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) 1991-2020 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 /* 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 #undef TARGET_ASM_OUTPUT_IDENT
  86 #define TARGET_ASM_OUTPUT_IDENT default_asm_output_ident_directive
  87
  88 #undef  SET_ASM_OP
  89 #define SET_ASM_OP      "\t.set\t"
  90
  91 /* Most svr4 assemblers want a .file directive at the beginning of
  92    their input file.  */
  93 #define TARGET_ASM_FILE_START_FILE_DIRECTIVE true
  94
  95 /* This is how to allocate empty space in some section.  The .zero
  96    pseudo-op is used for this on most svr4 assemblers.  */
  97
  98 #define SKIP_ASM_OP     "\t.zero\t"
  99
 100 #undef  ASM_OUTPUT_SKIP
 101 #define ASM_OUTPUT_SKIP(FILE, SIZE) \
 102    fprintf ((FILE), "%s" HOST_WIDE_INT_PRINT_UNSIGNED "\n",\
 103             SKIP_ASM_OP, (SIZE))
 104
 105 /* This is how to store into the string LABEL
 106    the symbol_ref name of an internal numbered label where
 107    PREFIX is the class of label and NUM is the number within the class.
 108    This is suitable for output with `assemble_name'.
 109
 110    For most svr4 systems, the convention is that any symbol which begins
 111    with a period is not put into the linker symbol table by the assembler.  */
 112
 113 #undef  ASM_GENERATE_INTERNAL_LABEL
 114 #define ASM_GENERATE_INTERNAL_LABEL(LABEL, PREFIX, NUM)         \
 115   do                                                            \
 116     {                                                           \
 117       char *__p;                                                \
 118       (LABEL)[0] = '*';                                         \
 119       (LABEL)[1] = '.';                                         \
 120       __p = stpcpy (&(LABEL)[2], PREFIX);                       \
 121       sprint_ul (__p, (unsigned long) (NUM));                   \
 122     }                                                           \
 123   while (0)
 124
 125 /* Output the label which precedes a jumptable.  Note that for all svr4
 126    systems where we actually generate jumptables (which is to say every
 127    svr4 target except i386, where we use casesi instead) we put the jump-
 128    tables into the .rodata section and since other stuff could have been
 129    put into the .rodata section prior to any given jumptable, we have to
 130    make sure that the location counter for the .rodata section gets pro-
 131    perly re-aligned prior to the actual beginning of the jump table.  */
 132
 133 #undef ALIGN_ASM_OP
 134 #define ALIGN_ASM_OP "\t.align\t"
 135
 136 #ifndef ASM_OUTPUT_BEFORE_CASE_LABEL
 137 #define ASM_OUTPUT_BEFORE_CASE_LABEL(FILE, PREFIX, NUM, TABLE) \
 138   ASM_OUTPUT_ALIGN ((FILE), 2)
 139 #endif
 140
 141 #undef  ASM_OUTPUT_CASE_LABEL
 142 #define ASM_OUTPUT_CASE_LABEL(FILE, PREFIX, NUM, JUMPTABLE)             \
 143   do                                                                    \
 144     {                                                                   \
 145       ASM_OUTPUT_BEFORE_CASE_LABEL (FILE, PREFIX, NUM, JUMPTABLE);      \
 146       (*targetm.asm_out.internal_label) (FILE, PREFIX, NUM);            \
 147     }                                                                   \
 148   while (0)
 149
 150 /* The standard SVR4 assembler seems to require that certain builtin
 151    library routines (e.g. .udiv) be explicitly declared as .globl
 152    in each assembly file where they are referenced.  */
 153
 154 #define ASM_OUTPUT_EXTERNAL_LIBCALL(FILE, FUN)  \
 155   (*targetm.asm_out.globalize_label) (FILE, XSTR (FUN, 0))
 156
 157 /* This says how to output assembler code to declare an
 158    uninitialized external linkage data object.  Under SVR4,
 159    the linker seems to want the alignment of data objects
 160    to depend on their types.  We do exactly that here.  */
 161
 162 #define COMMON_ASM_OP   "\t.comm\t"
 163
 164 #undef  ASM_OUTPUT_ALIGNED_COMMON
 165 #define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)              \
 166   do                                                                    \
 167     {                                                                   \
 168       fprintf ((FILE), "%s", COMMON_ASM_OP);                            \
 169       assemble_name ((FILE), (NAME));                                   \
 170       fprintf ((FILE), "," HOST_WIDE_INT_PRINT_UNSIGNED ",%u\n",                \
 171                (SIZE), (ALIGN) / BITS_PER_UNIT);                        \
 172     }                                                                   \
 173   while (0)
 174
 175 /* This says how to output assembler code to declare an
 176    uninitialized internal linkage data object.  Under SVR4,
 177    the linker seems to want the alignment of data objects
 178    to depend on their types.  We do exactly that here.  */
 179
 180 #define LOCAL_ASM_OP    "\t.local\t"
 181
 182 #undef  ASM_OUTPUT_ALIGNED_LOCAL
 183 #define ASM_OUTPUT_ALIGNED_LOCAL(FILE, NAME, SIZE, ALIGN)       \
 184   do                                                            \
 185     {                                                           \
 186       fprintf ((FILE), "%s", LOCAL_ASM_OP);                     \
 187       assemble_name ((FILE), (NAME));                           \
 188       fprintf ((FILE), "\n");                                   \
 189       ASM_OUTPUT_ALIGNED_COMMON (FILE, NAME, SIZE, ALIGN);      \
 190     }                                                           \
 191   while (0)
 192
 193 /* This is the pseudo-op used to generate a contiguous sequence of byte
 194    values from a double-quoted string WITHOUT HAVING A TERMINATING NUL
 195    AUTOMATICALLY APPENDED.  This is the same for most svr4 assemblers.  */
 196
 197 #undef  ASCII_DATA_ASM_OP
 198 #define ASCII_DATA_ASM_OP       "\t.ascii\t"
 199
 200 /* Support a read-only data section.  */
 201 #define READONLY_DATA_SECTION_ASM_OP    "\t.section\t.rodata"
 202
 203 /* On svr4, we *do* have support for the .init and .fini sections, and we
 204    can put stuff in there to be executed before and after `main'.  We let
 205    crtstuff.c and other files know this by defining the following symbols.
 206    The definitions say how to change sections to the .init and .fini
 207    sections.  This is the same for all known svr4 assemblers.  */
 208
 209 #define INIT_SECTION_ASM_OP     "\t.section\t.init"
 210 #define FINI_SECTION_ASM_OP     "\t.section\t.fini"
 211
 212 /* Output assembly directive to move to the beginning of current section.  */
 213 #ifdef HAVE_GAS_SUBSECTION_ORDERING
 214 # define ASM_SECTION_START_OP   "\t.subsection\t-1"
 215 # define ASM_OUTPUT_SECTION_START(FILE) \
 216   fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
 217 #endif
 218
 219 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
 220
 221 /* Switch into a generic section.  */
 222 #define TARGET_ASM_NAMED_SECTION  default_elf_asm_named_section
 223
 224 #undef  TARGET_ASM_SELECT_RTX_SECTION
 225 #define TARGET_ASM_SELECT_RTX_SECTION default_elf_select_rtx_section
 226 #undef  TARGET_ASM_SELECT_SECTION
 227 #define TARGET_ASM_SELECT_SECTION default_elf_select_section
 228 #undef  TARGET_HAVE_SWITCHABLE_BSS_SECTIONS
 229 #define TARGET_HAVE_SWITCHABLE_BSS_SECTIONS true
 230
 231 /* Define the strings used for the special svr4 .type and .size directives.
 232    These strings generally do not vary from one system running svr4 to
 233    another, but if a given system (e.g. m88k running svr) needs to use
 234    different pseudo-op names for these, they may be overridden in the
 235    file which includes this one.  */
 236
 237 #define TYPE_ASM_OP     "\t.type\t"
 238 #define SIZE_ASM_OP     "\t.size\t"
 239
 240 /* This is how we tell the assembler that a symbol is weak.  */
 241
 242 #define ASM_WEAKEN_LABEL(FILE, NAME)    \
 243   do                                    \
 244     {                                   \
 245       fputs ("\t.weak\t", (FILE));      \
 246       assemble_name ((FILE), (NAME));   \
 247       fputc ('\n', (FILE));             \
 248     }                                   \
 249   while (0)
 250
 251 #define ASM_OUTPUT_SYMVER_DIRECTIVE(FILE, NAME, NAME2)          \
 252   do                                                            \
 253     {                                                           \
 254       fputs ("\t.symver\t", (FILE));                            \
 255       assemble_name ((FILE), (NAME));                           \
 256       fputs (", ", (FILE));                                     \
 257       assemble_name ((FILE), (NAME2));                          \
 258       fputc ('\n', (FILE));                                     \
 259     }                                                           \
 260   while (0)
 261
 262 /* The following macro defines the format used to output the second
 263    operand of the .type assembler directive.  Different svr4 assemblers
 264    expect various different forms for this operand.  The one given here
 265    is just a default.  You may need to override it in your machine-
 266    specific tm.h file (depending upon the particulars of your assembler).  */
 267
 268 #define TYPE_OPERAND_FMT        "@%s"
 269
 270 /* Write the extra assembler code needed to declare a function's result.
 271    Most svr4 assemblers don't require any special declaration of the
 272    result value, but there are exceptions.  */
 273
 274 #ifndef ASM_DECLARE_RESULT
 275 #define ASM_DECLARE_RESULT(FILE, RESULT)
 276 #endif
 277
 278 /* These macros generate the special .type and .size directives which
 279    are used to set the corresponding fields of the linker symbol table
 280    entries in an ELF object file under SVR4.  These macros also output
 281    the starting labels for the relevant functions/objects.  */
 282
 283 /* Write the extra assembler code needed to declare a function properly.
 284    Some svr4 assemblers need to also have something extra said about the
 285    function's return value.  We allow for that here.  */
 286
 287 #ifndef ASM_DECLARE_FUNCTION_NAME
 288 #define ASM_DECLARE_FUNCTION_NAME(FILE, NAME, DECL)             \
 289   do                                                            \
 290     {                                                           \
 291       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "function");       \
 292       ASM_DECLARE_RESULT (FILE, DECL_RESULT (DECL));            \
 293       ASM_OUTPUT_FUNCTION_LABEL (FILE, NAME, DECL);             \
 294     }                                                           \
 295   while (0)
 296 #endif
 297
 298 /* Write the extra assembler code needed to declare the name of a
 299    cold function partition properly. Some svr4 assemblers need to also
 300    have something extra said about the function's return value.  We
 301    allow for that here.  */
 302
 303 #ifndef ASM_DECLARE_COLD_FUNCTION_NAME
 304 #define ASM_DECLARE_COLD_FUNCTION_NAME(FILE, NAME, DECL)        \
 305   do                                                            \
 306     {                                                           \
 307       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "function");       \
 308       ASM_DECLARE_RESULT (FILE, DECL_RESULT (DECL));            \
 309       ASM_OUTPUT_FUNCTION_LABEL (FILE, NAME, DECL);             \
 310     }                                                           \
 311   while (0)
 312 #endif
 313
 314 /* Write the extra assembler code needed to declare an object properly.  */
 315
 316 #ifdef HAVE_GAS_GNU_UNIQUE_OBJECT
 317 #define USE_GNU_UNIQUE_OBJECT flag_gnu_unique
 318 #else
 319 #define USE_GNU_UNIQUE_OBJECT 0
 320 #endif
 321
 322 #define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL)                       \
 323   do                                                                    \
 324     {                                                                   \
 325       HOST_WIDE_INT size;                                               \
 326                                                                         \
 327       /* For template static data member instantiations or              \
 328          inline fn local statics and their guard variables, use         \
 329          gnu_unique_object so that they will be combined even under     \
 330          RTLD_LOCAL.  Don't use gnu_unique_object for typeinfo,         \
 331          vtables and other read-only artificial decls.  */              \
 332       if (USE_GNU_UNIQUE_OBJECT && DECL_ONE_ONLY (DECL)                 \
 333           && (!DECL_ARTIFICIAL (DECL) || !TREE_READONLY (DECL)))        \
 334         ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "gnu_unique_object");    \
 335       else                                                              \
 336         ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object");               \
 337                                                                         \
 338       size_directive_output = 0;                                        \
 339       if (!flag_inhibit_size_directive                                  \
 340           && (DECL) && DECL_SIZE (DECL))                                \
 341         {                                                               \
 342           size_directive_output = 1;                                    \
 343           size = tree_to_uhwi (DECL_SIZE_UNIT (DECL));                  \
 344           ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, size);                 \
 345         }                                                               \
 346                                                                         \
 347       ASM_OUTPUT_LABEL (FILE, NAME);                                    \
 348     }                                                                   \
 349   while (0)
 350
 351 /* Output the size directive for a decl in rest_of_decl_compilation
 352    in the case where we did not do so before the initializer.
 353    Once we find the error_mark_node, we know that the value of
 354    size_directive_output was set
 355    by ASM_DECLARE_OBJECT_NAME when it was run for the same decl.  */
 356
 357 #undef ASM_FINISH_DECLARE_OBJECT
 358 #define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)\
 359   do                                                            \
 360     {                                                           \
 361       const char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0);   \
 362       HOST_WIDE_INT size;                                       \
 363                                                                 \
 364       if (!flag_inhibit_size_directive                          \
 365           && DECL_SIZE (DECL)                                   \
 366           && ! AT_END && TOP_LEVEL                              \
 367           && DECL_INITIAL (DECL) == error_mark_node             \
 368           && !size_directive_output)                            \
 369         {                                                       \
 370           size_directive_output = 1;                            \
 371           size = tree_to_uhwi (DECL_SIZE_UNIT (DECL));          \
 372           ASM_OUTPUT_SIZE_DIRECTIVE (FILE, name, size);         \
 373         }                                                       \
 374     }                                                           \
 375   while (0)
 376
 377 /* This is how to declare the size of a function.  */
 378 #ifndef ASM_DECLARE_FUNCTION_SIZE
 379 #define ASM_DECLARE_FUNCTION_SIZE(FILE, FNAME, DECL)            \
 380   do                                                            \
 381     {                                                           \
 382       if (!flag_inhibit_size_directive)                         \
 383         ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);                 \
 384     }                                                           \
 385   while (0)
 386 #endif
 387
 388 /* This is how to declare the size of a cold function partition.  */
 389 #ifndef ASM_DECLARE_COLD_FUNCTION_SIZE
 390 #define ASM_DECLARE_COLD_FUNCTION_SIZE(FILE, FNAME, DECL)       \
 391   do                                                            \
 392     {                                                           \
 393       if (!flag_inhibit_size_directive)                         \
 394         ASM_OUTPUT_MEASURED_SIZE (FILE, FNAME);                 \
 395     }                                                           \
 396   while (0)
 397 #endif
 398
 399 /* A table of bytes codes used by the ASM_OUTPUT_ASCII and
 400    ASM_OUTPUT_LIMITED_STRING macros.  Each byte in the table
 401    corresponds to a particular byte value [0..255].  For any
 402    given byte value, if the value in the corresponding table
 403    position is zero, the given character can be output directly.
 404    If the table value is 1, the byte must be output as a \ooo
 405    octal escape.  If the tables value is anything else, then the
 406    byte value should be output as a \ followed by the value
 407    in the table.  Note that we can use standard UN*X escape
 408    sequences for many control characters, but we don't use
 409    \a to represent BEL because some svr4 assemblers (e.g. on
 410    the i386) don't know about that.  Also, we don't use \v
 411    since some versions of gas, such as 2.2 did not accept it.  */
 412
 413 #define ELF_ASCII_ESCAPES \
 414 "\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\
 415 \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\
 416 \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\
 417 \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\
 418 \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\
 419 \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\
 420 \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\
 421 \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"
 422
 423 /* Some svr4 assemblers have a limit on the number of characters which
 424    can appear in the operand of a .string directive.  If your assembler
 425    has such a limitation, you should define STRING_LIMIT to reflect that
 426    limit.  Note that at least some svr4 assemblers have a limit on the
 427    actual number of bytes in the double-quoted string, and that they
 428    count each character in an escape sequence as one byte.  Thus, an
 429    escape sequence like \377 would count as four bytes.
 430
 431    If your target assembler doesn't support the .string directive, you
 432    should define this to zero.
 433 */
 434
 435 #define ELF_STRING_LIMIT        ((unsigned) 256)
 436
 437 #define STRING_ASM_OP   "\t.string\t"
 438
 439 /* The routine used to output NUL terminated strings.  We use a special
 440    version of this for most svr4 targets because doing so makes the
 441    generated assembly code more compact (and thus faster to assemble)
 442    as well as more readable, especially for targets like the i386
 443    (where the only alternative is to output character sequences as
 444    comma separated lists of numbers).  */
 445
 446 #define ASM_OUTPUT_LIMITED_STRING(FILE, STR)            \
 447   default_elf_asm_output_limited_string ((FILE), (STR))
 448
 449 /* The routine used to output sequences of byte values.  We use a special
 450    version of this for most svr4 targets because doing so makes the
 451    generated assembly code more compact (and thus faster to assemble)
 452    as well as more readable.  Note that if we find subparts of the
 453    character sequence which end with NUL (and which are shorter than
 454    STRING_LIMIT) we output those using ASM_OUTPUT_LIMITED_STRING.  */
 455
 456 #undef  ASM_OUTPUT_ASCII
 457 #define ASM_OUTPUT_ASCII(FILE, STR, LENGTH)                     \
 458   default_elf_asm_output_ascii ((FILE), (STR), (LENGTH))
 459
 460 /* Allow the use of the -frecord-gcc-switches switch via the
 461    elf_record_gcc_switches function defined in varasm.c.  */
 462 #undef  TARGET_ASM_RECORD_GCC_SWITCHES
 463 #define TARGET_ASM_RECORD_GCC_SWITCHES elf_record_gcc_switches
 464
 465 /* A C statement (sans semicolon) to output to the stdio stream STREAM
 466    any text necessary for declaring the name of an external symbol
 467    named NAME which is referenced in this compilation but not defined.
 468    It is needed to properly support non-default visibility.  */
 469
 470 #ifndef ASM_OUTPUT_EXTERNAL
 471 #define ASM_OUTPUT_EXTERNAL(FILE, DECL, NAME) \
 472   default_elf_asm_output_external (FILE, DECL, NAME)
 473 #endif
 474
 475 #undef TARGET_LIBC_HAS_FUNCTION
 476 #define TARGET_LIBC_HAS_FUNCTION no_c99_libc_has_function