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) 1991-2021 Free Software Foundation, Inc.
   4    Based on svr4.h contributed by Ron Guilmette (rfg@netcom.com).
   5
   6 This file is part of GCC.
   7
   8 GCC 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, or (at your option)
  11 any later version.
  12
  13 GCC 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 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 3.1, as published by the Free Software Foundation.
  21
  22 You should have received a copy of the GNU General Public License and
  23 a copy of the GCC Runtime Library Exception along with this program;
  24 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 <http://www.gnu.org/licenses/>.  */
  26
  27 #define TARGET_OBJFMT_CPP_BUILTINS()            \
  28   do                                            \
  29     {                                           \
  30         builtin_define ("__ELF__");             \
  31     }                                           \
  32   while (0)
  33
  34 /* Define a symbol indicating that we are using elfos.h.
  35    Some CPU specific configuration files use this.  */
  36 #define USING_ELFOS_H
  37
  38 /* The prefix to add to user-visible assembler symbols.
  39
  40    For ELF systems the convention is *not* to prepend a leading
  41    underscore onto user-level symbol names.  */
  42
  43 #undef  USER_LABEL_PREFIX
  44 #define USER_LABEL_PREFIX ""
  45
  46 /* The biggest alignment supported by ELF in bits. 32-bit ELF
  47    supports section alignment up to (0x80000000 * 8), while
  48    64-bit ELF supports (0x8000000000000000 * 8). If this macro
  49    is not defined, the default is the largest alignment supported
  50    by 32-bit ELF and representable on a 32-bit host. Use this
  51    macro to limit the alignment which can be specified using
  52    the `__attribute__ ((aligned (N)))' construct.  */
  53 #ifndef MAX_OFILE_ALIGNMENT
  54 #define MAX_OFILE_ALIGNMENT (((unsigned int) 1 << 28) * 8)
  55 #endif
  56
  57 /* Use periods rather than dollar signs in special g++ assembler names.  */
  58
  59 #define NO_DOLLAR_IN_LABEL
  60
  61 /* Writing `int' for a bit-field forces int alignment for the structure.  */
  62
  63 #ifndef PCC_BITFIELD_TYPE_MATTERS
  64 #define PCC_BITFIELD_TYPE_MATTERS 1
  65 #endif
  66
  67 /* All ELF targets can support DWARF-2.  */
  68
  69 #define DWARF2_DEBUGGING_INFO 1
  70
  71 /* All ELF targets can support CTF.  */
  72
  73 #define CTF_DEBUGGING_INFO 1
  74
  75 /* All ELF targets can support BTF.  */
  76
  77 #define BTF_DEBUGGING_INFO 1
  78
  79 /* The GNU tools operate better with dwarf2, and it is required by some
  80    psABI's.  Since we don't have any native tools to be compatible with,
  81    default to dwarf2.  */
  82
  83 #ifndef PREFERRED_DEBUGGING_TYPE
  84 #define PREFERRED_DEBUGGING_TYPE DWARF2_DEBUG
  85 #endif
  86
  87 /* All SVR4 targets use the ELF object file format.  */
  88 #define OBJECT_FORMAT_ELF
  89
  90
  91 /* Output #ident as a .ident.  */
  92
  93 #undef TARGET_ASM_OUTPUT_IDENT
  94 #define TARGET_ASM_OUTPUT_IDENT default_asm_output_ident_directive
  95
  96 #undef  SET_ASM_OP
  97 #define SET_ASM_OP      "\t.set\t"
  98
  99 /* Most svr4 assemblers want a .file directive at the beginning of
 100    their input file.  */
 101 #define TARGET_ASM_FILE_START_FILE_DIRECTIVE true
 102
 103 /* This is how to allocate empty space in some section.  The .zero
 104    pseudo-op is used for this on most svr4 assemblers.  */
 105
 106 #define SKIP_ASM_OP     "\t.zero\t"
 107
 108 #undef  ASM_OUTPUT_SKIP
 109 #define ASM_OUTPUT_SKIP(FILE, SIZE) \
 110    fprintf ((FILE), "%s" HOST_WIDE_INT_PRINT_UNSIGNED "\n",\
 111             SKIP_ASM_OP, (SIZE))
 112
 113 /* This is how to store into the string LABEL
 114    the symbol_ref name of an internal numbered label where
 115    PREFIX is the class of label and NUM is the number within the class.
 116    This is suitable for output with `assemble_name'.
 117
 118    For most svr4 systems, the convention is that any symbol which begins
 119    with a period is not put into the linker symbol table by the assembler.  */
 120
 121 #undef  ASM_GENERATE_INTERNAL_LABEL
 122 #define ASM_GENERATE_INTERNAL_LABEL(LABEL, PREFIX, NUM)         \
 123   do                                                            \
 124     {                                                           \
 125       char *__p;                                                \
 126       (LABEL)[0] = '*';                                         \
 127       (LABEL)[1] = '.';                                         \
 128       __p = stpcpy (&(LABEL)[2], PREFIX);                       \
 129       sprint_ul (__p, (unsigned long) (NUM));                   \
 130     }                                                           \
 131   while (0)
 132
 133 /* Output the label which precedes a jumptable.  Note that for all svr4
 134    systems where we actually generate jumptables (which is to say every
 135    svr4 target except i386, where we use casesi instead) we put the jump-
 136    tables into the .rodata section and since other stuff could have been
 137    put into the .rodata section prior to any given jumptable, we have to
 138    make sure that the location counter for the .rodata section gets pro-
 139    perly re-aligned prior to the actual beginning of the jump table.  */
 140
 141 #undef ALIGN_ASM_OP
 142 #define ALIGN_ASM_OP "\t.align\t"
 143
 144 #ifndef ASM_OUTPUT_BEFORE_CASE_LABEL
 145 #define ASM_OUTPUT_BEFORE_CASE_LABEL(FILE, PREFIX, NUM, TABLE) \
 146   ASM_OUTPUT_ALIGN ((FILE), 2)
 147 #endif
 148
 149 #undef  ASM_OUTPUT_CASE_LABEL
 150 #define ASM_OUTPUT_CASE_LABEL(FILE, PREFIX, NUM, JUMPTABLE)             \
 151   do                                                                    \
 152     {                                                                   \
 153       ASM_OUTPUT_BEFORE_CASE_LABEL (FILE, PREFIX, NUM, JUMPTABLE);      \
 154       (*targetm.asm_out.internal_label) (FILE, PREFIX, NUM);            \
 155     }                                                                   \
 156   while (0)
 157
 158 /* The standard SVR4 assembler seems to require that certain builtin
 159    library routines (e.g. .udiv) be explicitly declared as .globl
 160    in each assembly file where they are referenced.  */
 161
 162 #define ASM_OUTPUT_EXTERNAL_LIBCALL(FILE, FUN)  \
 163   (*targetm.asm_out.globalize_label) (FILE, XSTR (FUN, 0))
 164
 165 /* This says how to output assembler code to declare an
 166    uninitialized external linkage data object.  Under SVR4,
 167    the linker seems to want the alignment of data objects
 168    to depend on their types.  We do exactly that here.  */
 169
 170 #define COMMON_ASM_OP   "\t.comm\t"
 171
 172 #undef  ASM_OUTPUT_ALIGNED_COMMON
 173 #define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)              \
 174   do                                                                    \
 175     {                                                                   \
 176       fprintf ((FILE), "%s", COMMON_ASM_OP);                            \
 177       assemble_name ((FILE), (NAME));                                   \
 178       fprintf ((FILE), "," HOST_WIDE_INT_PRINT_UNSIGNED ",%u\n",                \
 179                (SIZE), (ALIGN) / BITS_PER_UNIT);                        \
 180     }                                                                   \
 181   while (0)
 182
 183 /* This says how to output assembler code to declare an
 184    uninitialized internal linkage data object.  Under SVR4,
 185    the linker seems to want the alignment of data objects
 186    to depend on their types.  We do exactly that here.  */
 187
 188 #define LOCAL_ASM_OP    "\t.local\t"
 189
 190 #undef  ASM_OUTPUT_ALIGNED_LOCAL
 191 #define ASM_OUTPUT_ALIGNED_LOCAL(FILE, NAME, SIZE, ALIGN)       \
 192   do                                                            \
 193     {                                                           \
 194       fprintf ((FILE), "%s", LOCAL_ASM_OP);                     \
 195       assemble_name ((FILE), (NAME));                           \
 196       fprintf ((FILE), "\n");                                   \
 197       ASM_OUTPUT_ALIGNED_COMMON (FILE, NAME, SIZE, ALIGN);      \
 198     }                                                           \
 199   while (0)
 200
 201 /* This is the pseudo-op used to generate a contiguous sequence of byte
 202    values from a double-quoted string WITHOUT HAVING A TERMINATING NUL
 203    AUTOMATICALLY APPENDED.  This is the same for most svr4 assemblers.  */
 204
 205 #undef  ASCII_DATA_ASM_OP
 206 #define ASCII_DATA_ASM_OP       "\t.ascii\t"
 207
 208 /* Support a read-only data section.  */
 209 #define READONLY_DATA_SECTION_ASM_OP    "\t.section\t.rodata"
 210
 211 /* On svr4, we *do* have support for the .init and .fini sections, and we
 212    can put stuff in there to be executed before and after `main'.  We let
 213    crtstuff.c and other files know this by defining the following symbols.
 214    The definitions say how to change sections to the .init and .fini
 215    sections.  This is the same for all known svr4 assemblers.  */
 216
 217 #define INIT_SECTION_ASM_OP     "\t.section\t.init"
 218 #define FINI_SECTION_ASM_OP     "\t.section\t.fini"
 219
 220 /* Output assembly directive to move to the beginning of current section.  */
 221 #ifdef HAVE_GAS_SUBSECTION_ORDERING
 222 # define ASM_SECTION_START_OP   "\t.subsection\t-1"
 223 # define ASM_OUTPUT_SECTION_START(FILE) \
 224   fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
 225 #endif
 226
 227 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
 228
 229 /* Switch into a generic section.  */
 230 #define TARGET_ASM_NAMED_SECTION  default_elf_asm_named_section
 231
 232 #undef  TARGET_ASM_SELECT_RTX_SECTION
 233 #define TARGET_ASM_SELECT_RTX_SECTION default_elf_select_rtx_section
 234 #undef  TARGET_ASM_SELECT_SECTION
 235 #define TARGET_ASM_SELECT_SECTION default_elf_select_section
 236 #undef  TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
 237 #define TARGET_HAVE_SWITCHABLE_BSS_SECTIONS true
 238
 239 /* Define the strings used for the special svr4 .type and .size directives.
 240    These strings generally do not vary from one system running svr4 to
 241    another, but if a given system (e.g. m88k running svr) needs to use
 242    different pseudo-op names for these, they may be overridden in the
 243    file which includes this one.  */
 244
 245 #define TYPE_ASM_OP     "\t.type\t"
 246 #define SIZE_ASM_OP     "\t.size\t"
 247
 248 /* This is how we tell the assembler that a symbol is weak.  */
 249
 250 #define ASM_WEAKEN_LABEL(FILE, NAME)    \
 251   do                                    \
 252     {                                   \
 253       fputs ("\t.weak\t", (FILE));      \
 254       assemble_name ((FILE), (NAME));   \
 255       fputc ('\n', (FILE));             \
 256     }                                   \
 257   while (0)
 258
 259 #define ASM_OUTPUT_SYMVER_DIRECTIVE(FILE, NAME, NAME2)          \
 260   do                                                            \
 261     {                                                           \
 262       fputs ("\t.symver\t", (FILE));                            \
 263       assemble_name ((FILE), (NAME));                           \
 264       fputs (", ", (FILE));                                     \
 265       assemble_name ((FILE), (NAME2));                          \
 266       fputc ('\n', (FILE));                                     \
 267     }                                                           \
 268   while (0)
 269
 270 /* The following macro defines the format used to output the second
 271    operand of the .type assembler directive.  Different svr4 assemblers
 272    expect various different forms for this operand.  The one given here
 273    is just a default.  You may need to override it in your machine-
 274    specific tm.h file (depending upon the particulars of your assembler).  */
 275
 276 #define TYPE_OPERAND_FMT        "@%s"
 277
 278 /* Write the extra assembler code needed to declare a function's result.
 279    Most svr4 assemblers don't require any special declaration of the
 280    result value, but there are exceptions.  */
 281
 282 #ifndef ASM_DECLARE_RESULT
 283 #define ASM_DECLARE_RESULT(FILE, RESULT)
 284 #endif
 285
 286 /* These macros generate the special .type and .size directives which
 287    are used to set the corresponding fields of the linker symbol table
 288    entries in an ELF object file under SVR4.  These macros also output
 289    the starting labels for the relevant functions/objects.  */
 290
 291 /* Write the extra assembler code needed to declare a function properly.
 292    Some svr4 assemblers need to also have something extra said about the
 293    function's return value.  We allow for that here.  */
 294
 295 #ifndef ASM_DECLARE_FUNCTION_NAME
 296 #define ASM_DECLARE_FUNCTION_NAME(FILE, NAME, DECL)             \
 297   do                                                            \
 298     {                                                           \
 299       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "function");       \
 300       ASM_DECLARE_RESULT (FILE, DECL_RESULT (DECL));            \
 301       ASM_OUTPUT_FUNCTION_LABEL (FILE, NAME, DECL);             \
 302     }                                                           \
 303   while (0)
 304 #endif
 305
 306 /* Write the extra assembler code needed to declare the name of a
 307    cold function partition properly. Some svr4 assemblers need to also
 308    have something extra said about the function's return value.  We
 309    allow for that here.  */
 310
 311 #ifndef ASM_DECLARE_COLD_FUNCTION_NAME
 312 #define ASM_DECLARE_COLD_FUNCTION_NAME(FILE, NAME, DECL)        \
 313   do                                                            \
 314     {                                                           \
 315       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "function");       \
 316       ASM_DECLARE_RESULT (FILE, DECL_RESULT (DECL));            \
 317       ASM_OUTPUT_FUNCTION_LABEL (FILE, NAME, DECL);             \
 318     }                                                           \
 319   while (0)
 320 #endif
 321
 322 /* Write the extra assembler code needed to declare an object properly.  */
 323
 324 #ifdef HAVE_GAS_GNU_UNIQUE_OBJECT
 325 #define USE_GNU_UNIQUE_OBJECT flag_gnu_unique
 326 #else
 327 #define USE_GNU_UNIQUE_OBJECT 0
 328 #endif
 329
 330 #define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL)                       \
 331   do                                                                    \
 332     {                                                                   \
 333       HOST_WIDE_INT size;                                               \
 334                                                                         \
 335       /* For template static data member instantiations or              \
 336          inline fn local statics and their guard variables, use         \
 337          gnu_unique_object so that they will be combined even under     \
 338          RTLD_LOCAL.  Don't use gnu_unique_object for typeinfo,         \
 339          vtables and other read-only artificial decls.  */              \
 340       if (USE_GNU_UNIQUE_OBJECT && DECL_ONE_ONLY (DECL)                 \
 341           && (!DECL_ARTIFICIAL (DECL) || !TREE_READONLY (DECL)))        \
 342         ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "gnu_unique_object");    \
 343       else                                                              \
 344         ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object");               \
 345                                                                         \
 346       size_directive_output = 0;                                        \
 347       if (!flag_inhibit_size_directive                                  \
 348           && (DECL) && DECL_SIZE (DECL))                                \
 349         {                                                               \
 350           size_directive_output = 1;                                    \
 351           size = tree_to_uhwi (DECL_SIZE_UNIT (DECL));                  \
 352           ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, size);                 \
 353         }                                                               \
 354                                                                         \
 355       ASM_OUTPUT_LABEL (FILE, NAME);                                    \
 356     }                                                                   \
 357   while (0)
 358
 359 /* Output the size directive for a decl in rest_of_decl_compilation
 360    in the case where we did not do so before the initializer.
 361    Once we find the error_mark_node, we know that the value of
 362    size_directive_output was set
 363    by ASM_DECLARE_OBJECT_NAME when it was run for the same decl.  */
 364
 365 #undef ASM_FINISH_DECLARE_OBJECT
 366 #define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)\
 367   do                                                            \
 368     {                                                           \
 369       const char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0);   \
 370       HOST_WIDE_INT size;                                       \
 371                                                                 \
 372       if (!flag_inhibit_size_directive                          \
 373           && DECL_SIZE (DECL)                                   \
 374           && ! AT_END && TOP_LEVEL                              \
 375           && DECL_INITIAL (DECL) == error_mark_node             \
 376           && !size_directive_output)                            \
 377         {                                                       \
 378           size_directive_output = 1;                            \
 379           size = tree_to_uhwi (DECL_SIZE_UNIT (DECL));          \
 380           ASM_OUTPUT_SIZE_DIRECTIVE (FILE, name, size);         \
 381         }                                                       \
 382     }                                                           \
 383   while (0)
 384
 385 /* This is how to declare the size of a function.  */
 386 #ifndef ASM_DECLARE_FUNCTION_SIZE
 387 #define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)            \
 388   do                                                            \
 389     {                                                           \
 390       if (!flag_inhibit_size_directive)                         \
 391         ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);                 \
 392     }                                                           \
 393   while (0)
 394 #endif
 395
 396 /* This is how to declare the size of a cold function partition.  */
 397 #ifndef ASM_DECLARE_COLD_FUNCTION_SIZE
 398 #define ASM_DECLARE_COLD_FUNCTION_SIZE(FILE, FNAME, DECL)       \
 399   do                                                            \
 400     {                                                           \
 401       if (!flag_inhibit_size_directive)                         \
 402         ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);                 \
 403     }                                                           \
 404   while (0)
 405 #endif
 406
 407 /* A table of bytes codes used by the ASM_OUTPUT_ASCII and
 408    ASM_OUTPUT_LIMITED_STRING macros.  Each byte in the table
 409    corresponds to a particular byte value [0..255].  For any
 410    given byte value, if the value in the corresponding table
 411    position is zero, the given character can be output directly.
 412    If the table value is 1, the byte must be output as a \ooo
 413    octal escape.  If the tables value is anything else, then the
 414    byte value should be output as a \ followed by the value
 415    in the table.  Note that we can use standard UN*X escape
 416    sequences for many control characters, but we don't use
 417    \a to represent BEL because some svr4 assemblers (e.g. on
 418    the i386) don't know about that.  Also, we don't use \v
 419    since some versions of gas, such as 2.2 did not accept it.  */
 420
 421 #define ELF_ASCII_ESCAPES \
 422 "\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\
 423 \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\
 424 \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\
 425 \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\
 426 \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\
 427 \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\
 428 \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\
 429 \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"
 430
 431 /* Some svr4 assemblers have a limit on the number of characters which
 432    can appear in the operand of a .string directive.  If your assembler
 433    has such a limitation, you should define STRING_LIMIT to reflect that
 434    limit.  Note that at least some svr4 assemblers have a limit on the
 435    actual number of bytes in the double-quoted string, and that they
 436    count each character in an escape sequence as one byte.  Thus, an
 437    escape sequence like \377 would count as four bytes.
 438
 439    If your target assembler doesn't support the .string directive, you
 440    should define this to zero.
 441 */
 442
 443 #define ELF_STRING_LIMIT        ((unsigned) 256)
 444
 445 #define STRING_ASM_OP   "\t.string\t"
 446
 447 /* The routine used to output NUL terminated strings.  We use a special
 448    version of this for most svr4 targets because doing so makes the
 449    generated assembly code more compact (and thus faster to assemble)
 450    as well as more readable, especially for targets like the i386
 451    (where the only alternative is to output character sequences as
 452    comma separated lists of numbers).  */
 453
 454 #define ASM_OUTPUT_LIMITED_STRING(FILE, STR)            \
 455   default_elf_asm_output_limited_string ((FILE), (STR))
 456
 457 /* The routine used to output sequences of byte values.  We use a special
 458    version of this for most svr4 targets because doing so makes the
 459    generated assembly code more compact (and thus faster to assemble)
 460    as well as more readable.  Note that if we find subparts of the
 461    character sequence which end with NUL (and which are shorter than
 462    STRING_LIMIT) we output those using ASM_OUTPUT_LIMITED_STRING.  */
 463
 464 #undef  ASM_OUTPUT_ASCII
 465 #define ASM_OUTPUT_ASCII(FILE, STR, LENGTH)                     \
 466   default_elf_asm_output_ascii ((FILE), (STR), (LENGTH))
 467
 468 /* Allow the use of the -frecord-gcc-switches switch via the
 469    elf_record_gcc_switches function defined in varasm.c.  */
 470 #undef  TARGET_ASM_RECORD_GCC_SWITCHES
 471 #define TARGET_ASM_RECORD_GCC_SWITCHES elf_record_gcc_switches
 472
 473 /* A C statement (sans semicolon) to output to the stdio stream STREAM
 474    any text necessary for declaring the name of an external symbol
 475    named NAME which is referenced in this compilation but not defined.
 476    It is needed to properly support non-default visibility.  */
 477
 478 #ifndef ASM_OUTPUT_EXTERNAL
 479 #define ASM_OUTPUT_EXTERNAL(FILE, DECL, NAME) \
 480   default_elf_asm_output_external (FILE, DECL, NAME)
 481 #endif
 482
 483 #undef TARGET_LIBC_HAS_FUNCTION
 484 #define TARGET_LIBC_HAS_FUNCTION no_c99_libc_has_function
 485
 486 /* ELF support needed only by D front-end.  */
 487
 488 #define TARGET_D_MINFO_SECTION "minfo"
 489 #define TARGET_D_MINFO_START_NAME "__start_minfo"
 490 #define TARGET_D_MINFO_END_NAME "__stop_minfo"