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
   3    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, 59 Temple Place - Suite 330,
  22 Boston, MA 02111-1307, 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         if (flag_pic)                           \
  78           {                                     \
  79             builtin_define ("__PIC__");         \
  80             builtin_define ("__pic__");         \
  81           }                                     \
  82     }                                           \
  83   while (0)
  84
  85 #undef CPP_SPEC
  86 #ifdef USE_GNULIBC_1
  87 #define CPP_SPEC "%{posix:-D_POSIX_SOURCE}"
  88 #else
  89 #define CPP_SPEC "%{posix:-D_POSIX_SOURCE} %{pthread:-D_REENTRANT}"
  90 #endif
  91
  92 #undef CC1_SPEC
  93 #define CC1_SPEC "%(cc1_cpu) %{profile:-p}"
  94
  95 /* Provide a LINK_SPEC appropriate for Linux.  Here we provide support
  96    for the special GCC options -static and -shared, which allow us to
  97    link things in one of these three modes by applying the appropriate
  98    combinations of options at link-time. We like to support here for
  99    as many of the other GNU linker options as possible. But I don't
 100    have the time to search for those flags. I am sure how to add
 101    support for -soname shared_object_name. H.J.
 102
 103    I took out %{v:%{!V:-V}}. It is too much :-(. They can use
 104    -Wl,-V.
 105
 106    When the -shared link option is used a final link is not being
 107    done.  */
 108
 109 /* If ELF is the default format, we should not use /lib/elf.  */
 110
 111 #undef  LINK_SPEC
 112 #ifdef USE_GNULIBC_1
 113 #define LINK_SPEC "-m elf_i386 %{shared:-shared} \
 114   %{!shared: \
 115     %{!ibcs: \
 116       %{!static: \
 117         %{rdynamic:-export-dynamic} \
 118         %{!dynamic-linker:-dynamic-linker /lib/ld-linux.so.1}} \
 119         %{static:-static}}}"
 120 #else
 121 #define LINK_SPEC "-m elf_i386 %{shared:-shared} \
 122   %{!shared: \
 123     %{!ibcs: \
 124       %{!static: \
 125         %{rdynamic:-export-dynamic} \
 126         %{!dynamic-linker:-dynamic-linker /lib/ld-linux.so.2}} \
 127         %{static:-static}}}"
 128 #endif
 129
 130 /* A C statement (sans semicolon) to output to the stdio stream
 131    FILE the assembler definition of uninitialized global DECL named
 132    NAME whose size is SIZE bytes and alignment is ALIGN bytes.
 133    Try to use asm_output_aligned_bss to implement this macro.  */
 134
 135 #define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN) \
 136   asm_output_aligned_bss (FILE, DECL, NAME, SIZE, ALIGN)
 137
 138 /* A C statement to output to the stdio stream FILE an assembler
 139    command to advance the location counter to a multiple of 1<<LOG
 140    bytes if it is within MAX_SKIP bytes.
 141
 142    This is used to align code labels according to Intel recommendations.  */
 143
 144 #ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
 145 #define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP)                    \
 146   do {                                                                  \
 147     if ((LOG) != 0) {                                                   \
 148       if ((MAX_SKIP) == 0) fprintf ((FILE), "\t.p2align %d\n", (LOG));  \
 149       else fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP));  \
 150     }                                                                   \
 151   } while (0)
 152 #endif
 153
 154 #if defined(__PIC__) && defined (USE_GNULIBC_1)
 155 /* This is a kludge. The i386 GNU/Linux dynamic linker needs ___brk_addr,
 156    __environ and atexit.  We have to make sure they are in the .dynsym
 157    section.  We do this by forcing the assembler to create undefined
 158    references to these symbols in the object file.  */
 159 #undef CRT_CALL_STATIC_FUNCTION
 160 #define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC)      \
 161    asm (SECTION_OP "\n\t"                               \
 162         "call " USER_LABEL_PREFIX #FUNC "\n"            \
 163         TEXT_SECTION_ASM_OP "\n\t"                      \
 164         ".extern ___brk_addr\n\t"                       \
 165         ".type ___brk_addr,@object\n\t"                 \
 166         ".extern __environ\n\t"                         \
 167         ".type __environ,@object\n\t"                   \
 168         ".extern atexit\n\t"                            \
 169         ".type atexit,@function");
 170 #endif
 171
 172 /* Handle special EH pointer encodings.  Absolute, pc-relative, and
 173    indirect are handled automatically.  */
 174 #define ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX(FILE, ENCODING, SIZE, ADDR, DONE) \
 175   do {                                                                  \
 176     if ((SIZE) == 4 && ((ENCODING) & 0x70) == DW_EH_PE_datarel)         \
 177       {                                                                 \
 178         fputs (ASM_LONG, FILE);                 \
 179         assemble_name (FILE, XSTR (ADDR, 0));                           \
 180         fputs (((ENCODING) & DW_EH_PE_indirect ? "@GOT" : "@GOTOFF"), FILE); \
 181         goto DONE;                                                      \
 182       }                                                                 \
 183   } while (0)
 184
 185 /* Used by crtstuff.c to initialize the base of data-relative relocations.
 186    These are GOT relative on x86, so return the pic register.  */
 187 #ifdef __PIC__
 188 #define CRT_GET_RFIB_DATA(BASE)                 \
 189   {                                             \
 190     register void *ebx_ __asm__("ebx");         \
 191     BASE = ebx_;                                \
 192   }
 193 #else
 194 #define CRT_GET_RFIB_DATA(BASE)                                         \
 195   __asm__ ("call\t.LPR%=\n"                                             \
 196            ".LPR%=:\n\t"                                                \
 197            "popl\t%0\n\t"                                               \
 198            /* Due to a GAS bug, this cannot use EAX.  That encodes      \
 199               smaller than the traditional EBX, which results in the    \
 200               offset being off by one.  */                              \
 201            "addl\t$_GLOBAL_OFFSET_TABLE_+[.-.LPR%=],%0"                 \
 202            : "=d"(BASE))
 203 #endif
 204
 205 #undef NEED_INDICATE_EXEC_STACK
 206 #define NEED_INDICATE_EXEC_STACK 1
 207
 208 /* Do code reading to identify a signal frame, and set the frame
 209    state data appropriately.  See unwind-dw2.c for the structs.  */
 210
 211 #ifdef IN_LIBGCC2
 212 /* There's no sys/ucontext.h for some (all?) libc1, so no
 213    signal-turned-exceptions for them.  There's also no configure-run for
 214    the target, so we can't check on (e.g.) HAVE_SYS_UCONTEXT_H.  Using the
 215    target libc1 macro should be enough.  */
 216 #if !(defined (USE_GNULIBC_1) || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 0))
 217 #include <signal.h>
 218 #include <sys/ucontext.h>
 219
 220 #define MD_FALLBACK_FRAME_STATE_FOR(CONTEXT, FS, SUCCESS)               \
 221   do {                                                                  \
 222     unsigned char *pc_ = (CONTEXT)->ra;                                 \
 223     struct sigcontext *sc_;                                             \
 224     long new_cfa_;                                                      \
 225                                                                         \
 226     /* popl %eax ; movl $__NR_sigreturn,%eax ; int $0x80  */            \
 227     if (*(unsigned short *)(pc_+0) == 0xb858                            \
 228         && *(unsigned int *)(pc_+2) == 119                              \
 229         && *(unsigned short *)(pc_+6) == 0x80cd)                        \
 230       sc_ = (CONTEXT)->cfa + 4;                                         \
 231     /* movl $__NR_rt_sigreturn,%eax ; int $0x80  */                     \
 232     else if (*(unsigned char *)(pc_+0) == 0xb8                          \
 233              && *(unsigned int *)(pc_+1) == 173                         \
 234              && *(unsigned short *)(pc_+5) == 0x80cd)                   \
 235       {                                                                 \
 236         struct rt_sigframe {                                            \
 237           int sig;                                                      \
 238           struct siginfo *pinfo;                                        \
 239           void *puc;                                                    \
 240           struct siginfo info;                                          \
 241           struct ucontext uc;                                           \
 242         } *rt_ = (CONTEXT)->cfa;                                        \
 243         sc_ = (struct sigcontext *) &rt_->uc.uc_mcontext;               \
 244       }                                                                 \
 245     else                                                                \
 246       break;                                                            \
 247                                                                         \
 248     new_cfa_ = sc_->esp;                                                \
 249     (FS)->cfa_how = CFA_REG_OFFSET;                                     \
 250     (FS)->cfa_reg = 4;                                                  \
 251     (FS)->cfa_offset = new_cfa_ - (long) (CONTEXT)->cfa;                \
 252                                                                         \
 253     /* The SVR4 register numbering macros aren't usable in libgcc.  */  \
 254     (FS)->regs.reg[0].how = REG_SAVED_OFFSET;                           \
 255     (FS)->regs.reg[0].loc.offset = (long)&sc_->eax - new_cfa_;          \
 256     (FS)->regs.reg[3].how = REG_SAVED_OFFSET;                           \
 257     (FS)->regs.reg[3].loc.offset = (long)&sc_->ebx - new_cfa_;          \
 258     (FS)->regs.reg[1].how = REG_SAVED_OFFSET;                           \
 259     (FS)->regs.reg[1].loc.offset = (long)&sc_->ecx - new_cfa_;          \
 260     (FS)->regs.reg[2].how = REG_SAVED_OFFSET;                           \
 261     (FS)->regs.reg[2].loc.offset = (long)&sc_->edx - new_cfa_;          \
 262     (FS)->regs.reg[6].how = REG_SAVED_OFFSET;                           \
 263     (FS)->regs.reg[6].loc.offset = (long)&sc_->esi - new_cfa_;          \
 264     (FS)->regs.reg[7].how = REG_SAVED_OFFSET;                           \
 265     (FS)->regs.reg[7].loc.offset = (long)&sc_->edi - new_cfa_;          \
 266     (FS)->regs.reg[5].how = REG_SAVED_OFFSET;                           \
 267     (FS)->regs.reg[5].loc.offset = (long)&sc_->ebp - new_cfa_;          \
 268     (FS)->regs.reg[8].how = REG_SAVED_OFFSET;                           \
 269     (FS)->regs.reg[8].loc.offset = (long)&sc_->eip - new_cfa_;          \
 270     (FS)->retaddr_column = 8;                                           \
 271     goto SUCCESS;                                                       \
 272   } while (0)
 273 #endif /* not USE_GNULIBC_1 */
 274 #endif /* IN_LIBGCC2 */