config/i386/linux.h

/* Definitions for Intel 386 running Linux-based GNU systems with ELF format.
   Copyright (C) 1994, 1995, 1996, 1997, 1998 Free Software Foundation, Inc.
   Contributed by Eric Youngdale.
   Modified for stabs-in-ELF by H.J. Lu.

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#define LINUX_DEFAULT_ELF

/* A lie, I guess, but the general idea behind linux/ELF is that we are
   supposed to be outputting something that will assemble under SVr4.
   This gets us pretty close.  */
#include <i386/i386.h>	/* Base i386 target machine definitions */
#include <i386/att.h>	/* Use the i386 AT&T assembler syntax */
#include <linux.h>	/* some common stuff */

#undef TARGET_VERSION
#define TARGET_VERSION fprintf (stderr, " (i386 Linux/ELF)");

/* The svr4 ABI for the i386 says that records and unions are returned
   in memory.  */
#undef DEFAULT_PCC_STRUCT_RETURN
#define DEFAULT_PCC_STRUCT_RETURN 1

#undef ASM_COMMENT_START
#define ASM_COMMENT_START "#"

/* This is how to output an element of a case-vector that is relative.
   This is only used for PIC code.  See comments by the `casesi' insn in
   i386.md for an explanation of the expression this outputs. */
#undef ASM_OUTPUT_ADDR_DIFF_ELT
#define ASM_OUTPUT_ADDR_DIFF_ELT(FILE, BODY, VALUE, REL) \
  fprintf (FILE, "\t.long _GLOBAL_OFFSET_TABLE_+[.-%s%d]\n", LPREFIX, VALUE)

/* Indicate that jump tables go in the text section.  This is
   necessary when compiling PIC code.  */
#define JUMP_TABLES_IN_TEXT_SECTION (flag_pic)

/* Copy this from the svr4 specifications... */
/* Define the register numbers to be used in Dwarf debugging information.
   The SVR4 reference port C compiler uses the following register numbers
   in its Dwarf output code:
	0 for %eax (gnu regno = 0)
	1 for %ecx (gnu regno = 2)
	2 for %edx (gnu regno = 1)
	3 for %ebx (gnu regno = 3)
	4 for %esp (gnu regno = 7)
	5 for %ebp (gnu regno = 6)
	6 for %esi (gnu regno = 4)
	7 for %edi (gnu regno = 5)
   The following three DWARF register numbers are never generated by
   the SVR4 C compiler or by the GNU compilers, but SDB on x86/svr4
   believes these numbers have these meanings.
	8  for %eip    (no gnu equivalent)
	9  for %eflags (no gnu equivalent)
	10 for %trapno (no gnu equivalent)
   It is not at all clear how we should number the FP stack registers
   for the x86 architecture.  If the version of SDB on x86/svr4 were
   a bit less brain dead with respect to floating-point then we would
   have a precedent to follow with respect to DWARF register numbers
   for x86 FP registers, but the SDB on x86/svr4 is so completely
   broken with respect to FP registers that it is hardly worth thinking
   of it as something to strive for compatibility with.
   The version of x86/svr4 SDB I have at the moment does (partially)
   seem to believe that DWARF register number 11 is associated with
   the x86 register %st(0), but that's about all.  Higher DWARF
   register numbers don't seem to be associated with anything in
   particular, and even for DWARF regno 11, SDB only seems to under-
   stand that it should say that a variable lives in %st(0) (when
   asked via an `=' command) if we said it was in DWARF regno 11,
   but SDB still prints garbage when asked for the value of the
   variable in question (via a `/' command).
   (Also note that the labels SDB prints for various FP stack regs
   when doing an `x' command are all wrong.)
   Note that these problems generally don't affect the native SVR4
   C compiler because it doesn't allow the use of -O with -g and
   because when it is *not* optimizing, it allocates a memory
   location for each floating-point variable, and the memory
   location is what gets described in the DWARF AT_location
   attribute for the variable in question.
   Regardless of the severe mental illness of the x86/svr4 SDB, we
   do something sensible here and we use the following DWARF
   register numbers.  Note that these are all stack-top-relative
   numbers.
	11 for %st(0) (gnu regno = 8)
	12 for %st(1) (gnu regno = 9)
	13 for %st(2) (gnu regno = 10)
	14 for %st(3) (gnu regno = 11)
	15 for %st(4) (gnu regno = 12)
	16 for %st(5) (gnu regno = 13)
	17 for %st(6) (gnu regno = 14)
	18 for %st(7) (gnu regno = 15)
*/
#undef DBX_REGISTER_NUMBER
#define DBX_REGISTER_NUMBER(n) \
((n) == 0 ? 0 \
 : (n) == 1 ? 2 \
 : (n) == 2 ? 1 \
 : (n) == 3 ? 3 \
 : (n) == 4 ? 6 \
 : (n) == 5 ? 7 \
 : (n) == 6 ? 5 \
 : (n) == 7 ? 4 \
 : ((n) >= FIRST_STACK_REG && (n) <= LAST_STACK_REG) ? (n)+3 \
 : (-1))

/* Output assembler code to FILE to increment profiler label # LABELNO
   for profiling a function entry.  */

#undef FUNCTION_PROFILER
#define FUNCTION_PROFILER(FILE, LABELNO)  \
{									\
  if (flag_pic)								\
    {									\
      fprintf (FILE, "\tleal %sP%d@GOTOFF(%%ebx),%%edx\n",		\
	       LPREFIX, (LABELNO));					\
      fprintf (FILE, "\tcall *mcount@GOT(%%ebx)\n");			\
    }									\
  else									\
    {									\
      fprintf (FILE, "\tmovl $%sP%d,%%edx\n", LPREFIX, (LABELNO));	\
      fprintf (FILE, "\tcall mcount\n");				\
    }									\
}

#undef SIZE_TYPE
#define SIZE_TYPE "unsigned int"

#undef PTRDIFF_TYPE
#define PTRDIFF_TYPE "int"

#undef WCHAR_TYPE
#define WCHAR_TYPE "long int"

#undef WCHAR_TYPE_SIZE
#define WCHAR_TYPE_SIZE BITS_PER_WORD

/* The egcs-1.1 branch is the last time we will have -Di386.  -D__i386__ is the thing to use.  */
#undef CPP_PREDEFINES
#define CPP_PREDEFINES "-D__ELF__ -Dunix -Di386 -D__i386__ -Dlinux -Asystem(posix)"

#undef CPP_SPEC
#ifdef USE_GNULIBC_1
#define CPP_SPEC "%(cpp_cpu) %{fPIC:-D__PIC__ -D__pic__} %{fpic:-D__PIC__ -D__pic__} %{posix:-D_POSIX_SOURCE}"
#else
#define CPP_SPEC "%(cpp_cpu) %{fPIC:-D__PIC__ -D__pic__} %{fpic:-D__PIC__ -D__pic__} %{posix:-D_POSIX_SOURCE} %{pthread:-D_REENTRANT}"
#endif

#undef CC1_SPEC
#define CC1_SPEC "%(cc1_cpu) %{profile:-p}"

/* Provide a LINK_SPEC appropriate for Linux.  Here we provide support
   for the special GCC options -static and -shared, which allow us to
   link things in one of these three modes by applying the appropriate
   combinations of options at link-time. We like to support here for
   as many of the other GNU linker options as possible. But I don't
   have the time to search for those flags. I am sure how to add
   support for -soname shared_object_name. H.J.

   I took out %{v:%{!V:-V}}. It is too much :-(. They can use
   -Wl,-V.

   When the -shared link option is used a final link is not being
   done.  */

/* If ELF is the default format, we should not use /lib/elf. */

#undef	LINK_SPEC
#ifdef USE_GNULIBC_1
#ifndef LINUX_DEFAULT_ELF
#define LINK_SPEC "-m elf_i386 %{shared:-shared} \
  %{!shared: \
    %{!ibcs: \
      %{!static: \
	%{rdynamic:-export-dynamic} \
	%{!dynamic-linker:-dynamic-linker /lib/elf/ld-linux.so.1} \
	%{!rpath:-rpath /lib/elf/}} %{static:-static}}}"
#else
#define LINK_SPEC "-m elf_i386 %{shared:-shared} \
  %{!shared: \
    %{!ibcs: \
      %{!static: \
	%{rdynamic:-export-dynamic} \
	%{!dynamic-linker:-dynamic-linker /lib/ld-linux.so.1}} \
	%{static:-static}}}"
#endif
#else
#define LINK_SPEC "-m elf_i386 %{shared:-shared} \
  %{!shared: \
    %{!ibcs: \
      %{!static: \
	%{rdynamic:-export-dynamic} \
	%{!dynamic-linker:-dynamic-linker /lib/ld-linux.so.2}} \
	%{static:-static}}}"
#endif

/* Get perform_* macros to build libgcc.a.  */
#include "i386/perform.h"

/* A C statement (sans semicolon) to output to the stdio stream
   FILE the assembler definition of uninitialized global DECL named
   NAME whose size is SIZE bytes and alignment is ALIGN bytes.
   Try to use asm_output_aligned_bss to implement this macro.  */

#define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN) \
  asm_output_aligned_bss (FILE, DECL, NAME, SIZE, ALIGN)

/* A C statement to output to the stdio stream FILE an assembler
   command to advance the location counter to a multiple of 1<<LOG
   bytes if it is within MAX_SKIP bytes.

   This is used to align code labels according to Intel recommendations.  */

#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
#define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP) \
  if ((LOG)!=0) \
    if ((MAX_SKIP)==0) fprintf ((FILE), "\t.p2align %d\n", (LOG)); \
    else fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP))
#endif