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
   3    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) <= 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 /* Biggest alignment supported by the object file format of this
 146    machine.  Use this macro to limit the alignment which can be
 147    specified using the `__attribute__ ((aligned (N)))' construct.  If
 148    not defined, the default value is `BIGGEST_ALIGNMENT'.
 149
 150    This value is really 2^63.  Since gcc figures the alignment in bits,
 151    we could only potentially get to 2^60 on suitable hosts.  Due to other
 152    considerations in varasm, we must restrict this to what fits in an int.  */
 153
 154 #undef  MAX_OFILE_ALIGNMENT
 155 #define MAX_OFILE_ALIGNMENT \
 156   (1 << (HOST_BITS_PER_INT < 64 ? HOST_BITS_PER_INT - 2 : 62))
 157
 158 /* This is the pseudo-op used to generate a contiguous sequence of byte
 159    values from a double-quoted string WITHOUT HAVING A TERMINATING NUL
 160    AUTOMATICALLY APPENDED.  This is the same for most svr4 assemblers.  */
 161
 162 #undef  ASCII_DATA_ASM_OP
 163 #define ASCII_DATA_ASM_OP       "\t.ascii\t"
 164
 165 #undef  READONLY_DATA_SECTION_ASM_OP
 166 #define READONLY_DATA_SECTION_ASM_OP    "\t.section\t.rodata"
 167 #undef  BSS_SECTION_ASM_OP
 168 #define BSS_SECTION_ASM_OP      "\t.section\t.bss"
 169 #undef  SBSS_SECTION_ASM_OP
 170 #define SBSS_SECTION_ASM_OP     "\t.section\t.sbss,\"aw\""
 171 #undef  SDATA_SECTION_ASM_OP
 172 #define SDATA_SECTION_ASM_OP    "\t.section\t.sdata,\"aw\""
 173
 174 /* On svr4, we *do* have support for the .init and .fini sections, and we
 175    can put stuff in there to be executed before and after `main'.  We let
 176    crtstuff.c and other files know this by defining the following symbols.
 177    The definitions say how to change sections to the .init and .fini
 178    sections.  This is the same for all known svr4 assemblers.  */
 179
 180 #undef  INIT_SECTION_ASM_OP
 181 #define INIT_SECTION_ASM_OP     "\t.section\t.init"
 182 #undef  FINI_SECTION_ASM_OP
 183 #define FINI_SECTION_ASM_OP     "\t.section\t.fini"
 184
 185 #ifdef HAVE_GAS_SUBSECTION_ORDERING
 186
 187 #define ASM_SECTION_START_OP    "\t.subsection\t-1"
 188
 189 /* Output assembly directive to move to the beginning of current section.  */
 190 #define ASM_OUTPUT_SECTION_START(FILE)  \
 191   fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
 192
 193 #endif
 194
 195 /* Switch into a generic section.  */
 196 #define TARGET_ASM_NAMED_SECTION  default_elf_asm_named_section
 197 #define TARGET_ASM_SELECT_SECTION  default_elf_select_section
 198
 199 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
 200
 201 /* Define the strings used for the special svr4 .type and .size directives.
 202    These strings generally do not vary from one system running svr4 to
 203    another, but if a given system (e.g. m88k running svr) needs to use
 204    different pseudo-op names for these, they may be overridden in the
 205    file which includes this one.  */
 206
 207 #undef  TYPE_ASM_OP
 208 #define TYPE_ASM_OP     "\t.type\t"
 209 #undef  SIZE_ASM_OP
 210 #define SIZE_ASM_OP     "\t.size\t"
 211
 212 /* This is how we tell the assembler that a symbol is weak.  */
 213
 214 #undef  ASM_WEAKEN_LABEL
 215 #define ASM_WEAKEN_LABEL(FILE, NAME) \
 216   do { fputs ("\t.weak\t", FILE); assemble_name (FILE, NAME); \
 217        fputc ('\n', FILE); } while (0)
 218
 219 /* This is how we tell the assembler that two symbols have the same value.  */
 220
 221 #undef  ASM_OUTPUT_DEF
 222 #define ASM_OUTPUT_DEF(FILE, ALIAS, NAME)                       \
 223   do {                                                          \
 224     assemble_name(FILE, ALIAS);                                 \
 225     fputs(" = ", FILE);                                         \
 226     assemble_name(FILE, NAME);                                  \
 227     fputc('\n', FILE);                                          \
 228   } while (0)
 229
 230 #undef  ASM_OUTPUT_DEF_FROM_DECLS
 231 #define ASM_OUTPUT_DEF_FROM_DECLS(FILE, DECL, TARGET)           \
 232   do {                                                          \
 233     const char *alias = XSTR (XEXP (DECL_RTL (DECL), 0), 0);    \
 234     const char *name = IDENTIFIER_POINTER (TARGET);             \
 235     if (TREE_CODE (DECL) == FUNCTION_DECL)                      \
 236       {                                                         \
 237         fputc ('$', FILE);                                      \
 238         assemble_name (FILE, alias);                            \
 239         fputs ("..ng = $", FILE);                               \
 240         assemble_name (FILE, name);                             \
 241         fputs ("..ng\n", FILE);                                 \
 242       }                                                         \
 243     assemble_name(FILE, alias);                                 \
 244     fputs(" = ", FILE);                                         \
 245     assemble_name(FILE, name);                                  \
 246     fputc('\n', FILE);                                          \
 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 #undef  TYPE_OPERAND_FMT
 256 #define TYPE_OPERAND_FMT        "@%s"
 257
 258 /* Write the extra assembler code needed to declare a function's result.
 259    Most svr4 assemblers don't require any special declaration of the
 260    result value, but there are exceptions.  */
 261
 262 #ifndef ASM_DECLARE_RESULT
 263 #define ASM_DECLARE_RESULT(FILE, RESULT)
 264 #endif
 265
 266 /* These macros generate the special .type and .size directives which
 267    are used to set the corresponding fields of the linker symbol table
 268    entries in an ELF object file under SVR4.  These macros also output
 269    the starting labels for the relevant functions/objects.  */
 270
 271 /* Write the extra assembler code needed to declare an object properly.  */
 272
 273 #undef  ASM_DECLARE_OBJECT_NAME
 274 #define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL)               \
 275   do {                                                          \
 276     HOST_WIDE_INT size;                                         \
 277     ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object");           \
 278     size_directive_output = 0;                                  \
 279     if (!flag_inhibit_size_directive                            \
 280         && DECL_SIZE (DECL)                                     \
 281         && (size = int_size_in_bytes (TREE_TYPE (DECL))) > 0)   \
 282       {                                                         \
 283         size_directive_output = 1;                              \
 284         ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, size);           \
 285       }                                                         \
 286     ASM_OUTPUT_LABEL(FILE, NAME);                               \
 287   } while (0)
 288
 289 /* Output the size directive for a decl in rest_of_decl_compilation
 290    in the case where we did not do so before the initializer.
 291    Once we find the error_mark_node, we know that the value of
 292    size_directive_output was set
 293    by ASM_DECLARE_OBJECT_NAME when it was run for the same decl.  */
 294
 295 #undef  ASM_FINISH_DECLARE_OBJECT
 296 #define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)        \
 297   do {                                                                  \
 298     const char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0);             \
 299     HOST_WIDE_INT size;                                                 \
 300     if (!flag_inhibit_size_directive                                    \
 301         && DECL_SIZE (DECL)                                             \
 302         && ! AT_END && TOP_LEVEL                                        \
 303         && DECL_INITIAL (DECL) == error_mark_node                       \
 304         && !size_directive_output                                       \
 305         && (size = int_size_in_bytes (TREE_TYPE (DECL))) > 0)           \
 306       {                                                                 \
 307         size_directive_output = 1;                                      \
 308         ASM_OUTPUT_SIZE_DIRECTIVE (FILE, name, size);                   \
 309       }                                                                 \
 310   } while (0)
 311
 312 /* A table of bytes codes used by the ASM_OUTPUT_ASCII and
 313    ASM_OUTPUT_LIMITED_STRING macros.  Each byte in the table
 314    corresponds to a particular byte value [0..255].  For any
 315    given byte value, if the value in the corresponding table
 316    position is zero, the given character can be output directly.
 317    If the table value is 1, the byte must be output as a \ooo
 318    octal escape.  If the tables value is anything else, then the
 319    byte value should be output as a \ followed by the value
 320    in the table.  Note that we can use standard UN*X escape
 321    sequences for many control characters, but we don't use
 322    \a to represent BEL because some svr4 assemblers (e.g. on
 323    the i386) don't know about that.  Also, we don't use \v
 324    since some versions of gas, such as 2.2 did not accept it.  */
 325
 326 #undef  ESCAPES
 327 #define ESCAPES \
 328 "\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\
 329 \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\
 330 \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\
 331 \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\
 332 \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\
 333 \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\
 334 \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\
 335 \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"
 336
 337 /* Some svr4 assemblers have a limit on the number of characters which
 338    can appear in the operand of a .string directive.  If your assembler
 339    has such a limitation, you should define STRING_LIMIT to reflect that
 340    limit.  Note that at least some svr4 assemblers have a limit on the
 341    actual number of bytes in the double-quoted string, and that they
 342    count each character in an escape sequence as one byte.  Thus, an
 343    escape sequence like \377 would count as four bytes.
 344
 345    If your target assembler doesn't support the .string directive, you
 346    should define this to zero.  */
 347
 348 #undef  STRING_LIMIT
 349 #define STRING_LIMIT    ((unsigned) 256)
 350 #undef  STRING_ASM_OP
 351 #define STRING_ASM_OP   "\t.string\t"
 352
 353 /* GAS is the only Alpha/ELF assembler.  */
 354 #undef  TARGET_GAS
 355 #define TARGET_GAS      (1)
 356
 357 /* Provide a STARTFILE_SPEC appropriate for ELF.  Here we add the
 358    (even more) magical crtbegin.o file which provides part of the
 359    support for getting C++ file-scope static object constructed
 360    before entering `main'.  */
 361
 362 #undef  STARTFILE_SPEC
 363 #ifdef HAVE_LD_PIE
 364 #define STARTFILE_SPEC \
 365   "%{!shared: %{pg|p:gcrt1.o%s;pie:Scrt1.o%s;:crt1.o%s}}\
 366    crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
 367 #else
 368 #define STARTFILE_SPEC \
 369   "%{!shared: %{pg|p:gcrt1.o%s;:crt1.o%s}}\
 370    crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
 371 #endif
 372
 373 /* Provide a ENDFILE_SPEC appropriate for ELF.  Here we tack on the
 374    magical crtend.o file which provides part of the support for
 375    getting C++ file-scope static object constructed before entering
 376    `main', followed by a normal ELF "finalizer" file, `crtn.o'.  */
 377
 378 #undef  ENDFILE_SPEC
 379 #define ENDFILE_SPEC \
 380   "%{ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
 381    %{shared|pie:crtendS.o%s;:crtend.o%s} crtn.o%s"
 382
 383 /* We support #pragma.  */
 384 #define HANDLE_SYSV_PRAGMA 1
 385
 386 /* Select a format to encode pointers in exception handling data.  CODE
 387    is 0 for data, 1 for code labels, 2 for function pointers.  GLOBAL is
 388    true if the symbol may be affected by dynamic relocations.
 389
 390    Since application size is already constrained to <2GB by the form of
 391    the ldgp relocation, we can use a 32-bit pc-relative relocation to
 392    static data.  Dynamic data is accessed indirectly to allow for read
 393    only EH sections.  */
 394 #define ASM_PREFERRED_EH_DATA_FORMAT(CODE,GLOBAL)       \
 395   (((GLOBAL) ? DW_EH_PE_indirect : 0) | DW_EH_PE_pcrel | DW_EH_PE_sdata4)
 396
 397 /* If defined, a C statement to be executed just prior to the output of
 398    assembler code for INSN.  */
 399 #define FINAL_PRESCAN_INSN(INSN, OPVEC, NOPERANDS)      \
 400  (alpha_this_literal_sequence_number = 0,               \
 401   alpha_this_gpdisp_sequence_number = 0)
 402 extern int alpha_this_literal_sequence_number;
 403 extern int alpha_this_gpdisp_sequence_number;
 404
 405 /* Since the bits of the _init and _fini function is spread across
 406    many object files, each potentially with its own GP, we must assume
 407    we need to load our GP.  Further, the .init/.fini section can
 408    easily be more than 4MB away from the function to call so we can't
 409    use bsr.  */
 410 #define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC)      \
 411    asm (SECTION_OP "\n"                                 \
 412 "       br $29,1f\n"                                    \
 413 "1:     ldgp $29,0($29)\n"                              \
 414 "       unop\n"                                         \
 415 "       jsr $26," USER_LABEL_PREFIX #FUNC "\n"          \
 416 "       .align 3\n"                                     \
 417 "       .previous");
 418
 419 /* If we have the capability create headers for efficient EH lookup.
 420    As of Jan 2002, only glibc 2.2.4 can actually make use of this, but
 421    I imagine that other systems will catch up.  In the meantime, it
 422    doesn't harm to make sure that the data exists to be used later.  */
 423 #if defined(HAVE_LD_EH_FRAME_HDR)
 424 #define LINK_EH_SPEC "%{!static:--eh-frame-hdr} "
 425 #endif