1 /* Generic hooks for the RTL middle-end. 2 Copyright (C) 2004, 2005, 2007, 2008 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 "expr.h" 27 #include "recog.h" 28 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 /* Handle SUBREGs and hard REGs that were rejected by 47 simplify_gen_subreg. */ 48 else if (REG_P (x) || GET_CODE (x) == SUBREG) 49 { 50 result = gen_lowpart_common (mode, copy_to_reg (x)); 51 gcc_assert (result != 0); 52 return result; 53 } 54 else 55 { 56 int offset = 0; 57 58 /* The only additional case we can do is MEM. */ 59 gcc_assert (MEM_P (x)); 60 61 /* The following exposes the use of "x" to CSE. */ 62 if (GET_MODE_SIZE (GET_MODE (x)) <= UNITS_PER_WORD 63 && SCALAR_INT_MODE_P (GET_MODE (x)) 64 && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode), 65 GET_MODE_BITSIZE (GET_MODE (x))) 66 && !reload_completed) 67 return gen_lowpart_general (mode, force_reg (GET_MODE (x), x)); 68 69 if (WORDS_BIG_ENDIAN) 70 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD) 71 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD)); 72 73 if (BYTES_BIG_ENDIAN) 74 /* Adjust the address so that the address-after-the-data 75 is unchanged. */ 76 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode)) 77 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x)))); 78 79 return adjust_address (x, mode, offset); 80 } 81 } 82 83 /* Similar to gen_lowpart, but cannot emit any instruction via 84 copy_to_reg or force_reg. Mainly used in simplify-rtx.c. */ 85 rtx 86 gen_lowpart_no_emit_general (enum machine_mode mode, rtx x) 87 { 88 rtx result = gen_lowpart_if_possible (mode, x); 89 if (result) 90 return result; 91 else 92 return x; 93 } 94 95 rtx 96 reg_num_sign_bit_copies_general (const_rtx x ATTRIBUTE_UNUSED, 97 enum machine_mode mode ATTRIBUTE_UNUSED, 98 const_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 (const_rtx x ATTRIBUTE_UNUSED, 108 enum machine_mode mode ATTRIBUTE_UNUSED, 109 const_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 } 116 117 bool 118 reg_truncated_to_mode_general (enum machine_mode mode ATTRIBUTE_UNUSED, 119 const_rtx x ATTRIBUTE_UNUSED) 120 { 121 return false; 122 } 123 124 /* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point 125 number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the 126 least-significant part of X. 127 MODE specifies how big a part of X to return. 128 129 If the requested operation cannot be done, 0 is returned. 130 131 This is similar to gen_lowpart_general. */ 132 133 rtx 134 gen_lowpart_if_possible (enum machine_mode mode, rtx x) 135 { 136 rtx result = gen_lowpart_common (mode, x); 137 138 if (result) 139 return result; 140 else if (MEM_P (x)) 141 { 142 /* This is the only other case we handle. */ 143 int offset = 0; 144 rtx new_rtx; 145 146 if (WORDS_BIG_ENDIAN) 147 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD) 148 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD)); 149 if (BYTES_BIG_ENDIAN) 150 /* Adjust the address so that the address-after-the-data is 151 unchanged. */ 152 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode)) 153 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x)))); 154 155 new_rtx = adjust_address_nv (x, mode, offset); 156 if (! memory_address_addr_space_p (mode, XEXP (new_rtx, 0), 157 MEM_ADDR_SPACE (x))) 158 return 0; 159 160 return new_rtx; 161 } 162 else if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode 163 && validate_subreg (mode, GET_MODE (x), x, 164 subreg_lowpart_offset (mode, GET_MODE (x)))) 165 return gen_lowpart_SUBREG (mode, x); 166 else 167 return 0; 168 } 169 170