119 lines
4.5 KiB
C
119 lines
4.5 KiB
C
/* Definitions for condition code handling in final.c and output routines.
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Copyright (C) 1987 Free Software Foundation, Inc.
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This file is part of GNU CC.
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GNU CC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU CC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU CC; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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/* None of the things in the files exist if we don't use CC0. */
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#ifdef HAVE_cc0
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/* The variable cc_status says how to interpret the condition code.
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It is set by output routines for an instruction that sets the cc's
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and examined by output routines for jump instructions.
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cc_status contains two components named `value1' and `value2'
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that record two equivalent expressions for the values that the
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condition codes were set from. (Either or both may be null if
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there is no useful expression to record.) These fields are
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used for eliminating redundant test and compare instructions
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in the cases where the condition codes were already set by the
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previous instruction.
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cc_status.flags contains flags which say that the condition codes
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were set in a nonstandard manner. The output of jump instructions
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uses these flags to compensate and produce the standard result
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with the nonstandard condition codes. Standard flags are defined here.
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The tm.h file can also define other machine-dependent flags.
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cc_status also contains a machine-dependent component `mdep'
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whose type, `CC_STATUS_MDEP', may be defined as a macro in the
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tm.h file. */
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#ifndef CC_STATUS_MDEP
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#define CC_STATUS_MDEP int
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#endif
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#ifndef CC_STATUS_MDEP_INIT
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#define CC_STATUS_MDEP_INIT 0
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#endif
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typedef struct {int flags; rtx value1, value2; CC_STATUS_MDEP mdep;} CC_STATUS;
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/* While outputting an insn as assembler code,
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this is the status BEFORE that insn. */
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extern CC_STATUS cc_prev_status;
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/* While outputting an insn as assembler code,
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this is being altered to the status AFTER that insn. */
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extern CC_STATUS cc_status;
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/* These are the machine-independent flags: */
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/* Set if the sign of the cc value is inverted:
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output a following jump-if-less as a jump-if-greater, etc. */
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#define CC_REVERSED 1
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/* This bit means that the current setting of the N bit is bogus
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and conditional jumps should use the Z bit in its place.
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This state obtains when an extraction of a signed single-bit field
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or an arithmetic shift right of a byte by 7 bits
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is turned into a btst, because btst does not set the N bit. */
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#define CC_NOT_POSITIVE 2
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/* This bit means that the current setting of the N bit is bogus
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and conditional jumps should pretend that the N bit is clear.
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Used after extraction of an unsigned bit
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or logical shift right of a byte by 7 bits is turned into a btst.
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The btst does not alter the N bit, but the result of that shift
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or extract is never negative. */
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#define CC_NOT_NEGATIVE 4
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/* This bit means that the current setting of the overflow flag
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is bogus and conditional jumps should pretend there is no overflow. */
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/* ??? Note that for most targets this macro is misnamed as it applies
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to the carry flag, not the overflow flag. */
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#define CC_NO_OVERFLOW 010
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/* This bit means that what ought to be in the Z bit
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should be tested as the complement of the N bit. */
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#define CC_Z_IN_NOT_N 020
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/* This bit means that what ought to be in the Z bit
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should be tested as the N bit. */
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#define CC_Z_IN_N 040
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/* Nonzero if we must invert the sense of the following branch, i.e.
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change EQ to NE. This is not safe for IEEE floating point operations!
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It is intended for use only when a combination of arithmetic
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or logical insns can leave the condition codes set in a fortuitous
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(though inverted) state. */
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#define CC_INVERTED 0100
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/* Nonzero if we must convert signed condition operators to unsigned.
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This is only used by machine description files. */
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#define CC_NOT_SIGNED 0200
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/* This is how to initialize the variable cc_status.
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final does this at appropriate moments. */
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#define CC_STATUS_INIT \
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(cc_status.flags = 0, cc_status.value1 = 0, cc_status.value2 = 0, \
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CC_STATUS_MDEP_INIT)
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#endif
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