gcc/config/i386/sysv4.h

   1 /* Target definitions for GNU compiler for Intel 80386 running System V.4
   2    Copyright (C) 1991 Free Software Foundation, Inc.
   3
   4    Written by Ron Guilmette (rfg@ncd.com).
   5
   6 This file is part of GNU CC.
   7
   8 GNU CC 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, or (at your option)
  11 any later version.
  12
  13 GNU CC 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 GNU CC; see the file COPYING.  If not, write to
  20 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
  21
  22 #include "i386/i386.h"  /* Base i386 target machine definitions */
  23 #include "i386/att.h"   /* Use the i386 AT&T assembler syntax */
  24 #include "svr4.h"       /* Definitions common to all SVR4 targets */
  25
  26 #undef TARGET_VERSION
  27 #define TARGET_VERSION fprintf (stderr, " (i386 System V Release 4)");
  28
  29 /* The svr4 ABI for the i386 says that records and unions are returned
  30    in memory.  */
  31
  32 #undef RETURN_IN_MEMORY
  33 #define RETURN_IN_MEMORY(TYPE) \
  34   (TYPE_MODE (TYPE) == BLKmode \
  35    || TREE_CODE (TYPE) == RECORD_TYPE || TREE_CODE(TYPE) == UNION_TYPE)
  36
  37 /* Define which macros to predefine.  __svr4__ is our extension.  */
  38 /* This used to define X86, but james@bigtex.cactus.org says that
  39    is supposed to be defined optionally by user programs--not by default.  */
  40 #define CPP_PREDEFINES \
  41   "-Di386 -Dunix -D__svr4__ -Asystem(unix) -Acpu(i386) -Amachine(i386)"
  42
  43 /* If the host and target formats match, output the floats as hex.  */
  44 #if HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT
  45 #if defined (HOST_WORDS_BIG_ENDIAN) == WORDS_BIG_ENDIAN
  46 /* This is how to output assembly code to define a `float' constant.
  47    We always have to use a .long pseudo-op to do this because the native
  48    SVR4 ELF assembler is buggy and it generates incorrect values when we
  49    try to use the .float pseudo-op instead.  */
  50
  51 #undef ASM_OUTPUT_FLOAT
  52 #define ASM_OUTPUT_FLOAT(FILE,VALUE)                                    \
  53 do { long value;                                                        \
  54      REAL_VALUE_TO_TARGET_SINGLE ((VALUE), value);                      \
  55      fprintf((FILE), "%s\t0x%x\n", ASM_LONG, value);                    \
  56    } while (0)
  57
  58 /* This is how to output assembly code to define a `double' constant.
  59    We always have to use a pair of .long pseudo-ops to do this because
  60    the native SVR4 ELF assembler is buggy and it generates incorrect
  61    values when we try to use the the .double pseudo-op instead.  */
  62
  63 #undef ASM_OUTPUT_DOUBLE
  64 #define ASM_OUTPUT_DOUBLE(FILE,VALUE)                                   \
  65 do { long value[2];                                                     \
  66      REAL_VALUE_TO_TARGET_DOUBLE ((VALUE), value);                      \
  67      fprintf((FILE), "%s\t0x%x\n", ASM_LONG, value[0]);                 \
  68      fprintf((FILE), "%s\t0x%x\n", ASM_LONG, value[1]);                 \
  69    } while (0)
  70 #endif /* word order matches */
  71 #endif /* HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT */
  72
  73 /* Output at beginning of assembler file.  */
  74 /* The .file command should always begin the output.  */
  75
  76 #undef ASM_FILE_START
  77 #define ASM_FILE_START(FILE)                                            \
  78   do {                                                                  \
  79         output_file_directive (FILE, main_input_filename);              \
  80         fprintf (FILE, "\t.version\t\"01.01\"\n");                      \
  81   } while (0)
  82
  83 /* Define the register numbers to be used in Dwarf debugging information.
  84    The SVR4 reference port C compiler uses the following register numbers
  85    in its Dwarf output code:
  86
  87         0 for %eax (gnu regno = 0)
  88         1 for %ecx (gnu regno = 2)
  89         2 for %edx (gnu regno = 1)
  90         3 for %ebx (gnu regno = 3)
  91         4 for %esp (gnu regno = 7)
  92         5 for %ebp (gnu regno = 6)
  93         6 for %esi (gnu regno = 4)
  94         7 for %edi (gnu regno = 5)
  95
  96    The following three DWARF register numbers are never generated by
  97    the SVR4 C compiler or by the GNU compilers, but SDB on x86/svr4
  98    believes these numbers have these meanings.
  99
 100         8  for %eip    (no gnu equivalent)
 101         9  for %eflags (no gnu equivalent)
 102         10 for %trapno (no gnu equivalent)
 103
 104    It is not at all clear how we should number the FP stack registers
 105    for the x86 architecture.  If the version of SDB on x86/svr4 were
 106    a bit less brain dead with respect to floating-point then we would
 107    have a precedent to follow with respect to DWARF register numbers
 108    for x86 FP registers, but the SDB on x86/svr4 is so completely
 109    broken with respect to FP registers that it is hardly worth thinking
 110    of it as something to strive for compatibility with.
 111
 112    The verison of x86/svr4 SDB I have at the moment does (partially)
 113    seem to believe that DWARF register number 11 is associated with
 114    the x86 register %st(0), but that's about all.  Higher DWARF
 115    register numbers don't seem to be associated with anything in
 116    particular, and even for DWARF regno 11, SDB only seems to under-
 117    stand that it should say that a variable lives in %st(0) (when
 118    asked via an `=' command) if we said it was in DWARF regno 11,
 119    but SDB still prints garbage when asked for the value of the
 120    variable in question (via a `/' command).
 121
 122    (Also note that the labels SDB prints for various FP stack regs
 123    when doing an `x' command are all wrong.)
 124
 125    Note that these problems generally don't affect the native SVR4
 126    C compiler because it doesn't allow the use of -O with -g and
 127    because when it is *not* optimizing, it allocates a memory
 128    location for each floating-point variable, and the memory
 129    location is what gets described in the DWARF AT_location
 130    attribute for the variable in question.
 131
 132    Regardless of the severe mental illness of the x86/svr4 SDB, we
 133    do something sensible here and we use the following DWARF
 134    register numbers.  Note that these are all stack-top-relative
 135    numbers.
 136
 137         11 for %st(0) (gnu regno = 8)
 138         12 for %st(1) (gnu regno = 9)
 139         13 for %st(2) (gnu regno = 10)
 140         14 for %st(3) (gnu regno = 11)
 141         15 for %st(4) (gnu regno = 12)
 142         16 for %st(5) (gnu regno = 13)
 143         17 for %st(6) (gnu regno = 14)
 144         18 for %st(7) (gnu regno = 15)
 145 */
 146
 147 #undef DBX_REGISTER_NUMBER
 148 #define DBX_REGISTER_NUMBER(n) \
 149 ((n) == 0 ? 0 \
 150  : (n) == 1 ? 2 \
 151  : (n) == 2 ? 1 \
 152  : (n) == 3 ? 3 \
 153  : (n) == 4 ? 6 \
 154  : (n) == 5 ? 7 \
 155  : (n) == 6 ? 5 \
 156  : (n) == 7 ? 4 \
 157  : ((n) >= FIRST_STACK_REG && (n) <= LAST_STACK_REG) ? (n)+3 \
 158  : (-1))
 159
 160 /* The routine used to output sequences of byte values.  We use a special
 161    version of this for most svr4 targets because doing so makes the
 162    generated assembly code more compact (and thus faster to assemble)
 163    as well as more readable.  Note that if we find subparts of the
 164    character sequence which end with NUL (and which are shorter than
 165    STRING_LIMIT) we output those using ASM_OUTPUT_LIMITED_STRING.  */
 166
 167 #undef ASM_OUTPUT_ASCII
 168 #define ASM_OUTPUT_ASCII(FILE, STR, LENGTH)                             \
 169   do                                                                    \
 170     {                                                                   \
 171       register unsigned char *_ascii_bytes = (unsigned char *) (STR);   \
 172       register unsigned char *limit = _ascii_bytes + (LENGTH);          \
 173       register unsigned bytes_in_chunk = 0;                             \
 174       for (; _ascii_bytes < limit; _ascii_bytes++)                      \
 175         {                                                               \
 176           register unsigned char *p;                                    \
 177           if (bytes_in_chunk >= 64)                                     \
 178             {                                                           \
 179               fputc ('\n', (FILE));                                     \
 180               bytes_in_chunk = 0;                                       \
 181             }                                                           \
 182           for (p = _ascii_bytes; p < limit && *p != '\0'; p++)          \
 183             continue;                                                   \
 184           if (p < limit && (p - _ascii_bytes) <= STRING_LIMIT)          \
 185             {                                                           \
 186               if (bytes_in_chunk > 0)                                   \
 187                 {                                                       \
 188                   fputc ('\n', (FILE));                                 \
 189                   bytes_in_chunk = 0;                                   \
 190                 }                                                       \
 191               ASM_OUTPUT_LIMITED_STRING ((FILE), _ascii_bytes);         \
 192               _ascii_bytes = p;                                         \
 193             }                                                           \
 194           else                                                          \
 195             {                                                           \
 196               if (bytes_in_chunk == 0)                                  \
 197                 fprintf ((FILE), "\t.byte\t");                          \
 198               else                                                      \
 199                 fputc (',', (FILE));                                    \
 200               fprintf ((FILE), "0x%02x", *_ascii_bytes);                \
 201               bytes_in_chunk += 5;                                      \
 202             }                                                           \
 203         }                                                               \
 204       if (bytes_in_chunk > 0)                                           \
 205         fprintf ((FILE), "\n");                                         \
 206     }                                                                   \
 207   while (0)
 208
 209 /* This is how to output an element of a case-vector that is relative.
 210    This is only used for PIC code.  See comments by the `casesi' insn in
 211    i386.md for an explanation of the expression this outputs. */
 212
 213 #undef ASM_OUTPUT_ADDR_DIFF_ELT
 214 #define ASM_OUTPUT_ADDR_DIFF_ELT(FILE, VALUE, REL) \
 215   fprintf (FILE, "\t.long _GLOBAL_OFFSET_TABLE_+[.-%s%d]\n", LPREFIX, VALUE)
 216
 217 /* Indicate that jump tables go in the text section.  This is
 218    necessary when compiling PIC code.  */
 219
 220 #define JUMP_TABLES_IN_TEXT_SECTION
 221
 222 /* Biggest alignment that any structure field can require on this
 223    machine, in bits.  If packing is in effect, this can be smaller than
 224    normal.  */
 225
 226 #define BIGGEST_FIELD_ALIGNMENT \
 227   (maximum_field_alignment ? maximum_field_alignment : 32)
 228
 229 extern int maximum_field_alignment;
 230
 231 /* If bit field type is int, don't let it cross an int,
 232    and give entire struct the alignment of an int.  */
 233 /* Required on the 386 since it doesn't have bitfield insns.  */
 234 /* If packing is in effect, then the type doesn't matter.  */
 235
 236 #undef PCC_BITFIELD_TYPE_MATTERS
 237 #define PCC_BITFIELD_TYPE_MATTERS (maximum_field_alignment == 0)
 238
 239 /* Handle #pragma pack and sometimes #pragma weak.  */
 240 #define HANDLE_SYSV_PRAGMA