1 /* Definitions for condition code handling in final.c and output routines. 2 Copyright (C) 1987, 2007 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 /* None of the things in the files exist if we don't use CC0. */ 21 22 #ifdef HAVE_cc0 23 24 /* The variable cc_status says how to interpret the condition code. 25 It is set by output routines for an instruction that sets the cc's 26 and examined by output routines for jump instructions. 27 28 cc_status contains two components named `value1' and `value2' 29 that record two equivalent expressions for the values that the 30 condition codes were set from. (Either or both may be null if 31 there is no useful expression to record.) These fields are 32 used for eliminating redundant test and compare instructions 33 in the cases where the condition codes were already set by the 34 previous instruction. 35 36 cc_status.flags contains flags which say that the condition codes 37 were set in a nonstandard manner. The output of jump instructions 38 uses these flags to compensate and produce the standard result 39 with the nonstandard condition codes. Standard flags are defined here. 40 The tm.h file can also define other machine-dependent flags. 41 42 cc_status also contains a machine-dependent component `mdep' 43 whose type, `CC_STATUS_MDEP', may be defined as a macro in the 44 tm.h file. */ 45 46 #ifndef CC_STATUS_MDEP 47 #define CC_STATUS_MDEP int 48 #endif 49 50 #ifndef CC_STATUS_MDEP_INIT 51 #define CC_STATUS_MDEP_INIT 0 52 #endif 53 54 typedef struct {int flags; rtx value1, value2; CC_STATUS_MDEP mdep;} CC_STATUS; 55 56 /* While outputting an insn as assembler code, 57 this is the status BEFORE that insn. */ 58 extern CC_STATUS cc_prev_status; 59 60 /* While outputting an insn as assembler code, 61 this is being altered to the status AFTER that insn. */ 62 extern CC_STATUS cc_status; 63 64 /* These are the machine-independent flags: */ 65 66 /* Set if the sign of the cc value is inverted: 67 output a following jump-if-less as a jump-if-greater, etc. */ 68 #define CC_REVERSED 1 69 70 /* This bit means that the current setting of the N bit is bogus 71 and conditional jumps should use the Z bit in its place. 72 This state obtains when an extraction of a signed single-bit field 73 or an arithmetic shift right of a byte by 7 bits 74 is turned into a btst, because btst does not set the N bit. */ 75 #define CC_NOT_POSITIVE 2 76 77 /* This bit means that the current setting of the N bit is bogus 78 and conditional jumps should pretend that the N bit is clear. 79 Used after extraction of an unsigned bit 80 or logical shift right of a byte by 7 bits is turned into a btst. 81 The btst does not alter the N bit, but the result of that shift 82 or extract is never negative. */ 83 #define CC_NOT_NEGATIVE 4 84 85 /* This bit means that the current setting of the overflow flag 86 is bogus and conditional jumps should pretend there is no overflow. */ 87 /* ??? Note that for most targets this macro is misnamed as it applies 88 to the carry flag, not the overflow flag. */ 89 #define CC_NO_OVERFLOW 010 90 91 /* This bit means that what ought to be in the Z bit 92 should be tested as the complement of the N bit. */ 93 #define CC_Z_IN_NOT_N 020 94 95 /* This bit means that what ought to be in the Z bit 96 should be tested as the N bit. */ 97 #define CC_Z_IN_N 040 98 99 /* Nonzero if we must invert the sense of the following branch, i.e. 100 change EQ to NE. This is not safe for IEEE floating point operations! 101 It is intended for use only when a combination of arithmetic 102 or logical insns can leave the condition codes set in a fortuitous 103 (though inverted) state. */ 104 #define CC_INVERTED 0100 105 106 /* Nonzero if we must convert signed condition operators to unsigned. 107 This is only used by machine description files. */ 108 #define CC_NOT_SIGNED 0200 109 110 /* This is how to initialize the variable cc_status. 111 final does this at appropriate moments. */ 112 113 #define CC_STATUS_INIT \ 114 (cc_status.flags = 0, cc_status.value1 = 0, cc_status.value2 = 0, \ 115 CC_STATUS_MDEP_INIT) 116 117 #endif 118