1/* Generic hooks for the RTL middle-end. 2 Copyright (C) 2004, 2005 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify it under 7the terms of the GNU General Public License as published by the Free 8Software Foundation; either version 2, or (at your option) any later 9version. 10 11GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12WARRANTY; without even the implied warranty of MERCHANTABILITY or 13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14for more details. 15 16You should have received a copy of the GNU General Public License 17along with GCC; see the file COPYING. If not, write to the Free 18Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 1902110-1301, 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#include "recog.h" 29 30 31/* For speed, we will copy the RTX hooks struct member-by-member 32 instead of doing indirect calls. For these reason, we initialize 33 *two* struct rtl_hooks globals: rtl_hooks is the one that is used 34 to actually call the hooks, while general_rtl_hooks is used 35 to restore the hooks by passes that modify them. */ 36 37const struct rtl_hooks general_rtl_hooks = RTL_HOOKS_INITIALIZER; 38struct rtl_hooks rtl_hooks = RTL_HOOKS_INITIALIZER; 39 40rtx 41gen_lowpart_general (enum machine_mode mode, rtx x) 42{ 43 rtx result = gen_lowpart_common (mode, x); 44 45 if (result) 46 return result; 47 /* If it's a REG, it must be a hard reg that's not valid in MODE. */ 48 else if (REG_P (x) 49 /* Or we could have a subreg of a floating point value. */ 50 || (GET_CODE (x) == SUBREG 51 && FLOAT_MODE_P (GET_MODE (SUBREG_REG (x))))) 52 { 53 result = gen_lowpart_common (mode, copy_to_reg (x)); 54 gcc_assert (result != 0); 55 return result; 56 } 57 else 58 { 59 int offset = 0; 60 61 /* The only additional case we can do is MEM. */ 62 gcc_assert (MEM_P (x)); 63 64 /* The following exposes the use of "x" to CSE. */ 65 if (GET_MODE_SIZE (GET_MODE (x)) <= UNITS_PER_WORD 66 && SCALAR_INT_MODE_P (GET_MODE (x)) 67 && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode), 68 GET_MODE_BITSIZE (GET_MODE (x))) 69 && ! no_new_pseudos) 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/* Similar to gen_lowpart, but cannot emit any instruction via 87 copy_to_reg or force_reg. Mainly used in simplify-rtx.c. */ 88rtx 89gen_lowpart_no_emit_general (enum machine_mode mode, rtx x) 90{ 91 rtx result = gen_lowpart_if_possible (mode, x); 92 if (result) 93 return result; 94 else 95 return x; 96} 97 98rtx 99reg_num_sign_bit_copies_general (rtx x ATTRIBUTE_UNUSED, 100 enum machine_mode mode ATTRIBUTE_UNUSED, 101 rtx known_x ATTRIBUTE_UNUSED, 102 enum machine_mode known_mode ATTRIBUTE_UNUSED, 103 unsigned int known_ret ATTRIBUTE_UNUSED, 104 unsigned int *result ATTRIBUTE_UNUSED) 105{ 106 return NULL; 107} 108 109rtx 110reg_nonzero_bits_general (rtx x ATTRIBUTE_UNUSED, 111 enum machine_mode mode ATTRIBUTE_UNUSED, 112 rtx known_x ATTRIBUTE_UNUSED, 113 enum machine_mode known_mode ATTRIBUTE_UNUSED, 114 unsigned HOST_WIDE_INT known_ret ATTRIBUTE_UNUSED, 115 unsigned HOST_WIDE_INT *nonzero ATTRIBUTE_UNUSED) 116{ 117 return NULL; 118} 119 120bool 121reg_truncated_to_mode_general (enum machine_mode mode ATTRIBUTE_UNUSED, 122 rtx x ATTRIBUTE_UNUSED) 123{ 124 return false; 125} 126 127/* Assuming that X is an rtx (e.g., MEM, REG or SUBREG) for a fixed-point 128 number, return an rtx (MEM, SUBREG, or CONST_INT) that refers to the 129 least-significant part of X. 130 MODE specifies how big a part of X to return. 131 132 If the requested operation cannot be done, 0 is returned. 133 134 This is similar to gen_lowpart_general. */ 135 136rtx 137gen_lowpart_if_possible (enum machine_mode mode, rtx x) 138{ 139 rtx result = gen_lowpart_common (mode, x); 140 141 if (result) 142 return result; 143 else if (MEM_P (x)) 144 { 145 /* This is the only other case we handle. */ 146 int offset = 0; 147 rtx new; 148 149 if (WORDS_BIG_ENDIAN) 150 offset = (MAX (GET_MODE_SIZE (GET_MODE (x)), UNITS_PER_WORD) 151 - MAX (GET_MODE_SIZE (mode), UNITS_PER_WORD)); 152 if (BYTES_BIG_ENDIAN) 153 /* Adjust the address so that the address-after-the-data is 154 unchanged. */ 155 offset -= (MIN (UNITS_PER_WORD, GET_MODE_SIZE (mode)) 156 - MIN (UNITS_PER_WORD, GET_MODE_SIZE (GET_MODE (x)))); 157 158 new = adjust_address_nv (x, mode, offset); 159 if (! memory_address_p (mode, XEXP (new, 0))) 160 return 0; 161 162 return new; 163 } 164 else if (mode != GET_MODE (x) && GET_MODE (x) != VOIDmode) 165 return gen_lowpart_SUBREG (mode, x); 166 else 167 return 0; 168} 169 170