1 /* Target definitions for GNU compiler for Intel 80386 running System V.4
2 Copyright (C) 1991 Free Software Foundation, Inc.
4 Written by Ron Guilmette (rfg@ncd.com).
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
22 #include "i386.h" /* Base i386 target machine definitions */
23 #include "att386.h" /* Use the i386 AT&T assembler syntax */
24 #include "svr4.h" /* Definitions common to all SVR4 targets */
28 #define TARGET_VERSION fprintf (stderr, " (i386 System V Release 4)");
30 /* By default, target has a 80387. */
32 #define TARGET_DEFAULT 1
34 /* Machines that use the AT&T assembler syntax
35 also return floating point values in an FP register. */
36 /* Define how to find the value returned by a function.
37 VALTYPE is the data type of the value (as a tree).
38 If the precise function being called is known, FUNC is its FUNCTION_DECL;
39 otherwise, FUNC is 0. */
41 #define VALUE_REGNO(MODE) \
42 (((MODE) == SFmode || (MODE) == DFmode) ? FIRST_FLOAT_REG : 0)
44 /* 1 if N is a possible register number for a function value. */
46 #define FUNCTION_VALUE_REGNO_P(N) ((N) == 0 || (N)== FIRST_FLOAT_REG)
48 /* The svr4 ABI for the i386 says that records and unions are returned
51 #undef RETURN_IN_MEMORY
52 #define RETURN_IN_MEMORY(TYPE) \
53 (TREE_CODE (TYPE) == RECORD_TYPE || TREE_CODE(TYPE) == UNION_TYPE)
55 /* Define which macros to predefine. __svr4__ is our extension. */
56 /* This used to define X86, but james@bigtex.cactus.org says that
57 is supposed to be defined optionally by user programs--not by default. */
58 #define CPP_PREDEFINES \
59 "-Di386 -Dunix -D__svr4__ -Asystem(unix) -Acpu(i386) -Amachine(i386)"
61 /* If the host and target formats match, output the floats as hex. */
62 #if HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT
63 #if defined (HOST_WORDS_BIG_ENDIAN) == WORDS_BIG_ENDIAN
64 /* This is how to output assembly code to define a `float' constant.
65 We always have to use a .long pseudo-op to do this because the native
66 SVR4 ELF assembler is buggy and it generates incorrect values when we
67 try to use the .float pseudo-op instead. */
69 #undef ASM_OUTPUT_FLOAT
70 #define ASM_OUTPUT_FLOAT(FILE,VALUE) \
72 REAL_VALUE_TO_TARGET_SINGLE ((VALUE), value); \
73 fprintf((FILE), "%s\t0x%x\n", ASM_LONG, value); \
76 /* This is how to output assembly code to define a `double' constant.
77 We always have to use a pair of .long pseudo-ops to do this because
78 the native SVR4 ELF assembler is buggy and it generates incorrect
79 values when we try to use the the .double pseudo-op instead. */
81 #undef ASM_OUTPUT_DOUBLE
82 #define ASM_OUTPUT_DOUBLE(FILE,VALUE) \
84 REAL_VALUE_TO_TARGET_DOUBLE ((VALUE), value); \
85 fprintf((FILE), "%s\t0x%x\n", ASM_LONG, value[0]); \
86 fprintf((FILE), "%s\t0x%x\n", ASM_LONG, value[1]); \
88 #endif /* word order matches */
89 #endif /* HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT */
91 /* Output at beginning of assembler file. */
92 /* The .file command should always begin the output. */
95 #define ASM_FILE_START(FILE) \
97 output_file_directive (FILE, main_input_filename); \
98 fprintf (FILE, "\t.version\t\"01.01\"\n"); \
101 /* Define the register numbers to be used in Dwarf debugging information.
102 The SVR4 reference port C compiler uses the following register numbers
103 in its Dwarf output code:
105 0 for %eax (gnu regno = 0)
106 1 for %ecx (gnu regno = 2)
107 2 for %edx (gnu regno = 1)
108 3 for %ebx (gnu regno = 3)
109 4 for %esp (gnu regno = 7)
110 5 for %ebp (gnu regno = 6)
111 6 for %esi (gnu regno = 4)
112 7 for %edi (gnu regno = 5)
114 The following three DWARF register numbers are never generated by
115 the SVR4 C compiler or by the GNU compilers, but SDB on x86/svr4
116 believes these numbers have these meanings.
118 8 for %eip (no gnu equivalent)
119 9 for %eflags (no gnu equivalent)
120 10 for %trapno (no gnu equivalent)
122 It is not at all clear how we should number the FP stack registers
123 for the x86 architecture. If the version of SDB on x86/svr4 were
124 a bit less brain dead with respect to floating-point then we would
125 have a precedent to follow with respect to DWARF register numbers
126 for x86 FP registers, but the SDB on x86/svr4 is so completely
127 broken with respect to FP registers that it is hardly worth thinking
128 of it as something to strive for compatibility with.
130 The verison of x86/svr4 SDB I have at the moment does (partially)
131 seem to believe that DWARF register number 11 is associated with
132 the x86 register %st(0), but that's about all. Higher DWARF
133 register numbers don't seem to be associated with anything in
134 particular, and even for DWARF regno 11, SDB only seems to under-
135 stand that it should say that a variable lives in %st(0) (when
136 asked via an `=' command) if we said it was in DWARF regno 11,
137 but SDB still prints garbage when asked for the value of the
138 variable in question (via a `/' command).
140 (Also note that the labels SDB prints for various FP stack regs
141 when doing an `x' command are all wrong.)
143 Note that these problems generally don't affect the native SVR4
144 C compiler because it doesn't allow the use of -O with -g and
145 because when it is *not* optimizing, it allocates a memory
146 location for each floating-point variable, and the memory
147 location is what gets described in the DWARF AT_location
148 attribute for the variable in question.
150 Regardless of the severe mental illness of the x86/svr4 SDB, we
151 do something sensible here and we use the following DWARF
152 register numbers. Note that these are all stack-top-relative
155 11 for %st(0) (gnu regno = 8)
156 12 for %st(1) (gnu regno = 9)
157 13 for %st(2) (gnu regno = 10)
158 14 for %st(3) (gnu regno = 11)
159 15 for %st(4) (gnu regno = 12)
160 16 for %st(5) (gnu regno = 13)
161 17 for %st(6) (gnu regno = 14)
162 18 for %st(7) (gnu regno = 15)
165 #undef DBX_REGISTER_NUMBER
166 #define DBX_REGISTER_NUMBER(n) \
175 : ((n) >= FIRST_STACK_REG && (n) <= LAST_STACK_REG) ? (n)+3 \
178 /* The routine used to output sequences of byte values. We use a special
179 version of this for most svr4 targets because doing so makes the
180 generated assembly code more compact (and thus faster to assemble)
181 as well as more readable. Note that if we find subparts of the
182 character sequence which end with NUL (and which are shorter than
183 STRING_LIMIT) we output those using ASM_OUTPUT_LIMITED_STRING. */
185 #undef ASM_OUTPUT_ASCII
186 #define ASM_OUTPUT_ASCII(FILE, STR, LENGTH) \
189 register unsigned char *_ascii_bytes = (unsigned char *) (STR); \
190 register unsigned char *limit = _ascii_bytes + (LENGTH); \
191 register unsigned bytes_in_chunk = 0; \
192 for (; _ascii_bytes < limit; _ascii_bytes++) \
194 register unsigned char *p; \
195 if (bytes_in_chunk >= 64) \
197 fputc ('\n', (FILE)); \
198 bytes_in_chunk = 0; \
200 for (p = _ascii_bytes; p < limit && *p != '\0'; p++) \
202 if (p < limit && (p - _ascii_bytes) <= STRING_LIMIT) \
204 if (bytes_in_chunk > 0) \
206 fputc ('\n', (FILE)); \
207 bytes_in_chunk = 0; \
209 ASM_OUTPUT_LIMITED_STRING ((FILE), _ascii_bytes); \
214 if (bytes_in_chunk == 0) \
215 fprintf ((FILE), "\t.byte\t"); \
217 fputc (',', (FILE)); \
218 fprintf ((FILE), "0x%02x", *_ascii_bytes); \
219 bytes_in_chunk += 5; \
222 if (bytes_in_chunk > 0) \
223 fprintf ((FILE), "\n"); \
227 /* This is how to output an element of a case-vector that is relative.
228 This is only used for PIC code. See comments by the `casesi' insn in
229 i386.md for an explanation of the expression this outputs. */
231 #undef ASM_OUTPUT_ADDR_DIFF_ELT
232 #define ASM_OUTPUT_ADDR_DIFF_ELT(FILE, VALUE, REL) \
233 fprintf (FILE, "\t.long _GLOBAL_OFFSET_TABLE_+[.-%s%d]\n", LPREFIX, VALUE)
235 /* Indicate that jump tables go in the text section. This is
236 necessary when compiling PIC code. */
238 #define JUMP_TABLES_IN_TEXT_SECTION
240 /* Biggest alignment that any structure field can require on this
241 machine, in bits. If packing is in effect, this can be smaller than
244 #define BIGGEST_FIELD_ALIGNMENT \
245 (maximum_field_alignment ? maximum_field_alignment : 32)
247 extern int maximum_field_alignment;
249 /* If bit field type is int, don't let it cross an int,
250 and give entire struct the alignment of an int. */
251 /* Required on the 386 since it doesn't have bitfield insns. */
252 /* If packing is in effect, then the type doesn't matter. */
254 #undef PCC_BITFIELD_TYPE_MATTERS
255 #define PCC_BITFIELD_TYPE_MATTERS (maximum_field_alignment == 0)
257 /* Code to handle #pragma directives. The interface is a bit messy,
258 but there's no simpler way to do this while still using yylex. */
259 #define HANDLE_PRAGMA(FILE) \
261 while (c == ' ' || c == '\t') \
263 if (c == '\n' || c == EOF) \
265 handle_pragma_token (0, 0); \
275 handle_pragma_token (token_buffer, yylval.ttype); \
278 handle_pragma_token (token_buffer, 0); \
281 c = nextchar, nextchar = -1; \