conditions.h revision 50397
116125Swpaul/* Definitions for condition code handling in final.c and output routines. 216125Swpaul Copyright (C) 1987 Free Software Foundation, Inc. 316125Swpaul 416125SwpaulThis file is part of GNU CC. 516125Swpaul 616125SwpaulGNU CC is free software; you can redistribute it and/or modify 716125Swpaulit under the terms of the GNU General Public License as published by 816125Swpaulthe Free Software Foundation; either version 2, or (at your option) 916125Swpaulany later version. 1016125Swpaul 1116125SwpaulGNU CC is distributed in the hope that it will be useful, 1216125Swpaulbut WITHOUT ANY WARRANTY; without even the implied warranty of 1316125SwpaulMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 1416125SwpaulGNU General Public License for more details. 1516125Swpaul 1616125SwpaulYou should have received a copy of the GNU General Public License 1716125Swpaulalong with GNU CC; see the file COPYING. If not, write to 1816125Swpaulthe Free Software Foundation, 59 Temple Place - Suite 330, 1916125SwpaulBoston, MA 02111-1307, USA. */ 2016125Swpaul 2116125Swpaul/* None of the things in the files exist if we don't use CC0. */ 2216125Swpaul 2316125Swpaul#ifdef HAVE_cc0 2416125Swpaul 2516125Swpaul/* The variable cc_status says how to interpret the condition code. 2616125Swpaul It is set by output routines for an instruction that sets the cc's 2716125Swpaul and examined by output routines for jump instructions. 2816125Swpaul 2916125Swpaul cc_status contains two components named `value1' and `value2' 3016125Swpaul that record two equivalent expressions for the values that the 3150479Speter condition codes were set from. (Either or both may be null if 3216125Swpaul there is no useful expression to record.) These fields are 3316125Swpaul used for eliminating redundant test and compare instructions 3416125Swpaul in the cases where the condition codes were already set by the 3516125Swpaul previous instruction. 3616125Swpaul 3716125Swpaul cc_status.flags contains flags which say that the condition codes 3816125Swpaul were set in a nonstandard manner. The output of jump instructions 3916125Swpaul uses these flags to compensate and produce the standard result 4068965Sru with the nonstandard condition codes. Standard flags are defined here. 4116125Swpaul The tm.h file can also define other machine-dependent flags. 4216125Swpaul 4316125Swpaul cc_status also contains a machine-dependent component `mdep' 4430378Scharnier whose type, `CC_STATUS_MDEP', may be defined as a macro in the 45108317Sschweikh tm.h file. */ 4657673Ssheldonh 47210723Sjoel#ifndef CC_STATUS_MDEP 4816125Swpaul#define CC_STATUS_MDEP int 4916125Swpaul#endif 5016125Swpaul 5116125Swpaul#ifndef CC_STATUS_MDEP_INIT 5216125Swpaul#define CC_STATUS_MDEP_INIT 0 5316125Swpaul#endif 5416125Swpaul 5516125Swpaultypedef struct {int flags; rtx value1, value2; CC_STATUS_MDEP mdep;} CC_STATUS; 5616125Swpaul 5716125Swpaul/* While outputting an insn as assembler code, 5816125Swpaul this is the status BEFORE that insn. */ 5916125Swpaulextern CC_STATUS cc_prev_status; 6016125Swpaul 6116125Swpaul/* While outputting an insn as assembler code, 6216125Swpaul this is being altered to the status AFTER that insn. */ 6316125Swpaulextern CC_STATUS cc_status; 6416125Swpaul 6516125Swpaul/* These are the machine-independent flags: */ 6616125Swpaul 6716125Swpaul/* Set if the sign of the cc value is inverted: 6816125Swpaul output a following jump-if-less as a jump-if-greater, etc. */ 6916125Swpaul#define CC_REVERSED 1 7016125Swpaul 7116125Swpaul/* This bit means that the current setting of the N bit is bogus 7216125Swpaul and conditional jumps should use the Z bit in its place. 7316125Swpaul This state obtains when an extraction of a signed single-bit field 7416125Swpaul or an arithmetic shift right of a byte by 7 bits 7557673Ssheldonh is turned into a btst, because btst does not set the N bit. */ 7657673Ssheldonh#define CC_NOT_POSITIVE 2 7716125Swpaul 7816125Swpaul/* This bit means that the current setting of the N bit is bogus 7916125Swpaul and conditional jumps should pretend that the N bit is clear. 8016125Swpaul Used after extraction of an unsigned bit 8157673Ssheldonh or logical shift right of a byte by 7 bits is turned into a btst. 8257673Ssheldonh The btst does not alter the N bit, but the result of that shift 8316125Swpaul or extract is never negative. */ 8416125Swpaul#define CC_NOT_NEGATIVE 4 8516125Swpaul 8616125Swpaul/* This bit means that the current setting of the overflow flag 8716125Swpaul is bogus and conditional jumps should pretend there is no overflow. */ 8816125Swpaul/* ??? Note that for most targets this macro is misnamed as it applies 8930378Scharnier to the carry flag, not the overflow flag. */ 9099968Scharnier#define CC_NO_OVERFLOW 010 9116125Swpaul 9257673Ssheldonh/* This bit means that what ought to be in the Z bit 9357673Ssheldonh should be tested as the complement of the N bit. */ 9430378Scharnier#define CC_Z_IN_NOT_N 020 9557673Ssheldonh 96210723Sjoel/* This bit means that what ought to be in the Z bit 9716125Swpaul should be tested as the N bit. */ 9816125Swpaul#define CC_Z_IN_N 040 9916125Swpaul 10016125Swpaul/* Nonzero if we must invert the sense of the following branch, i.e. 10116125Swpaul change EQ to NE. This is not safe for IEEE floating point operations! 10230378Scharnier It is intended for use only when a combination of arithmetic 10399968Scharnier or logical insns can leave the condition codes set in a fortuitous 10416125Swpaul (though inverted) state. */ 10516125Swpaul#define CC_INVERTED 0100 10616125Swpaul 107163902Smaxim/* Nonzero if we must convert signed condition operators to unsigned. 108163902Smaxim This is only used by machine description files. */ 109163902Smaxim#define CC_NOT_SIGNED 0200 110163902Smaxim 111163902Smaxim/* This is how to initialize the variable cc_status. 11257673Ssheldonh final does this at appropriate moments. */ 11316125Swpaul 11416125Swpaul#define CC_STATUS_INIT \ 11516125Swpaul (cc_status.flags = 0, cc_status.value1 = 0, cc_status.value2 = 0, \ 11616125Swpaul CC_STATUS_MDEP_INIT) 11730378Scharnier 11830378Scharnier#endif 11916125Swpaul