aboutsummaryrefslogtreecommitdiff
path: root/gdb/iq2000-tdep.c
blob: ab3b1963d985f694e1695d642268e9d630e58518 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
/* Target-dependent code for the IQ2000 architecture, for GDB, the GNU
   Debugger.

   Copyright (C) 2000, 2004, 2005, 2007 Free Software Foundation, Inc.

   Contributed by Red Hat.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "frame.h"
#include "frame-base.h"
#include "frame-unwind.h"
#include "dwarf2-frame.h"
#include "gdbtypes.h"
#include "value.h"
#include "dis-asm.h"
#include "gdb_string.h"
#include "arch-utils.h"
#include "regcache.h"
#include "osabi.h"
#include "gdbcore.h"

enum gdb_regnum
{
  E_R0_REGNUM,  E_R1_REGNUM,  E_R2_REGNUM,  E_R3_REGNUM, 
  E_R4_REGNUM,  E_R5_REGNUM,  E_R6_REGNUM,  E_R7_REGNUM, 
  E_R8_REGNUM,  E_R9_REGNUM,  E_R10_REGNUM, E_R11_REGNUM, 
  E_R12_REGNUM, E_R13_REGNUM, E_R14_REGNUM, E_R15_REGNUM, 
  E_R16_REGNUM, E_R17_REGNUM, E_R18_REGNUM, E_R19_REGNUM, 
  E_R20_REGNUM, E_R21_REGNUM, E_R22_REGNUM, E_R23_REGNUM, 
  E_R24_REGNUM, E_R25_REGNUM, E_R26_REGNUM, E_R27_REGNUM, 
  E_R28_REGNUM, E_R29_REGNUM, E_R30_REGNUM, E_R31_REGNUM, 
  E_PC_REGNUM, 
  E_LR_REGNUM        = E_R31_REGNUM, /* Link register.  */
  E_SP_REGNUM        = E_R29_REGNUM, /* Stack pointer.  */
  E_FP_REGNUM        = E_R27_REGNUM, /* Frame pointer.  */
  E_FN_RETURN_REGNUM = E_R2_REGNUM,  /* Function return value register.  */
  E_1ST_ARGREG       = E_R4_REGNUM,  /* 1st  function arg register.  */
  E_LAST_ARGREG      = E_R11_REGNUM, /* Last function arg register.  */
  E_NUM_REGS         = E_PC_REGNUM + 1
};

/* Use an invalid address value as 'not available' marker.  */
enum { REG_UNAVAIL = (CORE_ADDR) -1 };

struct iq2000_frame_cache
{
  /* Base address.  */
  CORE_ADDR  base;
  CORE_ADDR  pc;
  LONGEST    framesize;
  int        using_fp;
  CORE_ADDR  saved_sp;
  CORE_ADDR  saved_regs [E_NUM_REGS];
};

/* Harvard methods: */

static CORE_ADDR
insn_ptr_from_addr (CORE_ADDR addr)	/* CORE_ADDR to target pointer.  */
{
  return addr & 0x7fffffffL;
}

static CORE_ADDR
insn_addr_from_ptr (CORE_ADDR ptr)	/* target_pointer to CORE_ADDR.  */
{
  return (ptr & 0x7fffffffL) | 0x80000000L;
}

/* Function: pointer_to_address
   Convert a target pointer to an address in host (CORE_ADDR) format. */

static CORE_ADDR
iq2000_pointer_to_address (struct type * type, const void * buf)
{
  enum type_code target = TYPE_CODE (TYPE_TARGET_TYPE (type));
  CORE_ADDR addr = extract_unsigned_integer (buf, TYPE_LENGTH (type));

  if (target == TYPE_CODE_FUNC
      || target == TYPE_CODE_METHOD
      || (TYPE_FLAGS (TYPE_TARGET_TYPE (type)) & TYPE_FLAG_CODE_SPACE) != 0)
    addr = insn_addr_from_ptr (addr);

  return addr;
}

/* Function: address_to_pointer
   Convert a host-format address (CORE_ADDR) into a target pointer.  */

static void
iq2000_address_to_pointer (struct type *type, void *buf, CORE_ADDR addr)
{
  enum type_code target = TYPE_CODE (TYPE_TARGET_TYPE (type));

  if (target == TYPE_CODE_FUNC || target == TYPE_CODE_METHOD)
    addr = insn_ptr_from_addr (addr);
  store_unsigned_integer (buf, TYPE_LENGTH (type), addr);
}

/* Real register methods: */

/* Function: register_name
   Returns the name of the iq2000 register number N.  */

static const char *
iq2000_register_name (int regnum)
{
  static const char * names[E_NUM_REGS] =
    {
      "r0",  "r1",  "r2",  "r3",  "r4",
      "r5",  "r6",  "r7",  "r8",  "r9",
      "r10", "r11", "r12", "r13", "r14",
      "r15", "r16", "r17", "r18", "r19",
      "r20", "r21", "r22", "r23", "r24",
      "r25", "r26", "r27", "r28", "r29",
      "r30", "r31",
      "pc"
    };
  if (regnum < 0 || regnum >= E_NUM_REGS)
    return NULL;
  return names[regnum];
}

/* Prologue analysis methods:  */

/* ADDIU insn (001001 rs(5) rt(5) imm(16)).  */
#define INSN_IS_ADDIU(X)	(((X) & 0xfc000000) == 0x24000000) 
#define ADDIU_REG_SRC(X)	(((X) & 0x03e00000) >> 21)
#define ADDIU_REG_TGT(X)	(((X) & 0x001f0000) >> 16)
#define ADDIU_IMMEDIATE(X)	((signed short) ((X) & 0x0000ffff))

/* "MOVE" (OR) insn (000000 rs(5) rt(5) rd(5) 00000 100101).  */
#define INSN_IS_MOVE(X)		(((X) & 0xffe007ff) == 0x00000025)
#define MOVE_REG_SRC(X)		(((X) & 0x001f0000) >> 16)
#define MOVE_REG_TGT(X)		(((X) & 0x0000f800) >> 11)

/* STORE WORD insn (101011 rs(5) rt(5) offset(16)).  */
#define INSN_IS_STORE_WORD(X)	(((X) & 0xfc000000) == 0xac000000)
#define SW_REG_INDEX(X)		(((X) & 0x03e00000) >> 21)
#define SW_REG_SRC(X)		(((X) & 0x001f0000) >> 16)
#define SW_OFFSET(X)		((signed short) ((X) & 0x0000ffff))

/* Function: find_last_line_symbol

   Given an address range, first find a line symbol corresponding to
   the starting address.  Then find the last line symbol within the 
   range that has a line number less than or equal to the first line.

   For optimized code with code motion, this finds the last address
   for the lowest-numbered line within the address range.  */

static struct symtab_and_line
find_last_line_symbol (CORE_ADDR start, CORE_ADDR end, int notcurrent)
{
  struct symtab_and_line sal = find_pc_line (start, notcurrent);
  struct symtab_and_line best_sal = sal;

  if (sal.pc == 0 || sal.line == 0 || sal.end == 0)
    return sal;

  do
    {
      if (sal.line && sal.line <= best_sal.line)
	best_sal = sal;
      sal = find_pc_line (sal.end, notcurrent);
    }
  while (sal.pc && sal.pc < end);

  return best_sal;
}

/* Function: scan_prologue
   Decode the instructions within the given address range.
   Decide when we must have reached the end of the function prologue.
   If a frame_info pointer is provided, fill in its prologue information.

   Returns the address of the first instruction after the prologue.  */

static CORE_ADDR
iq2000_scan_prologue (CORE_ADDR scan_start,
		      CORE_ADDR scan_end,
		      struct frame_info *fi,
		      struct iq2000_frame_cache *cache)
{
  struct symtab_and_line sal;
  CORE_ADDR pc;
  CORE_ADDR loop_end;
  int found_store_lr = 0;
  int found_decr_sp = 0;
  int srcreg;
  int tgtreg;
  signed short offset;

  if (scan_end == (CORE_ADDR) 0)
    {
      loop_end = scan_start + 100;
      sal.end = sal.pc = 0;
    }
  else
    {
      loop_end = scan_end;
      if (fi)
	sal = find_last_line_symbol (scan_start, scan_end, 0);
    }

  /* Saved registers:
     We first have to save the saved register's offset, and 
     only later do we compute its actual address.  Since the
     offset can be zero, we must first initialize all the 
     saved regs to minus one (so we can later distinguish 
     between one that's not saved, and one that's saved at zero). */
  for (srcreg = 0; srcreg < E_NUM_REGS; srcreg ++)
    cache->saved_regs[srcreg] = -1;
  cache->using_fp = 0;
  cache->framesize = 0;

  for (pc = scan_start; pc < loop_end; pc += 4)
    {
      LONGEST insn = read_memory_unsigned_integer (pc, 4);
      /* Skip any instructions writing to (sp) or decrementing the
         SP. */
      if ((insn & 0xffe00000) == 0xac200000)
	{
	  /* sw using SP/%1 as base.  */
	  /* LEGACY -- from assembly-only port.  */
	  tgtreg = ((insn >> 16) & 0x1f);
	  if (tgtreg >= 0 && tgtreg < E_NUM_REGS)
	    cache->saved_regs[tgtreg] = -((signed short) (insn & 0xffff));

	  if (tgtreg == E_LR_REGNUM)
	    found_store_lr = 1;
	  continue;
	}

      if ((insn & 0xffff8000) == 0x20218000)
	{
	  /* addi %1, %1, -N == addi %sp, %sp, -N */
	  /* LEGACY -- from assembly-only port */
	  found_decr_sp = 1;
	  cache->framesize = -((signed short) (insn & 0xffff));
	  continue;
	}

      if (INSN_IS_ADDIU (insn))
	{
	  srcreg = ADDIU_REG_SRC (insn);
	  tgtreg = ADDIU_REG_TGT (insn);
	  offset = ADDIU_IMMEDIATE (insn);
	  if (srcreg == E_SP_REGNUM && tgtreg == E_SP_REGNUM)
	    cache->framesize = -offset;
	  continue;
	}

      if (INSN_IS_STORE_WORD (insn))
	{
	  srcreg = SW_REG_SRC (insn);
	  tgtreg = SW_REG_INDEX (insn);
	  offset = SW_OFFSET (insn);

	  if (tgtreg == E_SP_REGNUM || tgtreg == E_FP_REGNUM)
	    {
	      /* "push" to stack (via SP or FP reg) */
	      if (cache->saved_regs[srcreg] == -1) /* Don't save twice.  */
		cache->saved_regs[srcreg] = offset;
	      continue;
	    }
	}

      if (INSN_IS_MOVE (insn))
	{
	  srcreg = MOVE_REG_SRC (insn);
	  tgtreg = MOVE_REG_TGT (insn);

	  if (srcreg == E_SP_REGNUM && tgtreg == E_FP_REGNUM)
	    {
	      /* Copy sp to fp.  */
	      cache->using_fp = 1;
	      continue;
	    }
	}

      /* Unknown instruction encountered in frame.  Bail out?
         1) If we have a subsequent line symbol, we can keep going.
         2) If not, we need to bail out and quit scanning instructions.  */

      if (fi && sal.end && (pc < sal.end)) /* Keep scanning.  */
	continue;
      else /* bail */
	break;
    }

  return pc;
}

static void
iq2000_init_frame_cache (struct iq2000_frame_cache *cache)
{
  int i;

  cache->base = 0;
  cache->framesize = 0;
  cache->using_fp = 0;
  cache->saved_sp = 0;
  for (i = 0; i < E_NUM_REGS; i++)
    cache->saved_regs[i] = -1;
}

/* Function: iq2000_skip_prologue
   If the input address is in a function prologue, 
   returns the address of the end of the prologue;
   else returns the input address.

   Note: the input address is likely to be the function start, 
   since this function is mainly used for advancing a breakpoint
   to the first line, or stepping to the first line when we have
   stepped into a function call.  */

static CORE_ADDR
iq2000_skip_prologue (CORE_ADDR pc)
{
  CORE_ADDR func_addr = 0 , func_end = 0;

  if (find_pc_partial_function (pc, NULL, & func_addr, & func_end))
    {
      struct symtab_and_line sal;
      struct iq2000_frame_cache cache;

      /* Found a function.  */
      sal = find_pc_line (func_addr, 0);
      if (sal.end && sal.end < func_end)
	/* Found a line number, use it as end of prologue.  */
	return sal.end;

      /* No useable line symbol.  Use prologue parsing method.  */
      iq2000_init_frame_cache (&cache);
      return iq2000_scan_prologue (func_addr, func_end, NULL, &cache);
    }

  /* No function symbol -- just return the PC.  */
  return (CORE_ADDR) pc;
}

static struct iq2000_frame_cache *
iq2000_frame_cache (struct frame_info *next_frame, void **this_cache)
{
  struct iq2000_frame_cache *cache;
  CORE_ADDR current_pc;
  int i;

  if (*this_cache)
    return *this_cache;

  cache = FRAME_OBSTACK_ZALLOC (struct iq2000_frame_cache);
  iq2000_init_frame_cache (cache);
  *this_cache = cache;

  cache->base = frame_unwind_register_unsigned (next_frame, E_FP_REGNUM);
  //if (cache->base == 0)
    //return cache;

  current_pc = frame_pc_unwind (next_frame);
  find_pc_partial_function (current_pc, NULL, &cache->pc, NULL);
  if (cache->pc != 0)
    iq2000_scan_prologue (cache->pc, current_pc, next_frame, cache);
  if (!cache->using_fp)
    cache->base = frame_unwind_register_unsigned (next_frame, E_SP_REGNUM);

  cache->saved_sp = cache->base + cache->framesize;

  for (i = 0; i < E_NUM_REGS; i++)
    if (cache->saved_regs[i] != -1)
      cache->saved_regs[i] += cache->base;

  return cache;
}

static void
iq2000_frame_prev_register (struct frame_info *next_frame, void **this_cache,
			    int regnum, int *optimizedp,
			    enum lval_type *lvalp, CORE_ADDR *addrp,
			    int *realnump, void *valuep)
{
  struct iq2000_frame_cache *cache = iq2000_frame_cache (next_frame, this_cache);
  if (regnum == E_SP_REGNUM && cache->saved_sp)
    {
      *optimizedp = 0;
      *lvalp = not_lval;
      *addrp = 0;
      *realnump = -1;
      if (valuep)
        store_unsigned_integer (valuep, 4, cache->saved_sp);
      return;
    }

  if (regnum == E_PC_REGNUM)
    regnum = E_LR_REGNUM;

  if (regnum < E_NUM_REGS && cache->saved_regs[regnum] != -1)
    {
      *optimizedp = 0;
      *lvalp = lval_memory;
      *addrp = cache->saved_regs[regnum];
      *realnump = -1;
      if (valuep)
        read_memory (*addrp, valuep,
		     register_size (get_frame_arch (next_frame), regnum));
      return;
    }

  *optimizedp = 0;
  *lvalp = lval_register;
  *addrp = 0; 
  *realnump = regnum;
  if (valuep)
    frame_unwind_register (next_frame, (*realnump), valuep);
}

static void
iq2000_frame_this_id (struct frame_info *next_frame, void **this_cache,
		      struct frame_id *this_id)
{
  struct iq2000_frame_cache *cache = iq2000_frame_cache (next_frame, this_cache);

  /* This marks the outermost frame.  */
  if (cache->base == 0) 
    return;

  *this_id = frame_id_build (cache->saved_sp, cache->pc);
}

static const struct frame_unwind iq2000_frame_unwind = {
  NORMAL_FRAME,
  iq2000_frame_this_id,
  iq2000_frame_prev_register
};

static const struct frame_unwind *
iq2000_frame_sniffer (struct frame_info *next_frame)
{
  return &iq2000_frame_unwind;
}

static CORE_ADDR
iq2000_unwind_sp (struct gdbarch *gdbarch, struct frame_info *next_frame)
{
  return frame_unwind_register_unsigned (next_frame, E_SP_REGNUM);
}   

static CORE_ADDR
iq2000_unwind_pc (struct gdbarch *gdbarch, struct frame_info *next_frame)
{
  return frame_unwind_register_unsigned (next_frame, E_PC_REGNUM);
}

static struct frame_id
iq2000_unwind_dummy_id (struct gdbarch *gdbarch, struct frame_info *next_frame)
{
  return frame_id_build (iq2000_unwind_sp (gdbarch, next_frame),
                         frame_pc_unwind (next_frame));
}

static CORE_ADDR
iq2000_frame_base_address (struct frame_info *next_frame, void **this_cache)
{
  struct iq2000_frame_cache *cache = iq2000_frame_cache (next_frame, this_cache);

  return cache->base;
}
  
static const struct frame_base iq2000_frame_base = {
  &iq2000_frame_unwind,
  iq2000_frame_base_address,
  iq2000_frame_base_address, 
  iq2000_frame_base_address
};

static const unsigned char *
iq2000_breakpoint_from_pc (CORE_ADDR *pcptr, int *lenptr)
{
  static const unsigned char big_breakpoint[] = { 0x00, 0x00, 0x00, 0x0d };
  static const unsigned char little_breakpoint[] = { 0x0d, 0x00, 0x00, 0x00 };

  if ((*pcptr & 3) != 0)
    error ("breakpoint_from_pc: invalid breakpoint address 0x%lx",
	   (long) *pcptr);

  *lenptr = 4;
  return (gdbarch_byte_order (current_gdbarch)
	  == BFD_ENDIAN_BIG) ? big_breakpoint
					       : little_breakpoint;
}

/* Target function return value methods: */

/* Function: store_return_value
   Copy the function return value from VALBUF into the 
   proper location for a function return.  */

static void
iq2000_store_return_value (struct type *type, struct regcache *regcache,
			   const void *valbuf)
{
  int len = TYPE_LENGTH (type);
  int regno = E_FN_RETURN_REGNUM;

  while (len > 0)
    {
      char buf[4];
      int size = len % 4 ?: 4;

      memset (buf, 0, 4);
      memcpy (buf + 4 - size, valbuf, size);
      regcache_raw_write (regcache, regno++, buf);
      len -= size;
      valbuf = ((char *) valbuf) + size;
    }
}

/* Function: use_struct_convention 
   Returns non-zero if the given struct type will be returned using
   a special convention, rather than the normal function return method.  */

static int
iq2000_use_struct_convention (struct type *type)
{
  return ((TYPE_CODE (type) == TYPE_CODE_STRUCT)
	  || (TYPE_CODE (type) == TYPE_CODE_UNION))
	 && TYPE_LENGTH (type) > 8;
}

/* Function: extract_return_value
   Copy the function's return value into VALBUF. 
   This function is called only in the context of "target function calls",
   ie. when the debugger forces a function to be called in the child, and
   when the debugger forces a function to return prematurely via the
   "return" command.  */

static void
iq2000_extract_return_value (struct type *type, struct regcache *regcache,
			     void *valbuf)
{
  /* If the function's return value is 8 bytes or less, it is
     returned in a register, and if larger than 8 bytes, it is 
     returned in a stack location which is pointed to by the same
     register.  */
  CORE_ADDR return_buffer;
  int len = TYPE_LENGTH (type);

  if (len <= (2 * 4))
    {
      int regno = E_FN_RETURN_REGNUM;

      /* Return values of <= 8 bytes are returned in 
	 FN_RETURN_REGNUM.  */
      while (len > 0)
	{
	  ULONGEST tmp;
	  int size = len % 4 ?: 4;

	  /* By using store_unsigned_integer we avoid having to
	     do anything special for small big-endian values.  */
	  regcache_cooked_read_unsigned (regcache, regno++, &tmp);
	  store_unsigned_integer (valbuf, size, tmp);
	  len -= size;
	  valbuf = ((char *) valbuf) + size;
	}
    }
  else
    {
      /* Return values > 8 bytes are returned in memory,
	 pointed to by FN_RETURN_REGNUM.  */
      regcache_cooked_read (regcache, E_FN_RETURN_REGNUM, & return_buffer);
      read_memory (return_buffer, valbuf, TYPE_LENGTH (type));
    }
}

static enum return_value_convention
iq2000_return_value (struct gdbarch *gdbarch, struct type *type,
		     struct regcache *regcache,
		     void *readbuf, const void *writebuf)
{
  if (iq2000_use_struct_convention (type))
    return RETURN_VALUE_STRUCT_CONVENTION;
  if (writebuf)
    iq2000_store_return_value (type, regcache, writebuf);
  else if (readbuf)
    iq2000_extract_return_value (type, regcache, readbuf);
  return RETURN_VALUE_REGISTER_CONVENTION;
}

/* Function: register_virtual_type
   Returns the default type for register N.  */

static struct type *
iq2000_register_type (struct gdbarch *gdbarch, int regnum)
{
  return builtin_type_int32;
}

static CORE_ADDR
iq2000_frame_align (struct gdbarch *ignore, CORE_ADDR sp)
{
  /* This is the same frame alignment used by gcc.  */
  return ((sp + 7) & ~7);
}

/* Convenience function to check 8-byte types for being a scalar type
   or a struct with only one long long or double member. */
static int
iq2000_pass_8bytetype_by_address (struct type *type)
{
  struct type *ftype;

  /* Skip typedefs.  */
  while (TYPE_CODE (type) == TYPE_CODE_TYPEDEF)
    type = TYPE_TARGET_TYPE (type);
  /* Non-struct and non-union types are always passed by value.  */
  if (TYPE_CODE (type) != TYPE_CODE_STRUCT
      && TYPE_CODE (type) != TYPE_CODE_UNION)
    return 0;
  /* Structs with more than 1 field are always passed by address.  */
  if (TYPE_NFIELDS (type) != 1)
    return 1;
  /* Get field type.  */
  ftype = (TYPE_FIELDS (type))[0].type;
  /* The field type must have size 8, otherwise pass by address.  */
  if (TYPE_LENGTH (ftype) != 8)
    return 1;
  /* Skip typedefs of field type.  */
  while (TYPE_CODE (ftype) == TYPE_CODE_TYPEDEF)
    ftype = TYPE_TARGET_TYPE (ftype);
  /* If field is int or float, pass by value.  */
  if (TYPE_CODE (ftype) == TYPE_CODE_FLT
      || TYPE_CODE (ftype) == TYPE_CODE_INT)
    return 0;
  /* Everything else, pass by address. */
  return 1;
}

static CORE_ADDR
iq2000_push_dummy_call (struct gdbarch *gdbarch, struct value *function,
		        struct regcache *regcache, CORE_ADDR bp_addr,
		        int nargs, struct value **args, CORE_ADDR sp,
		        int struct_return, CORE_ADDR struct_addr)
{
  const bfd_byte *val;
  bfd_byte buf[4];
  struct type *type;
  int i, argreg, typelen, slacklen;
  int stackspace = 0;
  /* Used to copy struct arguments into the stack. */
  CORE_ADDR struct_ptr;

  /* First determine how much stack space we will need. */
  for (i = 0, argreg = E_1ST_ARGREG + (struct_return != 0); i < nargs; i++)
    {
      type = value_type (args[i]);
      typelen = TYPE_LENGTH (type);
      if (typelen <= 4)
        {
          /* Scalars of up to 4 bytes, 
             structs of up to 4 bytes, and
             pointers.  */
          if (argreg <= E_LAST_ARGREG)
            argreg++;
          else
            stackspace += 4;
        }
      else if (typelen == 8 && !iq2000_pass_8bytetype_by_address (type))
        {
          /* long long, 
             double, and possibly
             structs with a single field of long long or double. */
          if (argreg <= E_LAST_ARGREG - 1)
            {
              /* 8-byte arg goes into a register pair
                 (must start with an even-numbered reg) */
              if (((argreg - E_1ST_ARGREG) % 2) != 0)
                argreg ++;
              argreg += 2;
            }
          else
            {
              argreg = E_LAST_ARGREG + 1;       /* no more argregs. */
              /* 8-byte arg goes on stack, must be 8-byte aligned. */
              stackspace = ((stackspace + 7) & ~7);
              stackspace += 8;
            }
        }
      else
	{
	  /* Structs are passed as pointer to a copy of the struct.
	     So we need room on the stack for a copy of the struct
	     plus for the argument pointer. */
          if (argreg <= E_LAST_ARGREG)
            argreg++;
          else
            stackspace += 4;
	  /* Care for 8-byte alignment of structs saved on stack.  */
	  stackspace += ((typelen + 7) & ~7);
	}
    }

  /* Now copy params, in ascending order, into their assigned location
     (either in a register or on the stack). */

  sp -= (sp % 8);       /* align */
  struct_ptr = sp;
  sp -= stackspace;
  sp -= (sp % 8);       /* align again */
  stackspace = 0;

  argreg = E_1ST_ARGREG;
  if (struct_return)
    {
      /* A function that returns a struct will consume one argreg to do so. 
       */
      regcache_cooked_write_unsigned (regcache, argreg++, struct_addr);
    }

  for (i = 0; i < nargs; i++)
    {
      type = value_type (args[i]);
      typelen = TYPE_LENGTH (type);
      val = value_contents (args[i]);
      if (typelen <= 4)
        {
          /* Char, short, int, float, pointer, and structs <= four bytes. */
	  slacklen = (4 - (typelen % 4)) % 4;
	  memset (buf, 0, sizeof (buf));
	  memcpy (buf + slacklen, val, typelen);
          if (argreg <= E_LAST_ARGREG)
            {
              /* Passed in a register. */
	      regcache_raw_write (regcache, argreg++, buf);
            }
          else
            {
              /* Passed on the stack. */
              write_memory (sp + stackspace, buf, 4);
              stackspace += 4;
            }
        }
      else if (typelen == 8 && !iq2000_pass_8bytetype_by_address (type))
        {
          /* (long long), (double), or struct consisting of 
             a single (long long) or (double). */
          if (argreg <= E_LAST_ARGREG - 1)
            {
              /* 8-byte arg goes into a register pair
                 (must start with an even-numbered reg) */
              if (((argreg - E_1ST_ARGREG) % 2) != 0)
                argreg++;
	      regcache_raw_write (regcache, argreg++, val);
	      regcache_raw_write (regcache, argreg++, val + 4);
            }
          else
            {
              /* 8-byte arg goes on stack, must be 8-byte aligned. */
              argreg = E_LAST_ARGREG + 1;       /* no more argregs. */
              stackspace = ((stackspace + 7) & ~7);
              write_memory (sp + stackspace, val, typelen);
              stackspace += 8;
            }
        }
      else
        {
	  /* Store struct beginning at the upper end of the previously
	     computed stack space.  Then store the address of the struct
	     using the usual rules for a 4 byte value.  */
	  struct_ptr -= ((typelen + 7) & ~7);
	  write_memory (struct_ptr, val, typelen);
	  if (argreg <= E_LAST_ARGREG)
	    regcache_cooked_write_unsigned (regcache, argreg++, struct_ptr);
	  else
	    {
	      store_unsigned_integer (buf, 4, struct_ptr);
	      write_memory (sp + stackspace, buf, 4);
	      stackspace += 4;
	    }
        }
    }

  /* Store return address. */
  regcache_cooked_write_unsigned (regcache, E_LR_REGNUM, bp_addr);

  /* Update stack pointer.  */
  regcache_cooked_write_unsigned (regcache, E_SP_REGNUM, sp);

  /* And that should do it.  Return the new stack pointer. */
  return sp;
}

/* Function: gdbarch_init
   Initializer function for the iq2000 gdbarch vector.
   Called by gdbarch.  Sets up the gdbarch vector(s) for this target.  */

static struct gdbarch *
iq2000_gdbarch_init (struct gdbarch_info info, struct gdbarch_list *arches)
{
  struct gdbarch *gdbarch;

  /* Look up list for candidates - only one.  */
  arches = gdbarch_list_lookup_by_info (arches, &info);
  if (arches != NULL)
    return arches->gdbarch;

  gdbarch = gdbarch_alloc (&info, NULL);

  set_gdbarch_num_regs             (gdbarch, E_NUM_REGS);
  set_gdbarch_num_pseudo_regs      (gdbarch, 0);
  set_gdbarch_sp_regnum            (gdbarch, E_SP_REGNUM);
  set_gdbarch_pc_regnum            (gdbarch, E_PC_REGNUM);
  set_gdbarch_register_name        (gdbarch, iq2000_register_name);
  set_gdbarch_address_to_pointer   (gdbarch, iq2000_address_to_pointer);
  set_gdbarch_pointer_to_address   (gdbarch, iq2000_pointer_to_address);
  set_gdbarch_ptr_bit              (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_short_bit            (gdbarch, 2 * TARGET_CHAR_BIT);
  set_gdbarch_int_bit              (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_long_bit             (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_long_long_bit        (gdbarch, 8 * TARGET_CHAR_BIT);
  set_gdbarch_float_bit            (gdbarch, 4 * TARGET_CHAR_BIT);
  set_gdbarch_double_bit           (gdbarch, 8 * TARGET_CHAR_BIT);
  set_gdbarch_long_double_bit      (gdbarch, 8 * TARGET_CHAR_BIT);
  set_gdbarch_float_format         (gdbarch, floatformats_ieee_single);
  set_gdbarch_double_format        (gdbarch, floatformats_ieee_double);
  set_gdbarch_long_double_format   (gdbarch, floatformats_ieee_double);
  set_gdbarch_return_value	   (gdbarch, iq2000_return_value);
  set_gdbarch_breakpoint_from_pc   (gdbarch, iq2000_breakpoint_from_pc);
  set_gdbarch_frame_args_skip      (gdbarch, 0);
  set_gdbarch_skip_prologue        (gdbarch, iq2000_skip_prologue);
  set_gdbarch_inner_than           (gdbarch, core_addr_lessthan);
  set_gdbarch_print_insn           (gdbarch, print_insn_iq2000);
  set_gdbarch_register_type (gdbarch, iq2000_register_type);
  set_gdbarch_frame_align (gdbarch, iq2000_frame_align);
  set_gdbarch_unwind_sp (gdbarch, iq2000_unwind_sp);
  set_gdbarch_unwind_pc (gdbarch, iq2000_unwind_pc);
  set_gdbarch_unwind_dummy_id (gdbarch, iq2000_unwind_dummy_id);
  frame_base_set_default (gdbarch, &iq2000_frame_base);
  set_gdbarch_push_dummy_call (gdbarch, iq2000_push_dummy_call);

  gdbarch_init_osabi (info, gdbarch);

  frame_unwind_append_sniffer (gdbarch, dwarf2_frame_sniffer);
  frame_unwind_append_sniffer (gdbarch, iq2000_frame_sniffer);

  return gdbarch;
}

/* Function: _initialize_iq2000_tdep
   Initializer function for the iq2000 module.
   Called by gdb at start-up. */

void
_initialize_iq2000_tdep (void)
{
  register_gdbarch_init (bfd_arch_iq2000, iq2000_gdbarch_init);
}