linux.h revision 117395
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
7This file is part of GNU CC.
8
9GNU CC is free software; you can redistribute it and/or modify
10it under the terms of the GNU General Public License as published by
11the Free Software Foundation; either version 2, or (at your option)
12any later version.
13
14GNU CC is distributed in the hope that it will be useful,
15but WITHOUT ANY WARRANTY; without even the implied warranty of
16MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17GNU General Public License for more details.
18
19You should have received a copy of the GNU General Public License
20along with GNU CC; see the file COPYING.  If not, write to
21the Free Software Foundation, 59 Temple Place - Suite 330,
22Boston, MA 02111-1307, USA.  */
23
24#define LINUX_DEFAULT_ELF
25
26/* Output at beginning of assembler file.  */
27/* The .file command should always begin the output.  */
28#undef ASM_FILE_START
29#define ASM_FILE_START(FILE)						\
30  do {									\
31	output_file_directive (FILE, main_input_filename);		\
32	if (ix86_asm_dialect == ASM_INTEL)				\
33	  fputs ("\t.intel_syntax\n", FILE);				\
34  } while (0)
35
36#define TARGET_VERSION fprintf (stderr, " (i386 Linux/ELF)");
37
38/* The svr4 ABI for the i386 says that records and unions are returned
39   in memory.  */
40#undef DEFAULT_PCC_STRUCT_RETURN
41#define DEFAULT_PCC_STRUCT_RETURN 1
42
43#undef ASM_COMMENT_START
44#define ASM_COMMENT_START "#"
45
46#undef DBX_REGISTER_NUMBER
47#define DBX_REGISTER_NUMBER(n) \
48  (TARGET_64BIT ? dbx64_register_map[n] : svr4_dbx_register_map[n])
49
50/* Output assembler code to FILE to call the profiler.
51   To the best of my knowledge, no Linux libc has required the label
52   argument to mcount.  */
53
54#define NO_PROFILE_COUNTERS
55
56#undef MCOUNT_NAME
57#define MCOUNT_NAME "mcount"
58
59/* The GLIBC version of mcount for the x86 assumes that there is a
60   frame, so we cannot allow profiling without a frame pointer.  */
61
62#undef SUBTARGET_FRAME_POINTER_REQUIRED
63#define SUBTARGET_FRAME_POINTER_REQUIRED current_function_profile
64
65#undef SIZE_TYPE
66#define SIZE_TYPE "unsigned int"
67
68#undef PTRDIFF_TYPE
69#define PTRDIFF_TYPE "int"
70
71#undef WCHAR_TYPE
72#define WCHAR_TYPE "long int"
73
74#undef WCHAR_TYPE_SIZE
75#define WCHAR_TYPE_SIZE BITS_PER_WORD
76
77#define TARGET_OS_CPP_BUILTINS()		\
78  do						\
79    {						\
80	builtin_define_std ("linux");		\
81	builtin_define_std ("unix");		\
82	builtin_define ("__ELF__");		\
83	builtin_define ("__gnu_linux__");	\
84	builtin_assert ("system=posix");	\
85	if (flag_pic)				\
86	  {					\
87	    builtin_define ("__PIC__");		\
88	    builtin_define ("__pic__");		\
89	  }					\
90    }						\
91  while (0)
92
93#undef CPP_SPEC
94#ifdef USE_GNULIBC_1
95#define CPP_SPEC "%{posix:-D_POSIX_SOURCE}"
96#else
97#define CPP_SPEC "%{posix:-D_POSIX_SOURCE} %{pthread:-D_REENTRANT}"
98#endif
99
100#undef CC1_SPEC
101#define CC1_SPEC "%(cc1_cpu) %{profile:-p}"
102
103/* Provide a LINK_SPEC appropriate for Linux.  Here we provide support
104   for the special GCC options -static and -shared, which allow us to
105   link things in one of these three modes by applying the appropriate
106   combinations of options at link-time. We like to support here for
107   as many of the other GNU linker options as possible. But I don't
108   have the time to search for those flags. I am sure how to add
109   support for -soname shared_object_name. H.J.
110
111   I took out %{v:%{!V:-V}}. It is too much :-(. They can use
112   -Wl,-V.
113
114   When the -shared link option is used a final link is not being
115   done.  */
116
117/* If ELF is the default format, we should not use /lib/elf.  */
118
119#undef	LINK_SPEC
120#ifdef USE_GNULIBC_1
121#ifndef LINUX_DEFAULT_ELF
122#define LINK_SPEC "-m elf_i386 %{shared:-shared} \
123  %{!shared: \
124    %{!ibcs: \
125      %{!static: \
126	%{rdynamic:-export-dynamic} \
127	%{!dynamic-linker:-dynamic-linker /lib/elf/ld-linux.so.1} \
128	%{!rpath:-rpath /lib/elf/}} %{static:-static}}}"
129#else
130#define LINK_SPEC "-m elf_i386 %{shared:-shared} \
131  %{!shared: \
132    %{!ibcs: \
133      %{!static: \
134	%{rdynamic:-export-dynamic} \
135	%{!dynamic-linker:-dynamic-linker /lib/ld-linux.so.1}} \
136	%{static:-static}}}"
137#endif
138#else
139#define LINK_SPEC "-m elf_i386 %{shared:-shared} \
140  %{!shared: \
141    %{!ibcs: \
142      %{!static: \
143	%{rdynamic:-export-dynamic} \
144	%{!dynamic-linker:-dynamic-linker /lib/ld-linux.so.2}} \
145	%{static:-static}}}"
146#endif
147
148/* A C statement (sans semicolon) to output to the stdio stream
149   FILE the assembler definition of uninitialized global DECL named
150   NAME whose size is SIZE bytes and alignment is ALIGN bytes.
151   Try to use asm_output_aligned_bss to implement this macro.  */
152
153#define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN) \
154  asm_output_aligned_bss (FILE, DECL, NAME, SIZE, ALIGN)
155
156/* A C statement to output to the stdio stream FILE an assembler
157   command to advance the location counter to a multiple of 1<<LOG
158   bytes if it is within MAX_SKIP bytes.
159
160   This is used to align code labels according to Intel recommendations.  */
161
162#ifdef HAVE_GAS_MAX_SKIP_P2ALIGN
163#define ASM_OUTPUT_MAX_SKIP_ALIGN(FILE,LOG,MAX_SKIP)			\
164  do {									\
165    if ((LOG) != 0) {							\
166      if ((MAX_SKIP) == 0) fprintf ((FILE), "\t.p2align %d\n", (LOG));	\
167      else fprintf ((FILE), "\t.p2align %d,,%d\n", (LOG), (MAX_SKIP));	\
168    }									\
169  } while (0)
170#endif
171
172#if defined(__PIC__) && defined (USE_GNULIBC_1)
173/* This is a kludge. The i386 GNU/Linux dynamic linker needs ___brk_addr,
174   __environ and atexit.  We have to make sure they are in the .dynsym
175   section.  We do this by forcing the assembler to create undefined
176   references to these symbols in the object file.  */
177#undef CRT_CALL_STATIC_FUNCTION
178#define CRT_CALL_STATIC_FUNCTION(SECTION_OP, FUNC)	\
179   asm (SECTION_OP "\n\t"				\
180	"call " USER_LABEL_PREFIX #FUNC "\n"		\
181	TEXT_SECTION_ASM_OP "\n\t"			\
182	".extern ___brk_addr\n\t"			\
183	".type ___brk_addr,@object\n\t"			\
184	".extern __environ\n\t"				\
185	".type __environ,@object\n\t"			\
186	".extern atexit\n\t"				\
187	".type atexit,@function");
188#endif
189
190/* Handle special EH pointer encodings.  Absolute, pc-relative, and
191   indirect are handled automatically.  */
192#define ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX(FILE, ENCODING, SIZE, ADDR, DONE) \
193  do {									\
194    if ((SIZE) == 4 && ((ENCODING) & 0x70) == DW_EH_PE_datarel)		\
195      {									\
196        fputs (ASM_LONG, FILE);			\
197        assemble_name (FILE, XSTR (ADDR, 0));				\
198	fputs (((ENCODING) & DW_EH_PE_indirect ? "@GOT" : "@GOTOFF"), FILE); \
199        goto DONE;							\
200      }									\
201  } while (0)
202
203/* Used by crtstuff.c to initialize the base of data-relative relocations.
204   These are GOT relative on x86, so return the pic register.  */
205#ifdef __PIC__
206#define CRT_GET_RFIB_DATA(BASE)			\
207  {						\
208    register void *ebx_ __asm__("ebx");		\
209    BASE = ebx_;				\
210  }
211#else
212#define CRT_GET_RFIB_DATA(BASE)						\
213  __asm__ ("call\t.LPR%=\n"						\
214	   ".LPR%=:\n\t"						\
215	   "popl\t%0\n\t"						\
216	   /* Due to a GAS bug, this cannot use EAX.  That encodes	\
217	      smaller than the traditional EBX, which results in the	\
218	      offset being off by one.  */				\
219	   "addl\t$_GLOBAL_OFFSET_TABLE_+[.-.LPR%=],%0"			\
220	   : "=d"(BASE))
221#endif
222
223/* Do code reading to identify a signal frame, and set the frame
224   state data appropriately.  See unwind-dw2.c for the structs.  */
225
226#ifdef IN_LIBGCC2
227/* There's no sys/ucontext.h for some (all?) libc1, so no
228   signal-turned-exceptions for them.  There's also no configure-run for
229   the target, so we can't check on (e.g.) HAVE_SYS_UCONTEXT_H.  Using the
230   target libc1 macro should be enough.  */
231#ifndef USE_GNULIBC_1
232#include <signal.h>
233#include <sys/ucontext.h>
234
235#define MD_FALLBACK_FRAME_STATE_FOR(CONTEXT, FS, SUCCESS)		\
236  do {									\
237    unsigned char *pc_ = (CONTEXT)->ra;					\
238    struct sigcontext *sc_;						\
239    long new_cfa_;							\
240									\
241    /* popl %eax ; movl $__NR_sigreturn,%eax ; int $0x80  */		\
242    if (*(unsigned short *)(pc_+0) == 0xb858				\
243	&& *(unsigned int *)(pc_+2) == 119				\
244	&& *(unsigned short *)(pc_+6) == 0x80cd)			\
245      sc_ = (CONTEXT)->cfa + 4;						\
246    /* movl $__NR_rt_sigreturn,%eax ; int $0x80  */			\
247    else if (*(unsigned char *)(pc_+0) == 0xb8				\
248	     && *(unsigned int *)(pc_+1) == 173				\
249	     && *(unsigned short *)(pc_+5) == 0x80cd)			\
250      {									\
251	struct rt_sigframe {						\
252	  int sig;							\
253	  struct siginfo *pinfo;					\
254	  void *puc;							\
255	  struct siginfo info;						\
256	  struct ucontext uc;						\
257	} *rt_ = (CONTEXT)->cfa;					\
258	sc_ = (struct sigcontext *) &rt_->uc.uc_mcontext;		\
259      }									\
260    else								\
261      break;								\
262									\
263    new_cfa_ = sc_->esp;						\
264    (FS)->cfa_how = CFA_REG_OFFSET;					\
265    (FS)->cfa_reg = 4;							\
266    (FS)->cfa_offset = new_cfa_ - (long) (CONTEXT)->cfa;		\
267									\
268    /* The SVR4 register numbering macros aren't usable in libgcc.  */	\
269    (FS)->regs.reg[0].how = REG_SAVED_OFFSET;				\
270    (FS)->regs.reg[0].loc.offset = (long)&sc_->eax - new_cfa_;		\
271    (FS)->regs.reg[3].how = REG_SAVED_OFFSET;				\
272    (FS)->regs.reg[3].loc.offset = (long)&sc_->ebx - new_cfa_;		\
273    (FS)->regs.reg[1].how = REG_SAVED_OFFSET;				\
274    (FS)->regs.reg[1].loc.offset = (long)&sc_->ecx - new_cfa_;		\
275    (FS)->regs.reg[2].how = REG_SAVED_OFFSET;				\
276    (FS)->regs.reg[2].loc.offset = (long)&sc_->edx - new_cfa_;		\
277    (FS)->regs.reg[6].how = REG_SAVED_OFFSET;				\
278    (FS)->regs.reg[6].loc.offset = (long)&sc_->esi - new_cfa_;		\
279    (FS)->regs.reg[7].how = REG_SAVED_OFFSET;				\
280    (FS)->regs.reg[7].loc.offset = (long)&sc_->edi - new_cfa_;		\
281    (FS)->regs.reg[5].how = REG_SAVED_OFFSET;				\
282    (FS)->regs.reg[5].loc.offset = (long)&sc_->ebp - new_cfa_;		\
283    (FS)->regs.reg[8].how = REG_SAVED_OFFSET;				\
284    (FS)->regs.reg[8].loc.offset = (long)&sc_->eip - new_cfa_;		\
285    (FS)->retaddr_column = 8;						\
286    goto SUCCESS;							\
287  } while (0)
288#endif /* not USE_GNULIBC_1 */
289#endif /* IN_LIBGCC2 */
290