gcc/config/elfos.h

   1 /* elfos.h  --  operating system specific defines to be used when
   2    targeting GCC for some generic ELF system
   3    Copyright (C) 1991, 1994, 1995, 1999, 2000, 2001, 2002, 2003, 2004
   4    Free Software Foundation, Inc.
   5    Based on svr4.h contributed by Ron Guilmette (rfg@netcom.com).
   6
   7 This file is part of GCC.
   8
   9 GCC is free software; you can redistribute it and/or modify
  10 it under the terms of the GNU General Public License as published by
  11 the Free Software Foundation; either version 2, or (at your option)
  12 any later version.
  13
  14 GCC is distributed in the hope that it will be useful,
  15 but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 GNU General Public License for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with GCC; see the file COPYING.  If not, write to
  21 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  22 Boston, MA 02110-1301, USA.  */
  23
  24 #define TARGET_OBJFMT_CPP_BUILTINS()            \
  25   do                                            \
  26     {                                           \
  27         builtin_define ("__ELF__");             \
  28     }                                           \
  29   while (0)
  30
  31 /* Define a symbol indicating that we are using elfos.h.
  32    Some CPU specific configuration files use this.  */
  33 #define USING_ELFOS_H
  34
  35 /* The prefix to add to user-visible assembler symbols.
  36
  37    For ELF systems the convention is *not* to prepend a leading
  38    underscore onto user-level symbol names.  */
  39
  40 #undef  USER_LABEL_PREFIX
  41 #define USER_LABEL_PREFIX ""
  42
  43 /* The biggest alignment supported by ELF in bits. 32-bit ELF
  44    supports section alignment up to (0x80000000 * 8), while
  45    64-bit ELF supports (0x8000000000000000 * 8). If this macro
  46    is not defined, the default is the largest alignment supported
  47    by 32-bit ELF and representable on a 32-bit host. Use this
  48    macro to limit the alignment which can be specified using
  49    the `__attribute__ ((aligned (N)))' construct.  */
  50 #ifndef MAX_OFILE_ALIGNMENT
  51 #define MAX_OFILE_ALIGNMENT (((unsigned int) 1 << 28) * 8)
  52 #endif
  53
  54 /* Use periods rather than dollar signs in special g++ assembler names.  */
  55
  56 #define NO_DOLLAR_IN_LABEL
  57
  58 /* Writing `int' for a bit-field forces int alignment for the structure.  */
  59
  60 #ifndef PCC_BITFIELD_TYPE_MATTERS
  61 #define PCC_BITFIELD_TYPE_MATTERS 1
  62 #endif
  63
  64 /* Handle #pragma weak and #pragma pack.  */
  65
  66 #define HANDLE_SYSV_PRAGMA 1
  67
  68 /* All ELF targets can support DWARF-2.  */
  69
  70 #define DWARF2_DEBUGGING_INFO 1
  71
  72 /* The GNU tools operate better with dwarf2, and it is required by some
  73    psABI's.  Since we don't have any native tools to be compatible with,
  74    default to dwarf2.  */
  75
  76 #ifndef PREFERRED_DEBUGGING_TYPE
  77 #define PREFERRED_DEBUGGING_TYPE DWARF2_DEBUG
  78 #endif
  79
  80 /* All SVR4 targets use the ELF object file format.  */
  81 #define OBJECT_FORMAT_ELF
  82
  83
  84 /* Output #ident as a .ident.  */
  85
  86 #define ASM_OUTPUT_IDENT(FILE, NAME) \
  87   fprintf (FILE, "%s\"%s\"\n", IDENT_ASM_OP, NAME);
  88
  89 #define IDENT_ASM_OP "\t.ident\t"
  90
  91 #undef  SET_ASM_OP
  92 #define SET_ASM_OP      "\t.set\t"
  93
  94 /* Most svr4 assemblers want a .file directive at the beginning of
  95    their input file.  */
  96 #define TARGET_ASM_FILE_START_FILE_DIRECTIVE true
  97
  98 /* This is how to allocate empty space in some section.  The .zero
  99    pseudo-op is used for this on most svr4 assemblers.  */
 100
 101 #define SKIP_ASM_OP     "\t.zero\t"
 102
 103 #undef  ASM_OUTPUT_SKIP
 104 #define ASM_OUTPUT_SKIP(FILE, SIZE) \
 105    fprintf ((FILE), "%s"HOST_WIDE_INT_PRINT_UNSIGNED"\n",\
 106             SKIP_ASM_OP, (SIZE))
 107
 108 /* This is how to store into the string LABEL
 109    the symbol_ref name of an internal numbered label where
 110    PREFIX is the class of label and NUM is the number within the class.
 111    This is suitable for output with `assemble_name'.
 112
 113    For most svr4 systems, the convention is that any symbol which begins
 114    with a period is not put into the linker symbol table by the assembler.  */
 115
 116 #undef  ASM_GENERATE_INTERNAL_LABEL
 117 #define ASM_GENERATE_INTERNAL_LABEL(LABEL, PREFIX, NUM)         \
 118   do                                                            \
 119     {                                                           \
 120       sprintf (LABEL, "*.%s%u", PREFIX, (unsigned) (NUM));      \
 121     }                                                           \
 122   while (0)
 123
 124 /* Output the label which precedes a jumptable.  Note that for all svr4
 125    systems where we actually generate jumptables (which is to say every
 126    svr4 target except i386, where we use casesi instead) we put the jump-
 127    tables into the .rodata section and since other stuff could have been
 128    put into the .rodata section prior to any given jumptable, we have to
 129    make sure that the location counter for the .rodata section gets pro-
 130    perly re-aligned prior to the actual beginning of the jump table.  */
 131
 132 #undef ALIGN_ASM_OP
 133 #define ALIGN_ASM_OP "\t.align\t"
 134
 135 #ifndef ASM_OUTPUT_BEFORE_CASE_LABEL
 136 #define ASM_OUTPUT_BEFORE_CASE_LABEL(FILE, PREFIX, NUM, TABLE) \
 137   ASM_OUTPUT_ALIGN ((FILE), 2);
 138 #endif
 139
 140 #undef  ASM_OUTPUT_CASE_LABEL
 141 #define ASM_OUTPUT_CASE_LABEL(FILE, PREFIX, NUM, JUMPTABLE)             \
 142   do                                                                    \
 143     {                                                                   \
 144       ASM_OUTPUT_BEFORE_CASE_LABEL (FILE, PREFIX, NUM, JUMPTABLE)       \
 145         (*targetm.asm_out.internal_label) (FILE, PREFIX, NUM);                  \
 146     }                                                                   \
 147   while (0)
 148
 149 /* The standard SVR4 assembler seems to require that certain builtin
 150    library routines (e.g. .udiv) be explicitly declared as .globl
 151    in each assembly file where they are referenced.  */
 152
 153 #define ASM_OUTPUT_EXTERNAL_LIBCALL(FILE, FUN)  \
 154   (*targetm.asm_out.globalize_label) (FILE, XSTR (FUN, 0))
 155
 156 /* This says how to output assembler code to declare an
 157    uninitialized external linkage data object.  Under SVR4,
 158    the linker seems to want the alignment of data objects
 159    to depend on their types.  We do exactly that here.  */
 160
 161 #define COMMON_ASM_OP   "\t.comm\t"
 162
 163 #undef  ASM_OUTPUT_ALIGNED_COMMON
 164 #define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)              \
 165   do                                                                    \
 166     {                                                                   \
 167       fprintf ((FILE), "%s", COMMON_ASM_OP);                            \
 168       assemble_name ((FILE), (NAME));                                   \
 169       fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n",          \
 170                (SIZE), (ALIGN) / BITS_PER_UNIT);                        \
 171     }                                                                   \
 172   while (0)
 173
 174 /* This says how to output assembler code to declare an
 175    uninitialized internal linkage data object.  Under SVR4,
 176    the linker seems to want the alignment of data objects
 177    to depend on their types.  We do exactly that here.  */
 178
 179 #define LOCAL_ASM_OP    "\t.local\t"
 180
 181 #undef  ASM_OUTPUT_ALIGNED_LOCAL
 182 #define ASM_OUTPUT_ALIGNED_LOCAL(FILE, NAME, SIZE, ALIGN)       \
 183   do                                                            \
 184     {                                                           \
 185       fprintf ((FILE), "%s", LOCAL_ASM_OP);                     \
 186       assemble_name ((FILE), (NAME));                           \
 187       fprintf ((FILE), "\n");                                   \
 188       ASM_OUTPUT_ALIGNED_COMMON (FILE, NAME, SIZE, ALIGN);      \
 189     }                                                           \
 190   while (0)
 191
 192 /* This is the pseudo-op used to generate a contiguous sequence of byte
 193    values from a double-quoted string WITHOUT HAVING A TERMINATING NUL
 194    AUTOMATICALLY APPENDED.  This is the same for most svr4 assemblers.  */
 195
 196 #undef  ASCII_DATA_ASM_OP
 197 #define ASCII_DATA_ASM_OP       "\t.ascii\t"
 198
 199 /* Support a read-only data section.  */
 200 #define READONLY_DATA_SECTION_ASM_OP    "\t.section\t.rodata"
 201
 202 /* On svr4, we *do* have support for the .init and .fini sections, and we
 203    can put stuff in there to be executed before and after `main'.  We let
 204    crtstuff.c and other files know this by defining the following symbols.
 205    The definitions say how to change sections to the .init and .fini
 206    sections.  This is the same for all known svr4 assemblers.  */
 207
 208 #define INIT_SECTION_ASM_OP     "\t.section\t.init"
 209 #define FINI_SECTION_ASM_OP     "\t.section\t.fini"
 210
 211 /* Output assembly directive to move to the beginning of current section.  */
 212 #ifdef HAVE_GAS_SUBSECTION_ORDERING
 213 # define ASM_SECTION_START_OP   "\t.subsection\t-1"
 214 # define ASM_OUTPUT_SECTION_START(FILE) \
 215   fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
 216 #endif
 217
 218 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
 219
 220 /* Switch into a generic section.  */
 221 #define TARGET_ASM_NAMED_SECTION  default_elf_asm_named_section
 222
 223 #undef  TARGET_ASM_SELECT_RTX_SECTION
 224 #define TARGET_ASM_SELECT_RTX_SECTION default_elf_select_rtx_section
 225 #undef  TARGET_ASM_SELECT_SECTION
 226 #define TARGET_ASM_SELECT_SECTION default_elf_select_section
 227 #undef  TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
 228 #define TARGET_HAVE_SWITCHABLE_BSS_SECTIONS true
 229
 230 /* Define the strings used for the special svr4 .type and .size directives.
 231    These strings generally do not vary from one system running svr4 to
 232    another, but if a given system (e.g. m88k running svr) needs to use
 233    different pseudo-op names for these, they may be overridden in the
 234    file which includes this one.  */
 235
 236 #define TYPE_ASM_OP     "\t.type\t"
 237 #define SIZE_ASM_OP     "\t.size\t"
 238
 239 /* This is how we tell the assembler that a symbol is weak.  */
 240
 241 #define ASM_WEAKEN_LABEL(FILE, NAME)    \
 242   do                                    \
 243     {                                   \
 244       fputs ("\t.weak\t", (FILE));      \
 245       assemble_name ((FILE), (NAME));   \
 246       fputc ('\n', (FILE));             \
 247     }                                   \
 248   while (0)
 249
 250 /* The following macro defines the format used to output the second
 251    operand of the .type assembler directive.  Different svr4 assemblers
 252    expect various different forms for this operand.  The one given here
 253    is just a default.  You may need to override it in your machine-
 254    specific tm.h file (depending upon the particulars of your assembler).  */
 255
 256 #define TYPE_OPERAND_FMT        "@%s"
 257
 258 /* Write the extra assembler code needed to declare a function's result.
 259    Most svr4 assemblers don't require any special declaration of the
 260    result value, but there are exceptions.  */
 261
 262 #ifndef ASM_DECLARE_RESULT
 263 #define ASM_DECLARE_RESULT(FILE, RESULT)
 264 #endif
 265
 266 /* These macros generate the special .type and .size directives which
 267    are used to set the corresponding fields of the linker symbol table
 268    entries in an ELF object file under SVR4.  These macros also output
 269    the starting labels for the relevant functions/objects.  */
 270
 271 /* Write the extra assembler code needed to declare a function properly.
 272    Some svr4 assemblers need to also have something extra said about the
 273    function's return value.  We allow for that here.  */
 274
 275 #ifndef ASM_DECLARE_FUNCTION_NAME
 276 #define ASM_DECLARE_FUNCTION_NAME(FILE, NAME, DECL)             \
 277   do                                                            \
 278     {                                                           \
 279       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "function");       \
 280       ASM_DECLARE_RESULT (FILE, DECL_RESULT (DECL));            \
 281       ASM_OUTPUT_LABEL (FILE, NAME);                            \
 282     }                                                           \
 283   while (0)
 284 #endif
 285
 286 /* Write the extra assembler code needed to declare an object properly.  */
 287
 288 #define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL)               \
 289   do                                                            \
 290     {                                                           \
 291       HOST_WIDE_INT size;                                       \
 292                                                                 \
 293       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object");         \
 294                                                                 \
 295       size_directive_output = 0;                                \
 296       if (!flag_inhibit_size_directive                          \
 297           && (DECL) && DECL_SIZE (DECL))                        \
 298         {                                                       \
 299           size_directive_output = 1;                            \
 300           size = int_size_in_bytes (TREE_TYPE (DECL));          \
 301           ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, size);         \
 302         }                                                       \
 303                                                                 \
 304       ASM_OUTPUT_LABEL (FILE, NAME);                            \
 305     }                                                           \
 306   while (0)
 307
 308 /* Output the size directive for a decl in rest_of_decl_compilation
 309    in the case where we did not do so before the initializer.
 310    Once we find the error_mark_node, we know that the value of
 311    size_directive_output was set
 312    by ASM_DECLARE_OBJECT_NAME when it was run for the same decl.  */
 313
 314 #undef ASM_FINISH_DECLARE_OBJECT
 315 #define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)\
 316   do                                                            \
 317     {                                                           \
 318       const char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0);   \
 319       HOST_WIDE_INT size;                                       \
 320                                                                 \
 321       if (!flag_inhibit_size_directive                          \
 322           && DECL_SIZE (DECL)                                   \
 323           && ! AT_END && TOP_LEVEL                              \
 324           && DECL_INITIAL (DECL) == error_mark_node             \
 325           && !size_directive_output)                            \
 326         {                                                       \
 327           size_directive_output = 1;                            \
 328           size = int_size_in_bytes (TREE_TYPE (DECL));          \
 329           ASM_OUTPUT_SIZE_DIRECTIVE (FILE, name, size);         \
 330         }                                                       \
 331     }                                                           \
 332   while (0)
 333
 334 /* This is how to declare the size of a function.  */
 335 #ifndef ASM_DECLARE_FUNCTION_SIZE
 336 #define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)            \
 337   do                                                            \
 338     {                                                           \
 339       if (!flag_inhibit_size_directive)                         \
 340         ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);                 \
 341     }                                                           \
 342   while (0)
 343 #endif
 344
 345 /* A table of bytes codes used by the ASM_OUTPUT_ASCII and
 346    ASM_OUTPUT_LIMITED_STRING macros.  Each byte in the table
 347    corresponds to a particular byte value [0..255].  For any
 348    given byte value, if the value in the corresponding table
 349    position is zero, the given character can be output directly.
 350    If the table value is 1, the byte must be output as a \ooo
 351    octal escape.  If the tables value is anything else, then the
 352    byte value should be output as a \ followed by the value
 353    in the table.  Note that we can use standard UN*X escape
 354    sequences for many control characters, but we don't use
 355    \a to represent BEL because some svr4 assemblers (e.g. on
 356    the i386) don't know about that.  Also, we don't use \v
 357    since some versions of gas, such as 2.2 did not accept it.  */
 358
 359 #define ESCAPES \
 360 "\1\1\1\1\1\1\1\1btn\1fr\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\
 361 \0\0\"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
 362 \0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\\\0\0\0\
 363 \0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1\
 364 \1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\
 365 \1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\
 366 \1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\
 367 \1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1\1"
 368
 369 /* Some svr4 assemblers have a limit on the number of characters which
 370    can appear in the operand of a .string directive.  If your assembler
 371    has such a limitation, you should define STRING_LIMIT to reflect that
 372    limit.  Note that at least some svr4 assemblers have a limit on the
 373    actual number of bytes in the double-quoted string, and that they
 374    count each character in an escape sequence as one byte.  Thus, an
 375    escape sequence like \377 would count as four bytes.
 376
 377    If your target assembler doesn't support the .string directive, you
 378    should define this to zero.
 379 */
 380
 381 #define STRING_LIMIT    ((unsigned) 256)
 382
 383 #define STRING_ASM_OP   "\t.string\t"
 384
 385 /* The routine used to output NUL terminated strings.  We use a special
 386    version of this for most svr4 targets because doing so makes the
 387    generated assembly code more compact (and thus faster to assemble)
 388    as well as more readable, especially for targets like the i386
 389    (where the only alternative is to output character sequences as
 390    comma separated lists of numbers).  */
 391
 392 #define ASM_OUTPUT_LIMITED_STRING(FILE, STR)            \
 393   do                                                    \
 394     {                                                   \
 395       register const unsigned char *_limited_str =      \
 396         (const unsigned char *) (STR);                  \
 397       register unsigned ch;                             \
 398                                                         \
 399       fprintf ((FILE), "%s\"", STRING_ASM_OP);          \
 400                                                         \
 401       for (; (ch = *_limited_str); _limited_str++)      \
 402         {                                               \
 403           register int escape;                          \
 404                                                         \
 405           switch (escape = ESCAPES[ch])                 \
 406             {                                           \
 407             case 0:                                     \
 408               putc (ch, (FILE));                        \
 409               break;                                    \
 410             case 1:                                     \
 411               fprintf ((FILE), "\\%03o", ch);           \
 412               break;                                    \
 413             default:                                    \
 414               putc ('\\', (FILE));                      \
 415               putc (escape, (FILE));                    \
 416               break;                                    \
 417             }                                           \
 418         }                                               \
 419                                                         \
 420       fprintf ((FILE), "\"\n");                         \
 421     }                                                   \
 422   while (0)
 423
 424 /* The routine used to output sequences of byte values.  We use a special
 425    version of this for most svr4 targets because doing so makes the
 426    generated assembly code more compact (and thus faster to assemble)
 427    as well as more readable.  Note that if we find subparts of the
 428    character sequence which end with NUL (and which are shorter than
 429    STRING_LIMIT) we output those using ASM_OUTPUT_LIMITED_STRING.  */
 430
 431 #undef  ASM_OUTPUT_ASCII
 432 #define ASM_OUTPUT_ASCII(FILE, STR, LENGTH)                             \
 433   do                                                                    \
 434     {                                                                   \
 435       const unsigned char *_ascii_bytes =                               \
 436         (const unsigned char *) (STR);                                  \
 437       const unsigned char *limit = _ascii_bytes + (LENGTH);             \
 438       const unsigned char *last_null = NULL;                            \
 439       unsigned bytes_in_chunk = 0;                                      \
 440                                                                         \
 441       for (; _ascii_bytes < limit; _ascii_bytes++)                      \
 442         {                                                               \
 443           const unsigned char *p;                                       \
 444                                                                         \
 445           if (bytes_in_chunk >= 60)                                     \
 446             {                                                           \
 447               fprintf ((FILE), "\"\n");                                 \
 448               bytes_in_chunk = 0;                                       \
 449             }                                                           \
 450                                                                         \
 451           if (_ascii_bytes > last_null)                                 \
 452             {                                                           \
 453               for (p = _ascii_bytes; p < limit && *p != '\0'; p++)      \
 454                 continue;                                               \
 455               last_null = p;                                            \
 456             }                                                           \
 457           else                                                          \
 458             p = last_null;                                              \
 459                                                                         \
 460           if (p < limit && (p - _ascii_bytes) <= (long)STRING_LIMIT)    \
 461             {                                                           \
 462               if (bytes_in_chunk > 0)                                   \
 463                 {                                                       \
 464                   fprintf ((FILE), "\"\n");                             \
 465                   bytes_in_chunk = 0;                                   \
 466                 }                                                       \
 467                                                                         \
 468               ASM_OUTPUT_LIMITED_STRING ((FILE), _ascii_bytes);         \
 469               _ascii_bytes = p;                                         \
 470             }                                                           \
 471           else                                                          \
 472             {                                                           \
 473               register int escape;                                      \
 474               register unsigned ch;                                     \
 475                                                                         \
 476               if (bytes_in_chunk == 0)                                  \
 477                 fprintf ((FILE), "%s\"", ASCII_DATA_ASM_OP);            \
 478                                                                         \
 479               switch (escape = ESCAPES[ch = *_ascii_bytes])             \
 480                 {                                                       \
 481                 case 0:                                                 \
 482                   putc (ch, (FILE));                                    \
 483                   bytes_in_chunk++;                                     \
 484                   break;                                                \
 485                 case 1:                                                 \
 486                   fprintf ((FILE), "\\%03o", ch);                       \
 487                   bytes_in_chunk += 4;                                  \
 488                   break;                                                \
 489                 default:                                                \
 490                   putc ('\\', (FILE));                                  \
 491                   putc (escape, (FILE));                                \
 492                   bytes_in_chunk += 2;                                  \
 493                   break;                                                \
 494                 }                                                       \
 495             }                                                           \
 496         }                                                               \
 497                                                                         \
 498       if (bytes_in_chunk > 0)                                           \
 499         fprintf ((FILE), "\"\n");                                       \
 500     }                                                                   \
 501   while (0)
 502
 503 /* Allow the use of the -frecord-gcc-switches switch via the
 504    elf_record_gcc_switches function defined in varasm.c.  */
 505 #undef  TARGET_ASM_RECORD_GCC_SWITCHES
 506 #define TARGET_ASM_RECORD_GCC_SWITCHES elf_record_gcc_switches
 507
 508 /* A C statement (sans semicolon) to output to the stdio stream STREAM
 509    any text necessary for declaring the name of an external symbol
 510    named NAME which is referenced in this compilation but not defined.
 511    It is needed to properly support non-default visibility.  */
 512
 513 #ifndef ASM_OUTPUT_EXTERNAL
 514 #define ASM_OUTPUT_EXTERNAL(FILE, DECL, NAME) \
 515   default_elf_asm_output_external (FILE, DECL, NAME)
 516 #endif