gcc/rtlhooks.c

   1 /* Generic hooks for the RTL middle-end.
   2    Copyright (C) 2004-2015 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 3, 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 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 "hard-reg-set.h"
  31 #include "input.h"
  32 #include "function.h"
  33 #include "flags.h"
  34 #include "statistics.h"
  35 #include "alias.h"
  36 #include "inchash.h"
  37 #include "tree.h"
  38 #include "insn-config.h"
  39 #include "expmed.h"
  40 #include "dojump.h"
  41 #include "explow.h"
  42 #include "calls.h"
  43 #include "emit-rtl.h"
  44 #include "varasm.h"
  45 #include "stmt.h"
  46 #include "expr.h"
  47 #include "recog.h"
  48 \f
  49
  50 /* For speed, we will copy the RTX hooks struct member-by-member
  51    instead of doing indirect calls.  For these reason, we initialize
  52    *two* struct rtl_hooks globals: rtl_hooks is the one that is used
  53    to actually call the hooks, while general_rtl_hooks is used
  54    to restore the hooks by passes that modify them.  */
  55
  56 const struct rtl_hooks general_rtl_hooks = RTL_HOOKS_INITIALIZER;
  57 struct rtl_hooks rtl_hooks = RTL_HOOKS_INITIALIZER;
  58
  59 rtx
  60 gen_lowpart_general (machine_mode mode, rtx x)
  61 {
  62   rtx result = gen_lowpart_common (mode, x);
  63
  64   if (result)
  65     return result;
  66   /* Handle SUBREGs and hard REGs that were rejected by
  67      simplify_gen_subreg.  */
  68   else if (REG_P (x) || GET_CODE (x) == SUBREG)
  69     {
  70       result = gen_lowpart_common (mode, copy_to_reg (x));
  71       gcc_assert (result != 0);
  72       return result;
  73     }
  74   else
  75     {
  76       int offset = 0;
  77
  78       /* The only additional case we can do is MEM.  */
  79       gcc_assert (MEM_P (x));
  80
  81       /* The following exposes the use of "x" to CSE.  */
  82       if (GET_MODE_SIZE (GET_MODE (x)) <= UNITS_PER_WORD
  83           && SCALAR_INT_MODE_P (GET_MODE (x))
  84           && TRULY_NOOP_TRUNCATION_MODES_P (mode, GET_MODE (x))
  85           && !reload_completed)
  86         return gen_lowpart_general (mode, force_reg (GET_MODE (x), x));
  87
  88       if (WORDS_BIG_ENDIAN)
  89         offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
  90                   - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
  91
  92       if (BYTES_BIG_ENDIAN)
  93         /* Adjust the address so that the address-after-the-data
  94            is unchanged.  */
  95         offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
  96                    - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
  97
  98       return adjust_address (x, mode, offset);
  99     }
 100 }
 101
 102 rtx
 103 reg_num_sign_bit_copies_general (const_rtx x ATTRIBUTE_UNUSED,
 104                                  machine_mode mode ATTRIBUTE_UNUSED,
 105                                  const_rtx known_x ATTRIBUTE_UNUSED,
 106                                  machine_mode known_mode ATTRIBUTE_UNUSED,
 107                                  unsigned int known_ret ATTRIBUTE_UNUSED,
 108                                  unsigned int *result ATTRIBUTE_UNUSED)
 109 {
 110   return NULL;
 111 }
 112
 113 rtx
 114 reg_nonzero_bits_general (const_rtx x ATTRIBUTE_UNUSED,
 115                           machine_mode mode ATTRIBUTE_UNUSED,
 116                           const_rtx known_x ATTRIBUTE_UNUSED,
 117                           machine_mode known_mode ATTRIBUTE_UNUSED,
 118                           unsigned HOST_WIDE_INT known_ret ATTRIBUTE_UNUSED,
 119                           unsigned HOST_WIDE_INT *nonzero ATTRIBUTE_UNUSED)
 120 {
 121   return NULL;
 122 }
 123
 124 bool
 125 reg_truncated_to_mode_general (machine_mode mode ATTRIBUTE_UNUSED,
 126                                const_rtx x ATTRIBUTE_UNUSED)
 127 {
 128   return false;
 129 }
 130
 131 /* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point
 132    number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the
 133    least-significant part of X.
 134    MODE specifies how big a part of X to return.
 135
 136    If the requested operation cannot be done, 0 is returned.
 137
 138    This is similar to gen_lowpart_general.  */
 139
 140 rtx
 141 gen_lowpart_if_possible (machine_mode mode, rtx x)
 142 {
 143   rtx result = gen_lowpart_common (mode, x);
 144
 145   if (result)
 146     return result;
 147   else if (MEM_P (x))
 148     {
 149       /* This is the only other case we handle.  */
 150       int offset = 0;
 151       rtx new_rtx;
 152
 153       if (WORDS_BIG_ENDIAN)
 154         offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
 155                   - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
 156       if (BYTES_BIG_ENDIAN)
 157         /* Adjust the address so that the address-after-the-data is
 158            unchanged.  */
 159         offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
 160                    - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
 161
 162       new_rtx = adjust_address_nv (x, mode, offset);
 163       if (! memory_address_addr_space_p (mode, XEXP (new_rtx, 0),
 164                                          MEM_ADDR_SPACE (x)))
 165         return 0;
 166
 167       return new_rtx;
 168     }
 169   else if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode
 170            && validate_subreg (mode, GET_MODE (x), x,
 171                                 subreg_lowpart_offset (mode, GET_MODE (x))))
 172     return gen_lowpart_SUBREG (mode, x);
 173   else
 174     return 0;
 175 }
 176 \f