gcc/config/i386/linux.h

   1 /* Definitions for Intel 386 running Linux-based GNU systems with ELF format.
   2    Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2001, 2002, 2004, 2005,
   3    2006 Free Software Foundation, Inc.
   4    Contributed by Eric Youngdale.
   5    Modified for stabs-in-ELF by H.J. Lu.
   6
   7 This file is part of GCC.
   8
   9 GCC is free software; you can redistribute it and/or modify
  10 it under the terms of the GNU General Public License as published by
  11 the Free Software Foundation; either version 2, or (at your option)
  12 any later version.
  13
  14 GCC is distributed in the hope that it will be useful,
  15 but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 GNU General Public License for more details.
  18
  19 You should have received a copy of the GNU General Public License
  20 along with GCC; see the file COPYING.  If not, write to
  21 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  22 Boston, MA 02110-1301, USA.  */
  23
  24 /* Output at beginning of assembler file.  */
  25 /* The .file command should always begin the output.  */
  26 #define TARGET_ASM_FILE_START_FILE_DIRECTIVE true
  27
  28 #define TARGET_VERSION fprintf (stderr, " (i386 Linux/ELF)");
  29
  30 /* The svr4 ABI for the i386 says that records and unions are returned
  31    in memory.  */
  32 #undef DEFAULT_PCC_STRUCT_RETURN
  33 #define DEFAULT_PCC_STRUCT_RETURN 1
  34
  35 /* We arrange for the whole %gs segment to map the tls area.  */
  36 #undef TARGET_TLS_DIRECT_SEG_REFS_DEFAULT
  37 #define TARGET_TLS_DIRECT_SEG_REFS_DEFAULT MASK_TLS_DIRECT_SEG_REFS
  38
  39 #undef ASM_COMMENT_START
  40 #define ASM_COMMENT_START "#"
  41
  42 #undef DBX_REGISTER_NUMBER
  43 #define DBX_REGISTER_NUMBER(n) \
  44   (TARGET_64BIT ? dbx64_register_map[n] : svr4_dbx_register_map[n])
  45
  46 /* Output assembler code to FILE to call the profiler.
  47    To the best of my knowledge, no Linux libc has required the label
  48    argument to mcount.  */
  49
  50 #define NO_PROFILE_COUNTERS     1
  51
  52 #undef MCOUNT_NAME
  53 #define MCOUNT_NAME "mcount"
  54
  55 /* The GLIBC version of mcount for the x86 assumes that there is a
  56    frame, so we cannot allow profiling without a frame pointer.  */
  57
  58 #undef SUBTARGET_FRAME_POINTER_REQUIRED
  59 #define SUBTARGET_FRAME_POINTER_REQUIRED current_function_profile
  60
  61 #undef SIZE_TYPE
  62 #define SIZE_TYPE "unsigned int"
  63
  64 #undef PTRDIFF_TYPE
  65 #define PTRDIFF_TYPE "int"
  66
  67 #undef WCHAR_TYPE
  68 #define WCHAR_TYPE "long int"
  69
  70 #undef WCHAR_TYPE_SIZE
  71 #define WCHAR_TYPE_SIZE BITS_PER_WORD
  72
  73 #define TARGET_OS_CPP_BUILTINS()                \
  74   do                                            \
  75     {                                           \
  76         LINUX_TARGET_OS_CPP_BUILTINS();         \
  77     }                                           \
  78   while (0)
  79
  80 #undef CPP_SPEC
  81 #define CPP_SPEC "%{posix:-D_POSIX_SOURCE} %{pthread:-D_REENTRANT}"
  82
  83 #undef CC1_SPEC
  84 #define CC1_SPEC "%(cc1_cpu) %{profile:-p}"
  85
  86 /* Provide a LINK_SPEC appropriate for Linux.  Here we provide support
  87    for the special GCC options -static and -shared, which allow us to
  88    link things in one of these three modes by applying the appropriate
  89    combinations of options at link-time. We like to support here for
  90    as many of the other GNU linker options as possible. But I don't
  91    have the time to search for those flags. I am sure how to add
  92    support for -soname shared_object_name. H.J.
  93
  94    I took out %{v:%{!V:-V}}. It is too much :-(. They can use
  95    -Wl,-V.
  96
  97    When the -shared link option is used a final link is not being
  98    done.  */
  99
 100 /* If ELF is the default format, we should not use /lib/elf.  */
 101
 102 #define LINK_EMULATION "elf_i386"
 103 #define GLIBC_DYNAMIC_LINKER "/lib/ld-linux.so.2"
 104
 105 #undef  SUBTARGET_EXTRA_SPECS
 106 #define SUBTARGET_EXTRA_SPECS \
 107   { "link_emulation", LINK_EMULATION },\
 108   { "dynamic_linker", LINUX_DYNAMIC_LINKER }
 109
 110 #undef  LINK_SPEC
 111 #define LINK_SPEC "-m %(link_emulation) %{shared:-shared} \
 112   %{!shared: \
 113     %{!ibcs: \
 114       %{!static: \
 115         %{rdynamic:-export-dynamic} \
 116         %{!dynamic-linker:-dynamic-linker %(dynamic_linker)}} \
 117         %{static:-static}}}"
 118
 119 /* Similar to standard Linux, but adding -ffast-math support.  */
 120 #undef  ENDFILE_SPEC
 121 #define ENDFILE_SPEC \
 122   "%{ffast-math|funsafe-math-optimizations:crtfastmath.o%s} \
 123    %{shared|pie:crtendS.o%s;:crtend.o%s} crtn.o%s"
 124
 125 /* A C statement (sans semicolon) to output to the stdio stream
 126    FILE the assembler definition of uninitialized global DECL named
 127    NAME whose size is SIZE bytes and alignment is ALIGN bytes.
 128    Try to use asm_output_aligned_bss to implement this macro.  */
 129
 130 #define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN) \
 131   asm_output_aligned_bss (FILE, DECL, NAME, SIZE, ALIGN)
 132
 133 /* A C statement to output to the stdio stream FILE an assembler
 134    command to advance the location counter to a multiple of 1<<LOG
 135    bytes if it is within MAX_SKIP bytes.
 136
 137    This is used to align code labels according to Intel recommendations.  */
 138
 139 #ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
 140 #define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP)                    \
 141   do {                                                                  \
 142     if ((LOG) != 0) {                                                   \
 143       if ((MAX_SKIP) == 0) fprintf ((FILE), "\t.p2align %d\n", (LOG));  \
 144       else fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP));  \
 145     }                                                                   \
 146   } while (0)
 147 #endif
 148
 149 /* Handle special EH pointer encodings.  Absolute, pc-relative, and
 150    indirect are handled automatically.  */
 151 #define ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX(FILE, ENCODING, SIZE, ADDR, DONE) \
 152   do {                                                                  \
 153     if ((SIZE) == 4 && ((ENCODING) & 0x70) == DW_EH_PE_datarel)         \
 154       {                                                                 \
 155         fputs (ASM_LONG, FILE);                 \
 156         assemble_name (FILE, XSTR (ADDR, 0));                           \
 157         fputs (((ENCODING) & DW_EH_PE_indirect ? "@GOT" : "@GOTOFF"), FILE); \
 158         goto DONE;                                                      \
 159       }                                                                 \
 160   } while (0)
 161
 162 /* Used by crtstuff.c to initialize the base of data-relative relocations.
 163    These are GOT relative on x86, so return the pic register.  */
 164 #ifdef __PIC__
 165 #define CRT_GET_RFIB_DATA(BASE)                 \
 166   {                                             \
 167     register void *ebx_ __asm__("ebx");         \
 168     BASE = ebx_;                                \
 169   }
 170 #else
 171 #define CRT_GET_RFIB_DATA(BASE)                                         \
 172   __asm__ ("call\t.LPR%=\n"                                             \
 173            ".LPR%=:\n\t"                                                \
 174            "popl\t%0\n\t"                                               \
 175            /* Due to a GAS bug, this cannot use EAX.  That encodes      \
 176               smaller than the traditional EBX, which results in the    \
 177               offset being off by one.  */                              \
 178            "addl\t$_GLOBAL_OFFSET_TABLE_+[.-.LPR%=],%0"                 \
 179            : "=d"(BASE))
 180 #endif
 181
 182 #undef NEED_INDICATE_EXEC_STACK
 183 #define NEED_INDICATE_EXEC_STACK 1
 184
 185 #define MD_UNWIND_SUPPORT "config/i386/linux-unwind.h"
 186
 187 /* This macro may be overridden in i386/k*bsd-gnu.h.  */
 188 #define REG_NAME(reg) reg
 189
 190 #ifdef TARGET_LIBC_PROVIDES_SSP
 191 /* i386 glibc provides __stack_chk_guard in %gs:0x14.  */
 192 #define TARGET_THREAD_SSP_OFFSET        0x14
 193 #endif