xref: /dragonfly/contrib/gdb-7/gdb/i387-tdep.c (revision c3762235)
1 /* Intel 387 floating point stuff.
2 
3    Copyright (C) 1988-2013 Free Software Foundation, Inc.
4 
5    This file is part of GDB.
6 
7    This program is free software; you can redistribute it and/or modify
8    it under the terms of the GNU General Public License as published by
9    the Free Software Foundation; either version 3 of the License, or
10    (at your option) any later version.
11 
12    This program is distributed in the hope that it will be useful,
13    but WITHOUT ANY WARRANTY; without even the implied warranty of
14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15    GNU General Public License for more details.
16 
17    You should have received a copy of the GNU General Public License
18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
19 
20 #include "defs.h"
21 #include "doublest.h"
22 #include "floatformat.h"
23 #include "frame.h"
24 #include "gdbcore.h"
25 #include "inferior.h"
26 #include "language.h"
27 #include "regcache.h"
28 #include "value.h"
29 
30 #include "gdb_assert.h"
31 #include "gdb_string.h"
32 
33 #include "i386-tdep.h"
34 #include "i387-tdep.h"
35 #include "i386-xstate.h"
36 
37 /* Print the floating point number specified by RAW.  */
38 
39 static void
40 print_i387_value (struct gdbarch *gdbarch,
41 		  const gdb_byte *raw, struct ui_file *file)
42 {
43   DOUBLEST value;
44 
45   /* Using extract_typed_floating here might affect the representation
46      of certain numbers such as NaNs, even if GDB is running natively.
47      This is fine since our caller already detects such special
48      numbers and we print the hexadecimal representation anyway.  */
49   value = extract_typed_floating (raw, i387_ext_type (gdbarch));
50 
51   /* We try to print 19 digits.  The last digit may or may not contain
52      garbage, but we'd better print one too many.  We need enough room
53      to print the value, 1 position for the sign, 1 for the decimal
54      point, 19 for the digits and 6 for the exponent adds up to 27.  */
55 #ifdef PRINTF_HAS_LONG_DOUBLE
56   fprintf_filtered (file, " %-+27.19Lg", (long double) value);
57 #else
58   fprintf_filtered (file, " %-+27.19g", (double) value);
59 #endif
60 }
61 
62 /* Print the classification for the register contents RAW.  */
63 
64 static void
65 print_i387_ext (struct gdbarch *gdbarch,
66 		const gdb_byte *raw, struct ui_file *file)
67 {
68   int sign;
69   int integer;
70   unsigned int exponent;
71   unsigned long fraction[2];
72 
73   sign = raw[9] & 0x80;
74   integer = raw[7] & 0x80;
75   exponent = (((raw[9] & 0x7f) << 8) | raw[8]);
76   fraction[0] = ((raw[3] << 24) | (raw[2] << 16) | (raw[1] << 8) | raw[0]);
77   fraction[1] = (((raw[7] & 0x7f) << 24) | (raw[6] << 16)
78 		 | (raw[5] << 8) | raw[4]);
79 
80   if (exponent == 0x7fff && integer)
81     {
82       if (fraction[0] == 0x00000000 && fraction[1] == 0x00000000)
83 	/* Infinity.  */
84 	fprintf_filtered (file, " %cInf", (sign ? '-' : '+'));
85       else if (sign && fraction[0] == 0x00000000 && fraction[1] == 0x40000000)
86 	/* Real Indefinite (QNaN).  */
87 	fputs_unfiltered (" Real Indefinite (QNaN)", file);
88       else if (fraction[1] & 0x40000000)
89 	/* QNaN.  */
90 	fputs_filtered (" QNaN", file);
91       else
92 	/* SNaN.  */
93 	fputs_filtered (" SNaN", file);
94     }
95   else if (exponent < 0x7fff && exponent > 0x0000 && integer)
96     /* Normal.  */
97     print_i387_value (gdbarch, raw, file);
98   else if (exponent == 0x0000)
99     {
100       /* Denormal or zero.  */
101       print_i387_value (gdbarch, raw, file);
102 
103       if (integer)
104 	/* Pseudo-denormal.  */
105 	fputs_filtered (" Pseudo-denormal", file);
106       else if (fraction[0] || fraction[1])
107 	/* Denormal.  */
108 	fputs_filtered (" Denormal", file);
109     }
110   else
111     /* Unsupported.  */
112     fputs_filtered (" Unsupported", file);
113 }
114 
115 /* Print the status word STATUS.  If STATUS_P is false, then STATUS
116    was unavailable.  */
117 
118 static void
119 print_i387_status_word (int status_p,
120 			unsigned int status, struct ui_file *file)
121 {
122   fprintf_filtered (file, "Status Word:         ");
123   if (!status_p)
124     {
125       fprintf_filtered (file, "%s\n", _("<unavailable>"));
126       return;
127     }
128 
129   fprintf_filtered (file, "%s", hex_string_custom (status, 4));
130   fputs_filtered ("  ", file);
131   fprintf_filtered (file, " %s", (status & 0x0001) ? "IE" : "  ");
132   fprintf_filtered (file, " %s", (status & 0x0002) ? "DE" : "  ");
133   fprintf_filtered (file, " %s", (status & 0x0004) ? "ZE" : "  ");
134   fprintf_filtered (file, " %s", (status & 0x0008) ? "OE" : "  ");
135   fprintf_filtered (file, " %s", (status & 0x0010) ? "UE" : "  ");
136   fprintf_filtered (file, " %s", (status & 0x0020) ? "PE" : "  ");
137   fputs_filtered ("  ", file);
138   fprintf_filtered (file, " %s", (status & 0x0080) ? "ES" : "  ");
139   fputs_filtered ("  ", file);
140   fprintf_filtered (file, " %s", (status & 0x0040) ? "SF" : "  ");
141   fputs_filtered ("  ", file);
142   fprintf_filtered (file, " %s", (status & 0x0100) ? "C0" : "  ");
143   fprintf_filtered (file, " %s", (status & 0x0200) ? "C1" : "  ");
144   fprintf_filtered (file, " %s", (status & 0x0400) ? "C2" : "  ");
145   fprintf_filtered (file, " %s", (status & 0x4000) ? "C3" : "  ");
146 
147   fputs_filtered ("\n", file);
148 
149   fprintf_filtered (file,
150 		    "                       TOP: %d\n", ((status >> 11) & 7));
151 }
152 
153 /* Print the control word CONTROL.  If CONTROL_P is false, then
154    CONTROL was unavailable.  */
155 
156 static void
157 print_i387_control_word (int control_p,
158 			 unsigned int control, struct ui_file *file)
159 {
160   fprintf_filtered (file, "Control Word:        ");
161   if (!control_p)
162     {
163       fprintf_filtered (file, "%s\n", _("<unavailable>"));
164       return;
165     }
166 
167   fprintf_filtered (file, "%s", hex_string_custom (control, 4));
168   fputs_filtered ("  ", file);
169   fprintf_filtered (file, " %s", (control & 0x0001) ? "IM" : "  ");
170   fprintf_filtered (file, " %s", (control & 0x0002) ? "DM" : "  ");
171   fprintf_filtered (file, " %s", (control & 0x0004) ? "ZM" : "  ");
172   fprintf_filtered (file, " %s", (control & 0x0008) ? "OM" : "  ");
173   fprintf_filtered (file, " %s", (control & 0x0010) ? "UM" : "  ");
174   fprintf_filtered (file, " %s", (control & 0x0020) ? "PM" : "  ");
175 
176   fputs_filtered ("\n", file);
177 
178   fputs_filtered ("                       PC: ", file);
179   switch ((control >> 8) & 3)
180     {
181     case 0:
182       fputs_filtered ("Single Precision (24-bits)\n", file);
183       break;
184     case 1:
185       fputs_filtered ("Reserved\n", file);
186       break;
187     case 2:
188       fputs_filtered ("Double Precision (53-bits)\n", file);
189       break;
190     case 3:
191       fputs_filtered ("Extended Precision (64-bits)\n", file);
192       break;
193     }
194 
195   fputs_filtered ("                       RC: ", file);
196   switch ((control >> 10) & 3)
197     {
198     case 0:
199       fputs_filtered ("Round to nearest\n", file);
200       break;
201     case 1:
202       fputs_filtered ("Round down\n", file);
203       break;
204     case 2:
205       fputs_filtered ("Round up\n", file);
206       break;
207     case 3:
208       fputs_filtered ("Round toward zero\n", file);
209       break;
210     }
211 }
212 
213 /* Print out the i387 floating point state.  Note that we ignore FRAME
214    in the code below.  That's OK since floating-point registers are
215    never saved on the stack.  */
216 
217 void
218 i387_print_float_info (struct gdbarch *gdbarch, struct ui_file *file,
219 		       struct frame_info *frame, const char *args)
220 {
221   struct gdbarch_tdep *tdep = gdbarch_tdep (get_frame_arch (frame));
222   ULONGEST fctrl;
223   int fctrl_p;
224   ULONGEST fstat;
225   int fstat_p;
226   ULONGEST ftag;
227   int ftag_p;
228   ULONGEST fiseg;
229   int fiseg_p;
230   ULONGEST fioff;
231   int fioff_p;
232   ULONGEST foseg;
233   int foseg_p;
234   ULONGEST fooff;
235   int fooff_p;
236   ULONGEST fop;
237   int fop_p;
238   int fpreg;
239   int top;
240 
241   gdb_assert (gdbarch == get_frame_arch (frame));
242 
243   fctrl_p = read_frame_register_unsigned (frame,
244 					  I387_FCTRL_REGNUM (tdep), &fctrl);
245   fstat_p = read_frame_register_unsigned (frame,
246 					  I387_FSTAT_REGNUM (tdep), &fstat);
247   ftag_p = read_frame_register_unsigned (frame,
248 					 I387_FTAG_REGNUM (tdep), &ftag);
249   fiseg_p = read_frame_register_unsigned (frame,
250 					  I387_FISEG_REGNUM (tdep), &fiseg);
251   fioff_p = read_frame_register_unsigned (frame,
252 					  I387_FIOFF_REGNUM (tdep), &fioff);
253   foseg_p = read_frame_register_unsigned (frame,
254 					  I387_FOSEG_REGNUM (tdep), &foseg);
255   fooff_p = read_frame_register_unsigned (frame,
256 					  I387_FOOFF_REGNUM (tdep), &fooff);
257   fop_p = read_frame_register_unsigned (frame,
258 					I387_FOP_REGNUM (tdep), &fop);
259 
260   if (fstat_p)
261     {
262       top = ((fstat >> 11) & 7);
263 
264       for (fpreg = 7; fpreg >= 0; fpreg--)
265 	{
266 	  struct value *regval;
267 	  int regnum;
268 	  int i;
269 	  int tag = -1;
270 
271 	  fprintf_filtered (file, "%sR%d: ", fpreg == top ? "=>" : "  ", fpreg);
272 
273 	  if (ftag_p)
274 	    {
275 	      tag = (ftag >> (fpreg * 2)) & 3;
276 
277 	      switch (tag)
278 		{
279 		case 0:
280 		  fputs_filtered ("Valid   ", file);
281 		  break;
282 		case 1:
283 		  fputs_filtered ("Zero    ", file);
284 		  break;
285 		case 2:
286 		  fputs_filtered ("Special ", file);
287 		  break;
288 		case 3:
289 		  fputs_filtered ("Empty   ", file);
290 		  break;
291 		}
292 	    }
293 	  else
294 	    fputs_filtered ("Unknown ", file);
295 
296 	  regnum = (fpreg + 8 - top) % 8 + I387_ST0_REGNUM (tdep);
297 	  regval = get_frame_register_value (frame, regnum);
298 
299 	  if (value_entirely_available (regval))
300 	    {
301 	      const gdb_byte *raw = value_contents (regval);
302 
303 	      fputs_filtered ("0x", file);
304 	      for (i = 9; i >= 0; i--)
305 		fprintf_filtered (file, "%02x", raw[i]);
306 
307 	      if (tag != -1 && tag != 3)
308 		print_i387_ext (gdbarch, raw, file);
309 	    }
310 	  else
311 	    fprintf_filtered (file, "%s", _("<unavailable>"));
312 
313 	  fputs_filtered ("\n", file);
314 	}
315     }
316 
317   fputs_filtered ("\n", file);
318   print_i387_status_word (fstat_p, fstat, file);
319   print_i387_control_word (fctrl_p, fctrl, file);
320   fprintf_filtered (file, "Tag Word:            %s\n",
321 		    ftag_p ? hex_string_custom (ftag, 4) : _("<unavailable>"));
322   fprintf_filtered (file, "Instruction Pointer: %s:",
323 		    fiseg_p ? hex_string_custom (fiseg, 2) : _("<unavailable>"));
324   fprintf_filtered (file, "%s\n",
325 		    fioff_p ? hex_string_custom (fioff, 8) : _("<unavailable>"));
326   fprintf_filtered (file, "Operand Pointer:     %s:",
327 		    foseg_p ? hex_string_custom (foseg, 2) : _("<unavailable>"));
328   fprintf_filtered (file, "%s\n",
329 		    fooff_p ? hex_string_custom (fooff, 8) : _("<unavailable>"));
330   fprintf_filtered (file, "Opcode:              %s\n",
331 		    fop_p
332 		    ? (hex_string_custom (fop ? (fop | 0xd800) : 0, 4))
333 		    : _("<unavailable>"));
334 }
335 
336 
337 /* Return nonzero if a value of type TYPE stored in register REGNUM
338    needs any special handling.  */
339 
340 int
341 i387_convert_register_p (struct gdbarch *gdbarch, int regnum,
342 			 struct type *type)
343 {
344   if (i386_fp_regnum_p (gdbarch, regnum))
345     {
346       /* Floating point registers must be converted unless we are
347 	 accessing them in their hardware type.  */
348       if (type == i387_ext_type (gdbarch))
349 	return 0;
350       else
351 	return 1;
352     }
353 
354   return 0;
355 }
356 
357 /* Read a value of type TYPE from register REGNUM in frame FRAME, and
358    return its contents in TO.  */
359 
360 int
361 i387_register_to_value (struct frame_info *frame, int regnum,
362 			struct type *type, gdb_byte *to,
363 			int *optimizedp, int *unavailablep)
364 {
365   struct gdbarch *gdbarch = get_frame_arch (frame);
366   gdb_byte from[I386_MAX_REGISTER_SIZE];
367 
368   gdb_assert (i386_fp_regnum_p (gdbarch, regnum));
369 
370   /* We only support floating-point values.  */
371   if (TYPE_CODE (type) != TYPE_CODE_FLT)
372     {
373       warning (_("Cannot convert floating-point register value "
374 	       "to non-floating-point type."));
375       *optimizedp = *unavailablep = 0;
376       return 0;
377     }
378 
379   /* Convert to TYPE.  */
380   if (!get_frame_register_bytes (frame, regnum, 0, TYPE_LENGTH (type),
381 				 from, optimizedp, unavailablep))
382     return 0;
383 
384   convert_typed_floating (from, i387_ext_type (gdbarch), to, type);
385   *optimizedp = *unavailablep = 0;
386   return 1;
387 }
388 
389 /* Write the contents FROM of a value of type TYPE into register
390    REGNUM in frame FRAME.  */
391 
392 void
393 i387_value_to_register (struct frame_info *frame, int regnum,
394 			struct type *type, const gdb_byte *from)
395 {
396   struct gdbarch *gdbarch = get_frame_arch (frame);
397   gdb_byte to[I386_MAX_REGISTER_SIZE];
398 
399   gdb_assert (i386_fp_regnum_p (gdbarch, regnum));
400 
401   /* We only support floating-point values.  */
402   if (TYPE_CODE (type) != TYPE_CODE_FLT)
403     {
404       warning (_("Cannot convert non-floating-point type "
405 	       "to floating-point register value."));
406       return;
407     }
408 
409   /* Convert from TYPE.  */
410   convert_typed_floating (from, type, to, i387_ext_type (gdbarch));
411   put_frame_register (frame, regnum, to);
412 }
413 
414 
415 /* Handle FSAVE and FXSAVE formats.  */
416 
417 /* At fsave_offset[REGNUM] you'll find the offset to the location in
418    the data structure used by the "fsave" instruction where GDB
419    register REGNUM is stored.  */
420 
421 static int fsave_offset[] =
422 {
423   28 + 0 * 10,			/* %st(0) ...  */
424   28 + 1 * 10,
425   28 + 2 * 10,
426   28 + 3 * 10,
427   28 + 4 * 10,
428   28 + 5 * 10,
429   28 + 6 * 10,
430   28 + 7 * 10,			/* ... %st(7).  */
431   0,				/* `fctrl' (16 bits).  */
432   4,				/* `fstat' (16 bits).  */
433   8,				/* `ftag' (16 bits).  */
434   16,				/* `fiseg' (16 bits).  */
435   12,				/* `fioff'.  */
436   24,				/* `foseg' (16 bits).  */
437   20,				/* `fooff'.  */
438   18				/* `fop' (bottom 11 bits).  */
439 };
440 
441 #define FSAVE_ADDR(tdep, fsave, regnum) \
442   (fsave + fsave_offset[regnum - I387_ST0_REGNUM (tdep)])
443 
444 
445 /* Fill register REGNUM in REGCACHE with the appropriate value from
446    *FSAVE.  This function masks off any of the reserved bits in
447    *FSAVE.  */
448 
449 void
450 i387_supply_fsave (struct regcache *regcache, int regnum, const void *fsave)
451 {
452   struct gdbarch *gdbarch = get_regcache_arch (regcache);
453   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
454   enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
455   const gdb_byte *regs = fsave;
456   int i;
457 
458   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
459 
460   for (i = I387_ST0_REGNUM (tdep); i < I387_XMM0_REGNUM (tdep); i++)
461     if (regnum == -1 || regnum == i)
462       {
463 	if (fsave == NULL)
464 	  {
465 	    regcache_raw_supply (regcache, i, NULL);
466 	    continue;
467 	  }
468 
469 	/* Most of the FPU control registers occupy only 16 bits in the
470 	   fsave area.  Give those a special treatment.  */
471 	if (i >= I387_FCTRL_REGNUM (tdep)
472 	    && i != I387_FIOFF_REGNUM (tdep) && i != I387_FOOFF_REGNUM (tdep))
473 	  {
474 	    gdb_byte val[4];
475 
476 	    memcpy (val, FSAVE_ADDR (tdep, regs, i), 2);
477 	    val[2] = val[3] = 0;
478 	    if (i == I387_FOP_REGNUM (tdep))
479 	      val[1] &= ((1 << 3) - 1);
480 	    regcache_raw_supply (regcache, i, val);
481 	  }
482 	else
483 	  regcache_raw_supply (regcache, i, FSAVE_ADDR (tdep, regs, i));
484       }
485 
486   /* Provide dummy values for the SSE registers.  */
487   for (i = I387_XMM0_REGNUM (tdep); i < I387_MXCSR_REGNUM (tdep); i++)
488     if (regnum == -1 || regnum == i)
489       regcache_raw_supply (regcache, i, NULL);
490   if (regnum == -1 || regnum == I387_MXCSR_REGNUM (tdep))
491     {
492       gdb_byte buf[4];
493 
494       store_unsigned_integer (buf, 4, byte_order, 0x1f80);
495       regcache_raw_supply (regcache, I387_MXCSR_REGNUM (tdep), buf);
496     }
497 }
498 
499 /* Fill register REGNUM (if it is a floating-point register) in *FSAVE
500    with the value from REGCACHE.  If REGNUM is -1, do this for all
501    registers.  This function doesn't touch any of the reserved bits in
502    *FSAVE.  */
503 
504 void
505 i387_collect_fsave (const struct regcache *regcache, int regnum, void *fsave)
506 {
507   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
508   gdb_byte *regs = fsave;
509   int i;
510 
511   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
512 
513   for (i = I387_ST0_REGNUM (tdep); i < I387_XMM0_REGNUM (tdep); i++)
514     if (regnum == -1 || regnum == i)
515       {
516 	/* Most of the FPU control registers occupy only 16 bits in
517            the fsave area.  Give those a special treatment.  */
518 	if (i >= I387_FCTRL_REGNUM (tdep)
519 	    && i != I387_FIOFF_REGNUM (tdep) && i != I387_FOOFF_REGNUM (tdep))
520 	  {
521 	    gdb_byte buf[4];
522 
523 	    regcache_raw_collect (regcache, i, buf);
524 
525 	    if (i == I387_FOP_REGNUM (tdep))
526 	      {
527 		/* The opcode occupies only 11 bits.  Make sure we
528                    don't touch the other bits.  */
529 		buf[1] &= ((1 << 3) - 1);
530 		buf[1] |= ((FSAVE_ADDR (tdep, regs, i))[1] & ~((1 << 3) - 1));
531 	      }
532 	    memcpy (FSAVE_ADDR (tdep, regs, i), buf, 2);
533 	  }
534 	else
535 	  regcache_raw_collect (regcache, i, FSAVE_ADDR (tdep, regs, i));
536       }
537 }
538 
539 
540 /* At fxsave_offset[REGNUM] you'll find the offset to the location in
541    the data structure used by the "fxsave" instruction where GDB
542    register REGNUM is stored.  */
543 
544 static int fxsave_offset[] =
545 {
546   32,				/* %st(0) through ...  */
547   48,
548   64,
549   80,
550   96,
551   112,
552   128,
553   144,				/* ... %st(7) (80 bits each).  */
554   0,				/* `fctrl' (16 bits).  */
555   2,				/* `fstat' (16 bits).  */
556   4,				/* `ftag' (16 bits).  */
557   12,				/* `fiseg' (16 bits).  */
558   8,				/* `fioff'.  */
559   20,				/* `foseg' (16 bits).  */
560   16,				/* `fooff'.  */
561   6,				/* `fop' (bottom 11 bits).  */
562   160 + 0 * 16,			/* %xmm0 through ...  */
563   160 + 1 * 16,
564   160 + 2 * 16,
565   160 + 3 * 16,
566   160 + 4 * 16,
567   160 + 5 * 16,
568   160 + 6 * 16,
569   160 + 7 * 16,
570   160 + 8 * 16,
571   160 + 9 * 16,
572   160 + 10 * 16,
573   160 + 11 * 16,
574   160 + 12 * 16,
575   160 + 13 * 16,
576   160 + 14 * 16,
577   160 + 15 * 16,		/* ... %xmm15 (128 bits each).  */
578 };
579 
580 #define FXSAVE_ADDR(tdep, fxsave, regnum) \
581   (fxsave + fxsave_offset[regnum - I387_ST0_REGNUM (tdep)])
582 
583 /* We made an unfortunate choice in putting %mxcsr after the SSE
584    registers %xmm0-%xmm7 instead of before, since it makes supporting
585    the registers %xmm8-%xmm15 on AMD64 a bit involved.  Therefore we
586    don't include the offset for %mxcsr here above.  */
587 
588 #define FXSAVE_MXCSR_ADDR(fxsave) (fxsave + 24)
589 
590 static int i387_tag (const gdb_byte *raw);
591 
592 
593 /* Fill register REGNUM in REGCACHE with the appropriate
594    floating-point or SSE register value from *FXSAVE.  This function
595    masks off any of the reserved bits in *FXSAVE.  */
596 
597 void
598 i387_supply_fxsave (struct regcache *regcache, int regnum, const void *fxsave)
599 {
600   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
601   const gdb_byte *regs = fxsave;
602   int i;
603 
604   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
605   gdb_assert (tdep->num_xmm_regs > 0);
606 
607   for (i = I387_ST0_REGNUM (tdep); i < I387_MXCSR_REGNUM (tdep); i++)
608     if (regnum == -1 || regnum == i)
609       {
610 	if (regs == NULL)
611 	  {
612 	    regcache_raw_supply (regcache, i, NULL);
613 	    continue;
614 	  }
615 
616 	/* Most of the FPU control registers occupy only 16 bits in
617 	   the fxsave area.  Give those a special treatment.  */
618 	if (i >= I387_FCTRL_REGNUM (tdep) && i < I387_XMM0_REGNUM (tdep)
619 	    && i != I387_FIOFF_REGNUM (tdep) && i != I387_FOOFF_REGNUM (tdep))
620 	  {
621 	    gdb_byte val[4];
622 
623 	    memcpy (val, FXSAVE_ADDR (tdep, regs, i), 2);
624 	    val[2] = val[3] = 0;
625 	    if (i == I387_FOP_REGNUM (tdep))
626 	      val[1] &= ((1 << 3) - 1);
627 	    else if (i== I387_FTAG_REGNUM (tdep))
628 	      {
629 		/* The fxsave area contains a simplified version of
630 		   the tag word.  We have to look at the actual 80-bit
631 		   FP data to recreate the traditional i387 tag word.  */
632 
633 		unsigned long ftag = 0;
634 		int fpreg;
635 		int top;
636 
637 		top = ((FXSAVE_ADDR (tdep, regs,
638 				     I387_FSTAT_REGNUM (tdep)))[1] >> 3);
639 		top &= 0x7;
640 
641 		for (fpreg = 7; fpreg >= 0; fpreg--)
642 		  {
643 		    int tag;
644 
645 		    if (val[0] & (1 << fpreg))
646 		      {
647 			int thisreg = (fpreg + 8 - top) % 8
648 			               + I387_ST0_REGNUM (tdep);
649 			tag = i387_tag (FXSAVE_ADDR (tdep, regs, thisreg));
650 		      }
651 		    else
652 		      tag = 3;		/* Empty */
653 
654 		    ftag |= tag << (2 * fpreg);
655 		  }
656 		val[0] = ftag & 0xff;
657 		val[1] = (ftag >> 8) & 0xff;
658 	      }
659 	    regcache_raw_supply (regcache, i, val);
660 	  }
661 	else
662 	  regcache_raw_supply (regcache, i, FXSAVE_ADDR (tdep, regs, i));
663       }
664 
665   if (regnum == I387_MXCSR_REGNUM (tdep) || regnum == -1)
666     {
667       if (regs == NULL)
668 	regcache_raw_supply (regcache, I387_MXCSR_REGNUM (tdep), NULL);
669       else
670 	regcache_raw_supply (regcache, I387_MXCSR_REGNUM (tdep),
671 			     FXSAVE_MXCSR_ADDR (regs));
672     }
673 }
674 
675 /* Fill register REGNUM (if it is a floating-point or SSE register) in
676    *FXSAVE with the value from REGCACHE.  If REGNUM is -1, do this for
677    all registers.  This function doesn't touch any of the reserved
678    bits in *FXSAVE.  */
679 
680 void
681 i387_collect_fxsave (const struct regcache *regcache, int regnum, void *fxsave)
682 {
683   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
684   gdb_byte *regs = fxsave;
685   int i;
686 
687   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
688   gdb_assert (tdep->num_xmm_regs > 0);
689 
690   for (i = I387_ST0_REGNUM (tdep); i < I387_MXCSR_REGNUM (tdep); i++)
691     if (regnum == -1 || regnum == i)
692       {
693 	/* Most of the FPU control registers occupy only 16 bits in
694            the fxsave area.  Give those a special treatment.  */
695 	if (i >= I387_FCTRL_REGNUM (tdep) && i < I387_XMM0_REGNUM (tdep)
696 	    && i != I387_FIOFF_REGNUM (tdep) && i != I387_FOOFF_REGNUM (tdep))
697 	  {
698 	    gdb_byte buf[4];
699 
700 	    regcache_raw_collect (regcache, i, buf);
701 
702 	    if (i == I387_FOP_REGNUM (tdep))
703 	      {
704 		/* The opcode occupies only 11 bits.  Make sure we
705                    don't touch the other bits.  */
706 		buf[1] &= ((1 << 3) - 1);
707 		buf[1] |= ((FXSAVE_ADDR (tdep, regs, i))[1] & ~((1 << 3) - 1));
708 	      }
709 	    else if (i == I387_FTAG_REGNUM (tdep))
710 	      {
711 		/* Converting back is much easier.  */
712 
713 		unsigned short ftag;
714 		int fpreg;
715 
716 		ftag = (buf[1] << 8) | buf[0];
717 		buf[0] = 0;
718 		buf[1] = 0;
719 
720 		for (fpreg = 7; fpreg >= 0; fpreg--)
721 		  {
722 		    int tag = (ftag >> (fpreg * 2)) & 3;
723 
724 		    if (tag != 3)
725 		      buf[0] |= (1 << fpreg);
726 		  }
727 	      }
728 	    memcpy (FXSAVE_ADDR (tdep, regs, i), buf, 2);
729 	  }
730 	else
731 	  regcache_raw_collect (regcache, i, FXSAVE_ADDR (tdep, regs, i));
732       }
733 
734   if (regnum == I387_MXCSR_REGNUM (tdep) || regnum == -1)
735     regcache_raw_collect (regcache, I387_MXCSR_REGNUM (tdep),
736 			  FXSAVE_MXCSR_ADDR (regs));
737 }
738 
739 /* `xstate_bv' is at byte offset 512.  */
740 #define XSAVE_XSTATE_BV_ADDR(xsave) (xsave + 512)
741 
742 /* At xsave_avxh_offset[REGNUM] you'll find the offset to the location in
743    the upper 128bit of AVX register data structure used by the "xsave"
744    instruction where GDB register REGNUM is stored.  */
745 
746 static int xsave_avxh_offset[] =
747 {
748   576 + 0 * 16,		/* Upper 128bit of %ymm0 through ...  */
749   576 + 1 * 16,
750   576 + 2 * 16,
751   576 + 3 * 16,
752   576 + 4 * 16,
753   576 + 5 * 16,
754   576 + 6 * 16,
755   576 + 7 * 16,
756   576 + 8 * 16,
757   576 + 9 * 16,
758   576 + 10 * 16,
759   576 + 11 * 16,
760   576 + 12 * 16,
761   576 + 13 * 16,
762   576 + 14 * 16,
763   576 + 15 * 16		/* Upper 128bit of ... %ymm15 (128 bits each).  */
764 };
765 
766 #define XSAVE_AVXH_ADDR(tdep, xsave, regnum) \
767   (xsave + xsave_avxh_offset[regnum - I387_YMM0H_REGNUM (tdep)])
768 
769 /* Similar to i387_supply_fxsave, but use XSAVE extended state.  */
770 
771 void
772 i387_supply_xsave (struct regcache *regcache, int regnum,
773 		   const void *xsave)
774 {
775   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
776   const gdb_byte *regs = xsave;
777   int i;
778   unsigned int clear_bv;
779   static const gdb_byte zero[MAX_REGISTER_SIZE] = { 0 };
780   enum
781     {
782       none = 0x0,
783       x87 = 0x1,
784       sse = 0x2,
785       avxh = 0x4,
786       all = x87 | sse | avxh
787     } regclass;
788 
789   gdb_assert (regs != NULL);
790   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
791   gdb_assert (tdep->num_xmm_regs > 0);
792 
793   if (regnum == -1)
794     regclass = all;
795   else if (regnum >= I387_YMM0H_REGNUM (tdep)
796 	   && regnum < I387_YMMENDH_REGNUM (tdep))
797     regclass = avxh;
798   else if (regnum >= I387_XMM0_REGNUM(tdep)
799 	   && regnum < I387_MXCSR_REGNUM (tdep))
800     regclass = sse;
801   else if (regnum >= I387_ST0_REGNUM (tdep)
802 	   && regnum < I387_FCTRL_REGNUM (tdep))
803     regclass = x87;
804   else
805     regclass = none;
806 
807   if (regclass != none)
808     {
809       /* Get `xstat_bv'.  */
810       const gdb_byte *xstate_bv_p = XSAVE_XSTATE_BV_ADDR (regs);
811 
812       /* The supported bits in `xstat_bv' are 1 byte.  Clear part in
813 	 vector registers if its bit in xstat_bv is zero.  */
814       clear_bv = (~(*xstate_bv_p)) & tdep->xcr0;
815     }
816   else
817     clear_bv = I386_XSTATE_AVX_MASK;
818 
819   /* With the delayed xsave mechanism, in between the program
820      starting, and the program accessing the vector registers for the
821      first time, the register's values are invalid.  The kernel
822      initializes register states to zero when they are set the first
823      time in a program.  This means that from the user-space programs'
824      perspective, it's the same as if the registers have always been
825      zero from the start of the program.  Therefore, the debugger
826      should provide the same illusion to the user.  */
827 
828   switch (regclass)
829     {
830     case none:
831       break;
832 
833     case avxh:
834       if ((clear_bv & I386_XSTATE_AVX))
835 	regcache_raw_supply (regcache, regnum, zero);
836       else
837 	regcache_raw_supply (regcache, regnum,
838 			     XSAVE_AVXH_ADDR (tdep, regs, regnum));
839       return;
840 
841     case sse:
842       if ((clear_bv & I386_XSTATE_SSE))
843 	regcache_raw_supply (regcache, regnum, zero);
844       else
845 	regcache_raw_supply (regcache, regnum,
846 			     FXSAVE_ADDR (tdep, regs, regnum));
847       return;
848 
849     case x87:
850       if ((clear_bv & I386_XSTATE_X87))
851 	regcache_raw_supply (regcache, regnum, zero);
852       else
853 	regcache_raw_supply (regcache, regnum,
854 			     FXSAVE_ADDR (tdep, regs, regnum));
855       return;
856 
857     case all:
858       /* Handle the upper YMM registers.  */
859       if ((tdep->xcr0 & I386_XSTATE_AVX))
860 	{
861 	  if ((clear_bv & I386_XSTATE_AVX))
862 	    {
863 	      for (i = I387_YMM0H_REGNUM (tdep);
864 		   i < I387_YMMENDH_REGNUM (tdep);
865 		   i++)
866 		regcache_raw_supply (regcache, i, zero);
867 	    }
868 	  else
869 	    {
870 	      for (i = I387_YMM0H_REGNUM (tdep);
871 		   i < I387_YMMENDH_REGNUM (tdep);
872 		   i++)
873 		regcache_raw_supply (regcache, i,
874 				     XSAVE_AVXH_ADDR (tdep, regs, i));
875 	    }
876 	}
877 
878       /* Handle the XMM registers.  */
879       if ((tdep->xcr0 & I386_XSTATE_SSE))
880 	{
881 	  if ((clear_bv & I386_XSTATE_SSE))
882 	    {
883 	      for (i = I387_XMM0_REGNUM (tdep);
884 		   i < I387_MXCSR_REGNUM (tdep);
885 		   i++)
886 		regcache_raw_supply (regcache, i, zero);
887 	    }
888 	  else
889 	    {
890 	      for (i = I387_XMM0_REGNUM (tdep);
891 		   i < I387_MXCSR_REGNUM (tdep); i++)
892 		regcache_raw_supply (regcache, i,
893 				     FXSAVE_ADDR (tdep, regs, i));
894 	    }
895 	}
896 
897       /* Handle the x87 registers.  */
898       if ((tdep->xcr0 & I386_XSTATE_X87))
899 	{
900 	  if ((clear_bv & I386_XSTATE_X87))
901 	    {
902 	      for (i = I387_ST0_REGNUM (tdep);
903 		   i < I387_FCTRL_REGNUM (tdep);
904 		   i++)
905 		regcache_raw_supply (regcache, i, zero);
906 	    }
907 	  else
908 	    {
909 	      for (i = I387_ST0_REGNUM (tdep);
910 		   i < I387_FCTRL_REGNUM (tdep);
911 		   i++)
912 		regcache_raw_supply (regcache, i, FXSAVE_ADDR (tdep, regs, i));
913 	    }
914 	}
915       break;
916     }
917 
918   /* Only handle x87 control registers.  */
919   for (i = I387_FCTRL_REGNUM (tdep); i < I387_XMM0_REGNUM (tdep); i++)
920     if (regnum == -1 || regnum == i)
921       {
922 	/* Most of the FPU control registers occupy only 16 bits in
923 	   the xsave extended state.  Give those a special treatment.  */
924 	if (i != I387_FIOFF_REGNUM (tdep)
925 	    && i != I387_FOOFF_REGNUM (tdep))
926 	  {
927 	    gdb_byte val[4];
928 
929 	    memcpy (val, FXSAVE_ADDR (tdep, regs, i), 2);
930 	    val[2] = val[3] = 0;
931 	    if (i == I387_FOP_REGNUM (tdep))
932 	      val[1] &= ((1 << 3) - 1);
933 	    else if (i== I387_FTAG_REGNUM (tdep))
934 	      {
935 		/* The fxsave area contains a simplified version of
936 		   the tag word.  We have to look at the actual 80-bit
937 		   FP data to recreate the traditional i387 tag word.  */
938 
939 		unsigned long ftag = 0;
940 		int fpreg;
941 		int top;
942 
943 		top = ((FXSAVE_ADDR (tdep, regs,
944 				     I387_FSTAT_REGNUM (tdep)))[1] >> 3);
945 		top &= 0x7;
946 
947 		for (fpreg = 7; fpreg >= 0; fpreg--)
948 		  {
949 		    int tag;
950 
951 		    if (val[0] & (1 << fpreg))
952 		      {
953 			int thisreg = (fpreg + 8 - top) % 8
954 				       + I387_ST0_REGNUM (tdep);
955 			tag = i387_tag (FXSAVE_ADDR (tdep, regs, thisreg));
956 		      }
957 		    else
958 		      tag = 3;		/* Empty */
959 
960 		    ftag |= tag << (2 * fpreg);
961 		  }
962 		val[0] = ftag & 0xff;
963 		val[1] = (ftag >> 8) & 0xff;
964 	      }
965 	    regcache_raw_supply (regcache, i, val);
966 	  }
967 	else
968 	  regcache_raw_supply (regcache, i, FXSAVE_ADDR (tdep, regs, i));
969       }
970 
971   if (regnum == I387_MXCSR_REGNUM (tdep) || regnum == -1)
972     regcache_raw_supply (regcache, I387_MXCSR_REGNUM (tdep),
973 			 FXSAVE_MXCSR_ADDR (regs));
974 }
975 
976 /* Similar to i387_collect_fxsave, but use XSAVE extended state.  */
977 
978 void
979 i387_collect_xsave (const struct regcache *regcache, int regnum,
980 		    void *xsave, int gcore)
981 {
982   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
983   gdb_byte *regs = xsave;
984   int i;
985   enum
986     {
987       none = 0x0,
988       check = 0x1,
989       x87 = 0x2 | check,
990       sse = 0x4 | check,
991       avxh = 0x8 | check,
992       all = x87 | sse | avxh
993     } regclass;
994 
995   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
996   gdb_assert (tdep->num_xmm_regs > 0);
997 
998   if (regnum == -1)
999     regclass = all;
1000   else if (regnum >= I387_YMM0H_REGNUM (tdep)
1001 	   && regnum < I387_YMMENDH_REGNUM (tdep))
1002     regclass = avxh;
1003   else if (regnum >= I387_XMM0_REGNUM(tdep)
1004 	   && regnum < I387_MXCSR_REGNUM (tdep))
1005     regclass = sse;
1006   else if (regnum >= I387_ST0_REGNUM (tdep)
1007 	   && regnum < I387_FCTRL_REGNUM (tdep))
1008     regclass = x87;
1009   else
1010     regclass = none;
1011 
1012   if (gcore)
1013     {
1014       /* Clear XSAVE extended state.  */
1015       memset (regs, 0, I386_XSTATE_SIZE (tdep->xcr0));
1016 
1017       /* Update XCR0 and `xstate_bv' with XCR0 for gcore.  */
1018       if (tdep->xsave_xcr0_offset != -1)
1019 	memcpy (regs + tdep->xsave_xcr0_offset, &tdep->xcr0, 8);
1020       memcpy (XSAVE_XSTATE_BV_ADDR (regs), &tdep->xcr0, 8);
1021     }
1022 
1023   if ((regclass & check))
1024     {
1025       gdb_byte raw[I386_MAX_REGISTER_SIZE];
1026       gdb_byte *xstate_bv_p = XSAVE_XSTATE_BV_ADDR (regs);
1027       unsigned int xstate_bv = 0;
1028       /* The supported bits in `xstat_bv' are 1 byte.  */
1029       unsigned int clear_bv = (~(*xstate_bv_p)) & tdep->xcr0;
1030       gdb_byte *p;
1031 
1032       /* Clear register set if its bit in xstat_bv is zero.  */
1033       if (clear_bv)
1034 	{
1035 	  if ((clear_bv & I386_XSTATE_AVX))
1036 	    for (i = I387_YMM0H_REGNUM (tdep);
1037 		 i < I387_YMMENDH_REGNUM (tdep); i++)
1038 	      memset (XSAVE_AVXH_ADDR (tdep, regs, i), 0, 16);
1039 
1040 	  if ((clear_bv & I386_XSTATE_SSE))
1041 	    for (i = I387_XMM0_REGNUM (tdep);
1042 		 i < I387_MXCSR_REGNUM (tdep); i++)
1043 	      memset (FXSAVE_ADDR (tdep, regs, i), 0, 16);
1044 
1045 	  if ((clear_bv & I386_XSTATE_X87))
1046 	    for (i = I387_ST0_REGNUM (tdep);
1047 		 i < I387_FCTRL_REGNUM (tdep); i++)
1048 	      memset (FXSAVE_ADDR (tdep, regs, i), 0, 10);
1049 	}
1050 
1051       if (regclass == all)
1052 	{
1053 	  /* Check if any upper YMM registers are changed.  */
1054 	  if ((tdep->xcr0 & I386_XSTATE_AVX))
1055 	    for (i = I387_YMM0H_REGNUM (tdep);
1056 		 i < I387_YMMENDH_REGNUM (tdep); i++)
1057 	      {
1058 		regcache_raw_collect (regcache, i, raw);
1059 		p = XSAVE_AVXH_ADDR (tdep, regs, i);
1060 		if (memcmp (raw, p, 16))
1061 		  {
1062 		    xstate_bv |= I386_XSTATE_AVX;
1063 		    memcpy (p, raw, 16);
1064 		  }
1065 	      }
1066 
1067 	  /* Check if any SSE registers are changed.  */
1068 	  if ((tdep->xcr0 & I386_XSTATE_SSE))
1069 	    for (i = I387_XMM0_REGNUM (tdep);
1070 		 i < I387_MXCSR_REGNUM (tdep); i++)
1071 	      {
1072 		regcache_raw_collect (regcache, i, raw);
1073 		p = FXSAVE_ADDR (tdep, regs, i);
1074 		if (memcmp (raw, p, 16))
1075 		  {
1076 		    xstate_bv |= I386_XSTATE_SSE;
1077 		    memcpy (p, raw, 16);
1078 		  }
1079 	      }
1080 
1081 	  /* Check if any X87 registers are changed.  */
1082 	  if ((tdep->xcr0 & I386_XSTATE_X87))
1083 	    for (i = I387_ST0_REGNUM (tdep);
1084 		 i < I387_FCTRL_REGNUM (tdep); i++)
1085 	      {
1086 		regcache_raw_collect (regcache, i, raw);
1087 		p = FXSAVE_ADDR (tdep, regs, i);
1088 		if (memcmp (raw, p, 10))
1089 		  {
1090 		    xstate_bv |= I386_XSTATE_X87;
1091 		    memcpy (p, raw, 10);
1092 		  }
1093 	      }
1094 	}
1095       else
1096 	{
1097 	  /* Check if REGNUM is changed.  */
1098 	  regcache_raw_collect (regcache, regnum, raw);
1099 
1100 	  switch (regclass)
1101 	    {
1102 	    default:
1103 	      internal_error (__FILE__, __LINE__,
1104 			      _("invalid i387 regclass"));
1105 
1106 	    case avxh:
1107 	      /* This is an upper YMM register.  */
1108 	      p = XSAVE_AVXH_ADDR (tdep, regs, regnum);
1109 	      if (memcmp (raw, p, 16))
1110 		{
1111 		  xstate_bv |= I386_XSTATE_AVX;
1112 		  memcpy (p, raw, 16);
1113 		}
1114 	      break;
1115 
1116 	    case sse:
1117 	      /* This is an SSE register.  */
1118 	      p = FXSAVE_ADDR (tdep, regs, regnum);
1119 	      if (memcmp (raw, p, 16))
1120 		{
1121 		  xstate_bv |= I386_XSTATE_SSE;
1122 		  memcpy (p, raw, 16);
1123 		}
1124 	      break;
1125 
1126 	    case x87:
1127 	      /* This is an x87 register.  */
1128 	      p = FXSAVE_ADDR (tdep, regs, regnum);
1129 	      if (memcmp (raw, p, 10))
1130 		{
1131 		  xstate_bv |= I386_XSTATE_X87;
1132 		  memcpy (p, raw, 10);
1133 		}
1134 	      break;
1135 	    }
1136 	}
1137 
1138       /* Update the corresponding bits in `xstate_bv' if any SSE/AVX
1139 	 registers are changed.  */
1140       if (xstate_bv)
1141 	{
1142 	  /* The supported bits in `xstat_bv' are 1 byte.  */
1143 	  *xstate_bv_p |= (gdb_byte) xstate_bv;
1144 
1145 	  switch (regclass)
1146 	    {
1147 	    default:
1148 	      internal_error (__FILE__, __LINE__,
1149 			      _("invalid i387 regclass"));
1150 
1151 	    case all:
1152 	      break;
1153 
1154 	    case x87:
1155 	    case sse:
1156 	    case avxh:
1157 	      /* Register REGNUM has been updated.  Return.  */
1158 	      return;
1159 	    }
1160 	}
1161       else
1162 	{
1163 	  /* Return if REGNUM isn't changed.  */
1164 	  if (regclass != all)
1165 	    return;
1166 	}
1167     }
1168 
1169   /* Only handle x87 control registers.  */
1170   for (i = I387_FCTRL_REGNUM (tdep); i < I387_XMM0_REGNUM (tdep); i++)
1171     if (regnum == -1 || regnum == i)
1172       {
1173 	/* Most of the FPU control registers occupy only 16 bits in
1174 	   the xsave extended state.  Give those a special treatment.  */
1175 	if (i != I387_FIOFF_REGNUM (tdep)
1176 	    && i != I387_FOOFF_REGNUM (tdep))
1177 	  {
1178 	    gdb_byte buf[4];
1179 
1180 	    regcache_raw_collect (regcache, i, buf);
1181 
1182 	    if (i == I387_FOP_REGNUM (tdep))
1183 	      {
1184 		/* The opcode occupies only 11 bits.  Make sure we
1185 		   don't touch the other bits.  */
1186 		buf[1] &= ((1 << 3) - 1);
1187 		buf[1] |= ((FXSAVE_ADDR (tdep, regs, i))[1] & ~((1 << 3) - 1));
1188 	      }
1189 	    else if (i == I387_FTAG_REGNUM (tdep))
1190 	      {
1191 		/* Converting back is much easier.  */
1192 
1193 		unsigned short ftag;
1194 		int fpreg;
1195 
1196 		ftag = (buf[1] << 8) | buf[0];
1197 		buf[0] = 0;
1198 		buf[1] = 0;
1199 
1200 		for (fpreg = 7; fpreg >= 0; fpreg--)
1201 		  {
1202 		    int tag = (ftag >> (fpreg * 2)) & 3;
1203 
1204 		    if (tag != 3)
1205 		      buf[0] |= (1 << fpreg);
1206 		  }
1207 	      }
1208 	    memcpy (FXSAVE_ADDR (tdep, regs, i), buf, 2);
1209 	  }
1210 	else
1211 	  regcache_raw_collect (regcache, i, FXSAVE_ADDR (tdep, regs, i));
1212       }
1213 
1214   if (regnum == I387_MXCSR_REGNUM (tdep) || regnum == -1)
1215     regcache_raw_collect (regcache, I387_MXCSR_REGNUM (tdep),
1216 			  FXSAVE_MXCSR_ADDR (regs));
1217 }
1218 
1219 /* Recreate the FTW (tag word) valid bits from the 80-bit FP data in
1220    *RAW.  */
1221 
1222 static int
1223 i387_tag (const gdb_byte *raw)
1224 {
1225   int integer;
1226   unsigned int exponent;
1227   unsigned long fraction[2];
1228 
1229   integer = raw[7] & 0x80;
1230   exponent = (((raw[9] & 0x7f) << 8) | raw[8]);
1231   fraction[0] = ((raw[3] << 24) | (raw[2] << 16) | (raw[1] << 8) | raw[0]);
1232   fraction[1] = (((raw[7] & 0x7f) << 24) | (raw[6] << 16)
1233 		 | (raw[5] << 8) | raw[4]);
1234 
1235   if (exponent == 0x7fff)
1236     {
1237       /* Special.  */
1238       return (2);
1239     }
1240   else if (exponent == 0x0000)
1241     {
1242       if (fraction[0] == 0x0000 && fraction[1] == 0x0000 && !integer)
1243 	{
1244 	  /* Zero.  */
1245 	  return (1);
1246 	}
1247       else
1248 	{
1249 	  /* Special.  */
1250 	  return (2);
1251 	}
1252     }
1253   else
1254     {
1255       if (integer)
1256 	{
1257 	  /* Valid.  */
1258 	  return (0);
1259 	}
1260       else
1261 	{
1262 	  /* Special.  */
1263 	  return (2);
1264 	}
1265     }
1266 }
1267 
1268 /* Prepare the FPU stack in REGCACHE for a function return.  */
1269 
1270 void
1271 i387_return_value (struct gdbarch *gdbarch, struct regcache *regcache)
1272 {
1273   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
1274   ULONGEST fstat;
1275 
1276   /* Set the top of the floating-point register stack to 7.  The
1277      actual value doesn't really matter, but 7 is what a normal
1278      function return would end up with if the program started out with
1279      a freshly initialized FPU.  */
1280   regcache_raw_read_unsigned (regcache, I387_FSTAT_REGNUM (tdep), &fstat);
1281   fstat |= (7 << 11);
1282   regcache_raw_write_unsigned (regcache, I387_FSTAT_REGNUM (tdep), fstat);
1283 
1284   /* Mark %st(1) through %st(7) as empty.  Since we set the top of the
1285      floating-point register stack to 7, the appropriate value for the
1286      tag word is 0x3fff.  */
1287   regcache_raw_write_unsigned (regcache, I387_FTAG_REGNUM (tdep), 0x3fff);
1288 
1289 }
1290