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 "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 \f
  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
  61 const struct rtl_hooks general_rtl_hooks = RTL_HOOKS_INITIALIZER;
  62 struct rtl_hooks rtl_hooks = RTL_HOOKS_INITIALIZER;
  63
  64 rtx
  65 gen_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
 107 rtx
 108 reg_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
 118 rtx
 119 reg_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
 129 bool
 130 reg_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
 145 rtx
 146 gen_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 \f