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, 2007 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 3, 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 COPYING3.  If not see
  21 <http://www.gnu.org/licenses/>.  */
  22
  23 /* Output at beginning of assembler file.  */
  24 /* The .file command should always begin the output.  */
  25 #define TARGET_ASM_FILE_START_FILE_DIRECTIVE true
  26
  27 #define TARGET_VERSION fprintf (stderr, " (i386 Linux/ELF)");
  28
  29 /* The svr4 ABI for the i386 says that records and unions are returned
  30    in memory.  */
  31 #undef DEFAULT_PCC_STRUCT_RETURN
  32 #define DEFAULT_PCC_STRUCT_RETURN 1
  33
  34 /* We arrange for the whole %gs segment to map the tls area.  */
  35 #undef TARGET_TLS_DIRECT_SEG_REFS_DEFAULT
  36 #define TARGET_TLS_DIRECT_SEG_REFS_DEFAULT MASK_TLS_DIRECT_SEG_REFS
  37
  38 #undef ASM_COMMENT_START
  39 #define ASM_COMMENT_START "#"
  40
  41 #undef DBX_REGISTER_NUMBER
  42 #define DBX_REGISTER_NUMBER(n) \
  43   (TARGET_64BIT ? dbx64_register_map[n] : svr4_dbx_register_map[n])
  44
  45 /* Output assembler code to FILE to call the profiler.
  46    To the best of my knowledge, no Linux libc has required the label
  47    argument to mcount.  */
  48
  49 #define NO_PROFILE_COUNTERS     1
  50
  51 #undef MCOUNT_NAME
  52 #define MCOUNT_NAME "mcount"
  53
  54 /* The GLIBC version of mcount for the x86 assumes that there is a
  55    frame, so we cannot allow profiling without a frame pointer.  */
  56
  57 #undef SUBTARGET_FRAME_POINTER_REQUIRED
  58 #define SUBTARGET_FRAME_POINTER_REQUIRED current_function_profile
  59
  60 #undef SIZE_TYPE
  61 #define SIZE_TYPE "unsigned int"
  62
  63 #undef PTRDIFF_TYPE
  64 #define PTRDIFF_TYPE "int"
  65
  66 #undef WCHAR_TYPE
  67 #define WCHAR_TYPE "long int"
  68
  69 #undef WCHAR_TYPE_SIZE
  70 #define WCHAR_TYPE_SIZE BITS_PER_WORD
  71
  72 #define TARGET_OS_CPP_BUILTINS()                \
  73   do                                            \
  74     {                                           \
  75         LINUX_TARGET_OS_CPP_BUILTINS();         \
  76     }                                           \
  77   while (0)
  78
  79 #undef CPP_SPEC
  80 #define CPP_SPEC "%{posix:-D_POSIX_SOURCE} %{pthread:-D_REENTRANT}"
  81
  82 #undef CC1_SPEC
  83 #define CC1_SPEC "%(cc1_cpu) %{profile:-p}"
  84
  85 /* Provide a LINK_SPEC appropriate for Linux.  Here we provide support
  86    for the special GCC options -static and -shared, which allow us to
  87    link things in one of these three modes by applying the appropriate
  88    combinations of options at link-time. We like to support here for
  89    as many of the other GNU linker options as possible. But I don't
  90    have the time to search for those flags. I am sure how to add
  91    support for -soname shared_object_name. H.J.
  92
  93    I took out %{v:%{!V:-V}}. It is too much :-(. They can use
  94    -Wl,-V.
  95
  96    When the -shared link option is used a final link is not being
  97    done.  */
  98
  99 /* If ELF is the default format, we should not use /lib/elf.  */
 100
 101 /* These macros may be overridden in k*bsd-gnu.h and i386/k*bsd-gnu.h. */
 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    %{mpc32:crtprec32.o%s} \
 124    %{mpc64:crtprec64.o%s} \
 125    %{mpc80:crtprec80.o%s} \
 126    %{shared|pie:crtendS.o%s;:crtend.o%s} crtn.o%s"
 127
 128 /* A C statement (sans semicolon) to output to the stdio stream
 129    FILE the assembler definition of uninitialized global DECL named
 130    NAME whose size is SIZE bytes and alignment is ALIGN bytes.
 131    Try to use asm_output_aligned_bss to implement this macro.  */
 132
 133 #define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN) \
 134   asm_output_aligned_bss (FILE, DECL, NAME, SIZE, ALIGN)
 135
 136 /* A C statement to output to the stdio stream FILE an assembler
 137    command to advance the location counter to a multiple of 1<<LOG
 138    bytes if it is within MAX_SKIP bytes.
 139
 140    This is used to align code labels according to Intel recommendations.  */
 141
 142 #ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
 143 #define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP)                    \
 144   do {                                                                  \
 145     if ((LOG) != 0) {                                                   \
 146       if ((MAX_SKIP) == 0) fprintf ((FILE), "\t.p2align %d\n", (LOG));  \
 147       else {                                                            \
 148         fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP));     \
 149         /* Make sure that we have at least 8 byte alignment if > 8 byte \
 150            alignment is preferred.  */                                  \
 151         if ((LOG) > 3 && (1 << (LOG)) > ((MAX_SKIP) + 1))               \
 152           fprintf ((FILE), "\t.p2align 3\n");                           \
 153       }                                                                 \
 154     }                                                                   \
 155   } while (0)
 156 #endif
 157
 158 /* Handle special EH pointer encodings.  Absolute, pc-relative, and
 159    indirect are handled automatically.  */
 160 #define ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX(FILE, ENCODING, SIZE, ADDR, DONE) \
 161   do {                                                                  \
 162     if ((SIZE) == 4 && ((ENCODING) & 0x70) == DW_EH_PE_datarel)         \
 163       {                                                                 \
 164         fputs (ASM_LONG, FILE);                 \
 165         assemble_name (FILE, XSTR (ADDR, 0));                           \
 166         fputs (((ENCODING) & DW_EH_PE_indirect ? "@GOT" : "@GOTOFF"), FILE); \
 167         goto DONE;                                                      \
 168       }                                                                 \
 169   } while (0)
 170
 171 /* Used by crtstuff.c to initialize the base of data-relative relocations.
 172    These are GOT relative on x86, so return the pic register.  */
 173 #ifdef __PIC__
 174 #define CRT_GET_RFIB_DATA(BASE)                 \
 175   {                                             \
 176     register void *ebx_ __asm__("ebx");         \
 177     BASE = ebx_;                                \
 178   }
 179 #else
 180 #define CRT_GET_RFIB_DATA(BASE)                                         \
 181   __asm__ ("call\t.LPR%=\n"                                             \
 182            ".LPR%=:\n\t"                                                \
 183            "pop{l}\t%0\n\t"                                             \
 184            /* Due to a GAS bug, this cannot use EAX.  That encodes      \
 185               smaller than the traditional EBX, which results in the    \
 186               offset being off by one.  */                              \
 187            "add{l}\t{$_GLOBAL_OFFSET_TABLE_+[.-.LPR%=],%0"              \
 188                    "|%0,_GLOBAL_OFFSET_TABLE_+(.-.LPR%=)}"              \
 189            : "=d"(BASE))
 190 #endif
 191
 192 #undef NEED_INDICATE_EXEC_STACK
 193 #define NEED_INDICATE_EXEC_STACK 1
 194
 195 #define MD_UNWIND_SUPPORT "config/i386/linux-unwind.h"
 196
 197 /* This macro may be overridden in i386/k*bsd-gnu.h.  */
 198 #define REG_NAME(reg) reg
 199
 200 #ifdef TARGET_LIBC_PROVIDES_SSP
 201 /* i386 glibc provides __stack_chk_guard in %gs:0x14.  */
 202 #define TARGET_THREAD_SSP_OFFSET        0x14
 203 #endif