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
   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 2, 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 COPYING.  If not, write to
  20 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  21 Boston, MA 02110-1301, USA.  */
  22
  23 #undef OBJECT_FORMAT_COFF
  24 #undef EXTENDED_COFF
  25 #define OBJECT_FORMAT_ELF
  26
  27 /* ??? Move all SDB stuff from alpha.h to osf.h.  */
  28 #undef SDB_DEBUGGING_INFO
  29
  30 #define DBX_DEBUGGING_INFO 1
  31 #define DWARF2_DEBUGGING_INFO 1
  32
  33 #undef  PREFERRED_DEBUGGING_TYPE
  34 #define PREFERRED_DEBUGGING_TYPE DWARF2_DEBUG
  35
  36 #undef ASM_FINAL_SPEC
  37
  38 /* alpha/ doesn't use elfos.h for some reason.  */
  39 #define TARGET_OBJFMT_CPP_BUILTINS()            \
  40   do                                            \
  41     {                                           \
  42         builtin_define ("__ELF__");             \
  43     }                                           \
  44   while (0)
  45
  46 #undef  CC1_SPEC
  47 #define CC1_SPEC  "%{G*}"
  48
  49 #undef  ASM_SPEC
  50 #define ASM_SPEC  "%{G*} %{relax:-relax} %{!gstabs*:-no-mdebug}%{gstabs*:-mdebug}"
  51
  52 #undef  IDENT_ASM_OP
  53 #define IDENT_ASM_OP "\t.ident\t"
  54
  55 /* Output #ident as a .ident.  */
  56 #undef  ASM_OUTPUT_IDENT
  57 #define ASM_OUTPUT_IDENT(FILE, NAME) \
  58   fprintf (FILE, "%s\"%s\"\n", IDENT_ASM_OP, NAME);
  59
  60 /* This is how to allocate empty space in some section.  The .zero
  61    pseudo-op is used for this on most svr4 assemblers.  */
  62
  63 #undef  SKIP_ASM_OP
  64 #define SKIP_ASM_OP     "\t.zero\t"
  65
  66 #undef  ASM_OUTPUT_SKIP
  67 #define ASM_OUTPUT_SKIP(FILE, SIZE) \
  68   fprintf (FILE, "%s"HOST_WIDE_INT_PRINT_UNSIGNED"\n", SKIP_ASM_OP, (SIZE))
  69
  70 /* Output the label which precedes a jumptable.  Note that for all svr4
  71    systems where we actually generate jumptables (which is to say every
  72    svr4 target except i386, where we use casesi instead) we put the jump-
  73    tables into the .rodata section and since other stuff could have been
  74    put into the .rodata section prior to any given jumptable, we have to
  75    make sure that the location counter for the .rodata section gets pro-
  76    perly re-aligned prior to the actual beginning of the jump table.  */
  77
  78 #undef  ALIGN_ASM_OP
  79 #define ALIGN_ASM_OP "\t.align\t"
  80
  81 #ifndef ASM_OUTPUT_BEFORE_CASE_LABEL
  82 #define ASM_OUTPUT_BEFORE_CASE_LABEL(FILE, PREFIX, NUM, TABLE) \
  83   ASM_OUTPUT_ALIGN ((FILE), 2);
  84 #endif
  85
  86 #undef  ASM_OUTPUT_CASE_LABEL
  87 #define ASM_OUTPUT_CASE_LABEL(FILE, PREFIX, NUM, JUMPTABLE)             \
  88   do {                                                                  \
  89     ASM_OUTPUT_BEFORE_CASE_LABEL (FILE, PREFIX, NUM, JUMPTABLE)         \
  90     (*targetm.asm_out.internal_label) (FILE, PREFIX, NUM);                      \
  91   } while (0)
  92
  93 /* The standard SVR4 assembler seems to require that certain builtin
  94    library routines (e.g. .udiv) be explicitly declared as .globl
  95    in each assembly file where they are referenced.  */
  96
  97 #undef  ASM_OUTPUT_EXTERNAL_LIBCALL
  98 #define ASM_OUTPUT_EXTERNAL_LIBCALL(FILE, FUN)                          \
  99   (*targetm.asm_out.globalize_label) (FILE, XSTR (FUN, 0))
 100
 101 /* This says how to output assembler code to declare an
 102    uninitialized external linkage data object.  Under SVR4,
 103    the linker seems to want the alignment of data objects
 104    to depend on their types.  We do exactly that here.  */
 105
 106 #undef  COMMON_ASM_OP
 107 #define COMMON_ASM_OP   "\t.comm\t"
 108
 109 #undef  ASM_OUTPUT_ALIGNED_COMMON
 110 #define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)              \
 111 do {                                                                    \
 112   fprintf ((FILE), "%s", COMMON_ASM_OP);                                \
 113   assemble_name ((FILE), (NAME));                                       \
 114   fprintf ((FILE), "," HOST_WIDE_INT_PRINT_UNSIGNED ",%u\n", (SIZE), (ALIGN) / BITS_PER_UNIT);  \
 115 } while (0)
 116
 117 /* This says how to output assembler code to declare an
 118    uninitialized internal linkage data object.  Under SVR4,
 119    the linker seems to want the alignment of data objects
 120    to depend on their types.  We do exactly that here.  */
 121
 122 #undef  ASM_OUTPUT_ALIGNED_LOCAL
 123 #define ASM_OUTPUT_ALIGNED_LOCAL(FILE, NAME, SIZE, ALIGN)               \
 124 do {                                                                    \
 125   if ((SIZE) <= g_switch_value)                                         \
 126     switch_to_section (sbss_section);                                   \
 127   else                                                                  \
 128     switch_to_section (bss_section);                                    \
 129   ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object");                     \
 130   if (!flag_inhibit_size_directive)                                     \
 131     ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, SIZE);                       \
 132   ASM_OUTPUT_ALIGN ((FILE), exact_log2((ALIGN) / BITS_PER_UNIT));       \
 133   ASM_OUTPUT_LABEL(FILE, NAME);                                         \
 134   ASM_OUTPUT_SKIP((FILE), (SIZE) ? (SIZE) : 1);                         \
 135 } while (0)
 136
 137 /* This says how to output assembler code to declare an
 138    uninitialized external linkage data object.  */
 139
 140 #undef  ASM_OUTPUT_ALIGNED_BSS
 141 #define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN)           \
 142 do {                                                                    \
 143   ASM_OUTPUT_ALIGNED_LOCAL (FILE, NAME, SIZE, ALIGN);                   \
 144 } while (0)
 145
 146 /* Biggest alignment supported by the object file format of this
 147    machine.  Use this macro to limit the alignment which can be
 148    specified using the `__attribute__ ((aligned (N)))' construct.  If
 149    not defined, the default value is `BIGGEST_ALIGNMENT'.
 150
 151    This value is really 2^63.  Since gcc figures the alignment in bits,
 152    we could only potentially get to 2^60 on suitable hosts.  Due to other
 153    considerations in varasm, we must restrict this to what fits in an int.  */
 154
 155 #undef  MAX_OFILE_ALIGNMENT
 156 #define MAX_OFILE_ALIGNMENT \
 157   (1 << (HOST_BITS_PER_INT < 64 ? HOST_BITS_PER_INT - 2 : 62))
 158
 159 /* This is the pseudo-op used to generate a contiguous sequence of byte
 160    values from a double-quoted string WITHOUT HAVING A TERMINATING NUL
 161    AUTOMATICALLY APPENDED.  This is the same for most svr4 assemblers.  */
 162
 163 #undef  ASCII_DATA_ASM_OP
 164 #define ASCII_DATA_ASM_OP       "\t.ascii\t"
 165
 166 #undef  READONLY_DATA_SECTION_ASM_OP
 167 #define READONLY_DATA_SECTION_ASM_OP    "\t.section\t.rodata"
 168 #undef  BSS_SECTION_ASM_OP
 169 #define BSS_SECTION_ASM_OP      "\t.section\t.bss"
 170 #undef  SBSS_SECTION_ASM_OP
 171 #define SBSS_SECTION_ASM_OP     "\t.section\t.sbss,\"aw\""
 172 #undef  SDATA_SECTION_ASM_OP
 173 #define SDATA_SECTION_ASM_OP    "\t.section\t.sdata,\"aw\""
 174
 175 /* On svr4, we *do* have support for the .init and .fini sections, and we
 176    can put stuff in there to be executed before and after `main'.  We let
 177    crtstuff.c and other files know this by defining the following symbols.
 178    The definitions say how to change sections to the .init and .fini
 179    sections.  This is the same for all known svr4 assemblers.  */
 180
 181 #undef  INIT_SECTION_ASM_OP
 182 #define INIT_SECTION_ASM_OP     "\t.section\t.init"
 183 #undef  FINI_SECTION_ASM_OP
 184 #define FINI_SECTION_ASM_OP     "\t.section\t.fini"
 185
 186 #ifdef HAVE_GAS_SUBSECTION_ORDERING
 187
 188 #define ASM_SECTION_START_OP    "\t.subsection\t-1"
 189
 190 /* Output assembly directive to move to the beginning of current section.  */
 191 #define ASM_OUTPUT_SECTION_START(FILE)  \
 192   fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
 193
 194 #endif
 195
 196 /* Switch into a generic section.  */
 197 #define TARGET_ASM_NAMED_SECTION  default_elf_asm_named_section
 198 #define TARGET_ASM_SELECT_SECTION  default_elf_select_section
 199
 200 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
 201
 202 /* Define the strings used for the special svr4 .type and .size directives.
 203    These strings generally do not vary from one system running svr4 to
 204    another, but if a given system (e.g. m88k running svr) needs to use
 205    different pseudo-op names for these, they may be overridden in the
 206    file which includes this one.  */
 207
 208 #undef  TYPE_ASM_OP
 209 #define TYPE_ASM_OP     "\t.type\t"
 210 #undef  SIZE_ASM_OP
 211 #define SIZE_ASM_OP     "\t.size\t"
 212
 213 /* This is how we tell the assembler that a symbol is weak.  */
 214
 215 #undef  ASM_WEAKEN_LABEL
 216 #define ASM_WEAKEN_LABEL(FILE, NAME) \
 217   do { fputs ("\t.weak\t", FILE); assemble_name (FILE, NAME); \
 218        fputc ('\n', FILE); } while (0)
 219
 220 /* This is how we tell the assembler that two symbols have the same value.  */
 221
 222 #undef  ASM_OUTPUT_DEF
 223 #define ASM_OUTPUT_DEF(FILE, ALIAS, NAME)                       \
 224   do {                                                          \
 225     assemble_name(FILE, ALIAS);                                 \
 226     fputs(" = ", FILE);                                         \
 227     assemble_name(FILE, NAME);                                  \
 228     fputc('\n', FILE);                                          \
 229   } while (0)
 230
 231 #undef  ASM_OUTPUT_DEF_FROM_DECLS
 232 #define ASM_OUTPUT_DEF_FROM_DECLS(FILE, DECL, TARGET)           \
 233   do {                                                          \
 234     const char *alias = XSTR (XEXP (DECL_RTL (DECL), 0), 0);    \
 235     const char *name = IDENTIFIER_POINTER (TARGET);             \
 236     if (TREE_CODE (DECL) == FUNCTION_DECL)                      \
 237       {                                                         \
 238         fputc ('$', FILE);                                      \
 239         assemble_name (FILE, alias);                            \
 240         fputs ("..ng = $", FILE);                               \
 241         assemble_name (FILE, name);                             \
 242         fputs ("..ng\n", FILE);                                 \
 243       }                                                         \
 244     assemble_name(FILE, alias);                                 \
 245     fputs(" = ", FILE);                                         \
 246     assemble_name(FILE, name);                                  \
 247     fputc('\n', FILE);                                          \
 248   } while (0)
 249
 250 /* The following macro defines the format used to output the second
 251    operand of the .type assembler directive.  Different svr4 assemblers
 252    expect various different forms for this operand.  The one given here
 253    is just a default.  You may need to override it in your machine-
 254    specific tm.h file (depending upon the particulars of your assembler).  */
 255
 256 #undef  TYPE_OPERAND_FMT
 257 #define TYPE_OPERAND_FMT        "@%s"
 258
 259 /* Write the extra assembler code needed to declare a function's result.
 260    Most svr4 assemblers don't require any special declaration of the
 261    result value, but there are exceptions.  */
 262
 263 #ifndef ASM_DECLARE_RESULT
 264 #define ASM_DECLARE_RESULT(FILE, RESULT)
 265 #endif
 266
 267 /* These macros generate the special .type and .size directives which
 268    are used to set the corresponding fields of the linker symbol table
 269    entries in an ELF object file under SVR4.  These macros also output
 270    the starting labels for the relevant functions/objects.  */
 271
 272 /* Write the extra assembler code needed to declare an object properly.  */
 273
 274 #undef  ASM_DECLARE_OBJECT_NAME
 275 #define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL)               \
 276   do {                                                          \
 277     HOST_WIDE_INT size;                                         \
 278     ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object");           \
 279     size_directive_output = 0;                                  \
 280     if (!flag_inhibit_size_directive                            \
 281         && DECL_SIZE (DECL)                                     \
 282         && (size = int_size_in_bytes (TREE_TYPE (DECL))) > 0)   \
 283       {                                                         \
 284         size_directive_output = 1;                              \
 285         ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, size);           \
 286       }                                                         \
 287     ASM_OUTPUT_LABEL(FILE, NAME);                               \
 288   } while (0)
 289
 290 /* Output the size directive for a decl in rest_of_decl_compilation
 291    in the case where we did not do so before the initializer.
 292    Once we find the error_mark_node, we know that the value of
 293    size_directive_output was set
 294    by ASM_DECLARE_OBJECT_NAME when it was run for the same decl.  */
 295
 296 #undef  ASM_FINISH_DECLARE_OBJECT
 297 #define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)        \
 298   do {                                                                  \
 299     const char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0);             \
 300     HOST_WIDE_INT size;                                                 \
 301     if (!flag_inhibit_size_directive                                    \
 302         && DECL_SIZE (DECL)                                             \
 303         && ! AT_END && TOP_LEVEL                                        \
 304         && DECL_INITIAL (DECL) == error_mark_node                       \
 305         && !size_directive_output                                       \
 306         && (size = int_size_in_bytes (TREE_TYPE (DECL))) > 0)           \
 307       {                                                                 \
 308         size_directive_output = 1;                                      \
 309         ASM_OUTPUT_SIZE_DIRECTIVE (FILE, name, size);                   \
 310       }                                                                 \
 311   } while (0)
 312
 313 /* A table of bytes codes used by the ASM_OUTPUT_ASCII and
 314    ASM_OUTPUT_LIMITED_STRING macros.  Each byte in the table
 315    corresponds to a particular byte value [0..255].  For any
 316    given byte value, if the value in the corresponding table
 317    position is zero, the given character can be output directly.
 318    If the table value is 1, the byte must be output as a \ooo
 319    octal escape.  If the tables value is anything else, then the
 320    byte value should be output as a \ followed by the value
 321    in the table.  Note that we can use standard UN*X escape
 322    sequences for many control characters, but we don't use
 323    \a to represent BEL because some svr4 assemblers (e.g. on
 324    the i386) don't know about that.  Also, we don't use \v
 325    since some versions of gas, such as 2.2 did not accept it.  */
 326
 327 #undef  ESCAPES
 328 #define ESCAPES \
 329 "\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\
 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\
 332 \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\
 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 \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"
 337
 338 /* Some svr4 assemblers have a limit on the number of characters which
 339    can appear in the operand of a .string directive.  If your assembler
 340    has such a limitation, you should define STRING_LIMIT to reflect that
 341    limit.  Note that at least some svr4 assemblers have a limit on the
 342    actual number of bytes in the double-quoted string, and that they
 343    count each character in an escape sequence as one byte.  Thus, an
 344    escape sequence like \377 would count as four bytes.
 345
 346    If your target assembler doesn't support the .string directive, you
 347    should define this to zero.  */
 348
 349 #undef  STRING_LIMIT
 350 #define STRING_LIMIT    ((unsigned) 256)
 351 #undef  STRING_ASM_OP
 352 #define STRING_ASM_OP   "\t.string\t"
 353
 354 /* GAS is the only Alpha/ELF assembler.  */
 355 #undef  TARGET_GAS
 356 #define TARGET_GAS      (1)
 357
 358 /* Provide a STARTFILE_SPEC appropriate for ELF.  Here we add the
 359    (even more) magical crtbegin.o file which provides part of the
 360    support for getting C++ file-scope static object constructed
 361    before entering `main'.  */
 362
 363 #undef  STARTFILE_SPEC
 364 #ifdef HAVE_LD_PIE
 365 #define STARTFILE_SPEC \
 366   "%{!shared: %{pg|p:gcrt1.o%s;pie:Scrt1.o%s;:crt1.o%s}}\
 367    crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
 368 #else
 369 #define STARTFILE_SPEC \
 370   "%{!shared: %{pg|p:gcrt1.o%s;:crt1.o%s}}\
 371    crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
 372 #endif
 373
 374 /* Provide a ENDFILE_SPEC appropriate for ELF.  Here we tack on the
 375    magical crtend.o file which provides part of the support for
 376    getting C++ file-scope static object constructed before entering
 377    `main', followed by a normal ELF "finalizer" file, `crtn.o'.  */
 378
 379 #undef  ENDFILE_SPEC
 380 #define ENDFILE_SPEC \
 381   "%{ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
 382    %{shared|pie:crtendS.o%s;:crtend.o%s} crtn.o%s"
 383
 384 /* We support #pragma.  */
 385 #define HANDLE_SYSV_PRAGMA 1
 386
 387 /* Select a format to encode pointers in exception handling data.  CODE
 388    is 0 for data, 1 for code labels, 2 for function pointers.  GLOBAL is
 389    true if the symbol may be affected by dynamic relocations.
 390
 391    Since application size is already constrained to <2GB by the form of
 392    the ldgp relocation, we can use a 32-bit pc-relative relocation to
 393    static data.  Dynamic data is accessed indirectly to allow for read
 394    only EH sections.  */
 395 #define ASM_PREFERRED_EH_DATA_FORMAT(CODE,GLOBAL)       \
 396   (((GLOBAL) ? DW_EH_PE_indirect : 0) | DW_EH_PE_pcrel | DW_EH_PE_sdata4)
 397
 398 /* If defined, a C statement to be executed just prior to the output of
 399    assembler code for INSN.  */
 400 #define FINAL_PRESCAN_INSN(INSN, OPVEC, NOPERANDS)      \
 401  (alpha_this_literal_sequence_number = 0,               \
 402   alpha_this_gpdisp_sequence_number = 0)
 403 extern int alpha_this_literal_sequence_number;
 404 extern int alpha_this_gpdisp_sequence_number;
 405
 406 /* Since the bits of the _init and _fini function is spread across
 407    many object files, each potentially with its own GP, we must assume
 408    we need to load our GP.  Further, the .init/.fini section can
 409    easily be more than 4MB away from the function to call so we can't
 410    use bsr.  */
 411 #define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC)      \
 412    asm (SECTION_OP "\n"                                 \
 413 "       br $29,1f\n"                                    \
 414 "1:     ldgp $29,0($29)\n"                              \
 415 "       unop\n"                                         \
 416 "       jsr $26," USER_LABEL_PREFIX #FUNC "\n"          \
 417 "       .align 3\n"                                     \
 418 "       .previous");
 419
 420 /* If we have the capability create headers for efficient EH lookup.
 421    As of Jan 2002, only glibc 2.2.4 can actually make use of this, but
 422    I imagine that other systems will catch up.  In the meantime, it
 423    doesn't harm to make sure that the data exists to be used later.  */
 424 #if defined(HAVE_LD_EH_FRAME_HDR)
 425 #define LINK_EH_SPEC "%{!static:--eh-frame-hdr} "
 426 #endif