
790         while (!(valid_slots & (1 << slot))) {
791             slot--;
792         }
793         pkt->insn[i].slot = slot;
794         if (slot) {
795             /* I've assigned the slot, now decrement it for the next insn */
796             slot--;
797         }
798     }
799 
800     /* Fix the exceptions - mem insns to slot 0,1 */
801     for (i = pkt->num_insns - 1; i >= 0; i--) {
802         /* First memory instruction always goes to slot 0 */
803         if ((GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE) ||
804              GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE_PACKET_RULES)) &&
805             !hit_mem_insn) {
806             hit_mem_insn = true;
807             pkt->insn[i].slot = 0;
808             continue;
809         }
810 
811         /* Next memory instruction always goes to slot 1 */
812         if ((GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE) ||
813              GET_ATTRIB(pkt->insn[i].opcode, A_MEMLIKE_PACKET_RULES)) &&
814             hit_mem_insn) {
815             pkt->insn[i].slot = 1;
816         }
817     }
818 
819     /* Fix the exceptions - duplex always slot 0,1 */
820     for (i = pkt->num_insns - 1; i >= 0; i--) {
821         /* First subinsn always goes to slot 0 */
822         if (GET_ATTRIB(pkt->insn[i].opcode, A_SUBINSN) && !hit_duplex) {
823             hit_duplex = true;
824             pkt->insn[i].slot = 0;
825             continue;
826         }
827 
828         /* Next subinsn always goes to slot 1 */
829         if (GET_ATTRIB(pkt->insn[i].opcode, A_SUBINSN) && hit_duplex) {
830             pkt->insn[i].slot = 1;
831         }
832     }
833 
834     /* Fix the exceptions - slot 1 is never empty, always aligns to slot 0 */
835     for (i = pkt->num_insns - 1; i >= 0; i--) {
836         /* Is slot0 used? */
837         if (pkt->insn[i].slot == 0) {
838             bool is_endloop = (pkt->insn[i].opcode == J2_endloop01);
839             is_endloop |= (pkt->insn[i].opcode == J2_endloop0);
840             is_endloop |= (pkt->insn[i].opcode == J2_endloop1);
841 
842             /*
843              * Make sure it's not endloop since, we're overloading
844              * slot0 for endloop
845              */
846             if (!is_endloop) {
847                 slot0_found = true;
848             }
849         }
850         /* Is slot1 used? */
851         if (pkt->insn[i].slot == 1) {
852             slot1_found = true;
853             slot1_iidx = i;
854         }
855     }
856     /* Is slot0 empty and slot1 used? */
857     if ((!slot0_found) && slot1_found) {
858         /* Then push it to slot0 */
859         pkt->insn[slot1_iidx].slot = 0;
860     }
861 }
862 
863 /*
864  * decode_packet
865  * Decodes packet with given words
866  * Returns 0 on insufficient words,
867  * or number of words used on success
868  */
869 
870 int decode_packet(int max_words, const uint32_t *words, Packet *pkt,
871                   bool disas_only)
872 {
873     int num_insns = 0;
874     int words_read = 0;
875     bool end_of_packet = false;
876     int new_insns = 0;
877     uint32_t encoding32;
878 
879     /* Initialize */
880     memset(pkt, 0, sizeof(*pkt));
881     /* Try to build packet */
882     while (!end_of_packet && (words_read < max_words)) {
883         encoding32 = words[words_read];
884         end_of_packet = is_packet_end(encoding32);
885         new_insns = decode_insns(&pkt->insn[num_insns], encoding32);
886         g_assert(new_insns > 0);
887         /*
888          * If we saw an extender, mark next word extended so immediate
889          * decode works
890          */
891         if (pkt->insn[num_insns].opcode == A4_ext) {
892             pkt->insn[num_insns + 1].extension_valid = true;
893         }
894         num_insns += new_insns;
895         words_read++;
896     }
897 
898     pkt->num_insns = num_insns;
899     if (!end_of_packet) {
900         /* Ran out of words! */
901         return 0;
902     }
903     pkt->encod_pkt_size_in_bytes = words_read * 4;
904 
905     /*
906      * Check for :endloop in the parse bits
907      * Section 10.6 of the Programmer's Reference describes the encoding
908      *     The end of hardware loop 0 can be encoded with 2 words
909      *     The end of hardware loop 1 needs 3 words
910      */
911     if ((words_read == 2) && (decode_parsebits_is_loopend(words[0]))) {
912         decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 0);
913     }
914     if (words_read >= 3) {
915         bool has_loop0, has_loop1;
916         has_loop0 = decode_parsebits_is_loopend(words[0]);
917         has_loop1 = decode_parsebits_is_loopend(words[1]);
918         if (has_loop0 && has_loop1) {
919             decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 10);
920         } else if (has_loop1) {
921             decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 1);
922         } else if (has_loop0) {
923             decode_add_endloop_insn(&pkt->insn[pkt->num_insns++], 0);
924         }
925     }
926 
927     decode_apply_extenders(pkt);
928     if (!disas_only) {
929         decode_remove_extenders(pkt);
930     }
931     decode_set_slot_number(pkt);
932     decode_fill_newvalue_regno(pkt);
933 
934     if (!disas_only) {
935         decode_shuffle_for_execution(pkt);
936         decode_split_cmpjump(pkt);
937         decode_set_insn_attr_fields(pkt);
938     }
939 
940     return words_read;
941 }
942 
943 /* Used for "-d in_asm" logging */
944 int disassemble_hexagon(uint32_t *words, int nwords, bfd_vma pc,
945                         GString *buf)
946 {
947     Packet pkt;
948 
949     if (decode_packet(nwords, words, &pkt, true) > 0) {
950         snprint_a_pkt_disas(buf, &pkt, words, pc);
951         return pkt.encod_pkt_size_in_bytes;
952     } else {
953         g_string_assign(buf, "<invalid>");
954         return 0;
955     }
956 }
957