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    2007 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 3, 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 COPYING3.  If not see
  21 <http://www.gnu.org/licenses/>.  */
  22
  23 #define TARGET_OBJFMT_CPP_BUILTINS()            \
  24   do                                            \
  25     {                                           \
  26         builtin_define ("__ELF__");             \
  27     }                                           \
  28   while (0)
  29
  30 /* Define a symbol indicating that we are using elfos.h.
  31    Some CPU specific configuration files use this.  */
  32 #define USING_ELFOS_H
  33
  34 /* The prefix to add to user-visible assembler symbols.
  35
  36    For ELF systems the convention is *not* to prepend a leading
  37    underscore onto user-level symbol names.  */
  38
  39 #undef  USER_LABEL_PREFIX
  40 #define USER_LABEL_PREFIX ""
  41
  42 /* The biggest alignment supported by ELF in bits. 32-bit ELF
  43    supports section alignment up to (0x80000000 * 8), while
  44    64-bit ELF supports (0x8000000000000000 * 8). If this macro
  45    is not defined, the default is the largest alignment supported
  46    by 32-bit ELF and representable on a 32-bit host. Use this
  47    macro to limit the alignment which can be specified using
  48    the `__attribute__ ((aligned (N)))' construct.  */
  49 #ifndef MAX_OFILE_ALIGNMENT
  50 #define MAX_OFILE_ALIGNMENT (((unsigned int) 1 << 28) * 8)
  51 #endif
  52
  53 /* Use periods rather than dollar signs in special g++ assembler names.  */
  54
  55 #define NO_DOLLAR_IN_LABEL
  56
  57 /* Writing `int' for a bit-field forces int alignment for the structure.  */
  58
  59 #ifndef PCC_BITFIELD_TYPE_MATTERS
  60 #define PCC_BITFIELD_TYPE_MATTERS 1
  61 #endif
  62
  63 /* Handle #pragma weak and #pragma pack.  */
  64
  65 #define HANDLE_SYSV_PRAGMA 1
  66
  67 /* All ELF targets can support DWARF-2.  */
  68
  69 #define DWARF2_DEBUGGING_INFO 1
  70
  71 /* The GNU tools operate better with dwarf2, and it is required by some
  72    psABI's.  Since we don't have any native tools to be compatible with,
  73    default to dwarf2.  */
  74
  75 #ifndef PREFERRED_DEBUGGING_TYPE
  76 #define PREFERRED_DEBUGGING_TYPE DWARF2_DEBUG
  77 #endif
  78
  79 /* All SVR4 targets use the ELF object file format.  */
  80 #define OBJECT_FORMAT_ELF
  81
  82
  83 /* Output #ident as a .ident.  */
  84
  85 #define ASM_OUTPUT_IDENT(FILE, NAME) \
  86   fprintf (FILE, "%s\"%s\"\n", IDENT_ASM_OP, NAME);
  87
  88 #define IDENT_ASM_OP "\t.ident\t"
  89
  90 #undef  SET_ASM_OP
  91 #define SET_ASM_OP      "\t.set\t"
  92
  93 /* Most svr4 assemblers want a .file directive at the beginning of
  94    their input file.  */
  95 #define TARGET_ASM_FILE_START_FILE_DIRECTIVE true
  96
  97 /* This is how to allocate empty space in some section.  The .zero
  98    pseudo-op is used for this on most svr4 assemblers.  */
  99
 100 #define SKIP_ASM_OP     "\t.zero\t"
 101
 102 #undef  ASM_OUTPUT_SKIP
 103 #define ASM_OUTPUT_SKIP(FILE, SIZE) \
 104    fprintf ((FILE), "%s"HOST_WIDE_INT_PRINT_UNSIGNED"\n",\
 105             SKIP_ASM_OP, (SIZE))
 106
 107 /* This is how to store into the string LABEL
 108    the symbol_ref name of an internal numbered label where
 109    PREFIX is the class of label and NUM is the number within the class.
 110    This is suitable for output with `assemble_name'.
 111
 112    For most svr4 systems, the convention is that any symbol which begins
 113    with a period is not put into the linker symbol table by the assembler.  */
 114
 115 #undef  ASM_GENERATE_INTERNAL_LABEL
 116 #define ASM_GENERATE_INTERNAL_LABEL(LABEL, PREFIX, NUM)         \
 117   do                                                            \
 118     {                                                           \
 119       sprintf (LABEL, "*.%s%u", PREFIX, (unsigned) (NUM));      \
 120     }                                                           \
 121   while (0)
 122
 123 /* Output the label which precedes a jumptable.  Note that for all svr4
 124    systems where we actually generate jumptables (which is to say every
 125    svr4 target except i386, where we use casesi instead) we put the jump-
 126    tables into the .rodata section and since other stuff could have been
 127    put into the .rodata section prior to any given jumptable, we have to
 128    make sure that the location counter for the .rodata section gets pro-
 129    perly re-aligned prior to the actual beginning of the jump table.  */
 130
 131 #undef ALIGN_ASM_OP
 132 #define ALIGN_ASM_OP "\t.align\t"
 133
 134 #ifndef ASM_OUTPUT_BEFORE_CASE_LABEL
 135 #define ASM_OUTPUT_BEFORE_CASE_LABEL(FILE, PREFIX, NUM, TABLE) \
 136   ASM_OUTPUT_ALIGN ((FILE), 2);
 137 #endif
 138
 139 #undef  ASM_OUTPUT_CASE_LABEL
 140 #define ASM_OUTPUT_CASE_LABEL(FILE, PREFIX, NUM, JUMPTABLE)             \
 141   do                                                                    \
 142     {                                                                   \
 143       ASM_OUTPUT_BEFORE_CASE_LABEL (FILE, PREFIX, NUM, JUMPTABLE)       \
 144         (*targetm.asm_out.internal_label) (FILE, PREFIX, NUM);                  \
 145     }                                                                   \
 146   while (0)
 147
 148 /* The standard SVR4 assembler seems to require that certain builtin
 149    library routines (e.g. .udiv) be explicitly declared as .globl
 150    in each assembly file where they are referenced.  */
 151
 152 #define ASM_OUTPUT_EXTERNAL_LIBCALL(FILE, FUN)  \
 153   (*targetm.asm_out.globalize_label) (FILE, XSTR (FUN, 0))
 154
 155 /* This says how to output assembler code to declare an
 156    uninitialized external linkage data object.  Under SVR4,
 157    the linker seems to want the alignment of data objects
 158    to depend on their types.  We do exactly that here.  */
 159
 160 #define COMMON_ASM_OP   "\t.comm\t"
 161
 162 #undef  ASM_OUTPUT_ALIGNED_COMMON
 163 #define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)              \
 164   do                                                                    \
 165     {                                                                   \
 166       fprintf ((FILE), "%s", COMMON_ASM_OP);                            \
 167       assemble_name ((FILE), (NAME));                                   \
 168       fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n",          \
 169                (SIZE), (ALIGN) / BITS_PER_UNIT);                        \
 170     }                                                                   \
 171   while (0)
 172
 173 /* This says how to output assembler code to declare an
 174    uninitialized internal linkage data object.  Under SVR4,
 175    the linker seems to want the alignment of data objects
 176    to depend on their types.  We do exactly that here.  */
 177
 178 #define LOCAL_ASM_OP    "\t.local\t"
 179
 180 #undef  ASM_OUTPUT_ALIGNED_LOCAL
 181 #define ASM_OUTPUT_ALIGNED_LOCAL(FILE, NAME, SIZE, ALIGN)       \
 182   do                                                            \
 183     {                                                           \
 184       fprintf ((FILE), "%s", LOCAL_ASM_OP);                     \
 185       assemble_name ((FILE), (NAME));                           \
 186       fprintf ((FILE), "\n");                                   \
 187       ASM_OUTPUT_ALIGNED_COMMON (FILE, NAME, SIZE, ALIGN);      \
 188     }                                                           \
 189   while (0)
 190
 191 /* This is the pseudo-op used to generate a contiguous sequence of byte
 192    values from a double-quoted string WITHOUT HAVING A TERMINATING NUL
 193    AUTOMATICALLY APPENDED.  This is the same for most svr4 assemblers.  */
 194
 195 #undef  ASCII_DATA_ASM_OP
 196 #define ASCII_DATA_ASM_OP       "\t.ascii\t"
 197
 198 /* Support a read-only data section.  */
 199 #define READONLY_DATA_SECTION_ASM_OP    "\t.section\t.rodata"
 200
 201 /* On svr4, we *do* have support for the .init and .fini sections, and we
 202    can put stuff in there to be executed before and after `main'.  We let
 203    crtstuff.c and other files know this by defining the following symbols.
 204    The definitions say how to change sections to the .init and .fini
 205    sections.  This is the same for all known svr4 assemblers.  */
 206
 207 #define INIT_SECTION_ASM_OP     "\t.section\t.init"
 208 #define FINI_SECTION_ASM_OP     "\t.section\t.fini"
 209
 210 /* Output assembly directive to move to the beginning of current section.  */
 211 #ifdef HAVE_GAS_SUBSECTION_ORDERING
 212 # define ASM_SECTION_START_OP   "\t.subsection\t-1"
 213 # define ASM_OUTPUT_SECTION_START(FILE) \
 214   fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
 215 #endif
 216
 217 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
 218
 219 /* Switch into a generic section.  */
 220 #define TARGET_ASM_NAMED_SECTION  default_elf_asm_named_section
 221
 222 #undef  TARGET_ASM_SELECT_RTX_SECTION
 223 #define TARGET_ASM_SELECT_RTX_SECTION default_elf_select_rtx_section
 224 #undef  TARGET_ASM_SELECT_SECTION
 225 #define TARGET_ASM_SELECT_SECTION default_elf_select_section
 226 #undef  TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
 227 #define TARGET_HAVE_SWITCHABLE_BSS_SECTIONS true
 228
 229 /* Define the strings used for the special svr4 .type and .size directives.
 230    These strings generally do not vary from one system running svr4 to
 231    another, but if a given system (e.g. m88k running svr) needs to use
 232    different pseudo-op names for these, they may be overridden in the
 233    file which includes this one.  */
 234
 235 #define TYPE_ASM_OP     "\t.type\t"
 236 #define SIZE_ASM_OP     "\t.size\t"
 237
 238 /* This is how we tell the assembler that a symbol is weak.  */
 239
 240 #define ASM_WEAKEN_LABEL(FILE, NAME)    \
 241   do                                    \
 242     {                                   \
 243       fputs ("\t.weak\t", (FILE));      \
 244       assemble_name ((FILE), (NAME));   \
 245       fputc ('\n', (FILE));             \
 246     }                                   \
 247   while (0)
 248
 249 /* The following macro defines the format used to output the second
 250    operand of the .type assembler directive.  Different svr4 assemblers
 251    expect various different forms for this operand.  The one given here
 252    is just a default.  You may need to override it in your machine-
 253    specific tm.h file (depending upon the particulars of your assembler).  */
 254
 255 #define TYPE_OPERAND_FMT        "@%s"
 256
 257 /* Write the extra assembler code needed to declare a function's result.
 258    Most svr4 assemblers don't require any special declaration of the
 259    result value, but there are exceptions.  */
 260
 261 #ifndef ASM_DECLARE_RESULT
 262 #define ASM_DECLARE_RESULT(FILE, RESULT)
 263 #endif
 264
 265 /* These macros generate the special .type and .size directives which
 266    are used to set the corresponding fields of the linker symbol table
 267    entries in an ELF object file under SVR4.  These macros also output
 268    the starting labels for the relevant functions/objects.  */
 269
 270 /* Write the extra assembler code needed to declare a function properly.
 271    Some svr4 assemblers need to also have something extra said about the
 272    function's return value.  We allow for that here.  */
 273
 274 #ifndef ASM_DECLARE_FUNCTION_NAME
 275 #define ASM_DECLARE_FUNCTION_NAME(FILE, NAME, DECL)             \
 276   do                                                            \
 277     {                                                           \
 278       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "function");       \
 279       ASM_DECLARE_RESULT (FILE, DECL_RESULT (DECL));            \
 280       ASM_OUTPUT_LABEL (FILE, NAME);                            \
 281     }                                                           \
 282   while (0)
 283 #endif
 284
 285 /* Write the extra assembler code needed to declare an object properly.  */
 286
 287 #define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL)               \
 288   do                                                            \
 289     {                                                           \
 290       HOST_WIDE_INT size;                                       \
 291                                                                 \
 292       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object");         \
 293                                                                 \
 294       size_directive_output = 0;                                \
 295       if (!flag_inhibit_size_directive                          \
 296           && (DECL) && DECL_SIZE (DECL))                        \
 297         {                                                       \
 298           size_directive_output = 1;                            \
 299           size = int_size_in_bytes (TREE_TYPE (DECL));          \
 300           ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, size);         \
 301         }                                                       \
 302                                                                 \
 303       ASM_OUTPUT_LABEL (FILE, NAME);                            \
 304     }                                                           \
 305   while (0)
 306
 307 /* Output the size directive for a decl in rest_of_decl_compilation
 308    in the case where we did not do so before the initializer.
 309    Once we find the error_mark_node, we know that the value of
 310    size_directive_output was set
 311    by ASM_DECLARE_OBJECT_NAME when it was run for the same decl.  */
 312
 313 #undef ASM_FINISH_DECLARE_OBJECT
 314 #define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)\
 315   do                                                            \
 316     {                                                           \
 317       const char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0);   \
 318       HOST_WIDE_INT size;                                       \
 319                                                                 \
 320       if (!flag_inhibit_size_directive                          \
 321           && DECL_SIZE (DECL)                                   \
 322           && ! AT_END && TOP_LEVEL                              \
 323           && DECL_INITIAL (DECL) == error_mark_node             \
 324           && !size_directive_output)                            \
 325         {                                                       \
 326           size_directive_output = 1;                            \
 327           size = int_size_in_bytes (TREE_TYPE (DECL));          \
 328           ASM_OUTPUT_SIZE_DIRECTIVE (FILE, name, size);         \
 329         }                                                       \
 330     }                                                           \
 331   while (0)
 332
 333 /* This is how to declare the size of a function.  */
 334 #ifndef ASM_DECLARE_FUNCTION_SIZE
 335 #define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)            \
 336   do                                                            \
 337     {                                                           \
 338       if (!flag_inhibit_size_directive)                         \
 339         ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);                 \
 340     }                                                           \
 341   while (0)
 342 #endif
 343
 344 /* A table of bytes codes used by the ASM_OUTPUT_ASCII and
 345    ASM_OUTPUT_LIMITED_STRING macros.  Each byte in the table
 346    corresponds to a particular byte value [0..255].  For any
 347    given byte value, if the value in the corresponding table
 348    position is zero, the given character can be output directly.
 349    If the table value is 1, the byte must be output as a \ooo
 350    octal escape.  If the tables value is anything else, then the
 351    byte value should be output as a \ followed by the value
 352    in the table.  Note that we can use standard UN*X escape
 353    sequences for many control characters, but we don't use
 354    \a to represent BEL because some svr4 assemblers (e.g. on
 355    the i386) don't know about that.  Also, we don't use \v
 356    since some versions of gas, such as 2.2 did not accept it.  */
 357
 358 #define ESCAPES \
 359 "\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\
 360 \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\
 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\1\
 363 \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\
 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
 368 /* Some svr4 assemblers have a limit on the number of characters which
 369    can appear in the operand of a .string directive.  If your assembler
 370    has such a limitation, you should define STRING_LIMIT to reflect that
 371    limit.  Note that at least some svr4 assemblers have a limit on the
 372    actual number of bytes in the double-quoted string, and that they
 373    count each character in an escape sequence as one byte.  Thus, an
 374    escape sequence like \377 would count as four bytes.
 375
 376    If your target assembler doesn't support the .string directive, you
 377    should define this to zero.
 378 */
 379
 380 #define STRING_LIMIT    ((unsigned) 256)
 381
 382 #define STRING_ASM_OP   "\t.string\t"
 383
 384 /* The routine used to output NUL terminated strings.  We use a special
 385    version of this for most svr4 targets because doing so makes the
 386    generated assembly code more compact (and thus faster to assemble)
 387    as well as more readable, especially for targets like the i386
 388    (where the only alternative is to output character sequences as
 389    comma separated lists of numbers).  */
 390
 391 #define ASM_OUTPUT_LIMITED_STRING(FILE, STR)            \
 392   do                                                    \
 393     {                                                   \
 394       register const unsigned char *_limited_str =      \
 395         (const unsigned char *) (STR);                  \
 396       register unsigned ch;                             \
 397                                                         \
 398       fprintf ((FILE), "%s\"", STRING_ASM_OP);          \
 399                                                         \
 400       for (; (ch = *_limited_str); _limited_str++)      \
 401         {                                               \
 402           register int escape;                          \
 403                                                         \
 404           switch (escape = ESCAPES[ch])                 \
 405             {                                           \
 406             case 0:                                     \
 407               putc (ch, (FILE));                        \
 408               break;                                    \
 409             case 1:                                     \
 410               fprintf ((FILE), "\\%03o", ch);           \
 411               break;                                    \
 412             default:                                    \
 413               putc ('\\', (FILE));                      \
 414               putc (escape, (FILE));                    \
 415               break;                                    \
 416             }                                           \
 417         }                                               \
 418                                                         \
 419       fprintf ((FILE), "\"\n");                         \
 420     }                                                   \
 421   while (0)
 422
 423 /* The routine used to output sequences of byte values.  We use a special
 424    version of this for most svr4 targets because doing so makes the
 425    generated assembly code more compact (and thus faster to assemble)
 426    as well as more readable.  Note that if we find subparts of the
 427    character sequence which end with NUL (and which are shorter than
 428    STRING_LIMIT) we output those using ASM_OUTPUT_LIMITED_STRING.  */
 429
 430 #undef  ASM_OUTPUT_ASCII
 431 #define ASM_OUTPUT_ASCII(FILE, STR, LENGTH)                             \
 432   do                                                                    \
 433     {                                                                   \
 434       const unsigned char *_ascii_bytes =                               \
 435         (const unsigned char *) (STR);                                  \
 436       const unsigned char *limit = _ascii_bytes + (LENGTH);             \
 437       const unsigned char *last_null = NULL;                            \
 438       unsigned bytes_in_chunk = 0;                                      \
 439                                                                         \
 440       for (; _ascii_bytes < limit; _ascii_bytes++)                      \
 441         {                                                               \
 442           const unsigned char *p;                                       \
 443                                                                         \
 444           if (bytes_in_chunk >= 60)                                     \
 445             {                                                           \
 446               fprintf ((FILE), "\"\n");                                 \
 447               bytes_in_chunk = 0;                                       \
 448             }                                                           \
 449                                                                         \
 450           if (_ascii_bytes > last_null)                                 \
 451             {                                                           \
 452               for (p = _ascii_bytes; p < limit && *p != '\0'; p++)      \
 453                 continue;                                               \
 454               last_null = p;                                            \
 455             }                                                           \
 456           else                                                          \
 457             p = last_null;                                              \
 458                                                                         \
 459           if (p < limit && (p - _ascii_bytes) <= (long)STRING_LIMIT)    \
 460             {                                                           \
 461               if (bytes_in_chunk > 0)                                   \
 462                 {                                                       \
 463                   fprintf ((FILE), "\"\n");                             \
 464                   bytes_in_chunk = 0;                                   \
 465                 }                                                       \
 466                                                                         \
 467               ASM_OUTPUT_LIMITED_STRING ((FILE), _ascii_bytes);         \
 468               _ascii_bytes = p;                                         \
 469             }                                                           \
 470           else                                                          \
 471             {                                                           \
 472               register int escape;                                      \
 473               register unsigned ch;                                     \
 474                                                                         \
 475               if (bytes_in_chunk == 0)                                  \
 476                 fprintf ((FILE), "%s\"", ASCII_DATA_ASM_OP);            \
 477                                                                         \
 478               switch (escape = ESCAPES[ch = *_ascii_bytes])             \
 479                 {                                                       \
 480                 case 0:                                                 \
 481                   putc (ch, (FILE));                                    \
 482                   bytes_in_chunk++;                                     \
 483                   break;                                                \
 484                 case 1:                                                 \
 485                   fprintf ((FILE), "\\%03o", ch);                       \
 486                   bytes_in_chunk += 4;                                  \
 487                   break;                                                \
 488                 default:                                                \
 489                   putc ('\\', (FILE));                                  \
 490                   putc (escape, (FILE));                                \
 491                   bytes_in_chunk += 2;                                  \
 492                   break;                                                \
 493                 }                                                       \
 494             }                                                           \
 495         }                                                               \
 496                                                                         \
 497       if (bytes_in_chunk > 0)                                           \
 498         fprintf ((FILE), "\"\n");                                       \
 499     }                                                                   \
 500   while (0)
 501
 502 /* Allow the use of the -frecord-gcc-switches switch via the
 503    elf_record_gcc_switches function defined in varasm.c.  */
 504 #undef  TARGET_ASM_RECORD_GCC_SWITCHES
 505 #define TARGET_ASM_RECORD_GCC_SWITCHES elf_record_gcc_switches
 506
 507 /* A C statement (sans semicolon) to output to the stdio stream STREAM
 508    any text necessary for declaring the name of an external symbol
 509    named NAME which is referenced in this compilation but not defined.
 510    It is needed to properly support non-default visibility.  */
 511
 512 #ifndef ASM_OUTPUT_EXTERNAL
 513 #define ASM_OUTPUT_EXTERNAL(FILE, DECL, NAME) \
 514   default_elf_asm_output_external (FILE, DECL, NAME)
 515 #endif