1/* Generic hooks for the RTL middle-end.
2   Copyright (C) 2004-2015 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify it under
7the terms of the GNU General Public License as published by the Free
8Software Foundation; either version 3, or (at your option) any later
9version.
10
11GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12WARRANTY; without even the implied warranty of MERCHANTABILITY or
13FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14for more details.
15
16You should have received a copy of the GNU General Public License
17along with GCC; see the file COPYING3.  If not see
18<http://www.gnu.org/licenses/>.  */
19
20#include "config.h"
21#include "system.h"
22#include "coretypes.h"
23#include "tm.h"
24#include "rtl.h"
25#include "rtlhooks-def.h"
26#include "symtab.h"
27#include "hashtab.h"
28#include "hash-set.h"
29#include "vec.h"
30#include "machmode.h"
31#include "hard-reg-set.h"
32#include "input.h"
33#include "function.h"
34#include "flags.h"
35#include "statistics.h"
36#include "double-int.h"
37#include "real.h"
38#include "fixed-value.h"
39#include "alias.h"
40#include "wide-int.h"
41#include "inchash.h"
42#include "tree.h"
43#include "insn-config.h"
44#include "expmed.h"
45#include "dojump.h"
46#include "explow.h"
47#include "calls.h"
48#include "emit-rtl.h"
49#include "varasm.h"
50#include "stmt.h"
51#include "expr.h"
52#include "recog.h"
53
54
55/* For speed, we will copy the RTX hooks struct member-by-member
56   instead of doing indirect calls.  For these reason, we initialize
57   *two* struct rtl_hooks globals: rtl_hooks is the one that is used
58   to actually call the hooks, while general_rtl_hooks is used
59   to restore the hooks by passes that modify them.  */
60
61const struct rtl_hooks general_rtl_hooks = RTL_HOOKS_INITIALIZER;
62struct rtl_hooks rtl_hooks = RTL_HOOKS_INITIALIZER;
63
64rtx
65gen_lowpart_general (machine_mode mode, rtx x)
66{
67  rtx result = gen_lowpart_common (mode, x);
68
69  if (result)
70    return result;
71  /* Handle SUBREGs and hard REGs that were rejected by
72     simplify_gen_subreg.  */
73  else if (REG_P (x) || GET_CODE (x) == SUBREG)
74    {
75      result = gen_lowpart_common (mode, copy_to_reg (x));
76      gcc_assert (result != 0);
77      return result;
78    }
79  else
80    {
81      int offset = 0;
82
83      /* The only additional case we can do is MEM.  */
84      gcc_assert (MEM_P (x));
85
86      /* The following exposes the use of "x" to CSE.  */
87      if (GET_MODE_SIZE (GET_MODE (x)) <= UNITS_PER_WORD
88	  && SCALAR_INT_MODE_P (GET_MODE (x))
89	  && TRULY_NOOP_TRUNCATION_MODES_P (mode, GET_MODE (x))
90	  && !reload_completed)
91	return gen_lowpart_general (mode, force_reg (GET_MODE (x), x));
92
93      if (WORDS_BIG_ENDIAN)
94	offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
95		  - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
96
97      if (BYTES_BIG_ENDIAN)
98	/* Adjust the address so that the address-after-the-data
99	   is unchanged.  */
100	offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
101		   - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
102
103      return adjust_address (x, mode, offset);
104    }
105}
106
107rtx
108reg_num_sign_bit_copies_general (const_rtx x ATTRIBUTE_UNUSED,
109				 machine_mode mode ATTRIBUTE_UNUSED,
110                                 const_rtx known_x ATTRIBUTE_UNUSED,
111				 machine_mode known_mode ATTRIBUTE_UNUSED,
112                                 unsigned int known_ret ATTRIBUTE_UNUSED,
113                                 unsigned int *result ATTRIBUTE_UNUSED)
114{
115  return NULL;
116}
117
118rtx
119reg_nonzero_bits_general (const_rtx x ATTRIBUTE_UNUSED,
120			  machine_mode mode ATTRIBUTE_UNUSED,
121			  const_rtx known_x ATTRIBUTE_UNUSED,
122                          machine_mode known_mode ATTRIBUTE_UNUSED,
123                          unsigned HOST_WIDE_INT known_ret ATTRIBUTE_UNUSED,
124                          unsigned HOST_WIDE_INT *nonzero ATTRIBUTE_UNUSED)
125{
126  return NULL;
127}
128
129bool
130reg_truncated_to_mode_general (machine_mode mode ATTRIBUTE_UNUSED,
131			       const_rtx x ATTRIBUTE_UNUSED)
132{
133  return false;
134}
135
136/* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point
137   number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the
138   least-significant part of X.
139   MODE specifies how big a part of X to return.
140
141   If the requested operation cannot be done, 0 is returned.
142
143   This is similar to gen_lowpart_general.  */
144
145rtx
146gen_lowpart_if_possible (machine_mode mode, rtx x)
147{
148  rtx result = gen_lowpart_common (mode, x);
149
150  if (result)
151    return result;
152  else if (MEM_P (x))
153    {
154      /* This is the only other case we handle.  */
155      int offset = 0;
156      rtx new_rtx;
157
158      if (WORDS_BIG_ENDIAN)
159	offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
160		  - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
161      if (BYTES_BIG_ENDIAN)
162	/* Adjust the address so that the address-after-the-data is
163	   unchanged.  */
164	offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
165		   - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
166
167      new_rtx = adjust_address_nv (x, mode, offset);
168      if (! memory_address_addr_space_p (mode, XEXP (new_rtx, 0),
169					 MEM_ADDR_SPACE (x)))
170	return 0;
171
172      return new_rtx;
173    }
174  else if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode
175	   && validate_subreg (mode, GET_MODE (x), x,
176			        subreg_lowpart_offset (mode, GET_MODE (x))))
177    return gen_lowpart_SUBREG (mode, x);
178  else
179    return 0;
180}
181
182