re PR c++/79790 ([C++17] ICE class template argument deduction failed)
[official-gcc.git] / gcc / rtlhooks.c
blob654f2825fd93199c1fc6991d83a45efd53c5f797
1 /* Generic hooks for the RTL middle-end.
2 Copyright (C) 2004-2017 Free Software Foundation, Inc.
4 This file is part of GCC.
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 3, or (at your option) any later
9 version.
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.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "tm.h"
24 #include "function.h"
25 #include "rtl.h"
26 #include "tree.h"
27 #include "insn-config.h"
28 #include "memmodel.h"
29 #include "emit-rtl.h"
30 #include "recog.h"
31 #include "rtlhooks-def.h"
32 #include "explow.h"
35 /* For speed, we will copy the RTX hooks struct member-by-member
36 instead of doing indirect calls. For these reason, we initialize
37 *two* struct rtl_hooks globals: rtl_hooks is the one that is used
38 to actually call the hooks, while general_rtl_hooks is used
39 to restore the hooks by passes that modify them. */
41 const struct rtl_hooks general_rtl_hooks = RTL_HOOKS_INITIALIZER;
42 struct rtl_hooks rtl_hooks = RTL_HOOKS_INITIALIZER;
44 rtx
45 gen_lowpart_general (machine_mode mode, rtx x)
47 rtx result = gen_lowpart_common (mode, x);
49 if (result)
50 return result;
51 /* Handle SUBREGs and hard REGs that were rejected by
52 simplify_gen_subreg. */
53 else if (REG_P (x) || GET_CODE (x) == SUBREG)
55 result = gen_lowpart_common (mode, copy_to_reg (x));
56 gcc_assert (result != 0);
57 return result;
59 else
61 int offset = 0;
63 /* The only additional case we can do is MEM. */
64 gcc_assert (MEM_P (x));
66 /* The following exposes the use of "x" to CSE. */
67 if (GET_MODE_SIZE (GET_MODE (x)) <= UNITS_PER_WORD
68 && SCALAR_INT_MODE_P (GET_MODE (x))
69 && TRULY_NOOP_TRUNCATION_MODES_P (mode, GET_MODE (x))
70 && !reload_completed)
71 return gen_lowpart_general (mode, force_reg (GET_MODE (x), x));
73 if (WORDS_BIG_ENDIAN)
74 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
75 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
77 if (BYTES_BIG_ENDIAN)
78 /* Adjust the address so that the address-after-the-data
79 is unchanged. */
80 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
81 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
83 return adjust_address (x, mode, offset);
87 rtx
88 reg_num_sign_bit_copies_general (const_rtx x ATTRIBUTE_UNUSED,
89 machine_mode mode ATTRIBUTE_UNUSED,
90 const_rtx known_x ATTRIBUTE_UNUSED,
91 machine_mode known_mode ATTRIBUTE_UNUSED,
92 unsigned int known_ret ATTRIBUTE_UNUSED,
93 unsigned int *result ATTRIBUTE_UNUSED)
95 return NULL;
98 rtx
99 reg_nonzero_bits_general (const_rtx x ATTRIBUTE_UNUSED,
100 machine_mode mode ATTRIBUTE_UNUSED,
101 const_rtx known_x ATTRIBUTE_UNUSED,
102 machine_mode known_mode ATTRIBUTE_UNUSED,
103 unsigned HOST_WIDE_INT known_ret ATTRIBUTE_UNUSED,
104 unsigned HOST_WIDE_INT *nonzero ATTRIBUTE_UNUSED)
106 return NULL;
109 bool
110 reg_truncated_to_mode_general (machine_mode mode ATTRIBUTE_UNUSED,
111 const_rtx x ATTRIBUTE_UNUSED)
113 return false;
116 /* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point
117 number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the
118 least-significant part of X.
119 MODE specifies how big a part of X to return.
121 If the requested operation cannot be done, 0 is returned.
123 This is similar to gen_lowpart_general. */
126 gen_lowpart_if_possible (machine_mode mode, rtx x)
128 rtx result = gen_lowpart_common (mode, x);
130 if (result)
131 return result;
132 else if (MEM_P (x))
134 /* This is the only other case we handle. */
135 int offset = 0;
136 rtx new_rtx;
138 if (WORDS_BIG_ENDIAN)
139 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
140 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
141 if (BYTES_BIG_ENDIAN)
142 /* Adjust the address so that the address-after-the-data is
143 unchanged. */
144 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
145 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
147 new_rtx = adjust_address_nv (x, mode, offset);
148 if (! memory_address_addr_space_p (mode, XEXP (new_rtx, 0),
149 MEM_ADDR_SPACE (x)))
150 return 0;
152 return new_rtx;
154 else if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode
155 && validate_subreg (mode, GET_MODE (x), x,
156 subreg_lowpart_offset (mode, GET_MODE (x))))
157 return gen_lowpart_SUBREG (mode, x);
158 else
159 return 0;