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1.1 root 1: /* Target definitions for GNU compiler for Intel 80386 running System V.4
2: Copyright (C) 1991 Free Software Foundation, Inc.
3:
4: Written by Ron Guilmette ([email protected]).
5:
6: This file is part of GNU CC.
7:
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)
11: any later version.
12:
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.
17:
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. */
21:
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 */
25:
26: #undef TARGET_VERSION
27: #define TARGET_VERSION fprintf (stderr, " (i386 System V Release 4)");
28:
29: /* The svr4 ABI for the i386 says that records and unions are returned
30: in memory. */
31:
32: #undef RETURN_IN_MEMORY
33: #define RETURN_IN_MEMORY(TYPE) \
34: (TREE_CODE (TYPE) == RECORD_TYPE || TREE_CODE(TYPE) == UNION_TYPE)
35:
36: /* Define which macros to predefine. __svr4__ is our extension. */
37: /* This used to define X86, but [email protected] says that
38: is supposed to be defined optionally by user programs--not by default. */
39: #define CPP_PREDEFINES \
40: "-Di386 -Dunix -D__svr4__ -Asystem(unix) -Acpu(i386) -Amachine(i386)"
41:
1.1.1.2 root 42: /* If the host and target formats match, output the floats as hex. */
43: #if HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT
44: #if defined (HOST_WORDS_BIG_ENDIAN) == WORDS_BIG_ENDIAN
45: /* This is how to output assembly code to define a `float' constant.
46: We always have to use a .long pseudo-op to do this because the native
47: SVR4 ELF assembler is buggy and it generates incorrect values when we
48: try to use the .float pseudo-op instead. */
49:
50: #undef ASM_OUTPUT_FLOAT
51: #define ASM_OUTPUT_FLOAT(FILE,VALUE) \
52: do { long value; \
53: REAL_VALUE_TO_TARGET_SINGLE ((VALUE), value); \
54: fprintf((FILE), "%s\t0x%x\n", ASM_LONG, value); \
55: } while (0)
56:
57: /* This is how to output assembly code to define a `double' constant.
58: We always have to use a pair of .long pseudo-ops to do this because
59: the native SVR4 ELF assembler is buggy and it generates incorrect
60: values when we try to use the the .double pseudo-op instead. */
61:
62: #undef ASM_OUTPUT_DOUBLE
63: #define ASM_OUTPUT_DOUBLE(FILE,VALUE) \
64: do { long value[2]; \
65: REAL_VALUE_TO_TARGET_DOUBLE ((VALUE), value); \
66: fprintf((FILE), "%s\t0x%x\n", ASM_LONG, value[0]); \
67: fprintf((FILE), "%s\t0x%x\n", ASM_LONG, value[1]); \
68: } while (0)
69: #endif /* word order matches */
70: #endif /* HOST_FLOAT_FORMAT == TARGET_FLOAT_FORMAT */
71:
1.1 root 72: /* Output at beginning of assembler file. */
73: /* The .file command should always begin the output. */
74:
75: #undef ASM_FILE_START
76: #define ASM_FILE_START(FILE) \
77: do { \
78: output_file_directive (FILE, main_input_filename); \
79: fprintf (FILE, "\t.version\t\"01.01\"\n"); \
80: } while (0)
81:
82: /* Define the register numbers to be used in Dwarf debugging information.
83: The SVR4 reference port C compiler uses the following register numbers
84: in its Dwarf output code:
85:
1.1.1.2 root 86: 0 for %eax (gnu regno = 0)
87: 1 for %ecx (gnu regno = 2)
88: 2 for %edx (gnu regno = 1)
89: 3 for %ebx (gnu regno = 3)
90: 4 for %esp (gnu regno = 7)
91: 5 for %ebp (gnu regno = 6)
92: 6 for %esi (gnu regno = 4)
93: 7 for %edi (gnu regno = 5)
94:
95: The following three DWARF register numbers are never generated by
96: the SVR4 C compiler or by the GNU compilers, but SDB on x86/svr4
97: believes these numbers have these meanings.
98:
99: 8 for %eip (no gnu equivalent)
100: 9 for %eflags (no gnu equivalent)
101: 10 for %trapno (no gnu equivalent)
102:
103: It is not at all clear how we should number the FP stack registers
104: for the x86 architecture. If the version of SDB on x86/svr4 were
105: a bit less brain dead with respect to floating-point then we would
106: have a precedent to follow with respect to DWARF register numbers
107: for x86 FP registers, but the SDB on x86/svr4 is so completely
108: broken with respect to FP registers that it is hardly worth thinking
1.1.1.3 ! root 109: of it as something to strive for compatibility with.
1.1.1.2 root 110:
111: The verison of x86/svr4 SDB I have at the moment does (partially)
112: seem to believe that DWARF register number 11 is associated with
113: the x86 register %st(0), but that's about all. Higher DWARF
114: register numbers don't seem to be associated with anything in
115: particular, and even for DWARF regno 11, SDB only seems to under-
116: stand that it should say that a variable lives in %st(0) (when
117: asked via an `=' command) if we said it was in DWARF regno 11,
118: but SDB still prints garbage when asked for the value of the
119: variable in question (via a `/' command).
120:
121: (Also note that the labels SDB prints for various FP stack regs
122: when doing an `x' command are all wrong.)
123:
124: Note that these problems generally don't affect the native SVR4
125: C compiler because it doesn't allow the use of -O with -g and
126: because when it is *not* optimizing, it allocates a memory
127: location for each floating-point variable, and the memory
128: location is what gets described in the DWARF AT_location
129: attribute for the variable in question.
130:
131: Regardless of the severe mental illness of the x86/svr4 SDB, we
132: do something sensible here and we use the following DWARF
133: register numbers. Note that these are all stack-top-relative
134: numbers.
135:
136: 11 for %st(0) (gnu regno = 8)
137: 12 for %st(1) (gnu regno = 9)
138: 13 for %st(2) (gnu regno = 10)
139: 14 for %st(3) (gnu regno = 11)
140: 15 for %st(4) (gnu regno = 12)
141: 16 for %st(5) (gnu regno = 13)
142: 17 for %st(6) (gnu regno = 14)
143: 18 for %st(7) (gnu regno = 15)
1.1 root 144: */
145:
146: #undef DBX_REGISTER_NUMBER
147: #define DBX_REGISTER_NUMBER(n) \
148: ((n) == 0 ? 0 \
149: : (n) == 1 ? 2 \
150: : (n) == 2 ? 1 \
151: : (n) == 3 ? 3 \
152: : (n) == 4 ? 6 \
153: : (n) == 5 ? 7 \
154: : (n) == 6 ? 5 \
155: : (n) == 7 ? 4 \
1.1.1.2 root 156: : ((n) >= FIRST_STACK_REG && (n) <= LAST_STACK_REG) ? (n)+3 \
1.1.1.3 ! root 157: : (-1))
1.1 root 158:
159: /* The routine used to output sequences of byte values. We use a special
160: version of this for most svr4 targets because doing so makes the
161: generated assembly code more compact (and thus faster to assemble)
162: as well as more readable. Note that if we find subparts of the
163: character sequence which end with NUL (and which are shorter than
164: STRING_LIMIT) we output those using ASM_OUTPUT_LIMITED_STRING. */
165:
166: #undef ASM_OUTPUT_ASCII
167: #define ASM_OUTPUT_ASCII(FILE, STR, LENGTH) \
168: do \
169: { \
170: register unsigned char *_ascii_bytes = (unsigned char *) (STR); \
171: register unsigned char *limit = _ascii_bytes + (LENGTH); \
172: register unsigned bytes_in_chunk = 0; \
173: for (; _ascii_bytes < limit; _ascii_bytes++) \
174: { \
175: register unsigned char *p; \
176: if (bytes_in_chunk >= 64) \
177: { \
178: fputc ('\n', (FILE)); \
179: bytes_in_chunk = 0; \
180: } \
181: for (p = _ascii_bytes; p < limit && *p != '\0'; p++) \
182: continue; \
183: if (p < limit && (p - _ascii_bytes) <= STRING_LIMIT) \
184: { \
185: if (bytes_in_chunk > 0) \
186: { \
187: fputc ('\n', (FILE)); \
188: bytes_in_chunk = 0; \
189: } \
190: ASM_OUTPUT_LIMITED_STRING ((FILE), _ascii_bytes); \
191: _ascii_bytes = p; \
192: } \
193: else \
194: { \
195: if (bytes_in_chunk == 0) \
196: fprintf ((FILE), "\t.byte\t"); \
197: else \
198: fputc (',', (FILE)); \
199: fprintf ((FILE), "0x%02x", *_ascii_bytes); \
200: bytes_in_chunk += 5; \
201: } \
202: } \
203: if (bytes_in_chunk > 0) \
204: fprintf ((FILE), "\n"); \
205: } \
206: while (0)
207:
208: /* This is how to output an element of a case-vector that is relative.
209: This is only used for PIC code. See comments by the `casesi' insn in
210: i386.md for an explanation of the expression this outputs. */
211:
212: #undef ASM_OUTPUT_ADDR_DIFF_ELT
213: #define ASM_OUTPUT_ADDR_DIFF_ELT(FILE, VALUE, REL) \
214: fprintf (FILE, "\t.long _GLOBAL_OFFSET_TABLE_+[.-%s%d]\n", LPREFIX, VALUE)
215:
216: /* Indicate that jump tables go in the text section. This is
217: necessary when compiling PIC code. */
218:
219: #define JUMP_TABLES_IN_TEXT_SECTION
220:
221: /* Biggest alignment that any structure field can require on this
222: machine, in bits. If packing is in effect, this can be smaller than
223: normal. */
224:
225: #define BIGGEST_FIELD_ALIGNMENT \
226: (maximum_field_alignment ? maximum_field_alignment : 32)
227:
228: extern int maximum_field_alignment;
229:
230: /* If bit field type is int, don't let it cross an int,
231: and give entire struct the alignment of an int. */
232: /* Required on the 386 since it doesn't have bitfield insns. */
233: /* If packing is in effect, then the type doesn't matter. */
234:
235: #undef PCC_BITFIELD_TYPE_MATTERS
236: #define PCC_BITFIELD_TYPE_MATTERS (maximum_field_alignment == 0)
237:
1.1.1.3 ! root 238: /* Handle #pragma pack and sometimes #pragma weak. */
! 239: #define HANDLE_SYSV_PRAGMA
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