linux64.h

gcc-you can use this code to learn something about gcc, and inquire further into linux,

/* Definitions for AMD x86-64 running Linux-based GNU systems with ELF format.
   Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
   Contributed by Jan Hubicka <[e-mail]>, based on linux.h.

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

#define TARGET_VERSION fprintf (stderr, " (x86-64 Linux/ELF)");

#define TARGET_OS_CPP_BUILTINS()				\
  do								\
    {								\
	builtin_define_std ("linux");				\
	builtin_define_std ("unix");				\
	builtin_define ("__gnu_linux__");			\
	builtin_define ("__ELF__");				\
	builtin_assert ("system=posix");			\
	if (flag_pic)						\
	  {							\
	    builtin_define ("__PIC__");				\
	    builtin_define ("__pic__");				\
	  }							\
	if (TARGET_64BIT)					\
	  {							\
	    builtin_define ("__LP64__");			\
	    builtin_define ("_LP64");				\
	  }							\
    }								\
  while (0)

#undef CPP_SPEC
#define CPP_SPEC "%{posix:-D_POSIX_SOURCE} %{pthread:-D_REENTRANT}"

/* The svr4 ABI for the i386 says that records and unions are returned
   in memory.  In the 64bit compilation we will turn this flag off in
   override_options, as we never do pcc_struct_return scheme on this target.  */
#undef DEFAULT_PCC_STRUCT_RETURN
#define DEFAULT_PCC_STRUCT_RETURN 1

/* Provide a LINK_SPEC.  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.

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

#undef	LINK_SPEC
#define LINK_SPEC "%{!m32:-m elf_x86_64} %{m32:-m elf_i386} \
  %{shared:-shared} \
  %{!shared: \
    %{!static: \
      %{rdynamic:-export-dynamic} \
      %{m32:%{!dynamic-linker:-dynamic-linker /lib/ld-linux.so.2}} \
      %{!m32:%{!dynamic-linker:-dynamic-linker /lib64/ld-linux-x86-64.so.2}}} \
    %{static:-static}}"

#undef  STARTFILE_SPEC
#define STARTFILE_SPEC \
  "%{!shared: \
     %{pg:gcrt1.o%s} %{!pg:%{p:gcrt1.o%s} \
     %{!p:%{profile:gcrt1.o%s} %{!profile:crt1.o%s}}}} \
   crti.o%s %{static:crtbeginT.o%s} \
   %{!static:%{!shared:crtbegin.o%s} %{shared:crtbeginS.o%s}}"

#undef  ENDFILE_SPEC
#define ENDFILE_SPEC "%{!shared:crtend.o%s} %{shared:crtendS.o%s} crtn.o%s"

#define MULTILIB_DEFAULTS { "m64" }

/* Do code reading to identify a signal frame, and set the frame
   state data appropriately.  See unwind-dw2.c for the structs.  
   Don't use this at all if inhibit_libc is used.  */

#ifndef inhibit_libc
#ifdef IN_LIBGCC2
#include <signal.h>
#include <sys/ucontext.h>
#endif

#ifdef __x86_64__
#define MD_FALLBACK_FRAME_STATE_FOR(CONTEXT, FS, SUCCESS)		\
  do {									\
    unsigned char *pc_ = (CONTEXT)->ra;					\
    struct sigcontext *sc_;						\
    long new_cfa_;							\
									\
    /* movq __NR_rt_sigreturn, %rax ; syscall  */			\
    if (*(unsigned char *)(pc_+0) == 0x48				\
	&& *(unsigned long *)(pc_+1) == 0x050f0000000fc0c7)		\
      {									\
	struct ucontext *uc_ = (CONTEXT)->cfa;				\
	sc_ = (struct sigcontext *) &uc_->uc_mcontext;			\
      }									\
    else								\
      break;								\
									\
    new_cfa_ = sc_->rsp;						\
    (FS)->cfa_how = CFA_REG_OFFSET;					\
    /* Register 7 is rsp  */						\
    (FS)->cfa_reg = 7;							\
    (FS)->cfa_offset = new_cfa_ - (long) (CONTEXT)->cfa;		\
									\
    /* The SVR4 register numbering macros aren't usable in libgcc.  */	\
    (FS)->regs.reg[0].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[0].loc.offset = (long)&sc_->rax - new_cfa_;		\
    (FS)->regs.reg[1].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[1].loc.offset = (long)&sc_->rdx - new_cfa_;		\
    (FS)->regs.reg[2].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[2].loc.offset = (long)&sc_->rcx - new_cfa_;		\
    (FS)->regs.reg[3].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[3].loc.offset = (long)&sc_->rbx - new_cfa_;		\
    (FS)->regs.reg[4].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[4].loc.offset = (long)&sc_->rsi - new_cfa_;		\
    (FS)->regs.reg[5].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[5].loc.offset = (long)&sc_->rdi - new_cfa_;		\
    (FS)->regs.reg[6].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[6].loc.offset = (long)&sc_->rbp - new_cfa_;		\
    (FS)->regs.reg[8].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[8].loc.offset = (long)&sc_->r8 - new_cfa_;		\
    (FS)->regs.reg[9].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[9].loc.offset = (long)&sc_->r9 - new_cfa_;		\
    (FS)->regs.reg[10].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[10].loc.offset = (long)&sc_->r10 - new_cfa_;		\
    (FS)->regs.reg[11].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[11].loc.offset = (long)&sc_->r11 - new_cfa_;		\
    (FS)->regs.reg[12].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[12].loc.offset = (long)&sc_->r12 - new_cfa_;		\
    (FS)->regs.reg[13].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[13].loc.offset = (long)&sc_->r13 - new_cfa_;		\
    (FS)->regs.reg[14].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[14].loc.offset = (long)&sc_->r14 - new_cfa_;		\
    (FS)->regs.reg[15].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[15].loc.offset = (long)&sc_->r15 - new_cfa_;		\
    (FS)->regs.reg[16].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[16].loc.offset = (long)&sc_->rip - new_cfa_;		\
    (FS)->retaddr_column = 16;						\
    goto SUCCESS;							\
  } while (0)
#else /* ifdef __x86_64__  */
#define MD_FALLBACK_FRAME_STATE_FOR(CONTEXT, FS, SUCCESS)		\
  do {									\
    unsigned char *pc_ = (CONTEXT)->ra;					\
    struct sigcontext *sc_;						\
    long new_cfa_;							\
									\
    /* popl %eax ; movl $__NR_sigreturn,%eax ; int $0x80  */		\
    if (*(unsigned short *)(pc_+0) == 0xb858				\
	&& *(unsigned int *)(pc_+2) == 119				\
	&& *(unsigned short *)(pc_+6) == 0x80cd)			\
      sc_ = (CONTEXT)->cfa + 4;						\
    /* movl $__NR_rt_sigreturn,%eax ; int $0x80  */			\
    else if (*(unsigned char *)(pc_+0) == 0xb8				\
	     && *(unsigned int *)(pc_+1) == 173				\
	     && *(unsigned short *)(pc_+5) == 0x80cd)			\
      {									\
	struct rt_sigframe {						\
	  int sig;							\
	  struct siginfo *pinfo;					\
	  void *puc;							\
	  struct siginfo info;						\
	  struct ucontext uc;						\
	} *rt_ = (CONTEXT)->cfa;					\
	sc_ = (struct sigcontext *) &rt_->uc.uc_mcontext;		\
      }									\
    else								\
      break;								\
									\
    new_cfa_ = sc_->esp;						\
    (FS)->cfa_how = CFA_REG_OFFSET;					\
    (FS)->cfa_reg = 4;							\
    (FS)->cfa_offset = new_cfa_ - (long) (CONTEXT)->cfa;		\
									\
    /* The SVR4 register numbering macros aren't usable in libgcc.  */	\
    (FS)->regs.reg[0].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[0].loc.offset = (long)&sc_->eax - new_cfa_;		\
    (FS)->regs.reg[3].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[3].loc.offset = (long)&sc_->ebx - new_cfa_;		\
    (FS)->regs.reg[1].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[1].loc.offset = (long)&sc_->ecx - new_cfa_;		\
    (FS)->regs.reg[2].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[2].loc.offset = (long)&sc_->edx - new_cfa_;		\
    (FS)->regs.reg[6].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[6].loc.offset = (long)&sc_->esi - new_cfa_;		\
    (FS)->regs.reg[7].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[7].loc.offset = (long)&sc_->edi - new_cfa_;		\
    (FS)->regs.reg[5].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[5].loc.offset = (long)&sc_->ebp - new_cfa_;		\
    (FS)->regs.reg[8].how = REG_SAVED_OFFSET;				\
    (FS)->regs.reg[8].loc.offset = (long)&sc_->eip - new_cfa_;		\
    (FS)->retaddr_column = 8;						\
    goto SUCCESS;							\
  } while (0)
#endif /* ifdef __x86_64__  */
#endif /* ifdef inhibit_libc  */