1 /* Target-dependent code for the MIPS architecture, for GDB, the GNU Debugger.
2 Copyright 1988, 1989, 1990, 1991, 1992, 1993 Free Software Foundation, Inc.
3 Contributed by Alessandro Forin(af@cs.cmu.edu) at CMU
4 and by Per Bothner(bothner@cs.wisc.edu) at U.Wisconsin.
6 This file is part of GDB.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
31 #include <sys/types.h>
34 #include <sys/param.h>
37 #include <sys/ioctl.h>
45 #define MIPSMAGIC MIPSELMAGIC
47 #define MIPSMAGIC MIPSEBMAGIC
51 #define VM_MIN_ADDRESS (unsigned)0x400000
53 #include <sys/user.h> /* After a.out.h */
58 /* Some MIPS boards don't support floating point, so we permit the
59 user to turn it off. */
62 #define PROC_LOW_ADDR(proc) ((proc)->pdr.adr) /* least address */
63 #define PROC_HIGH_ADDR(proc) ((proc)->pdr.iline) /* upper address bound */
64 #define PROC_FRAME_OFFSET(proc) ((proc)->pdr.frameoffset)
65 #define PROC_FRAME_REG(proc) ((proc)->pdr.framereg)
66 #define PROC_REG_MASK(proc) ((proc)->pdr.regmask)
67 #define PROC_FREG_MASK(proc) ((proc)->pdr.fregmask)
68 #define PROC_REG_OFFSET(proc) ((proc)->pdr.regoffset)
69 #define PROC_FREG_OFFSET(proc) ((proc)->pdr.fregoffset)
70 #define PROC_PC_REG(proc) ((proc)->pdr.pcreg)
71 #define PROC_SYMBOL(proc) (*(struct symbol**)&(proc)->pdr.isym)
72 #define _PROC_MAGIC_ 0x0F0F0F0F
73 #define PROC_DESC_IS_DUMMY(proc) ((proc)->pdr.isym == _PROC_MAGIC_)
74 #define SET_PROC_DESC_IS_DUMMY(proc) ((proc)->pdr.isym = _PROC_MAGIC_)
76 struct linked_proc_info
78 struct mips_extra_func_info info;
79 struct linked_proc_info *next;
80 } *linked_proc_desc_table = NULL;
83 #define READ_FRAME_REG(fi, regno) read_next_frame_reg((fi)->next, regno)
86 read_next_frame_reg(fi, regno)
90 #define SIGFRAME_BASE sizeof(struct sigcontext)
91 #define SIGFRAME_PC_OFF (-SIGFRAME_BASE+ 2*sizeof(int))
92 #define SIGFRAME_SP_OFF (-SIGFRAME_BASE+32*sizeof(int))
93 #define SIGFRAME_RA_OFF (-SIGFRAME_BASE+34*sizeof(int))
94 for (; fi; fi = fi->next)
95 if (in_sigtramp(fi->pc, 0)) {
96 /* No idea if this code works. --PB. */
98 if (regno == PC_REGNUM) offset = SIGFRAME_PC_OFF;
99 else if (regno == RA_REGNUM) offset = SIGFRAME_RA_OFF;
100 else if (regno == SP_REGNUM) offset = SIGFRAME_SP_OFF;
102 return read_memory_integer(fi->frame + offset, 4);
104 else if (regno == SP_REGNUM) return fi->frame;
105 else if (fi->saved_regs->regs[regno])
106 return read_memory_integer(fi->saved_regs->regs[regno], 4);
107 return read_register(regno);
111 mips_frame_saved_pc(frame)
114 mips_extra_func_info_t proc_desc = frame->proc_desc;
115 int pcreg = proc_desc ? PROC_PC_REG(proc_desc) : RA_REGNUM;
117 if (proc_desc && PROC_DESC_IS_DUMMY(proc_desc))
118 return read_memory_integer(frame->frame - 4, 4);
120 return read_next_frame_reg(frame, pcreg);
123 static struct mips_extra_func_info temp_proc_desc;
124 static struct frame_saved_regs temp_saved_regs;
127 heuristic_proc_start(pc)
130 CORE_ADDR start_pc = pc;
131 CORE_ADDR fence = start_pc - 200;
133 if (start_pc == 0) return 0;
134 if (fence < VM_MIN_ADDRESS) fence = VM_MIN_ADDRESS;
136 /* search back for previous return */
137 for (start_pc -= 4; ; start_pc -= 4)
138 if (start_pc < fence) return 0;
139 else if (ABOUT_TO_RETURN(start_pc))
142 start_pc += 8; /* skip return, and its delay slot */
144 /* skip nops (usually 1) 0 - is this */
145 while (start_pc < pc && read_memory_integer (start_pc, 4) == 0)
151 static mips_extra_func_info_t
152 heuristic_proc_desc(start_pc, limit_pc, next_frame)
153 CORE_ADDR start_pc, limit_pc;
156 CORE_ADDR sp = next_frame ? next_frame->frame : read_register (SP_REGNUM);
159 int has_frame_reg = 0;
160 int reg30; /* Value of $r30. Used by gcc for frame-pointer */
161 unsigned long reg_mask = 0;
163 if (start_pc == 0) return NULL;
164 bzero(&temp_proc_desc, sizeof(temp_proc_desc));
165 bzero(&temp_saved_regs, sizeof(struct frame_saved_regs));
166 PROC_LOW_ADDR(&temp_proc_desc) = start_pc;
168 if (start_pc + 200 < limit_pc) limit_pc = start_pc + 200;
171 for (cur_pc = start_pc; cur_pc < limit_pc; cur_pc += 4) {
175 status = read_memory_nobpt (cur_pc, (char *)&word, 4);
176 if (status) memory_error (status, cur_pc);
177 SWAP_TARGET_AND_HOST (&word, sizeof (word));
178 if ((word & 0xFFFF0000) == 0x27bd0000) /* addiu $sp,$sp,-i */
179 frame_size += (-word) & 0xFFFF;
180 else if ((word & 0xFFFF0000) == 0x23bd0000) /* addu $sp,$sp,-i */
181 frame_size += (-word) & 0xFFFF;
182 else if ((word & 0xFFE00000) == 0xafa00000) { /* sw reg,offset($sp) */
183 int reg = (word & 0x001F0000) >> 16;
184 reg_mask |= 1 << reg;
185 temp_saved_regs.regs[reg] = sp + (short)word;
187 else if ((word & 0xFFFF0000) == 0x27be0000) { /* addiu $30,$sp,size */
188 if ((unsigned short)word != frame_size)
189 reg30 = sp + (unsigned short)word;
190 else if (!has_frame_reg) {
193 reg30 = read_next_frame_reg(next_frame, 30);
194 alloca_adjust = reg30 - (sp + (unsigned short)word);
195 if (alloca_adjust > 0) {
196 /* FP > SP + frame_size. This may be because
197 /* of an alloca or somethings similar.
198 * Fix sp to "pre-alloca" value, and try again.
205 else if ((word & 0xFFE00000) == 0xafc00000) { /* sw reg,offset($30) */
206 int reg = (word & 0x001F0000) >> 16;
207 reg_mask |= 1 << reg;
208 temp_saved_regs.regs[reg] = reg30 + (short)word;
212 PROC_FRAME_REG(&temp_proc_desc) = 30;
213 PROC_FRAME_OFFSET(&temp_proc_desc) = 0;
216 PROC_FRAME_REG(&temp_proc_desc) = SP_REGNUM;
217 PROC_FRAME_OFFSET(&temp_proc_desc) = frame_size;
219 PROC_REG_MASK(&temp_proc_desc) = reg_mask;
220 PROC_PC_REG(&temp_proc_desc) = RA_REGNUM;
221 return &temp_proc_desc;
224 static mips_extra_func_info_t
225 find_proc_desc(pc, next_frame)
229 mips_extra_func_info_t proc_desc;
230 struct block *b = block_for_pc(pc);
232 b ? lookup_symbol(MIPS_EFI_SYMBOL_NAME, b, LABEL_NAMESPACE, 0, NULL) : NULL;
236 /* IF this is the topmost frame AND
237 * (this proc does not have debugging information OR
238 * the PC is in the procedure prologue)
239 * THEN create a "heuristic" proc_desc (by analyzing
240 * the actual code) to replace the "official" proc_desc.
242 proc_desc = (mips_extra_func_info_t)SYMBOL_VALUE(sym);
243 if (next_frame == NULL) {
244 struct symtab_and_line val;
245 struct symbol *proc_symbol =
246 PROC_DESC_IS_DUMMY(proc_desc) ? 0 : PROC_SYMBOL(proc_desc);
249 val = find_pc_line (BLOCK_START
250 (SYMBOL_BLOCK_VALUE(proc_symbol)),
252 val.pc = val.end ? val.end : pc;
254 if (!proc_symbol || pc < val.pc) {
255 mips_extra_func_info_t found_heuristic =
256 heuristic_proc_desc(PROC_LOW_ADDR(proc_desc),
258 if (found_heuristic) proc_desc = found_heuristic;
264 /* Is linked_proc_desc_table really necessary? It only seems to be used
265 by procedure call dummys. However, the procedures being called ought
266 to have their own proc_descs, and even if they don't,
267 heuristic_proc_desc knows how to create them! */
269 register struct linked_proc_info *link;
270 for (link = linked_proc_desc_table; link; link = link->next)
271 if (PROC_LOW_ADDR(&link->info) <= pc
272 && PROC_HIGH_ADDR(&link->info) > pc)
275 heuristic_proc_desc(heuristic_proc_start(pc), pc, next_frame);
280 mips_extra_func_info_t cached_proc_desc;
283 mips_frame_chain(frame)
286 mips_extra_func_info_t proc_desc;
287 CORE_ADDR saved_pc = FRAME_SAVED_PC(frame);
289 if (saved_pc == 0 || inside_entry_file (saved_pc))
292 proc_desc = find_proc_desc(saved_pc, frame);
296 cached_proc_desc = proc_desc;
297 return read_next_frame_reg(frame, PROC_FRAME_REG(proc_desc))
298 + PROC_FRAME_OFFSET(proc_desc);
302 init_extra_frame_info(fci)
303 struct frame_info *fci;
305 extern struct obstack frame_cache_obstack;
306 /* Use proc_desc calculated in frame_chain */
307 mips_extra_func_info_t proc_desc = fci->next ? cached_proc_desc :
308 find_proc_desc(fci->pc, fci->next);
310 fci->saved_regs = (struct frame_saved_regs*)
311 obstack_alloc (&frame_cache_obstack, sizeof(struct frame_saved_regs));
312 bzero(fci->saved_regs, sizeof(struct frame_saved_regs));
314 proc_desc == &temp_proc_desc ? 0 : proc_desc;
318 CORE_ADDR reg_position;
320 /* r0 bit means kernel trap */
321 int kernel_trap = PROC_REG_MASK(proc_desc) & 1;
323 /* Fixup frame-pointer - only needed for top frame */
324 /* This may not be quite right, if proc has a real frame register */
325 if (fci->pc == PROC_LOW_ADDR(proc_desc))
326 fci->frame = read_register (SP_REGNUM);
328 fci->frame = READ_FRAME_REG(fci, PROC_FRAME_REG(proc_desc))
329 + PROC_FRAME_OFFSET(proc_desc);
331 if (proc_desc == &temp_proc_desc)
332 *fci->saved_regs = temp_saved_regs;
335 /* find which general-purpose registers were saved */
336 reg_position = fci->frame + PROC_REG_OFFSET(proc_desc);
337 mask = kernel_trap ? 0xFFFFFFFF : PROC_REG_MASK(proc_desc);
338 for (ireg= 31; mask; --ireg, mask <<= 1)
339 if (mask & 0x80000000)
341 fci->saved_regs->regs[ireg] = reg_position;
344 /* find which floating-point registers were saved */
345 reg_position = fci->frame + PROC_FREG_OFFSET(proc_desc);
346 /* The freg_offset points to where the first *double* register is saved.
347 * So skip to the high-order word. */
349 mask = kernel_trap ? 0xFFFFFFFF : PROC_FREG_MASK(proc_desc);
350 for (ireg = 31; mask; --ireg, mask <<= 1)
351 if (mask & 0x80000000)
353 fci->saved_regs->regs[FP0_REGNUM+ireg] = reg_position;
358 /* hack: if argument regs are saved, guess these contain args */
359 if ((PROC_REG_MASK(proc_desc) & 0xF0) == 0) fci->num_args = -1;
360 else if ((PROC_REG_MASK(proc_desc) & 0x80) == 0) fci->num_args = 4;
361 else if ((PROC_REG_MASK(proc_desc) & 0x40) == 0) fci->num_args = 3;
362 else if ((PROC_REG_MASK(proc_desc) & 0x20) == 0) fci->num_args = 2;
363 else if ((PROC_REG_MASK(proc_desc) & 0x10) == 0) fci->num_args = 1;
365 fci->saved_regs->regs[PC_REGNUM] = fci->saved_regs->regs[RA_REGNUM];
369 /* MIPS stack frames are almost impenetrable. When execution stops,
370 we basically have to look at symbol information for the function
371 that we stopped in, which tells us *which* register (if any) is
372 the base of the frame pointer, and what offset from that register
373 the frame itself is at.
375 This presents a problem when trying to examine a stack in memory
376 (that isn't executing at the moment), using the "frame" command. We
377 don't have a PC, nor do we have any registers except SP.
379 This routine takes two arguments, SP and PC, and tries to make the
380 cached frames look as if these two arguments defined a frame on the
381 cache. This allows the rest of info frame to extract the important
382 arguments without difficulty. */
385 setup_arbitrary_frame (argc, argv)
390 error ("MIPS frame specifications require two arguments: sp and pc");
392 return create_new_frame (argv[0], argv[1]);
397 mips_push_arguments(nargs, args, sp, struct_return, struct_addr)
402 CORE_ADDR struct_addr;
406 int accumulate_size = struct_return ? 4 : 0;
407 struct mips_arg { char *contents; int len; int offset; };
408 struct mips_arg *mips_args =
409 (struct mips_arg*)alloca(nargs * sizeof(struct mips_arg));
410 register struct mips_arg *m_arg;
411 for (i = 0, m_arg = mips_args; i < nargs; i++, m_arg++) {
412 extern value value_arg_coerce();
413 value arg = value_arg_coerce (args[i]);
414 m_arg->len = TYPE_LENGTH (VALUE_TYPE (arg));
415 /* This entire mips-specific routine is because doubles must be aligned
416 * on 8-byte boundaries. It still isn't quite right, because MIPS decided
417 * to align 'struct {int a, b}' on 4-byte boundaries (even though this
418 * breaks their varargs implementation...). A correct solution
419 * requires an simulation of gcc's 'alignof' (and use of 'alignof'
420 * in stdarg.h/varargs.h).
422 if (m_arg->len > 4) accumulate_size = (accumulate_size + 7) & -8;
423 m_arg->offset = accumulate_size;
424 accumulate_size = (accumulate_size + m_arg->len + 3) & -4;
425 m_arg->contents = VALUE_CONTENTS(arg);
427 accumulate_size = (accumulate_size + 7) & (-8);
428 if (accumulate_size < 16) accumulate_size = 16;
429 sp -= accumulate_size;
430 for (i = nargs; m_arg--, --i >= 0; )
431 write_memory(sp + m_arg->offset, m_arg->contents, m_arg->len);
434 write_memory(sp, (char *)&buf, sizeof(CORE_ADDR));
439 /* MASK(i,j) == (1<<i) + (1<<(i+1)) + ... + (1<<j)). Assume i<=j<31. */
440 #define MASK(i,j) ((1 << (j)+1)-1 ^ (1 << (i))-1)
443 mips_push_dummy_frame()
446 struct linked_proc_info *link = (struct linked_proc_info*)
447 xmalloc(sizeof(struct linked_proc_info));
448 mips_extra_func_info_t proc_desc = &link->info;
449 CORE_ADDR sp = read_register (SP_REGNUM);
450 CORE_ADDR save_address;
451 REGISTER_TYPE buffer;
452 link->next = linked_proc_desc_table;
453 linked_proc_desc_table = link;
454 #define PUSH_FP_REGNUM 16 /* must be a register preserved across calls */
455 #define GEN_REG_SAVE_MASK MASK(1,16)|MASK(24,28)|(1<<31)
456 #define GEN_REG_SAVE_COUNT 22
457 #define FLOAT_REG_SAVE_MASK MASK(0,19)
458 #define FLOAT_REG_SAVE_COUNT 20
459 #define SPECIAL_REG_SAVE_COUNT 4
461 * The registers we must save are all those not preserved across
462 * procedure calls. Dest_Reg (see tm-mips.h) must also be saved.
463 * In addition, we must save the PC, and PUSH_FP_REGNUM.
464 * (Ideally, we should also save MDLO/-HI and FP Control/Status reg.)
466 * Dummy frame layout:
469 * Saved MMHI, MMLO, FPC_CSR
474 * Saved D18 (i.e. F19, F18)
476 * Saved D0 (i.e. F1, F0)
477 * CALL_DUMMY (subroutine stub; see tm-mips.h)
478 * Parameter build area (not yet implemented)
481 PROC_REG_MASK(proc_desc) = GEN_REG_SAVE_MASK;
482 PROC_FREG_MASK(proc_desc) = mips_fpu ? FLOAT_REG_SAVE_MASK : 0;
483 PROC_REG_OFFSET(proc_desc) = /* offset of (Saved R31) from FP */
484 -sizeof(long) - 4 * SPECIAL_REG_SAVE_COUNT;
485 PROC_FREG_OFFSET(proc_desc) = /* offset of (Saved D18) from FP */
486 -sizeof(double) - 4 * (SPECIAL_REG_SAVE_COUNT + GEN_REG_SAVE_COUNT);
487 /* save general registers */
488 save_address = sp + PROC_REG_OFFSET(proc_desc);
489 for (ireg = 32; --ireg >= 0; )
490 if (PROC_REG_MASK(proc_desc) & (1 << ireg))
492 buffer = read_register (ireg);
493 write_memory (save_address, (char *)&buffer, sizeof(REGISTER_TYPE));
496 /* save floating-points registers */
497 save_address = sp + PROC_FREG_OFFSET(proc_desc);
498 for (ireg = 32; --ireg >= 0; )
499 if (PROC_FREG_MASK(proc_desc) & (1 << ireg))
501 buffer = read_register (ireg + FP0_REGNUM);
502 write_memory (save_address, (char *)&buffer, 4);
505 write_register (PUSH_FP_REGNUM, sp);
506 PROC_FRAME_REG(proc_desc) = PUSH_FP_REGNUM;
507 PROC_FRAME_OFFSET(proc_desc) = 0;
508 buffer = read_register (PC_REGNUM);
509 write_memory (sp - 4, (char *)&buffer, sizeof(REGISTER_TYPE));
510 buffer = read_register (HI_REGNUM);
511 write_memory (sp - 8, (char *)&buffer, sizeof(REGISTER_TYPE));
512 buffer = read_register (LO_REGNUM);
513 write_memory (sp - 12, (char *)&buffer, sizeof(REGISTER_TYPE));
514 buffer = read_register (mips_fpu ? FCRCS_REGNUM : ZERO_REGNUM);
515 write_memory (sp - 16, (char *)&buffer, sizeof(REGISTER_TYPE));
516 sp -= 4 * (GEN_REG_SAVE_COUNT
517 + (mips_fpu ? FLOAT_REG_SAVE_COUNT : 0)
518 + SPECIAL_REG_SAVE_COUNT);
519 write_register (SP_REGNUM, sp);
520 PROC_LOW_ADDR(proc_desc) = sp - CALL_DUMMY_SIZE + CALL_DUMMY_START_OFFSET;
521 PROC_HIGH_ADDR(proc_desc) = sp;
522 SET_PROC_DESC_IS_DUMMY(proc_desc);
523 PROC_PC_REG(proc_desc) = RA_REGNUM;
530 FRAME frame = get_current_frame ();
531 CORE_ADDR new_sp = frame->frame;
533 mips_extra_func_info_t proc_desc = frame->proc_desc;
535 write_register (PC_REGNUM, FRAME_SAVED_PC(frame));
538 for (regnum = 32; --regnum >= 0; )
539 if (PROC_REG_MASK(proc_desc) & (1 << regnum))
540 write_register (regnum,
541 read_memory_integer (frame->saved_regs->regs[regnum],
543 for (regnum = 32; --regnum >= 0; )
544 if (PROC_FREG_MASK(proc_desc) & (1 << regnum))
545 write_register (regnum + FP0_REGNUM,
546 read_memory_integer (frame->saved_regs->regs[regnum + FP0_REGNUM], 4));
548 write_register (SP_REGNUM, new_sp);
549 flush_cached_frames ();
550 /* We let mips_init_extra_frame_info figure out the frame pointer */
551 set_current_frame (create_new_frame (0, read_pc ()));
553 if (PROC_DESC_IS_DUMMY(proc_desc))
555 struct linked_proc_info *pi_ptr, *prev_ptr;
557 for (pi_ptr = linked_proc_desc_table, prev_ptr = NULL;
559 prev_ptr = pi_ptr, pi_ptr = pi_ptr->next)
561 if (&pi_ptr->info == proc_desc)
566 error ("Can't locate dummy extra frame info\n");
568 if (prev_ptr != NULL)
569 prev_ptr->next = pi_ptr->next;
571 linked_proc_desc_table = pi_ptr->next;
575 write_register (HI_REGNUM, read_memory_integer(new_sp - 8, 4));
576 write_register (LO_REGNUM, read_memory_integer(new_sp - 12, 4));
578 write_register (FCRCS_REGNUM, read_memory_integer(new_sp - 16, 4));
583 mips_print_register (regnum, all)
586 unsigned char raw_buffer[MAX_REGISTER_RAW_SIZE * 2]; /* *2 for doubles */
589 /* Get the data in raw format. */
590 if (read_relative_register_raw_bytes (regnum, raw_buffer))
592 printf_filtered ("%s: [Invalid]", reg_names[regnum]);
596 /* If an even floating pointer register, also print as double. */
597 if (regnum >= FP0_REGNUM && regnum < FP0_REGNUM+32
598 && !((regnum-FP0_REGNUM) & 1)) {
599 read_relative_register_raw_bytes (regnum+1, raw_buffer+4);
600 printf_filtered ("(d%d: ", regnum-FP0_REGNUM);
601 val_print (builtin_type_double, raw_buffer, 0,
602 stdout, 0, 1, 0, Val_pretty_default);
603 printf_filtered ("); ");
605 fputs_filtered (reg_names[regnum], stdout);
606 #ifndef NUMERIC_REG_NAMES
608 printf_filtered ("(r%d): ", regnum);
611 printf_filtered (": ");
613 /* If virtual format is floating, print it that way. */
614 if (TYPE_CODE (REGISTER_VIRTUAL_TYPE (regnum)) == TYPE_CODE_FLT
615 && ! INVALID_FLOAT (raw_buffer, REGISTER_VIRTUAL_SIZE(regnum))) {
616 val_print (REGISTER_VIRTUAL_TYPE (regnum), raw_buffer, 0,
617 stdout, 0, 1, 0, Val_pretty_default);
619 /* Else print as integer in hex. */
624 bcopy (raw_buffer, &val, sizeof (long));
625 SWAP_TARGET_AND_HOST ((char *)&val, sizeof (long));
627 printf_filtered ("0");
629 printf_filtered (local_hex_format(), val);
631 printf_filtered ("%s=%d", local_hex_string(val), val);
635 /* Replacement for generic do_registers_info. */
637 mips_do_registers_info (regnum, fpregs)
642 mips_print_register (regnum, 0);
643 printf_filtered ("\n");
646 for (regnum = 0; regnum < NUM_REGS; ) {
647 if ((!fpregs) && regnum >= FP0_REGNUM && regnum <= FCRIR_REGNUM) {
651 mips_print_register (regnum, 1);
653 if ((regnum & 3) == 0 || regnum == NUM_REGS)
654 printf_filtered (";\n");
656 printf_filtered ("; ");
660 /* Return number of args passed to a frame. described by FIP.
661 Can return -1, meaning no way to tell. */
664 mips_frame_num_args(fip)
668 struct chain_info_t *p;
670 p = mips_find_cached_frame(FRAME_FP(fip));
672 return p->the_info.numargs;
678 /* Bad floats: Returns 0 if P points to a valid IEEE floating point number,
679 1 if P points to a denormalized number or a NaN. LEN says whether this is
680 a single-precision or double-precision float */
681 #define SINGLE_EXP_BITS 8
682 #define DOUBLE_EXP_BITS 11
691 exponent = exponent << 1 >> (32 - SINGLE_EXP_BITS - 1);
692 return ((exponent == -1) || (! exponent && *p));
696 #if TARGET_BYTE_ORDER == BIG_ENDIAN
701 exponent = exponent << 1 >> (32 - DOUBLE_EXP_BITS - 1);
702 return ((exponent == -1) || (! exponent && *p * *(p+1)));
707 /* To skip prologues, I use this predicate. Returns either PC
708 itself if the code at PC does not look like a function prologue,
709 PC+4 if it does (our caller does not need anything more fancy). */
712 mips_skip_prologue(pc)
720 /* For -g modules and most functions anyways the
721 first instruction adjusts the stack.
722 But we allow some number of stores before the stack adjustment.
723 (These are emitted by varags functions compiled by gcc-2.0. */
724 for (offset = 0; offset < 100; offset += 4) {
725 inst = read_memory_integer(pc + offset, 4);
726 if ((inst & 0xffff0000) == 0x27bd0000) /* addiu $sp,$sp,offset */
727 return pc + offset + 4;
728 if ((inst & 0xFFE00000) != 0xAFA00000) /* sw reg,n($sp) */
732 /* Well, it looks like a frameless. Let's make sure.
733 Note that we are not called on the current PC,
734 but on the function`s start PC, and I have definitely
735 seen optimized code that adjusts the SP quite later */
736 b = block_for_pc(pc);
739 f = lookup_symbol(MIPS_EFI_SYMBOL_NAME, b, LABEL_NAMESPACE, 0, NULL);
741 /* Ideally, I would like to use the adjusted info
742 from mips_frame_info(), but for all practical
743 purposes it will not matter (and it would require
744 a different definition of SKIP_PROLOGUE())
746 Actually, it would not hurt to skip the storing
747 of arguments on the stack as well. */
748 if (((mips_extra_func_info_t)SYMBOL_VALUE(f))->pdr.frameoffset)
754 /* Let the user turn off floating point. */
757 _initialize_mips_tdep ()
760 (add_set_cmd ("mips_fpu", class_support, var_boolean,
762 "Set use of floating point coprocessor.\n\
763 Turn off to avoid using floating point instructions when calling functions\n\
764 or dealing with return values.", &setlist),