gdb/i387-tdep.c

   1 /* Intel 387 floating point stuff.
   2
   3    Copyright (C) 1988, 1989, 1991, 1992, 1993, 1994, 1998, 1999, 2000, 2001,
   4    2002, 2003, 2004, 2005, 2007 Free Software Foundation, Inc.
   5
   6    This file is part of GDB.
   7
   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 3 of the License, or
  11    (at your option) any later version.
  12
  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.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "defs.h"
  22 #include "doublest.h"
  23 #include "floatformat.h"
  24 #include "frame.h"
  25 #include "gdbcore.h"
  26 #include "inferior.h"
  27 #include "language.h"
  28 #include "regcache.h"
  29 #include "value.h"
  30
  31 #include "gdb_assert.h"
  32 #include "gdb_string.h"
  33
  34 #include "i386-tdep.h"
  35 #include "i387-tdep.h"
  36
  37 /* Print the floating point number specified by RAW.  */
  38
  39 static void
  40 print_i387_value (const gdb_byte *raw, struct ui_file *file)
  41 {
  42   DOUBLEST value;
  43
  44   /* Using extract_typed_floating here might affect the representation
  45      of certain numbers such as NaNs, even if GDB is running natively.
  46      This is fine since our caller already detects such special
  47      numbers and we print the hexadecimal representation anyway.  */
  48   value = extract_typed_floating (raw, builtin_type_i387_ext);
  49
  50   /* We try to print 19 digits.  The last digit may or may not contain
  51      garbage, but we'd better print one too many.  We need enough room
  52      to print the value, 1 position for the sign, 1 for the decimal
  53      point, 19 for the digits and 6 for the exponent adds up to 27.  */
  54 #ifdef PRINTF_HAS_LONG_DOUBLE
  55   fprintf_filtered (file, " %-+27.19Lg", (long double) value);
  56 #else
  57   fprintf_filtered (file, " %-+27.19g", (double) value);
  58 #endif
  59 }
  60
  61 /* Print the classification for the register contents RAW.  */
  62
  63 static void
  64 print_i387_ext (const gdb_byte *raw, struct ui_file *file)
  65 {
  66   int sign;
  67   int integer;
  68   unsigned int exponent;
  69   unsigned long fraction[2];
  70
  71   sign = raw[9] & 0x80;
  72   integer = raw[7] & 0x80;
  73   exponent = (((raw[9] & 0x7f) << 8) | raw[8]);
  74   fraction[0] = ((raw[3] << 24) | (raw[2] << 16) | (raw[1] << 8) | raw[0]);
  75   fraction[1] = (((raw[7] & 0x7f) << 24) | (raw[6] << 16)
  76                  | (raw[5] << 8) | raw[4]);
  77
  78   if (exponent == 0x7fff && integer)
  79     {
  80       if (fraction[0] == 0x00000000 && fraction[1] == 0x00000000)
  81         /* Infinity.  */
  82         fprintf_filtered (file, " %cInf", (sign ? '-' : '+'));
  83       else if (sign && fraction[0] == 0x00000000 && fraction[1] == 0x40000000)
  84         /* Real Indefinite (QNaN).  */
  85         fputs_unfiltered (" Real Indefinite (QNaN)", file);
  86       else if (fraction[1] & 0x40000000)
  87         /* QNaN.  */
  88         fputs_filtered (" QNaN", file);
  89       else
  90         /* SNaN.  */
  91         fputs_filtered (" SNaN", file);
  92     }
  93   else if (exponent < 0x7fff && exponent > 0x0000 && integer)
  94     /* Normal.  */
  95     print_i387_value (raw, file);
  96   else if (exponent == 0x0000)
  97     {
  98       /* Denormal or zero.  */
  99       print_i387_value (raw, file);
 100
 101       if (integer)
 102         /* Pseudo-denormal.  */
 103         fputs_filtered (" Pseudo-denormal", file);
 104       else if (fraction[0] || fraction[1])
 105         /* Denormal.  */
 106         fputs_filtered (" Denormal", file);
 107     }
 108   else
 109     /* Unsupported.  */
 110     fputs_filtered (" Unsupported", file);
 111 }
 112
 113 /* Print the status word STATUS.  */
 114
 115 static void
 116 print_i387_status_word (unsigned int status, struct ui_file *file)
 117 {
 118   fprintf_filtered (file, "Status Word:         %s",
 119                     hex_string_custom (status, 4));
 120   fputs_filtered ("  ", file);
 121   fprintf_filtered (file, " %s", (status & 0x0001) ? "IE" : "  ");
 122   fprintf_filtered (file, " %s", (status & 0x0002) ? "DE" : "  ");
 123   fprintf_filtered (file, " %s", (status & 0x0004) ? "ZE" : "  ");
 124   fprintf_filtered (file, " %s", (status & 0x0008) ? "OE" : "  ");
 125   fprintf_filtered (file, " %s", (status & 0x0010) ? "UE" : "  ");
 126   fprintf_filtered (file, " %s", (status & 0x0020) ? "PE" : "  ");
 127   fputs_filtered ("  ", file);
 128   fprintf_filtered (file, " %s", (status & 0x0080) ? "ES" : "  ");
 129   fputs_filtered ("  ", file);
 130   fprintf_filtered (file, " %s", (status & 0x0040) ? "SF" : "  ");
 131   fputs_filtered ("  ", file);
 132   fprintf_filtered (file, " %s", (status & 0x0100) ? "C0" : "  ");
 133   fprintf_filtered (file, " %s", (status & 0x0200) ? "C1" : "  ");
 134   fprintf_filtered (file, " %s", (status & 0x0400) ? "C2" : "  ");
 135   fprintf_filtered (file, " %s", (status & 0x4000) ? "C3" : "  ");
 136
 137   fputs_filtered ("\n", file);
 138
 139   fprintf_filtered (file,
 140                     "                       TOP: %d\n", ((status >> 11) & 7));
 141 }
 142
 143 /* Print the control word CONTROL.  */
 144
 145 static void
 146 print_i387_control_word (unsigned int control, struct ui_file *file)
 147 {
 148   fprintf_filtered (file, "Control Word:        %s",
 149                     hex_string_custom (control, 4));
 150   fputs_filtered ("  ", file);
 151   fprintf_filtered (file, " %s", (control & 0x0001) ? "IM" : "  ");
 152   fprintf_filtered (file, " %s", (control & 0x0002) ? "DM" : "  ");
 153   fprintf_filtered (file, " %s", (control & 0x0004) ? "ZM" : "  ");
 154   fprintf_filtered (file, " %s", (control & 0x0008) ? "OM" : "  ");
 155   fprintf_filtered (file, " %s", (control & 0x0010) ? "UM" : "  ");
 156   fprintf_filtered (file, " %s", (control & 0x0020) ? "PM" : "  ");
 157
 158   fputs_filtered ("\n", file);
 159
 160   fputs_filtered ("                       PC: ", file);
 161   switch ((control >> 8) & 3)
 162     {
 163     case 0:
 164       fputs_filtered ("Single Precision (24-bits)\n", file);
 165       break;
 166     case 1:
 167       fputs_filtered ("Reserved\n", file);
 168       break;
 169     case 2:
 170       fputs_filtered ("Double Precision (53-bits)\n", file);
 171       break;
 172     case 3:
 173       fputs_filtered ("Extended Precision (64-bits)\n", file);
 174       break;
 175     }
 176
 177   fputs_filtered ("                       RC: ", file);
 178   switch ((control >> 10) & 3)
 179     {
 180     case 0:
 181       fputs_filtered ("Round to nearest\n", file);
 182       break;
 183     case 1:
 184       fputs_filtered ("Round down\n", file);
 185       break;
 186     case 2:
 187       fputs_filtered ("Round up\n", file);
 188       break;
 189     case 3:
 190       fputs_filtered ("Round toward zero\n", file);
 191       break;
 192     }
 193 }
 194
 195 /* Print out the i387 floating point state.  Note that we ignore FRAME
 196    in the code below.  That's OK since floating-point registers are
 197    never saved on the stack.  */
 198
 199 void
 200 i387_print_float_info (struct gdbarch *gdbarch, struct ui_file *file,
 201                        struct frame_info *frame, const char *args)
 202 {
 203   struct gdbarch_tdep *tdep = gdbarch_tdep (get_frame_arch (frame));
 204   gdb_byte buf[4];
 205   ULONGEST fctrl;
 206   ULONGEST fstat;
 207   ULONGEST ftag;
 208   ULONGEST fiseg;
 209   ULONGEST fioff;
 210   ULONGEST foseg;
 211   ULONGEST fooff;
 212   ULONGEST fop;
 213   int fpreg;
 214   int top;
 215
 216   gdb_assert (gdbarch == get_frame_arch (frame));
 217
 218   /* Define I387_ST0_REGNUM such that we use the proper definitions
 219      for FRAME's architecture.  */
 220 #define I387_ST0_REGNUM tdep->st0_regnum
 221
 222   fctrl = get_frame_register_unsigned (frame, I387_FCTRL_REGNUM);
 223   fstat = get_frame_register_unsigned (frame, I387_FSTAT_REGNUM);
 224   ftag = get_frame_register_unsigned (frame, I387_FTAG_REGNUM);
 225   fiseg = get_frame_register_unsigned (frame, I387_FISEG_REGNUM);
 226   fioff = get_frame_register_unsigned (frame, I387_FIOFF_REGNUM);
 227   foseg = get_frame_register_unsigned (frame, I387_FOSEG_REGNUM);
 228   fooff = get_frame_register_unsigned (frame, I387_FOOFF_REGNUM);
 229   fop = get_frame_register_unsigned (frame, I387_FOP_REGNUM);
 230
 231   top = ((fstat >> 11) & 7);
 232
 233   for (fpreg = 7; fpreg >= 0; fpreg--)
 234     {
 235       gdb_byte raw[I386_MAX_REGISTER_SIZE];
 236       int tag = (ftag >> (fpreg * 2)) & 3;
 237       int i;
 238
 239       fprintf_filtered (file, "%sR%d: ", fpreg == top ? "=>" : "  ", fpreg);
 240
 241       switch (tag)
 242         {
 243         case 0:
 244           fputs_filtered ("Valid   ", file);
 245           break;
 246         case 1:
 247           fputs_filtered ("Zero    ", file);
 248           break;
 249         case 2:
 250           fputs_filtered ("Special ", file);
 251           break;
 252         case 3:
 253           fputs_filtered ("Empty   ", file);
 254           break;
 255         }
 256
 257       get_frame_register (frame, (fpreg + 8 - top) % 8 + I387_ST0_REGNUM, raw);
 258
 259       fputs_filtered ("0x", file);
 260       for (i = 9; i >= 0; i--)
 261         fprintf_filtered (file, "%02x", raw[i]);
 262
 263       if (tag != 3)
 264         print_i387_ext (raw, file);
 265
 266       fputs_filtered ("\n", file);
 267     }
 268
 269   fputs_filtered ("\n", file);
 270
 271   print_i387_status_word (fstat, file);
 272   print_i387_control_word (fctrl, file);
 273   fprintf_filtered (file, "Tag Word:            %s\n",
 274                     hex_string_custom (ftag, 4));
 275   fprintf_filtered (file, "Instruction Pointer: %s:",
 276                     hex_string_custom (fiseg, 2));
 277   fprintf_filtered (file, "%s\n", hex_string_custom (fioff, 8));
 278   fprintf_filtered (file, "Operand Pointer:     %s:",
 279                     hex_string_custom (foseg, 2));
 280   fprintf_filtered (file, "%s\n", hex_string_custom (fooff, 8));
 281   fprintf_filtered (file, "Opcode:              %s\n",
 282                     hex_string_custom (fop ? (fop | 0xd800) : 0, 4));
 283
 284 #undef I387_ST0_REGNUM
 285 }
 286 \f
 287
 288 /* Read a value of type TYPE from register REGNUM in frame FRAME, and
 289    return its contents in TO.  */
 290
 291 void
 292 i387_register_to_value (struct frame_info *frame, int regnum,
 293                         struct type *type, gdb_byte *to)
 294 {
 295   gdb_byte from[I386_MAX_REGISTER_SIZE];
 296
 297   gdb_assert (i386_fp_regnum_p (regnum));
 298
 299   /* We only support floating-point values.  */
 300   if (TYPE_CODE (type) != TYPE_CODE_FLT)
 301     {
 302       warning (_("Cannot convert floating-point register value "
 303                "to non-floating-point type."));
 304       return;
 305     }
 306
 307   /* Convert to TYPE.  This should be a no-op if TYPE is equivalent to
 308      the extended floating-point format used by the FPU.  */
 309   get_frame_register (frame, regnum, from);
 310   convert_typed_floating (from, builtin_type_i387_ext, to, type);
 311 }
 312
 313 /* Write the contents FROM of a value of type TYPE into register
 314    REGNUM in frame FRAME.  */
 315
 316 void
 317 i387_value_to_register (struct frame_info *frame, int regnum,
 318                         struct type *type, const gdb_byte *from)
 319 {
 320   gdb_byte to[I386_MAX_REGISTER_SIZE];
 321
 322   gdb_assert (i386_fp_regnum_p (regnum));
 323
 324   /* We only support floating-point values.  */
 325   if (TYPE_CODE (type) != TYPE_CODE_FLT)
 326     {
 327       warning (_("Cannot convert non-floating-point type "
 328                "to floating-point register value."));
 329       return;
 330     }
 331
 332   /* Convert from TYPE.  This should be a no-op if TYPE is equivalent
 333      to the extended floating-point format used by the FPU.  */
 334   convert_typed_floating (from, type, to, builtin_type_i387_ext);
 335   put_frame_register (frame, regnum, to);
 336 }
 337 \f
 338
 339 /* Handle FSAVE and FXSAVE formats.  */
 340
 341 /* At fsave_offset[REGNUM] you'll find the offset to the location in
 342    the data structure used by the "fsave" instruction where GDB
 343    register REGNUM is stored.  */
 344
 345 static int fsave_offset[] =
 346 {
 347   28 + 0 * 10,                  /* %st(0) ...  */
 348   28 + 1 * 10,
 349   28 + 2 * 10,
 350   28 + 3 * 10,
 351   28 + 4 * 10,
 352   28 + 5 * 10,
 353   28 + 6 * 10,
 354   28 + 7 * 10,                  /* ... %st(7).  */
 355   0,                            /* `fctrl' (16 bits).  */
 356   4,                            /* `fstat' (16 bits).  */
 357   8,                            /* `ftag' (16 bits).  */
 358   16,                           /* `fiseg' (16 bits).  */
 359   12,                           /* `fioff'.  */
 360   24,                           /* `foseg' (16 bits).  */
 361   20,                           /* `fooff'.  */
 362   18                            /* `fop' (bottom 11 bits).  */
 363 };
 364
 365 #define FSAVE_ADDR(fsave, regnum) \
 366   (fsave + fsave_offset[regnum - I387_ST0_REGNUM])
 367 \f
 368
 369 /* Fill register REGNUM in REGCACHE with the appropriate value from
 370    *FSAVE.  This function masks off any of the reserved bits in
 371    *FSAVE.  */
 372
 373 void
 374 i387_supply_fsave (struct regcache *regcache, int regnum, const void *fsave)
 375 {
 376   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 377   const gdb_byte *regs = fsave;
 378   int i;
 379
 380   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 381
 382   /* Define I387_ST0_REGNUM and I387_NUM_XMM_REGS such that we use the
 383      proper definitions for REGCACHE's architecture.  */
 384
 385 #define I387_ST0_REGNUM tdep->st0_regnum
 386 #define I387_NUM_XMM_REGS tdep->num_xmm_regs
 387
 388   for (i = I387_ST0_REGNUM; i < I387_XMM0_REGNUM; i++)
 389     if (regnum == -1 || regnum == i)
 390       {
 391         if (fsave == NULL)
 392           {
 393             regcache_raw_supply (regcache, i, NULL);
 394             continue;
 395           }
 396
 397         /* Most of the FPU control registers occupy only 16 bits in the
 398            fsave area.  Give those a special treatment.  */
 399         if (i >= I387_FCTRL_REGNUM
 400             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 401           {
 402             gdb_byte val[4];
 403
 404             memcpy (val, FSAVE_ADDR (regs, i), 2);
 405             val[2] = val[3] = 0;
 406             if (i == I387_FOP_REGNUM)
 407               val[1] &= ((1 << 3) - 1);
 408             regcache_raw_supply (regcache, i, val);
 409           }
 410         else
 411           regcache_raw_supply (regcache, i, FSAVE_ADDR (regs, i));
 412       }
 413
 414   /* Provide dummy values for the SSE registers.  */
 415   for (i = I387_XMM0_REGNUM; i < I387_MXCSR_REGNUM; i++)
 416     if (regnum == -1 || regnum == i)
 417       regcache_raw_supply (regcache, i, NULL);
 418   if (regnum == -1 || regnum == I387_MXCSR_REGNUM)
 419     {
 420       gdb_byte buf[4];
 421
 422       store_unsigned_integer (buf, 4, 0x1f80);
 423       regcache_raw_supply (regcache, I387_MXCSR_REGNUM, buf);
 424     }
 425
 426 #undef I387_ST0_REGNUM
 427 #undef I387_NUM_XMM_REGS
 428 }
 429
 430 /* Fill register REGNUM (if it is a floating-point register) in *FSAVE
 431    with the value from REGCACHE.  If REGNUM is -1, do this for all
 432    registers.  This function doesn't touch any of the reserved bits in
 433    *FSAVE.  */
 434
 435 void
 436 i387_collect_fsave (const struct regcache *regcache, int regnum, void *fsave)
 437 {
 438   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 439   gdb_byte *regs = fsave;
 440   int i;
 441
 442   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 443
 444   /* Define I387_ST0_REGNUM such that we use the proper definitions
 445      for REGCACHE's architecture.  */
 446 #define I387_ST0_REGNUM tdep->st0_regnum
 447
 448   for (i = I387_ST0_REGNUM; i < I387_XMM0_REGNUM; i++)
 449     if (regnum == -1 || regnum == i)
 450       {
 451         /* Most of the FPU control registers occupy only 16 bits in
 452            the fsave area.  Give those a special treatment.  */
 453         if (i >= I387_FCTRL_REGNUM
 454             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 455           {
 456             gdb_byte buf[4];
 457
 458             regcache_raw_collect (regcache, i, buf);
 459
 460             if (i == I387_FOP_REGNUM)
 461               {
 462                 /* The opcode occupies only 11 bits.  Make sure we
 463                    don't touch the other bits.  */
 464                 buf[1] &= ((1 << 3) - 1);
 465                 buf[1] |= ((FSAVE_ADDR (regs, i))[1] & ~((1 << 3) - 1));
 466               }
 467             memcpy (FSAVE_ADDR (regs, i), buf, 2);
 468           }
 469         else
 470           regcache_raw_collect (regcache, i, FSAVE_ADDR (regs, i));
 471       }
 472 #undef I387_ST0_REGNUM
 473 }
 474 \f
 475
 476 /* At fxsave_offset[REGNUM] you'll find the offset to the location in
 477    the data structure used by the "fxsave" instruction where GDB
 478    register REGNUM is stored.  */
 479
 480 static int fxsave_offset[] =
 481 {
 482   32,                           /* %st(0) through ...  */
 483   48,
 484   64,
 485   80,
 486   96,
 487   112,
 488   128,
 489   144,                          /* ... %st(7) (80 bits each).  */
 490   0,                            /* `fctrl' (16 bits).  */
 491   2,                            /* `fstat' (16 bits).  */
 492   4,                            /* `ftag' (16 bits).  */
 493   12,                           /* `fiseg' (16 bits).  */
 494   8,                            /* `fioff'.  */
 495   20,                           /* `foseg' (16 bits).  */
 496   16,                           /* `fooff'.  */
 497   6,                            /* `fop' (bottom 11 bits).  */
 498   160 + 0 * 16,                 /* %xmm0 through ...  */
 499   160 + 1 * 16,
 500   160 + 2 * 16,
 501   160 + 3 * 16,
 502   160 + 4 * 16,
 503   160 + 5 * 16,
 504   160 + 6 * 16,
 505   160 + 7 * 16,
 506   160 + 8 * 16,
 507   160 + 9 * 16,
 508   160 + 10 * 16,
 509   160 + 11 * 16,
 510   160 + 12 * 16,
 511   160 + 13 * 16,
 512   160 + 14 * 16,
 513   160 + 15 * 16,                /* ... %xmm15 (128 bits each).  */
 514 };
 515
 516 #define FXSAVE_ADDR(fxsave, regnum) \
 517   (fxsave + fxsave_offset[regnum - I387_ST0_REGNUM])
 518
 519 /* We made an unfortunate choice in putting %mxcsr after the SSE
 520    registers %xmm0-%xmm7 instead of before, since it makes supporting
 521    the registers %xmm8-%xmm15 on AMD64 a bit involved.  Therefore we
 522    don't include the offset for %mxcsr here above.  */
 523
 524 #define FXSAVE_MXCSR_ADDR(fxsave) (fxsave + 24)
 525
 526 static int i387_tag (const gdb_byte *raw);
 527 \f
 528
 529 /* Fill register REGNUM in REGCACHE with the appropriate
 530    floating-point or SSE register value from *FXSAVE.  This function
 531    masks off any of the reserved bits in *FXSAVE.  */
 532
 533 void
 534 i387_supply_fxsave (struct regcache *regcache, int regnum, const void *fxsave)
 535 {
 536   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 537   const gdb_byte *regs = fxsave;
 538   int i;
 539
 540   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 541   gdb_assert (tdep->num_xmm_regs > 0);
 542
 543   /* Define I387_ST0_REGNUM and I387_NUM_XMM_REGS such that we use the
 544      proper definitions for REGCACHE's architecture.  */
 545
 546 #define I387_ST0_REGNUM tdep->st0_regnum
 547 #define I387_NUM_XMM_REGS tdep->num_xmm_regs
 548
 549   for (i = I387_ST0_REGNUM; i < I387_MXCSR_REGNUM; i++)
 550     if (regnum == -1 || regnum == i)
 551       {
 552         if (regs == NULL)
 553           {
 554             regcache_raw_supply (regcache, i, NULL);
 555             continue;
 556           }
 557
 558         /* Most of the FPU control registers occupy only 16 bits in
 559            the fxsave area.  Give those a special treatment.  */
 560         if (i >= I387_FCTRL_REGNUM && i < I387_XMM0_REGNUM
 561             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 562           {
 563             gdb_byte val[4];
 564
 565             memcpy (val, FXSAVE_ADDR (regs, i), 2);
 566             val[2] = val[3] = 0;
 567             if (i == I387_FOP_REGNUM)
 568               val[1] &= ((1 << 3) - 1);
 569             else if (i== I387_FTAG_REGNUM)
 570               {
 571                 /* The fxsave area contains a simplified version of
 572                    the tag word.  We have to look at the actual 80-bit
 573                    FP data to recreate the traditional i387 tag word.  */
 574
 575                 unsigned long ftag = 0;
 576                 int fpreg;
 577                 int top;
 578
 579                 top = ((FXSAVE_ADDR (regs, I387_FSTAT_REGNUM))[1] >> 3);
 580                 top &= 0x7;
 581
 582                 for (fpreg = 7; fpreg >= 0; fpreg--)
 583                   {
 584                     int tag;
 585
 586                     if (val[0] & (1 << fpreg))
 587                       {
 588                         int regnum = (fpreg + 8 - top) % 8 + I387_ST0_REGNUM;
 589                         tag = i387_tag (FXSAVE_ADDR (regs, regnum));
 590                       }
 591                     else
 592                       tag = 3;          /* Empty */
 593
 594                     ftag |= tag << (2 * fpreg);
 595                   }
 596                 val[0] = ftag & 0xff;
 597                 val[1] = (ftag >> 8) & 0xff;
 598               }
 599             regcache_raw_supply (regcache, i, val);
 600           }
 601         else
 602           regcache_raw_supply (regcache, i, FXSAVE_ADDR (regs, i));
 603       }
 604
 605   if (regnum == I387_MXCSR_REGNUM || regnum == -1)
 606     {
 607       if (regs == NULL)
 608         regcache_raw_supply (regcache, I387_MXCSR_REGNUM, NULL);
 609       else
 610         regcache_raw_supply (regcache, I387_MXCSR_REGNUM,
 611                              FXSAVE_MXCSR_ADDR (regs));
 612     }
 613
 614 #undef I387_ST0_REGNUM
 615 #undef I387_NUM_XMM_REGS
 616 }
 617
 618 /* Fill register REGNUM (if it is a floating-point or SSE register) in
 619    *FXSAVE with the value from REGCACHE.  If REGNUM is -1, do this for
 620    all registers.  This function doesn't touch any of the reserved
 621    bits in *FXSAVE.  */
 622
 623 void
 624 i387_collect_fxsave (const struct regcache *regcache, int regnum, void *fxsave)
 625 {
 626   struct gdbarch_tdep *tdep = gdbarch_tdep (get_regcache_arch (regcache));
 627   gdb_byte *regs = fxsave;
 628   int i;
 629
 630   gdb_assert (tdep->st0_regnum >= I386_ST0_REGNUM);
 631   gdb_assert (tdep->num_xmm_regs > 0);
 632
 633   /* Define I387_ST0_REGNUM and I387_NUM_XMM_REGS such that we use the
 634      proper definitions for REGCACHE's architecture.  */
 635
 636 #define I387_ST0_REGNUM tdep->st0_regnum
 637 #define I387_NUM_XMM_REGS tdep->num_xmm_regs
 638
 639   for (i = I387_ST0_REGNUM; i < I387_MXCSR_REGNUM; i++)
 640     if (regnum == -1 || regnum == i)
 641       {
 642         /* Most of the FPU control registers occupy only 16 bits in
 643            the fxsave area.  Give those a special treatment.  */
 644         if (i >= I387_FCTRL_REGNUM && i < I387_XMM0_REGNUM
 645             && i != I387_FIOFF_REGNUM && i != I387_FOOFF_REGNUM)
 646           {
 647             gdb_byte buf[4];
 648
 649             regcache_raw_collect (regcache, i, buf);
 650
 651             if (i == I387_FOP_REGNUM)
 652               {
 653                 /* The opcode occupies only 11 bits.  Make sure we
 654                    don't touch the other bits.  */
 655                 buf[1] &= ((1 << 3) - 1);
 656                 buf[1] |= ((FXSAVE_ADDR (regs, i))[1] & ~((1 << 3) - 1));
 657               }
 658             else if (i == I387_FTAG_REGNUM)
 659               {
 660                 /* Converting back is much easier.  */
 661
 662                 unsigned short ftag;
 663                 int fpreg;
 664
 665                 ftag = (buf[1] << 8) | buf[0];
 666                 buf[0] = 0;
 667                 buf[1] = 0;
 668
 669                 for (fpreg = 7; fpreg >= 0; fpreg--)
 670                   {
 671                     int tag = (ftag >> (fpreg * 2)) & 3;
 672
 673                     if (tag != 3)
 674                       buf[0] |= (1 << fpreg);
 675                   }
 676               }
 677             memcpy (FXSAVE_ADDR (regs, i), buf, 2);
 678           }
 679         else
 680           regcache_raw_collect (regcache, i, FXSAVE_ADDR (regs, i));
 681       }
 682
 683   if (regnum == I387_MXCSR_REGNUM || regnum == -1)
 684     regcache_raw_collect (regcache, I387_MXCSR_REGNUM,
 685                           FXSAVE_MXCSR_ADDR (regs));
 686
 687 #undef I387_ST0_REGNUM
 688 #undef I387_NUM_XMM_REGS
 689 }
 690
 691 /* Recreate the FTW (tag word) valid bits from the 80-bit FP data in
 692    *RAW.  */
 693
 694 static int
 695 i387_tag (const gdb_byte *raw)
 696 {
 697   int integer;
 698   unsigned int exponent;
 699   unsigned long fraction[2];
 700
 701   integer = raw[7] & 0x80;
 702   exponent = (((raw[9] & 0x7f) << 8) | raw[8]);
 703   fraction[0] = ((raw[3] << 24) | (raw[2] << 16) | (raw[1] << 8) | raw[0]);
 704   fraction[1] = (((raw[7] & 0x7f) << 24) | (raw[6] << 16)
 705                  | (raw[5] << 8) | raw[4]);
 706
 707   if (exponent == 0x7fff)
 708     {
 709       /* Special.  */
 710       return (2);
 711     }
 712   else if (exponent == 0x0000)
 713     {
 714       if (fraction[0] == 0x0000 && fraction[1] == 0x0000 && !integer)
 715         {
 716           /* Zero.  */
 717           return (1);
 718         }
 719       else
 720         {
 721           /* Special.  */
 722           return (2);
 723         }
 724     }
 725   else
 726     {
 727       if (integer)
 728         {
 729           /* Valid.  */
 730           return (0);
 731         }
 732       else
 733         {
 734           /* Special.  */
 735           return (2);
 736         }
 737     }
 738 }
 739
 740 /* Prepare the FPU stack in REGCACHE for a function return.  */
 741
 742 void
 743 i387_return_value (struct gdbarch *gdbarch, struct regcache *regcache)
 744 {
 745   struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
 746   ULONGEST fstat;
 747
 748   /* Define I387_ST0_REGNUM such that we use the proper
 749      definitions for the architecture.  */
 750 #define I387_ST0_REGNUM tdep->st0_regnum
 751
 752   /* Set the top of the floating-point register stack to 7.  The
 753      actual value doesn't really matter, but 7 is what a normal
 754      function return would end up with if the program started out with
 755      a freshly initialized FPU.  */
 756   regcache_raw_read_unsigned (regcache, I387_FSTAT_REGNUM, &fstat);
 757   fstat |= (7 << 11);
 758   regcache_raw_write_unsigned (regcache, I387_FSTAT_REGNUM, fstat);
 759
 760   /* Mark %st(1) through %st(7) as empty.  Since we set the top of the
 761      floating-point register stack to 7, the appropriate value for the
 762      tag word is 0x3fff.  */
 763   regcache_raw_write_unsigned (regcache, I387_FTAG_REGNUM, 0x3fff);
 764
 765 #undef I387_ST0_REGNUM
 766 }