1 /* Generic hooks for the RTL middle-end. 2 Copyright (C) 2004-2016 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 "function.h" 25 #include "rtl.h" 26 #include "tree.h" 27 #include "insn-config.h" 28 #include "emit-rtl.h" 29 #include "recog.h" 30 #include "rtlhooks-def.h" 31 #include "explow.h" 32 33 34 /* For speed, we will copy the RTX hooks struct member-by-member 35 instead of doing indirect calls. For these reason, we initialize 36 *two* struct rtl_hooks globals: rtl_hooks is the one that is used 37 to actually call the hooks, while general_rtl_hooks is used 38 to restore the hooks by passes that modify them. */ 39 40 const struct rtl_hooks general_rtl_hooks = RTL_HOOKS_INITIALIZER; 41 struct rtl_hooks rtl_hooks = RTL_HOOKS_INITIALIZER; 42 43 rtx 44 gen_lowpart_general (machine_mode mode, rtx x) 45 { 46 rtx result = gen_lowpart_common (mode, x); 47 48 if (result) 49 return result; 50 /* Handle SUBREGs and hard REGs that were rejected by 51 simplify_gen_subreg. */ 52 else if (REG_P (x) || GET_CODE (x) == SUBREG) 53 { 54 result = gen_lowpart_common (mode, copy_to_reg (x)); 55 gcc_assert (result != 0); 56 return result; 57 } 58 else 59 { 60 int offset = 0; 61 62 /* The only additional case we can do is MEM. */ 63 gcc_assert (MEM_P (x)); 64 65 /* The following exposes the use of "x" to CSE. */ 66 if (GET_MODE_SIZE (GET_MODE (x)) <= UNITS_PER_WORD 67 && SCALAR_INT_MODE_P (GET_MODE (x)) 68 && TRULY_NOOP_TRUNCATION_MODES_P (mode, GET_MODE (x)) 69 && !reload_completed) 70 return gen_lowpart_general (mode, force_reg (GET_MODE (x), x)); 71 72 if (WORDS_BIG_ENDIAN) 73 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD) 74 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD)); 75 76 if (BYTES_BIG_ENDIAN) 77 /* Adjust the address so that the address-after-the-data 78 is unchanged. */ 79 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode)) 80 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x)))); 81 82 return adjust_address (x, mode, offset); 83 } 84 } 85 86 rtx 87 reg_num_sign_bit_copies_general (const_rtx x ATTRIBUTE_UNUSED, 88 machine_mode mode ATTRIBUTE_UNUSED, 89 const_rtx known_x ATTRIBUTE_UNUSED, 90 machine_mode known_mode ATTRIBUTE_UNUSED, 91 unsigned int known_ret ATTRIBUTE_UNUSED, 92 unsigned int *result ATTRIBUTE_UNUSED) 93 { 94 return NULL; 95 } 96 97 rtx 98 reg_nonzero_bits_general (const_rtx x ATTRIBUTE_UNUSED, 99 machine_mode mode ATTRIBUTE_UNUSED, 100 const_rtx known_x ATTRIBUTE_UNUSED, 101 machine_mode known_mode ATTRIBUTE_UNUSED, 102 unsigned HOST_WIDE_INT known_ret ATTRIBUTE_UNUSED, 103 unsigned HOST_WIDE_INT *nonzero ATTRIBUTE_UNUSED) 104 { 105 return NULL; 106 } 107 108 bool 109 reg_truncated_to_mode_general (machine_mode mode ATTRIBUTE_UNUSED, 110 const_rtx x ATTRIBUTE_UNUSED) 111 { 112 return false; 113 } 114 115 /* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point 116 number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the 117 least-significant part of X. 118 MODE specifies how big a part of X to return. 119 120 If the requested operation cannot be done, 0 is returned. 121 122 This is similar to gen_lowpart_general. */ 123 124 rtx 125 gen_lowpart_if_possible (machine_mode mode, rtx x) 126 { 127 rtx result = gen_lowpart_common (mode, x); 128 129 if (result) 130 return result; 131 else if (MEM_P (x)) 132 { 133 /* This is the only other case we handle. */ 134 int offset = 0; 135 rtx new_rtx; 136 137 if (WORDS_BIG_ENDIAN) 138 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD) 139 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD)); 140 if (BYTES_BIG_ENDIAN) 141 /* Adjust the address so that the address-after-the-data is 142 unchanged. */ 143 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode)) 144 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x)))); 145 146 new_rtx = adjust_address_nv (x, mode, offset); 147 if (! memory_address_addr_space_p (mode, XEXP (new_rtx, 0), 148 MEM_ADDR_SPACE (x))) 149 return 0; 150 151 return new_rtx; 152 } 153 else if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode 154 && validate_subreg (mode, GET_MODE (x), x, 155 subreg_lowpart_offset (mode, GET_MODE (x)))) 156 return gen_lowpart_SUBREG (mode, x); 157 else 158 return 0; 159 } 160 161