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 #undef MIPS_DEBUGGING_INFO
  29 #undef DBX_DEBUGGING_INFO
  30
  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) <= (unsigned HOST_WIDE_INT) 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 /* The biggest alignment supported by ELF in bits. 32-bit ELF
 147    supports section alignment up to (0x80000000 * 8), while
 148    64-bit ELF supports (0x8000000000000000 * 8). If this macro
 149    is not defined, the default is the largest alignment supported
 150    by 32-bit ELF and representable on a 32-bit host. Use this
 151    macro to limit the alignment which can be specified using
 152    the `__attribute__ ((aligned (N)))' construct.
 153
 154    This value is really 2^63.  Since gcc figures the alignment in bits,
 155    we could only potentially get to 2^60 on suitable hosts.  Due to other
 156    considerations in varasm, we must restrict this to what fits in an int.  */
 157
 158 #undef  MAX_OFILE_ALIGNMENT
 159 #define MAX_OFILE_ALIGNMENT (((unsigned int) 1 << 28) * 8)
 160
 161 /* This is the pseudo-op used to generate a contiguous sequence of byte
 162    values from a double-quoted string WITHOUT HAVING A TERMINATING NUL
 163    AUTOMATICALLY APPENDED.  This is the same for most svr4 assemblers.  */
 164
 165 #undef  ASCII_DATA_ASM_OP
 166 #define ASCII_DATA_ASM_OP       "\t.ascii\t"
 167
 168 #undef  READONLY_DATA_SECTION_ASM_OP
 169 #define READONLY_DATA_SECTION_ASM_OP    "\t.section\t.rodata"
 170 #undef  BSS_SECTION_ASM_OP
 171 #define BSS_SECTION_ASM_OP      "\t.section\t.bss"
 172 #undef  SBSS_SECTION_ASM_OP
 173 #define SBSS_SECTION_ASM_OP     "\t.section\t.sbss,\"aw\""
 174 #undef  SDATA_SECTION_ASM_OP
 175 #define SDATA_SECTION_ASM_OP    "\t.section\t.sdata,\"aw\""
 176
 177 /* On svr4, we *do* have support for the .init and .fini sections, and we
 178    can put stuff in there to be executed before and after `main'.  We let
 179    crtstuff.c and other files know this by defining the following symbols.
 180    The definitions say how to change sections to the .init and .fini
 181    sections.  This is the same for all known svr4 assemblers.  */
 182
 183 #undef  INIT_SECTION_ASM_OP
 184 #define INIT_SECTION_ASM_OP     "\t.section\t.init"
 185 #undef  FINI_SECTION_ASM_OP
 186 #define FINI_SECTION_ASM_OP     "\t.section\t.fini"
 187
 188 #ifdef HAVE_GAS_SUBSECTION_ORDERING
 189
 190 #define ASM_SECTION_START_OP    "\t.subsection\t-1"
 191
 192 /* Output assembly directive to move to the beginning of current section.  */
 193 #define ASM_OUTPUT_SECTION_START(FILE)  \
 194   fprintf ((FILE), "%s\n", ASM_SECTION_START_OP)
 195
 196 #endif
 197
 198 /* Switch into a generic section.  */
 199 #define TARGET_ASM_NAMED_SECTION  default_elf_asm_named_section
 200 #define TARGET_ASM_SELECT_SECTION  default_elf_select_section
 201
 202 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
 203
 204 /* Define the strings used for the special svr4 .type and .size directives.
 205    These strings generally do not vary from one system running svr4 to
 206    another, but if a given system (e.g. m88k running svr) needs to use
 207    different pseudo-op names for these, they may be overridden in the
 208    file which includes this one.  */
 209
 210 #undef  TYPE_ASM_OP
 211 #define TYPE_ASM_OP     "\t.type\t"
 212 #undef  SIZE_ASM_OP
 213 #define SIZE_ASM_OP     "\t.size\t"
 214
 215 /* This is how we tell the assembler that a symbol is weak.  */
 216
 217 #undef  ASM_WEAKEN_LABEL
 218 #define ASM_WEAKEN_LABEL(FILE, NAME) \
 219   do { fputs ("\t.weak\t", FILE); assemble_name (FILE, NAME); \
 220        fputc ('\n', FILE); } while (0)
 221
 222 /* This is how we tell the assembler that two symbols have the same value.  */
 223
 224 #undef  ASM_OUTPUT_DEF
 225 #define ASM_OUTPUT_DEF(FILE, ALIAS, NAME)                       \
 226   do {                                                          \
 227     assemble_name(FILE, ALIAS);                                 \
 228     fputs(" = ", FILE);                                         \
 229     assemble_name(FILE, NAME);                                  \
 230     fputc('\n', FILE);                                          \
 231   } while (0)
 232
 233 #undef  ASM_OUTPUT_DEF_FROM_DECLS
 234 #define ASM_OUTPUT_DEF_FROM_DECLS(FILE, DECL, TARGET)           \
 235   do {                                                          \
 236     const char *alias = XSTR (XEXP (DECL_RTL (DECL), 0), 0);    \
 237     const char *name = IDENTIFIER_POINTER (TARGET);             \
 238     if (TREE_CODE (DECL) == FUNCTION_DECL)                      \
 239       {                                                         \
 240         fputc ('$', FILE);                                      \
 241         assemble_name (FILE, alias);                            \
 242         fputs ("..ng = $", FILE);                               \
 243         assemble_name (FILE, name);                             \
 244         fputs ("..ng\n", FILE);                                 \
 245       }                                                         \
 246     assemble_name(FILE, alias);                                 \
 247     fputs(" = ", FILE);                                         \
 248     assemble_name(FILE, name);                                  \
 249     fputc('\n', FILE);                                          \
 250   } while (0)
 251
 252 /* The following macro defines the format used to output the second
 253    operand of the .type assembler directive.  Different svr4 assemblers
 254    expect various different forms for this operand.  The one given here
 255    is just a default.  You may need to override it in your machine-
 256    specific tm.h file (depending upon the particulars of your assembler).  */
 257
 258 #undef  TYPE_OPERAND_FMT
 259 #define TYPE_OPERAND_FMT        "@%s"
 260
 261 /* Write the extra assembler code needed to declare a function's result.
 262    Most svr4 assemblers don't require any special declaration of the
 263    result value, but there are exceptions.  */
 264
 265 #ifndef ASM_DECLARE_RESULT
 266 #define ASM_DECLARE_RESULT(FILE, RESULT)
 267 #endif
 268
 269 /* These macros generate the special .type and .size directives which
 270    are used to set the corresponding fields of the linker symbol table
 271    entries in an ELF object file under SVR4.  These macros also output
 272    the starting labels for the relevant functions/objects.  */
 273
 274 /* Write the extra assembler code needed to declare an object properly.  */
 275
 276 #ifdef HAVE_GAS_GNU_UNIQUE_OBJECT
 277 #define USE_GNU_UNIQUE_OBJECT 1
 278 #else
 279 #define USE_GNU_UNIQUE_OBJECT 0
 280 #endif
 281
 282 #undef  ASM_DECLARE_OBJECT_NAME
 283 #define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL)                       \
 284   do {                                                                  \
 285     HOST_WIDE_INT size;                                                 \
 286                                                                         \
 287     /* For template static data member instantiations or                \
 288        inline fn local statics and their guard variables, use           \
 289        gnu_unique_object so that they will be combined even under       \
 290        RTLD_LOCAL.  Don't use gnu_unique_object for typeinfo,           \
 291        vtables and other read-only artificial decls.  */                \
 292     if (USE_GNU_UNIQUE_OBJECT   && DECL_ONE_ONLY (DECL)                 \
 293         && (!DECL_ARTIFICIAL (DECL) || !TREE_READONLY (DECL)))          \
 294       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "gnu_unique_object");      \
 295     else                                                                \
 296       ASM_OUTPUT_TYPE_DIRECTIVE (FILE, NAME, "object");                 \
 297                                                                         \
 298     size_directive_output = 0;                                          \
 299     if (!flag_inhibit_size_directive                                    \
 300         && (DECL) && DECL_SIZE (DECL))                                  \
 301       {                                                                 \
 302         size_directive_output = 1;                                      \
 303         size = int_size_in_bytes (TREE_TYPE (DECL));                    \
 304         ASM_OUTPUT_SIZE_DIRECTIVE (FILE, NAME, size);                   \
 305       }                                                                 \
 306                                                                         \
 307     ASM_OUTPUT_LABEL (FILE, NAME);                                      \
 308   } while (0)
 309
 310 /* Output the size directive for a decl in rest_of_decl_compilation
 311    in the case where we did not do so before the initializer.
 312    Once we find the error_mark_node, we know that the value of
 313    size_directive_output was set
 314    by ASM_DECLARE_OBJECT_NAME when it was run for the same decl.  */
 315
 316 #undef  ASM_FINISH_DECLARE_OBJECT
 317 #define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)        \
 318   do {                                                                  \
 319     const char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0);             \
 320     HOST_WIDE_INT size;                                                 \
 321     if (!flag_inhibit_size_directive                                    \
 322         && DECL_SIZE (DECL)                                             \
 323         && ! AT_END && TOP_LEVEL                                        \
 324         && DECL_INITIAL (DECL) == error_mark_node                       \
 325         && !size_directive_output                                       \
 326         && (size = int_size_in_bytes (TREE_TYPE (DECL))) > 0)           \
 327       {                                                                 \
 328         size_directive_output = 1;                                      \
 329         ASM_OUTPUT_SIZE_DIRECTIVE (FILE, name, size);                   \
 330       }                                                                 \
 331   } while (0)
 332
 333 /* A table of bytes codes used by the ASM_OUTPUT_ASCII and
 334    ASM_OUTPUT_LIMITED_STRING macros.  Each byte in the table
 335    corresponds to a particular byte value [0..255].  For any
 336    given byte value, if the value in the corresponding table
 337    position is zero, the given character can be output directly.
 338    If the table value is 1, the byte must be output as a \ooo
 339    octal escape.  If the tables value is anything else, then the
 340    byte value should be output as a \ followed by the value
 341    in the table.  Note that we can use standard UN*X escape
 342    sequences for many control characters, but we don't use
 343    \a to represent BEL because some svr4 assemblers (e.g. on
 344    the i386) don't know about that.  Also, we don't use \v
 345    since some versions of gas, such as 2.2 did not accept it.  */
 346
 347 #undef  ESCAPES
 348 #define ESCAPES \
 349 "\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\
 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\
 352 \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\
 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 \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"
 357
 358 /* Some svr4 assemblers have a limit on the number of characters which
 359    can appear in the operand of a .string directive.  If your assembler
 360    has such a limitation, you should define STRING_LIMIT to reflect that
 361    limit.  Note that at least some svr4 assemblers have a limit on the
 362    actual number of bytes in the double-quoted string, and that they
 363    count each character in an escape sequence as one byte.  Thus, an
 364    escape sequence like \377 would count as four bytes.
 365
 366    If your target assembler doesn't support the .string directive, you
 367    should define this to zero.  */
 368
 369 #undef  STRING_LIMIT
 370 #define STRING_LIMIT    ((unsigned) 256)
 371 #undef  STRING_ASM_OP
 372 #define STRING_ASM_OP   "\t.string\t"
 373
 374 /* GAS is the only Alpha/ELF assembler.  */
 375 #undef  TARGET_GAS
 376 #define TARGET_GAS      (1)
 377
 378 /* Provide a STARTFILE_SPEC appropriate for ELF.  Here we add the
 379    (even more) magical crtbegin.o file which provides part of the
 380    support for getting C++ file-scope static object constructed
 381    before entering `main'.  */
 382
 383 #undef  STARTFILE_SPEC
 384 #ifdef HAVE_LD_PIE
 385 #define STARTFILE_SPEC \
 386   "%{!shared: %{pg|p:gcrt1.o%s;pie:Scrt1.o%s;:crt1.o%s}}\
 387    crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
 388 #else
 389 #define STARTFILE_SPEC \
 390   "%{!shared: %{pg|p:gcrt1.o%s;:crt1.o%s}}\
 391    crti.o%s %{static:crtbeginT.o%s;shared|pie:crtbeginS.o%s;:crtbegin.o%s}"
 392 #endif
 393
 394 /* Provide a ENDFILE_SPEC appropriate for ELF.  Here we tack on the
 395    magical crtend.o file which provides part of the support for
 396    getting C++ file-scope static object constructed before entering
 397    `main', followed by a normal ELF "finalizer" file, `crtn.o'.  */
 398
 399 #undef  ENDFILE_SPEC
 400 #define ENDFILE_SPEC \
 401   "%{Ofast|ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
 402    %{shared|pie:crtendS.o%s;:crtend.o%s} crtn.o%s"
 403
 404 /* Select a format to encode pointers in exception handling data.  CODE
 405    is 0 for data, 1 for code labels, 2 for function pointers.  GLOBAL is
 406    true if the symbol may be affected by dynamic relocations.
 407
 408    Since application size is already constrained to <2GB by the form of
 409    the ldgp relocation, we can use a 32-bit pc-relative relocation to
 410    static data.  Dynamic data is accessed indirectly to allow for read
 411    only EH sections.  */
 412 #define ASM_PREFERRED_EH_DATA_FORMAT(CODE,GLOBAL)       \
 413   (((GLOBAL) ? DW_EH_PE_indirect : 0) | DW_EH_PE_pcrel | DW_EH_PE_sdata4)
 414
 415 /* If defined, a C statement to be executed just prior to the output of
 416    assembler code for INSN.  */
 417 #define FINAL_PRESCAN_INSN(INSN, OPVEC, NOPERANDS)      \
 418  (alpha_this_literal_sequence_number = 0,               \
 419   alpha_this_gpdisp_sequence_number = 0)
 420 extern int alpha_this_literal_sequence_number;
 421 extern int alpha_this_gpdisp_sequence_number;
 422
 423 /* Since the bits of the _init and _fini function is spread across
 424    many object files, each potentially with its own GP, we must assume
 425    we need to load our GP.  Further, the .init/.fini section can
 426    easily be more than 4MB away from the function to call so we can't
 427    use bsr.  */
 428 #define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC)      \
 429    asm (SECTION_OP "\n"                                 \
 430 "       br $29,1f\n"                                    \
 431 "1:     ldgp $29,0($29)\n"                              \
 432 "       unop\n"                                         \
 433 "       jsr $26," USER_LABEL_PREFIX #FUNC "\n"          \
 434 "       .align 3\n"                                     \
 435 "       .previous");
 436
 437 /* If we have the capability create headers for efficient EH lookup.
 438    As of Jan 2002, only glibc 2.2.4 can actually make use of this, but
 439    I imagine that other systems will catch up.  In the meantime, it
 440    doesn't harm to make sure that the data exists to be used later.  */
 441 #if defined(HAVE_LD_EH_FRAME_HDR)
 442 #define LINK_EH_SPEC "%{!static:--eh-frame-hdr} "
 443 #endif
 444
 445 /* A C statement (sans semicolon) to output to the stdio stream STREAM
 446    any text necessary for declaring the name of an external symbol
 447    named NAME which is referenced in this compilation but not defined.
 448    It is needed to properly support non-default visibility.  */
 449
 450 #ifndef ASM_OUTPUT_EXTERNAL
 451 #define ASM_OUTPUT_EXTERNAL(FILE, DECL, NAME) \
 452   default_elf_asm_output_external (FILE, DECL, NAME)
 453 #endif