gcc/config/alpha/elf.h

   1 /* Definitions of target machine for GNU compiler, for DEC Alpha w/ELF.
   2    Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2007, 2008,
   3    2009, 2010 Free Software Foundation, Inc.
   4    Contributed by Richard Henderson (rth@tamu.edu).
   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 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #undef OBJECT_FORMAT_COFF
  23 #undef EXTENDED_COFF
  24 #define OBJECT_FORMAT_ELF
  25
  26 /* ??? Move all SDB stuff from alpha.h to osf.h.  */
  27 #undef SDB_DEBUGGING_INFO
  28
  29 #define DBX_DEBUGGING_INFO 1
  30 #define DWARF2_DEBUGGING_INFO 1
  31
  32 #undef  PREFERRED_DEBUGGING_TYPE
  33 #define PREFERRED_DEBUGGING_TYPE DWARF2_DEBUG
  34
  35 #undef ASM_FINAL_SPEC
  36
  37 /* alpha/ doesn't use elfos.h for some reason.  */
  38 #define TARGET_OBJFMT_CPP_BUILTINS()            \
  39   do                                            \
  40     {                                           \
  41         builtin_define ("__ELF__");             \
  42     }                                           \
  43   while (0)
  44
  45 #undef  CC1_SPEC
  46 #define CC1_SPEC  "%{G*}"
  47
  48 #undef  ASM_SPEC
  49 #define ASM_SPEC  "%{G*} %{relax:-relax} %{!gstabs*:-no-mdebug}%{gstabs*:-mdebug}"
  50
  51 #undef  IDENT_ASM_OP
  52 #define IDENT_ASM_OP "\t.ident\t"
  53
  54 /* Output #ident as a .ident.  */
  55 #undef  ASM_OUTPUT_IDENT
  56 #define ASM_OUTPUT_IDENT(FILE, NAME) \
  57   fprintf (FILE, "%s\"%s\"\n", IDENT_ASM_OP, NAME);
  58
  59 /* This is how to allocate empty space in some section.  The .zero
  60    pseudo-op is used for this on most svr4 assemblers.  */
  61
  62 #undef  SKIP_ASM_OP
  63 #define SKIP_ASM_OP     "\t.zero\t"
  64
  65 #undef  ASM_OUTPUT_SKIP
  66 #define ASM_OUTPUT_SKIP(FILE, SIZE) \
  67   fprintf (FILE, "%s"HOST_WIDE_INT_PRINT_UNSIGNED"\n", SKIP_ASM_OP, (SIZE))
  68
  69 /* Output the label which precedes a jumptable.  Note that for all svr4
  70    systems where we actually generate jumptables (which is to say every
  71    svr4 target except i386, where we use casesi instead) we put the jump-
  72    tables into the .rodata section and since other stuff could have been
  73    put into the .rodata section prior to any given jumptable, we have to
  74    make sure that the location counter for the .rodata section gets pro-
  75    perly re-aligned prior to the actual beginning of the jump table.  */
  76
  77 #undef  ALIGN_ASM_OP
  78 #define ALIGN_ASM_OP "\t.align\t"
  79
  80 #ifndef ASM_OUTPUT_BEFORE_CASE_LABEL
  81 #define ASM_OUTPUT_BEFORE_CASE_LABEL(FILE, PREFIX, NUM, TABLE) \
  82   ASM_OUTPUT_ALIGN ((FILE), 2);
  83 #endif
  84
  85 #undef  ASM_OUTPUT_CASE_LABEL
  86 #define ASM_OUTPUT_CASE_LABEL(FILE, PREFIX, NUM, JUMPTABLE)             \
  87   do {                                                                  \
  88     ASM_OUTPUT_BEFORE_CASE_LABEL (FILE, PREFIX, NUM, JUMPTABLE)         \
  89     (*targetm.asm_out.internal_label) (FILE, PREFIX, NUM);                      \
  90   } while (0)
  91
  92 /* The standard SVR4 assembler seems to require that certain builtin
  93    library routines (e.g. .udiv) be explicitly declared as .globl
  94    in each assembly file where they are referenced.  */
  95
  96 #undef  ASM_OUTPUT_EXTERNAL_LIBCALL
  97 #define ASM_OUTPUT_EXTERNAL_LIBCALL(FILE, FUN)                          \
  98   (*targetm.asm_out.globalize_label) (FILE, XSTR (FUN, 0))
  99
 100 /* This says how to output assembler code to declare an
 101    uninitialized external linkage data object.  Under SVR4,
 102    the linker seems to want the alignment of data objects
 103    to depend on their types.  We do exactly that here.  */
 104
 105 #undef  COMMON_ASM_OP
 106 #define COMMON_ASM_OP   "\t.comm\t"
 107
 108 #undef  ASM_OUTPUT_ALIGNED_COMMON
 109 #define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)              \
 110 do {                                                                    \
 111   fprintf ((FILE), "%s", COMMON_ASM_OP);                                \
 112   assemble_name ((FILE), (NAME));                                       \
 113   fprintf ((FILE), "," HOST_WIDE_INT_PRINT_UNSIGNED ",%u\n", (SIZE), (ALIGN) / BITS_PER_UNIT);  \
 114 } while (0)
 115
 116 /* This says how to output assembler code to declare an
 117    uninitialized internal linkage data object.  Under SVR4,
 118    the linker seems to want the alignment of data objects
 119    to depend on their types.  We do exactly that here.  */
 120
 121 #undef  ASM_OUTPUT_ALIGNED_LOCAL
 122 #define ASM_OUTPUT_ALIGNED_LOCAL(FILE, NAME, SIZE, ALIGN)               \
 123 do {                                                                    \
 124   if ((SIZE) <= (unsigned HOST_WIDE_INT) g_switch_value)                \
 125     switch_to_section (sbss_section);                                   \
 126   else                                                                  \
 127     switch_to_section (bss_section);                                    \
 128   ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object");                     \
 129   if (!flag_inhibit_size_directive)                                     \
 130     ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, SIZE);                       \
 131   ASM_OUTPUT_ALIGN ((FILE), exact_log2((ALIGN) / BITS_PER_UNIT));       \
 132   ASM_OUTPUT_LABEL(FILE, NAME);                                         \
 133   ASM_OUTPUT_SKIP((FILE), (SIZE) ? (SIZE) : 1);                         \
 134 } while (0)
 135
 136 /* This says how to output assembler code to declare an
 137    uninitialized external linkage data object.  */
 138
 139 #undef  ASM_OUTPUT_ALIGNED_BSS
 140 #define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN)           \
 141 do {                                                                    \
 142   ASM_OUTPUT_ALIGNED_LOCAL (FILE, NAME, SIZE, ALIGN);                   \
 143 } while (0)
 144
 145 /* The biggest alignment supported by ELF in bits. 32-bit ELF
 146    supports section alignment up to (0x80000000 * 8), while
 147    64-bit ELF supports (0x8000000000000000 * 8). If this macro
 148    is not defined, the default is the largest alignment supported
 149    by 32-bit ELF and representable on a 32-bit host. Use this
 150    macro to limit the alignment which can be specified using
 151    the `__attribute__ ((aligned (N)))' construct.
 152
 153    This value is really 2^63.  Since gcc figures the alignment in bits,
 154    we could only potentially get to 2^60 on suitable hosts.  Due to other
 155    considerations in varasm, we must restrict this to what fits in an int.  */
 156
 157 #undef  MAX_OFILE_ALIGNMENT
 158 #define MAX_OFILE_ALIGNMENT (((unsigned int) 1 << 28) * 8)
 159
 160 /* This is the pseudo-op used to generate a contiguous sequence of byte
 161    values from a double-quoted string WITHOUT HAVING A TERMINATING NUL
 162    AUTOMATICALLY APPENDED.  This is the same for most svr4 assemblers.  */
 163
 164 #undef  ASCII_DATA_ASM_OP
 165 #define ASCII_DATA_ASM_OP       "\t.ascii\t"
 166
 167 #undef  READONLY_DATA_SECTION_ASM_OP
 168 #define READONLY_DATA_SECTION_ASM_OP    "\t.section\t.rodata"
 169 #undef  BSS_SECTION_ASM_OP
 170 #define BSS_SECTION_ASM_OP      "\t.section\t.bss"
 171 #undef  SBSS_SECTION_ASM_OP
 172 #define SBSS_SECTION_ASM_OP     "\t.section\t.sbss,\"aw\""
 173 #undef  SDATA_SECTION_ASM_OP
 174 #define SDATA_SECTION_ASM_OP    "\t.section\t.sdata,\"aw\""
 175
 176 /* On svr4, we *do* have support for the .init and .fini sections, and we
 177    can put stuff in there to be executed before and after `main'.  We let
 178    crtstuff.c and other files know this by defining the following symbols.
 179    The definitions say how to change sections to the .init and .fini
 180    sections.  This is the same for all known svr4 assemblers.  */
 181
 182 #undef  INIT_SECTION_ASM_OP
 183 #define INIT_SECTION_ASM_OP     "\t.section\t.init"
 184 #undef  FINI_SECTION_ASM_OP
 185 #define FINI_SECTION_ASM_OP     "\t.section\t.fini"
 186
 187 #ifdef HAVE_GAS_SUBSECTION_ORDERING
 188
 189 #define ASM_SECTION_START_OP    "\t.subsection\t-1"
 190
 191 /* Output assembly directive to move to the beginning of current section.  */
 192 #define ASM_OUTPUT_SECTION_START(FILE)  \
 193   fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
 194
 195 #endif
 196
 197 /* Switch into a generic section.  */
 198 #define TARGET_ASM_NAMED_SECTION  default_elf_asm_named_section
 199 #define TARGET_ASM_SELECT_SECTION  default_elf_select_section
 200
 201 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
 202
 203 /* Define the strings used for the special svr4 .type and .size directives.
 204    These strings generally do not vary from one system running svr4 to
 205    another, but if a given system (e.g. m88k running svr) needs to use
 206    different pseudo-op names for these, they may be overridden in the
 207    file which includes this one.  */
 208
 209 #undef  TYPE_ASM_OP
 210 #define TYPE_ASM_OP     "\t.type\t"
 211 #undef  SIZE_ASM_OP
 212 #define SIZE_ASM_OP     "\t.size\t"
 213
 214 /* This is how we tell the assembler that a symbol is weak.  */
 215
 216 #undef  ASM_WEAKEN_LABEL
 217 #define ASM_WEAKEN_LABEL(FILE, NAME) \
 218   do { fputs ("\t.weak\t", FILE); assemble_name (FILE, NAME); \
 219        fputc ('\n', FILE); } while (0)
 220
 221 /* This is how we tell the assembler that two symbols have the same value.  */
 222
 223 #undef  ASM_OUTPUT_DEF
 224 #define ASM_OUTPUT_DEF(FILE, ALIAS, NAME)                       \
 225   do {                                                          \
 226     assemble_name(FILE, ALIAS);                                 \
 227     fputs(" = ", FILE);                                         \
 228     assemble_name(FILE, NAME);                                  \
 229     fputc('\n', FILE);                                          \
 230   } while (0)
 231
 232 #undef  ASM_OUTPUT_DEF_FROM_DECLS
 233 #define ASM_OUTPUT_DEF_FROM_DECLS(FILE, DECL, TARGET)           \
 234   do {                                                          \
 235     const char *alias = XSTR (XEXP (DECL_RTL (DECL), 0), 0);    \
 236     const char *name = IDENTIFIER_POINTER (TARGET);             \
 237     if (TREE_CODE (DECL) == FUNCTION_DECL)                      \
 238       {                                                         \
 239         fputc ('$', FILE);                                      \
 240         assemble_name (FILE, alias);                            \
 241         fputs ("..ng = $", FILE);                               \
 242         assemble_name (FILE, name);                             \
 243         fputs ("..ng\n", FILE);                                 \
 244       }                                                         \
 245     assemble_name(FILE, alias);                                 \
 246     fputs(" = ", FILE);                                         \
 247     assemble_name(FILE, name);                                  \
 248     fputc('\n', FILE);                                          \
 249   } while (0)
 250
 251 /* The following macro defines the format used to output the second
 252    operand of the .type assembler directive.  Different svr4 assemblers
 253    expect various different forms for this operand.  The one given here
 254    is just a default.  You may need to override it in your machine-
 255    specific tm.h file (depending upon the particulars of your assembler).  */
 256
 257 #undef  TYPE_OPERAND_FMT
 258 #define TYPE_OPERAND_FMT        "@%s"
 259
 260 /* Write the extra assembler code needed to declare a function's result.
 261    Most svr4 assemblers don't require any special declaration of the
 262    result value, but there are exceptions.  */
 263
 264 #ifndef ASM_DECLARE_RESULT
 265 #define ASM_DECLARE_RESULT(FILE, RESULT)
 266 #endif
 267
 268 /* These macros generate the special .type and .size directives which
 269    are used to set the corresponding fields of the linker symbol table
 270    entries in an ELF object file under SVR4.  These macros also output
 271    the starting labels for the relevant functions/objects.  */
 272
 273 /* Write the extra assembler code needed to declare an object properly.  */
 274
 275 #ifdef HAVE_GAS_GNU_UNIQUE_OBJECT
 276 #define USE_GNU_UNIQUE_OBJECT 1
 277 #else
 278 #define USE_GNU_UNIQUE_OBJECT 0
 279 #endif
 280
 281 #undef  ASM_DECLARE_OBJECT_NAME
 282 #define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL)                       \
 283   do {                                                                  \
 284     HOST_WIDE_INT size;                                                 \
 285                                                                         \
 286     /* For template static data member instantiations or                \
 287        inline fn local statics and their guard variables, use           \
 288        gnu_unique_object so that they will be combined even under       \
 289        RTLD_LOCAL.  Don't use gnu_unique_object for typeinfo,           \
 290        vtables and other read-only artificial decls.  */                \
 291     if (USE_GNU_UNIQUE_OBJECT   && DECL_ONE_ONLY (DECL)                 \
 292         && (!DECL_ARTIFICIAL (DECL) || !TREE_READONLY (DECL)))          \
 293       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "gnu_unique_object");      \
 294     else                                                                \
 295       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object");                 \
 296                                                                         \
 297     size_directive_output = 0;                                          \
 298     if (!flag_inhibit_size_directive                                    \
 299         && (DECL) && DECL_SIZE (DECL))                                  \
 300       {                                                                 \
 301         size_directive_output = 1;                                      \
 302         size = int_size_in_bytes (TREE_TYPE (DECL));                    \
 303         ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, size);                   \
 304       }                                                                 \
 305                                                                         \
 306     ASM_OUTPUT_LABEL (FILE, NAME);                                      \
 307   } while (0)
 308
 309 /* Output the size directive for a decl in rest_of_decl_compilation
 310    in the case where we did not do so before the initializer.
 311    Once we find the error_mark_node, we know that the value of
 312    size_directive_output was set
 313    by ASM_DECLARE_OBJECT_NAME when it was run for the same decl.  */
 314
 315 #undef  ASM_FINISH_DECLARE_OBJECT
 316 #define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)        \
 317   do {                                                                  \
 318     const char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0);             \
 319     HOST_WIDE_INT size;                                                 \
 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         && (size = int_size_in_bytes (TREE_TYPE (DECL))) > 0)           \
 326       {                                                                 \
 327         size_directive_output = 1;                                      \
 328         ASM_OUTPUT_SIZE_DIRECTIVE (FILE, name, size);                   \
 329       }                                                                 \
 330   } while (0)
 331
 332 /* A table of bytes codes used by the ASM_OUTPUT_ASCII and
 333    ASM_OUTPUT_LIMITED_STRING macros.  Each byte in the table
 334    corresponds to a particular byte value [0..255].  For any
 335    given byte value, if the value in the corresponding table
 336    position is zero, the given character can be output directly.
 337    If the table value is 1, the byte must be output as a \ooo
 338    octal escape.  If the tables value is anything else, then the
 339    byte value should be output as a \ followed by the value
 340    in the table.  Note that we can use standard UN*X escape
 341    sequences for many control characters, but we don't use
 342    \a to represent BEL because some svr4 assemblers (e.g. on
 343    the i386) don't know about that.  Also, we don't use \v
 344    since some versions of gas, such as 2.2 did not accept it.  */
 345
 346 #undef  ESCAPES
 347 #define ESCAPES \
 348 "\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\
 349 \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\
 350 \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\
 351 \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\
 352 \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\
 353 \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\
 354 \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\
 355 \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"
 356
 357 /* Some svr4 assemblers have a limit on the number of characters which
 358    can appear in the operand of a .string directive.  If your assembler
 359    has such a limitation, you should define STRING_LIMIT to reflect that
 360    limit.  Note that at least some svr4 assemblers have a limit on the
 361    actual number of bytes in the double-quoted string, and that they
 362    count each character in an escape sequence as one byte.  Thus, an
 363    escape sequence like \377 would count as four bytes.
 364
 365    If your target assembler doesn't support the .string directive, you
 366    should define this to zero.  */
 367
 368 #undef  STRING_LIMIT
 369 #define STRING_LIMIT    ((unsigned) 256)
 370 #undef  STRING_ASM_OP
 371 #define STRING_ASM_OP   "\t.string\t"
 372
 373 /* GAS is the only Alpha/ELF assembler.  */
 374 #undef  TARGET_GAS
 375 #define TARGET_GAS      (1)
 376
 377 /* Provide a STARTFILE_SPEC appropriate for ELF.  Here we add the
 378    (even more) magical crtbegin.o file which provides part of the
 379    support for getting C++ file-scope static object constructed
 380    before entering `main'.  */
 381
 382 #undef  STARTFILE_SPEC
 383 #ifdef HAVE_LD_PIE
 384 #define STARTFILE_SPEC \
 385   "%{!shared: %{pg|p:gcrt1.o%s;pie:Scrt1.o%s;:crt1.o%s}}\
 386    crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
 387 #else
 388 #define STARTFILE_SPEC \
 389   "%{!shared: %{pg|p:gcrt1.o%s;:crt1.o%s}}\
 390    crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
 391 #endif
 392
 393 /* Provide a ENDFILE_SPEC appropriate for ELF.  Here we tack on the
 394    magical crtend.o file which provides part of the support for
 395    getting C++ file-scope static object constructed before entering
 396    `main', followed by a normal ELF "finalizer" file, `crtn.o'.  */
 397
 398 #undef  ENDFILE_SPEC
 399 #define ENDFILE_SPEC \
 400   "%{ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
 401    %{shared|pie:crtendS.o%s;:crtend.o%s} crtn.o%s"
 402
 403 /* We support #pragma.  */
 404 #define HANDLE_SYSV_PRAGMA 1
 405
 406 /* Select a format to encode pointers in exception handling data.  CODE
 407    is 0 for data, 1 for code labels, 2 for function pointers.  GLOBAL is
 408    true if the symbol may be affected by dynamic relocations.
 409
 410    Since application size is already constrained to <2GB by the form of
 411    the ldgp relocation, we can use a 32-bit pc-relative relocation to
 412    static data.  Dynamic data is accessed indirectly to allow for read
 413    only EH sections.  */
 414 #define ASM_PREFERRED_EH_DATA_FORMAT(CODE,GLOBAL)       \
 415   (((GLOBAL) ? DW_EH_PE_indirect : 0) | DW_EH_PE_pcrel | DW_EH_PE_sdata4)
 416
 417 /* If defined, a C statement to be executed just prior to the output of
 418    assembler code for INSN.  */
 419 #define FINAL_PRESCAN_INSN(INSN, OPVEC, NOPERANDS)      \
 420  (alpha_this_literal_sequence_number = 0,               \
 421   alpha_this_gpdisp_sequence_number = 0)
 422 extern int alpha_this_literal_sequence_number;
 423 extern int alpha_this_gpdisp_sequence_number;
 424
 425 /* Since the bits of the _init and _fini function is spread across
 426    many object files, each potentially with its own GP, we must assume
 427    we need to load our GP.  Further, the .init/.fini section can
 428    easily be more than 4MB away from the function to call so we can't
 429    use bsr.  */
 430 #define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC)      \
 431    asm (SECTION_OP "\n"                                 \
 432 "       br $29,1f\n"                                    \
 433 "1:     ldgp $29,0($29)\n"                              \
 434 "       unop\n"                                         \
 435 "       jsr $26," USER_LABEL_PREFIX #FUNC "\n"          \
 436 "       .align 3\n"                                     \
 437 "       .previous");
 438
 439 /* If we have the capability create headers for efficient EH lookup.
 440    As of Jan 2002, only glibc 2.2.4 can actually make use of this, but
 441    I imagine that other systems will catch up.  In the meantime, it
 442    doesn't harm to make sure that the data exists to be used later.  */
 443 #if defined(HAVE_LD_EH_FRAME_HDR)
 444 #define LINK_EH_SPEC "%{!static:--eh-frame-hdr} "
 445 #endif
 446
 447 /* A C statement (sans semicolon) to output to the stdio stream STREAM
 448    any text necessary for declaring the name of an external symbol
 449    named NAME which is referenced in this compilation but not defined.
 450    It is needed to properly support non-default visibility.  */
 451
 452 #ifndef ASM_OUTPUT_EXTERNAL
 453 #define ASM_OUTPUT_EXTERNAL(FILE, DECL, NAME) \
 454   default_elf_asm_output_external (FILE, DECL, NAME)
 455 #endif