gcc/rtlhooks.c

   1 /* Generic hooks for the RTL middle-end.
   2    Copyright (C) 2004 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, 59 Temple Place - Suite 330, Boston, MA
  19 02111-1307, 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 \f
  29
  30 /* For speed, we will copy the RTX hooks struct member-by-member
  31    instead of doing indirect calls.  For these reason, we initialize
  32    *two* struct rtl_hooks globals: rtl_hooks is the one that is used
  33    to actually call the hooks, while general_rtl_hooks is used
  34    to restore the hooks by passes that modify them.  */
  35
  36 const struct rtl_hooks general_rtl_hooks = RTL_HOOKS_INITIALIZER;
  37 struct rtl_hooks rtl_hooks = RTL_HOOKS_INITIALIZER;
  38
  39 rtx
  40 gen_lowpart_general (enum machine_mode mode, rtx x)
  41 {
  42   rtx result = gen_lowpart_common (mode, x);
  43
  44   if (result)
  45     return result;
  46   else if (REG_P (x))
  47     {
  48       /* Must be a hard reg that's not valid in MODE.  */
  49       result = gen_lowpart_common (mode, copy_to_reg (x));
  50       gcc_assert (result != 0);
  51       return result;
  52     }
  53   else
  54     {
  55       int offset = 0;
  56
  57       /* The only additional case we can do is MEM.  */
  58       gcc_assert (MEM_P (x));
  59
  60       /* The following exposes the use of "x" to CSE.  */
  61       if (GET_MODE_SIZE (GET_MODE (x)) <= UNITS_PER_WORD
  62           && SCALAR_INT_MODE_P (GET_MODE (x))
  63           && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
  64                                     GET_MODE_BITSIZE (GET_MODE (x)))
  65           && ! no_new_pseudos)
  66         return gen_lowpart_general (mode, force_reg (GET_MODE (x), x));
  67
  68       if (WORDS_BIG_ENDIAN)
  69         offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD)
  70                   - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD));
  71
  72       if (BYTES_BIG_ENDIAN)
  73         /* Adjust the address so that the address-after-the-data
  74            is unchanged.  */
  75         offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode))
  76                    - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x))));
  77
  78       return adjust_address (x, mode, offset);
  79     }
  80 }
  81
  82 /* Similar to gen_lowpart, but cannot emit any instruction via
  83    copy_to_reg or force_reg.  Mainly used in simplify-rtx.c.  */
  84 rtx
  85 gen_lowpart_no_emit_general (enum machine_mode mode, rtx x)
  86 {
  87   rtx result = gen_lowpart_common (mode, x);
  88   if (result)
  89     return result;
  90   if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode)
  91     return gen_lowpart_SUBREG (mode, x);
  92   return x;
  93 }
  94
  95 rtx
  96 reg_num_sign_bit_copies_general (rtx x ATTRIBUTE_UNUSED,
  97                                  enum machine_mode mode ATTRIBUTE_UNUSED,
  98                                  rtx known_x ATTRIBUTE_UNUSED,
  99                                  enum machine_mode known_mode ATTRIBUTE_UNUSED,
 100                                  unsigned int known_ret ATTRIBUTE_UNUSED,
 101                                  unsigned int *result ATTRIBUTE_UNUSED)
 102 {
 103   return NULL;
 104 }
 105
 106 rtx
 107 reg_nonzero_bits_general (rtx x ATTRIBUTE_UNUSED,
 108                           enum machine_mode mode ATTRIBUTE_UNUSED,
 109                           rtx known_x ATTRIBUTE_UNUSED,
 110                           enum machine_mode known_mode ATTRIBUTE_UNUSED,
 111                           unsigned HOST_WIDE_INT known_ret ATTRIBUTE_UNUSED,
 112                           unsigned HOST_WIDE_INT *nonzero ATTRIBUTE_UNUSED)
 113 {
 114   return NULL;
 115 }