1 /* Generic hooks for the RTL middle-end.
2 Copyright (C) 2004, 2005 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 2, or (at your option) any later
9 version.
10
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
19 02110-1301, USA. */
20
21 #include "config.h"
22 #include "system.h"
23 #include "coretypes.h"
24 #include "tm.h"
25 #include "rtl.h"
26 #include "rtlhooks-def.h"
27 #include "expr.h"
28 #include "recog.h"
29
30
31 /* For speed, we will copy the RTX hooks struct member-by-member
32 instead of doing indirect calls. For these reason, we initialize
33 *two* struct rtl_hooks globals: rtl_hooks is the one that is used
34 to actually call the hooks, while general_rtl_hooks is used
35 to restore the hooks by passes that modify them. */
36
37 const struct rtl_hooks general_rtl_hooks = RTL_HOOKS_INITIALIZER;
38 struct rtl_hooks rtl_hooks = RTL_HOOKS_INITIALIZER;
39
40 rtx
gen_lowpart_general(enum machine_mode mode,rtx x)41 gen_lowpart_general (enum machine_mode mode, rtx x)
42 {
43 rtx result = gen_lowpart_common (mode, x);
44
45 if (result)
46 return result;
47 /* If it's a REG, it must be a hard reg that's not valid in MODE. */
48 else if (REG_P (x)
49 /* Or we could have a subreg of a floating point value. */
50 || (GET_CODE (x) == SUBREG
51 && FLOAT_MODE_P (GET_MODE (SUBREG_REG (x)))))
52 {
53 result = gen_lowpart_common (mode, copy_to_reg (x));
54 gcc_assert (result != 0);
55 return result;
56 }
57 else
58 {
59 int offset = 0;
60
61 /* The only additional case we can do is MEM. */
62 gcc_assert (MEM_P (x));
63
64 /* The following exposes the use of "x" to CSE. */
65 if (GET_MODE_SIZE (GET_MODE (x)) <= UNITS_PER_WORD
66 && SCALAR_INT_MODE_P (GET_MODE (x))
67 && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
68 GET_MODE_BITSIZE (GET_MODE (x)))
69 && ! no_new_pseudos)
70 return gen_lowpart_general (mode, force_reg (GET_MODE (x), x));
71
72 if (WORDS_BIG_ENDIAN)
73 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
74 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
75
76 if (BYTES_BIG_ENDIAN)
77 /* Adjust the address so that the address-after-the-data
78 is unchanged. */
79 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
80 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
81
82 return adjust_address (x, mode, offset);
83 }
84 }
85
86 /* Similar to gen_lowpart, but cannot emit any instruction via
87 copy_to_reg or force_reg. Mainly used in simplify-rtx.c. */
88 rtx
gen_lowpart_no_emit_general(enum machine_mode mode,rtx x)89 gen_lowpart_no_emit_general (enum machine_mode mode, rtx x)
90 {
91 rtx result = gen_lowpart_if_possible (mode, x);
92 if (result)
93 return result;
94 else
95 return x;
96 }
97
98 rtx
reg_num_sign_bit_copies_general(rtx x ATTRIBUTE_UNUSED,enum machine_mode mode ATTRIBUTE_UNUSED,rtx known_x ATTRIBUTE_UNUSED,enum machine_mode known_mode ATTRIBUTE_UNUSED,unsigned int known_ret ATTRIBUTE_UNUSED,unsigned int * result ATTRIBUTE_UNUSED)99 reg_num_sign_bit_copies_general (rtx x ATTRIBUTE_UNUSED,
100 enum machine_mode mode ATTRIBUTE_UNUSED,
101 rtx known_x ATTRIBUTE_UNUSED,
102 enum machine_mode known_mode ATTRIBUTE_UNUSED,
103 unsigned int known_ret ATTRIBUTE_UNUSED,
104 unsigned int *result ATTRIBUTE_UNUSED)
105 {
106 return NULL;
107 }
108
109 rtx
reg_nonzero_bits_general(rtx x ATTRIBUTE_UNUSED,enum machine_mode mode ATTRIBUTE_UNUSED,rtx known_x ATTRIBUTE_UNUSED,enum machine_mode known_mode ATTRIBUTE_UNUSED,unsigned HOST_WIDE_INT known_ret ATTRIBUTE_UNUSED,unsigned HOST_WIDE_INT * nonzero ATTRIBUTE_UNUSED)110 reg_nonzero_bits_general (rtx x ATTRIBUTE_UNUSED,
111 enum machine_mode mode ATTRIBUTE_UNUSED,
112 rtx known_x ATTRIBUTE_UNUSED,
113 enum machine_mode known_mode ATTRIBUTE_UNUSED,
114 unsigned HOST_WIDE_INT known_ret ATTRIBUTE_UNUSED,
115 unsigned HOST_WIDE_INT *nonzero ATTRIBUTE_UNUSED)
116 {
117 return NULL;
118 }
119
120 bool
reg_truncated_to_mode_general(enum machine_mode mode ATTRIBUTE_UNUSED,rtx x ATTRIBUTE_UNUSED)121 reg_truncated_to_mode_general (enum machine_mode mode ATTRIBUTE_UNUSED,
122 rtx x ATTRIBUTE_UNUSED)
123 {
124 return false;
125 }
126
127 /* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point
128 number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the
129 least-significant part of X.
130 MODE specifies how big a part of X to return.
131
132 If the requested operation cannot be done, 0 is returned.
133
134 This is similar to gen_lowpart_general. */
135
136 rtx
gen_lowpart_if_possible(enum machine_mode mode,rtx x)137 gen_lowpart_if_possible (enum machine_mode mode, rtx x)
138 {
139 rtx result = gen_lowpart_common (mode, x);
140
141 if (result)
142 return result;
143 else if (MEM_P (x))
144 {
145 /* This is the only other case we handle. */
146 int offset = 0;
147 rtx new;
148
149 if (WORDS_BIG_ENDIAN)
150 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
151 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
152 if (BYTES_BIG_ENDIAN)
153 /* Adjust the address so that the address-after-the-data is
154 unchanged. */
155 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
156 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
157
158 new = adjust_address_nv (x, mode, offset);
159 if (! memory_address_p (mode, XEXP (new, 0)))
160 return 0;
161
162 return new;
163 }
164 else if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode)
165 return gen_lowpart_SUBREG (mode, x);
166 else
167 return 0;
168 }
169
170