gcc/config/mips/elf.h

   1 /* Definitions of target machine for GNU compiler.  MIPS R3000 version with
   2    GOFAST floating point library.
   3    Copyright (C) 1994, 1997, 1999 Free Software Foundation, Inc.
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU CC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 /* Use ELF.  */
  23 #define OBJECT_FORMAT_ELF
  24
  25 /* Until we figure out what MIPS ELF targets normally use, just do
  26    stabs in ELF.  */
  27 #ifndef PREFERRED_DEBUGGING_TYPE
  28 #define PREFERRED_DEBUGGING_TYPE DBX_DEBUG
  29 #endif
  30
  31 /* Mostly like ECOFF.  */
  32 #include "gofast.h"
  33 #include "mips/ecoff.h"
  34
  35 /* We need to use .esize and .etype instead of .size and .type to
  36    avoid conflicting with ELF directives.  */
  37 #undef PUT_SDB_SIZE
  38 #define PUT_SDB_SIZE(a)                                 \
  39 do {                                                    \
  40   extern FILE *asm_out_text_file;                       \
  41   fprintf (asm_out_text_file, "\t.esize\t%d;", (a));    \
  42 } while (0)
  43
  44 #undef PUT_SDB_TYPE
  45 #define PUT_SDB_TYPE(a)                                 \
  46 do {                                                    \
  47   extern FILE *asm_out_text_file;                       \
  48   fprintf (asm_out_text_file, "\t.etype\t0x%x;", (a));  \
  49 } while (0)
  50
  51 /* Biggest alignment supported by the object file format of this
  52    machine.  Use this macro to limit the alignment which can be
  53    specified using the `__attribute__ ((aligned (N)))' construct.  If
  54    not defined, the default value is `BIGGEST_ALIGNMENT'.  */
  55
  56 #define MAX_OFILE_ALIGNMENT (32768*8)
  57
  58 /* A C statement to output something to the assembler file to switch to section
  59    NAME for object DECL which is either a FUNCTION_DECL, a VAR_DECL or
  60    NULL_TREE.  Some target formats do not support arbitrary sections.  Do not
  61    define this macro in such cases.  */
  62
  63 #define ASM_OUTPUT_SECTION_NAME(F, DECL, NAME, RELOC) \
  64 do {                                                            \
  65   extern FILE *asm_out_text_file;                               \
  66   if ((DECL) && TREE_CODE (DECL) == FUNCTION_DECL)              \
  67     fprintf (asm_out_text_file, "\t.section %s,\"ax\",@progbits\n", (NAME)); \
  68   else if ((DECL) && DECL_READONLY_SECTION (DECL, RELOC))       \
  69     fprintf (F, "\t.section %s,\"a\",@progbits\n", (NAME));     \
  70   else                                                          \
  71     fprintf (F, "\t.section %s,\"aw\",@progbits\n", (NAME));    \
  72 } while (0)
  73
  74 /* The following macro defines the format used to output the second
  75    operand of the .type assembler directive.  Different svr4 assemblers
  76    expect various different forms for this operand.  The one given here
  77    is just a default.  You may need to override it in your machine-
  78    specific tm.h file (depending upon the particulars of your assembler).  */
  79
  80 #define TYPE_OPERAND_FMT        "@%s"
  81
  82 /* Define the strings used for the special svr4 .type and .size directives.
  83    These strings generally do not vary from one system running svr4 to
  84    another, but if a given system (e.g. m88k running svr) needs to use
  85    different pseudo-op names for these, they may be overridden in the
  86    file which includes this one.  */
  87
  88 #undef TYPE_ASM_OP
  89 #undef SIZE_ASM_OP
  90 #define TYPE_ASM_OP     ".type"
  91 #define SIZE_ASM_OP     ".size"
  92
  93 /* If defined, a C expression whose value is a string containing the
  94    assembler operation to identify the following data as
  95    uninitialized global data.  If not defined, and neither
  96    `ASM_OUTPUT_BSS' nor `ASM_OUTPUT_ALIGNED_BSS' are defined,
  97    uninitialized global data will be output in the data section if
  98    `-fno-common' is passed, otherwise `ASM_OUTPUT_COMMON' will be
  99    used.  */
 100 #ifndef BSS_SECTION_ASM_OP
 101 #define BSS_SECTION_ASM_OP      ".section\t.bss"
 102 #endif
 103
 104 #define SBSS_SECTION_ASM_OP     "\t.section .sbss"
 105
 106 /* Like `ASM_OUTPUT_BSS' except takes the required alignment as a
 107    separate, explicit argument.  If you define this macro, it is used
 108    in place of `ASM_OUTPUT_BSS', and gives you more flexibility in
 109    handling the required alignment of the variable.  The alignment is
 110    specified as the number of bits.
 111
 112    Try to use function `asm_output_aligned_bss' defined in file
 113    `varasm.c' when defining this macro. */
 114 #ifndef ASM_OUTPUT_ALIGNED_BSS
 115 #define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN) \
 116 do {                                                                    \
 117   ASM_GLOBALIZE_LABEL (FILE, NAME);                                     \
 118   if (SIZE > 0 && SIZE <= mips_section_threshold)                       \
 119     sbss_section ();                                                    \
 120   else                                                                  \
 121     bss_section ();                                                     \
 122   ASM_OUTPUT_ALIGN (FILE, floor_log2 (ALIGN / BITS_PER_UNIT));          \
 123   last_assemble_variable_decl = DECL;                                   \
 124   ASM_DECLARE_OBJECT_NAME (FILE, NAME, DECL);                           \
 125   ASM_OUTPUT_SKIP (FILE, SIZE ? SIZE : 1);                              \
 126 } while (0)
 127 #endif
 128
 129 /* These macros generate the special .type and .size directives which
 130    are used to set the corresponding fields of the linker symbol table
 131    entries in an ELF object file under SVR4.  These macros also output
 132    the starting labels for the relevant functions/objects.  */
 133
 134 /* Write the extra assembler code needed to declare an object properly.  */
 135
 136 #undef ASM_DECLARE_OBJECT_NAME
 137 #define ASM_DECLARE_OBJECT_NAME(FILE, NAME, DECL)                       \
 138   do {                                                                  \
 139     fprintf (FILE, "\t%s\t ", TYPE_ASM_OP);                             \
 140     assemble_name (FILE, NAME);                                         \
 141     putc (',', FILE);                                                   \
 142     fprintf (FILE, TYPE_OPERAND_FMT, "object");                         \
 143     putc ('\n', FILE);                                                  \
 144     size_directive_output = 0;                                          \
 145     if (!flag_inhibit_size_directive && DECL_SIZE (DECL))               \
 146       {                                                                 \
 147         size_directive_output = 1;                                      \
 148         fprintf (FILE, "\t%s\t ", SIZE_ASM_OP);                         \
 149         assemble_name (FILE, NAME);                                     \
 150         fprintf (FILE, ",%d\n",  int_size_in_bytes (TREE_TYPE (DECL))); \
 151       }                                                                 \
 152     mips_declare_object (FILE, NAME, "", ":\n", 0);                     \
 153   } while (0)
 154
 155 /* Output the size directive for a decl in rest_of_decl_compilation
 156    in the case where we did not do so before the initializer.
 157    Once we find the error_mark_node, we know that the value of
 158    size_directive_output was set
 159    by ASM_DECLARE_OBJECT_NAME when it was run for the same decl.  */
 160
 161 #undef ASM_FINISH_DECLARE_OBJECT
 162 #define ASM_FINISH_DECLARE_OBJECT(FILE, DECL, TOP_LEVEL, AT_END)         \
 163 do {                                                                     \
 164      char *name = XSTR (XEXP (DECL_RTL (DECL), 0), 0);                   \
 165      if (!flag_inhibit_size_directive && DECL_SIZE (DECL)                \
 166          && ! AT_END && TOP_LEVEL                                        \
 167          && DECL_INITIAL (DECL) == error_mark_node                       \
 168          && !size_directive_output)                                      \
 169        {                                                                 \
 170          size_directive_output = 1;                                      \
 171          fprintf (FILE, "\t%s\t ", SIZE_ASM_OP);                         \
 172          assemble_name (FILE, name);                                     \
 173          fprintf (FILE, ",%d\n", int_size_in_bytes (TREE_TYPE (DECL)));  \
 174        }                                                                 \
 175    } while (0)
 176
 177 #define ASM_OUTPUT_DEF(FILE,LABEL1,LABEL2)                            \
 178  do { fputc ( '\t', FILE);                                            \
 179       assemble_name (FILE, LABEL1);                                   \
 180       fputs ( " = ", FILE);                                           \
 181       assemble_name (FILE, LABEL2);                                   \
 182       fputc ( '\n', FILE);                                            \
 183  } while (0)
 184
 185 /* Note about .weak vs. .weakext
 186    The mips native assemblers support .weakext, but not .weak.
 187    mips-elf gas supports .weak, but not .weakext.
 188    mips-elf gas has been changed to support both .weak and .weakext,
 189    but until that support is generally available, the 'if' below
 190    should serve. */
 191
 192 #define ASM_WEAKEN_LABEL(FILE,NAME) ASM_OUTPUT_WEAK_ALIAS(FILE,NAME,0)
 193 #define ASM_OUTPUT_WEAK_ALIAS(FILE,NAME,VALUE)  \
 194  do {                                           \
 195   if (TARGET_GAS)                               \
 196       fputs ("\t.weak\t", FILE);                \
 197   else                                          \
 198       fputs ("\t.weakext\t", FILE);             \
 199   assemble_name (FILE, NAME);                   \
 200   if (VALUE)                                    \
 201     {                                           \
 202       fputc (' ', FILE);                        \
 203       assemble_name (FILE, VALUE);              \
 204     }                                           \
 205   fputc ('\n', FILE);                           \
 206  } while (0)
 207
 208 #define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
 209 #undef UNIQUE_SECTION_P
 210 #define UNIQUE_SECTION_P(DECL) (DECL_ONE_ONLY (DECL))
 211 #define UNIQUE_SECTION(DECL,RELOC)                                         \
 212 do {                                                                       \
 213   int len, size, sec;                                                      \
 214   char *name, *string, *prefix;                                            \
 215   static char *prefixes[4][2] = {                                          \
 216     { ".text.", ".gnu.linkonce.t." },                                      \
 217     { ".rodata.", ".gnu.linkonce.r." },                                    \
 218     { ".data.", ".gnu.linkonce.d." },                                      \
 219     { ".sdata.", ".gnu.linkonce.s." }                                      \
 220   };                                                                       \
 221                                                                            \
 222   name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (DECL));                  \
 223   size = int_size_in_bytes (TREE_TYPE (decl));                             \
 224                                                                            \
 225   /* Determine the base section we are interested in:                      \
 226      0=text, 1=rodata, 2=data, 3=sdata, [4=bss].  */                       \
 227   if (TREE_CODE (DECL) == FUNCTION_DECL)                                   \
 228     sec = 0;                                                               \
 229   else if (DECL_INITIAL (DECL) == 0                                        \
 230            || DECL_INITIAL (DECL) == error_mark_node)                      \
 231     sec = 2;                                                               \
 232   else if ((TARGET_EMBEDDED_PIC || TARGET_MIPS16)                          \
 233       && TREE_CODE (decl) == STRING_CST                                    \
 234       && !flag_writable_strings)                                           \
 235     {                                                                      \
 236       /* For embedded position independent code, put constant strings      \
 237          in the text section, because the data section is limited to       \
 238          64K in size.  For mips16 code, put strings in the text            \
 239          section so that a PC relative load instruction can be used to     \
 240          get their address.  */                                            \
 241       sec = 0;                                                             \
 242     }                                                                      \
 243   else if (TARGET_EMBEDDED_DATA)                                           \
 244     {                                                                      \
 245       /* For embedded applications, always put an object in read-only data \
 246          if possible, in order to reduce RAM usage.  */                    \
 247                                                                            \
 248       if (DECL_READONLY_SECTION (DECL, RELOC))                             \
 249         sec = 1;                                                           \
 250       else if (size > 0 && size <= mips_section_threshold)                 \
 251         sec = 3;                                                           \
 252       else                                                                 \
 253         sec = 2;                                                           \
 254     }                                                                      \
 255   else                                                                     \
 256     {                                                                      \
 257       /* For hosted applications, always put an object in small data if    \
 258          possible, as this gives the best performance.  */                 \
 259                                                                            \
 260       if (size > 0 && size <= mips_section_threshold)                      \
 261         sec = 3;                                                           \
 262       else if (DECL_READONLY_SECTION (DECL, RELOC))                        \
 263         sec = 1;                                                           \
 264       else                                                                 \
 265         sec = 2;                                                           \
 266     }                                                                      \
 267                                                                            \
 268   prefix = prefixes[sec][DECL_ONE_ONLY (DECL)];                            \
 269   len = strlen (name) + strlen (prefix);                                   \
 270   string = alloca (len + 1);                                               \
 271   sprintf (string, "%s%s", prefix, name);                                  \
 272                                                                            \
 273   DECL_SECTION_NAME (DECL) = build_string (len, string);                   \
 274 } while (0)
 275
 276 /* Support the ctors/dtors and other sections.  */
 277
 278 /* Define the pseudo-ops used to switch to the .ctors and .dtors sections.
 279
 280    Note that we want to give these sections the SHF_WRITE attribute
 281    because these sections will actually contain data (i.e. tables of
 282    addresses of functions in the current root executable or shared library
 283    file) and, in the case of a shared library, the relocatable addresses
 284    will have to be properly resolved/relocated (and then written into) by
 285    the dynamic linker when it actually attaches the given shared library
 286    to the executing process.  (Note that on SVR4, you may wish to use the
 287    `-z text' option to the ELF linker, when building a shared library, as
 288    an additional check that you are doing everything right.  But if you do
 289    use the `-z text' option when building a shared library, you will get
 290    errors unless the .ctors and .dtors sections are marked as writable
 291    via the SHF_WRITE attribute.)  */
 292
 293 #define CTORS_SECTION_ASM_OP    "\t.section\t.ctors,\"aw\""
 294 #define DTORS_SECTION_ASM_OP    "\t.section\t.dtors,\"aw\""
 295
 296 /* A list of other sections which the compiler might be "in" at any
 297    given time.  */
 298 #undef EXTRA_SECTIONS
 299 #define EXTRA_SECTIONS in_sdata, in_sbss, in_rdata, in_ctors, in_dtors
 300
 301 #define INVOKE__main
 302
 303 #undef EXTRA_SECTION_FUNCTIONS
 304 #define EXTRA_SECTION_FUNCTIONS                                         \
 305   SECTION_FUNCTION_TEMPLATE(sdata_section, in_sdata, SDATA_SECTION_ASM_OP) \
 306   SECTION_FUNCTION_TEMPLATE(sbss_section, in_sbss, SBSS_SECTION_ASM_OP) \
 307   SECTION_FUNCTION_TEMPLATE(rdata_section, in_rdata, RDATA_SECTION_ASM_OP) \
 308   SECTION_FUNCTION_TEMPLATE(ctors_section, in_ctors, CTORS_SECTION_ASM_OP) \
 309   SECTION_FUNCTION_TEMPLATE(dtors_section, in_dtors, DTORS_SECTION_ASM_OP)
 310
 311 #define SECTION_FUNCTION_TEMPLATE(FN, ENUM, OP)                               \
 312 void FN ()                                                            \
 313 {                                                                     \
 314   if (in_section != ENUM)                                             \
 315     {                                                                 \
 316       fprintf (asm_out_file, "%s\n", OP);                             \
 317       in_section = ENUM;                                              \
 318     }                                                                 \
 319 }
 320
 321
 322 /* A C statement (sans semicolon) to output an element in the table of
 323    global constructors.  */
 324 #define ASM_OUTPUT_CONSTRUCTOR(FILE,NAME)                             \
 325   do {                                                                \
 326     ctors_section ();                                                 \
 327     fprintf (FILE, "\t%s\t", TARGET_LONG64 ? ".dword" : ".word");     \
 328     assemble_name (FILE, NAME);                                       \
 329     fprintf (FILE, "\n");                                             \
 330   } while (0)
 331
 332
 333 /* A C statement (sans semicolon) to output an element in the table of
 334    global destructors.  */
 335 #define ASM_OUTPUT_DESTRUCTOR(FILE,NAME)                              \
 336   do {                                                                \
 337     dtors_section ();                                                 \
 338     fprintf (FILE, "\t%s\t", TARGET_LONG64 ? ".dword" : ".word");     \
 339     assemble_name (FILE, NAME);                                       \
 340     fprintf (FILE, "\n");                                             \
 341   } while (0)
 342
 343 #define CTOR_LIST_BEGIN                                 \
 344 asm (CTORS_SECTION_ASM_OP);                             \
 345 func_ptr __CTOR_LIST__[1] = { (func_ptr) (-1) }
 346
 347 #define CTOR_LIST_END                                   \
 348 asm (CTORS_SECTION_ASM_OP);                             \
 349 func_ptr __CTOR_END__[1] = { (func_ptr) 0 };
 350
 351 #define DTOR_LIST_BEGIN                                 \
 352 asm (DTORS_SECTION_ASM_OP);                             \
 353 func_ptr __DTOR_LIST__[1] = { (func_ptr) (-1) }
 354
 355 #define DTOR_LIST_END                                   \
 356 asm (DTORS_SECTION_ASM_OP);                             \
 357 func_ptr __DTOR_END__[1] = { (func_ptr) 0 };
 358
 359 /* Don't set the target flags, this is done by the linker script */
 360 #undef LIB_SPEC
 361 #define LIB_SPEC ""
 362
 363 #undef  STARTFILE_SPEC
 364 #define STARTFILE_SPEC "crtbegin%O%s %{!mno-crt0:crt0%O%s}"
 365
 366 #undef  ENDFILE_SPEC
 367 #define ENDFILE_SPEC "crtend%O%s"