1 /* Generic hooks for the RTL middle-end. 2 Copyright (C) 2004-2017 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 "memmodel.h" 29 #include "emit-rtl.h" 30 #include "recog.h" 31 #include "rtlhooks-def.h" 32 #include "explow.h" 33 34 35 /* For speed, we will copy the RTX hooks struct member-by-member 36 instead of doing indirect calls. For these reason, we initialize 37 *two* struct rtl_hooks globals: rtl_hooks is the one that is used 38 to actually call the hooks, while general_rtl_hooks is used 39 to restore the hooks by passes that modify them. */ 40 41 const struct rtl_hooks general_rtl_hooks = RTL_HOOKS_INITIALIZER; 42 struct rtl_hooks rtl_hooks = RTL_HOOKS_INITIALIZER; 43 44 rtx 45 gen_lowpart_general (machine_mode mode, rtx x) 46 { 47 rtx result = gen_lowpart_common (mode, x); 48 49 if (result) 50 return result; 51 /* Handle SUBREGs and hard REGs that were rejected by 52 simplify_gen_subreg. */ 53 else if (REG_P (x) || GET_CODE (x) == SUBREG) 54 { 55 result = gen_lowpart_common (mode, copy_to_reg (x)); 56 gcc_assert (result != 0); 57 return result; 58 } 59 else 60 { 61 int offset = 0; 62 63 /* The only additional case we can do is MEM. */ 64 gcc_assert (MEM_P (x)); 65 66 /* The following exposes the use of "x" to CSE. */ 67 if (GET_MODE_SIZE (GET_MODE (x)) <= UNITS_PER_WORD 68 && SCALAR_INT_MODE_P (GET_MODE (x)) 69 && TRULY_NOOP_TRUNCATION_MODES_P (mode, GET_MODE (x)) 70 && !reload_completed) 71 return gen_lowpart_general (mode, force_reg (GET_MODE (x), x)); 72 73 if (WORDS_BIG_ENDIAN) 74 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD) 75 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD)); 76 77 if (BYTES_BIG_ENDIAN) 78 /* Adjust the address so that the address-after-the-data 79 is unchanged. */ 80 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode)) 81 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x)))); 82 83 return adjust_address (x, mode, offset); 84 } 85 } 86 87 rtx 88 reg_num_sign_bit_copies_general (const_rtx x ATTRIBUTE_UNUSED, 89 machine_mode mode ATTRIBUTE_UNUSED, 90 const_rtx known_x ATTRIBUTE_UNUSED, 91 machine_mode known_mode ATTRIBUTE_UNUSED, 92 unsigned int known_ret ATTRIBUTE_UNUSED, 93 unsigned int *result ATTRIBUTE_UNUSED) 94 { 95 return NULL; 96 } 97 98 rtx 99 reg_nonzero_bits_general (const_rtx x ATTRIBUTE_UNUSED, 100 machine_mode mode ATTRIBUTE_UNUSED, 101 const_rtx known_x ATTRIBUTE_UNUSED, 102 machine_mode known_mode ATTRIBUTE_UNUSED, 103 unsigned HOST_WIDE_INT known_ret ATTRIBUTE_UNUSED, 104 unsigned HOST_WIDE_INT *nonzero ATTRIBUTE_UNUSED) 105 { 106 return NULL; 107 } 108 109 bool 110 reg_truncated_to_mode_general (machine_mode mode ATTRIBUTE_UNUSED, 111 const_rtx x ATTRIBUTE_UNUSED) 112 { 113 return false; 114 } 115 116 /* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point 117 number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the 118 least-significant part of X. 119 MODE specifies how big a part of X to return. 120 121 If the requested operation cannot be done, 0 is returned. 122 123 This is similar to gen_lowpart_general. */ 124 125 rtx 126 gen_lowpart_if_possible (machine_mode mode, rtx x) 127 { 128 rtx result = gen_lowpart_common (mode, x); 129 130 if (result) 131 return result; 132 else if (MEM_P (x)) 133 { 134 /* This is the only other case we handle. */ 135 int offset = 0; 136 rtx new_rtx; 137 138 if (WORDS_BIG_ENDIAN) 139 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD) 140 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD)); 141 if (BYTES_BIG_ENDIAN) 142 /* Adjust the address so that the address-after-the-data is 143 unchanged. */ 144 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode)) 145 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x)))); 146 147 new_rtx = adjust_address_nv (x, mode, offset); 148 if (! memory_address_addr_space_p (mode, XEXP (new_rtx, 0), 149 MEM_ADDR_SPACE (x))) 150 return 0; 151 152 return new_rtx; 153 } 154 else if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode 155 && validate_subreg (mode, GET_MODE (x), x, 156 subreg_lowpart_offset (mode, GET_MODE (x)))) 157 return gen_lowpart_SUBREG (mode, x); 158 else 159 return 0; 160 } 161 162