Annotation of GNUtools/cc/rtl.h, revision 1.1

1.1     ! root        1: /* Register Transfer Language (RTL) definitions for GNU C-Compiler
        !             2:    Copyright (C) 1987, 1991, 1992, 1993 Free Software Foundation, Inc.
        !             3: 
        !             4: This file is part of GNU CC.
        !             5: 
        !             6: GNU CC is free software; you can redistribute it and/or modify
        !             7: it under the terms of the GNU General Public License as published by
        !             8: the Free Software Foundation; either version 2, or (at your option)
        !             9: any later version.
        !            10: 
        !            11: GNU CC is distributed in the hope that it will be useful,
        !            12: but WITHOUT ANY WARRANTY; without even the implied warranty of
        !            13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        !            14: GNU General Public License for more details.
        !            15: 
        !            16: You should have received a copy of the GNU General Public License
        !            17: along with GNU CC; see the file COPYING.  If not, write to
        !            18: the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
        !            19: 
        !            20: 
        !            21: #include "machmode.h"
        !            22: 
        !            23: #undef FFS  /* Some systems predefine this symbol; don't let it interfere.  */
        !            24: #undef FLOAT /* Likewise.  */
        !            25: #undef ABS /* Likewise.  */
        !            26: #undef PC /* Likewise.  */
        !            27: 
        !            28: /* Register Transfer Language EXPRESSIONS CODES */
        !            29: 
        !            30: #define RTX_CODE       enum rtx_code
        !            31: enum rtx_code  {
        !            32: 
        !            33: #define DEF_RTL_EXPR(ENUM, NAME, FORMAT, CLASS)   ENUM ,
        !            34: #include "rtl.def"             /* rtl expressions are documented here */
        !            35: #undef DEF_RTL_EXPR
        !            36: 
        !            37:   LAST_AND_UNUSED_RTX_CODE};   /* A convenient way to get a value for
        !            38:                                   NUM_RTX_CODE.
        !            39:                                   Assumes default enum value assignment.  */
        !            40: 
        !            41: #define NUM_RTX_CODE ((int)LAST_AND_UNUSED_RTX_CODE)
        !            42:                                /* The cast here, saves many elsewhere.  */
        !            43: 
        !            44: extern int rtx_length[];
        !            45: #define GET_RTX_LENGTH(CODE)           (rtx_length[(int)(CODE)])
        !            46: 
        !            47: extern char *rtx_name[];
        !            48: #define GET_RTX_NAME(CODE)             (rtx_name[(int)(CODE)])
        !            49: 
        !            50: extern char *rtx_format[];
        !            51: #define GET_RTX_FORMAT(CODE)           (rtx_format[(int)(CODE)])
        !            52: 
        !            53: extern char rtx_class[];
        !            54: #define GET_RTX_CLASS(CODE)            (rtx_class[(int)(CODE)])
        !            55: 
        !            56: /* Common union for an element of an rtx.  */
        !            57: 
        !            58: typedef union rtunion_def
        !            59: {
        !            60:   HOST_WIDE_INT rtwint;
        !            61:   int rtint;
        !            62:   char *rtstr;
        !            63:   struct rtx_def *rtx;
        !            64:   struct rtvec_def *rtvec;
        !            65:   enum machine_mode rttype;
        !            66: } rtunion;
        !            67: 
        !            68: /* RTL expression ("rtx").  */
        !            69: 
        !            70: typedef struct rtx_def
        !            71: {
        !            72: #ifdef ONLY_INT_FIELDS
        !            73: #ifdef CODE_FIELD_BUG
        !            74:   unsigned int code : 16;
        !            75: #else
        !            76:   unsigned short code;
        !            77: #endif
        !            78: #else
        !            79:   /* The kind of expression this is.  */
        !            80:   enum rtx_code code : 16;
        !            81: #endif
        !            82:   /* The kind of value the expression has.  */
        !            83: #ifdef ONLY_INT_FIELDS
        !            84:   int mode : 8;
        !            85: #else
        !            86:   enum machine_mode mode : 8;
        !            87: #endif
        !            88:   /* 1 in an INSN if it can alter flow of control
        !            89:      within this function.  Not yet used!  */
        !            90:   unsigned int jump : 1;
        !            91:   /* 1 in an INSN if it can call another function.  Not yet used!  */
        !            92:   unsigned int call : 1;
        !            93:   /* 1 in a MEM or REG if value of this expression will never change
        !            94:      during the current function, even though it is not
        !            95:      manifestly constant.
        !            96:      1 in a SUBREG if it is from a promoted variable that is unsigned.
        !            97:      1 in a SYMBOL_REF if it addresses something in the per-function
        !            98:      constants pool.
        !            99:      1 in a CALL_INSN if it is a const call.
        !           100:      1 in a JUMP_INSN if it is a branch that should be annulled.  Valid from
        !           101:      reorg until end of compilation; cleared before used.  */
        !           102:   unsigned int unchanging : 1;
        !           103:   /* 1 in a MEM expression if contents of memory are volatile.
        !           104:      1 in an INSN, CALL_INSN, JUMP_INSN, CODE_LABEL or BARRIER
        !           105:      if it is deleted.
        !           106:      1 in a REG expression if corresponds to a variable declared by the user.
        !           107:      0 for an internally generated temporary.
        !           108:      In a SYMBOL_REF, this flag is used for machine-specific purposes.
        !           109:      In a LABEL_REF or in a REG_LABEL note, this is LABEL_REF_NONLOCAL_P.  */
        !           110:   unsigned int volatil : 1;
        !           111:   /* 1 in a MEM referring to a field of a structure (not a union!).
        !           112:      0 if the MEM was a variable or the result of a * operator in C;
        !           113:      1 if it was the result of a . or -> operator (on a struct) in C.
        !           114:      1 in a REG if the register is used only in exit code a loop.
        !           115:      1 in a SUBREG expression if was generated from a variable with a 
        !           116:      promoted mode.
        !           117:      1 in a CODE_LABEL if the label is used for nonlocal gotos
        !           118:      and must not be deleted even if its count is zero.
        !           119:      1 in a LABEL_REF if this is a reference to a label outside the
        !           120:      current loop.
        !           121:      1 in an INSN, JUMP_INSN, or CALL_INSN if this insn must be scheduled
        !           122:      together with the preceding insn.  Valid only within sched.
        !           123:      1 in an INSN, JUMP_INSN, or CALL_INSN if insn is in a delay slot and
        !           124:      from the target of a branch.  Valid from reorg until end of compilation;
        !           125:      cleared before used.  */
        !           126:   unsigned int in_struct : 1;
        !           127:   /* 1 if this rtx is used.  This is used for copying shared structure.
        !           128:      See `unshare_all_rtl'.
        !           129:      In a REG, this is not needed for that purpose, and used instead 
        !           130:      in `leaf_renumber_regs_insn'.
        !           131:      In a SYMBOL_REF, means that emit_library_call
        !           132:      has used it as the function.  */
        !           133:   unsigned int used : 1;
        !           134:   /* Nonzero if this rtx came from procedure integration.
        !           135:      In a REG, nonzero means this reg refers to the return value
        !           136:      of the current function.  */
        !           137:   unsigned integrated : 1;
        !           138:   /* The first element of the operands of this rtx.
        !           139:      The number of operands and their types are controlled
        !           140:      by the `code' field, according to rtl.def.  */
        !           141:   rtunion fld[1];
        !           142: } *rtx;
        !           143: 
        !           144: 
        !           145: /* Add prototype support.  */
        !           146: #ifndef PROTO
        !           147: #if defined (USE_PROTOTYPES) ? USE_PROTOTYPES : defined (__STDC__)
        !           148: #define PROTO(ARGS) ARGS
        !           149: #else
        !           150: #define PROTO(ARGS) ()
        !           151: #endif
        !           152: #endif
        !           153: 
        !           154: #define NULL_RTX (rtx) 0
        !           155: 
        !           156: /* Define a generic NULL if one hasn't already been defined.  */
        !           157: 
        !           158: #ifndef NULL
        !           159: #define NULL 0
        !           160: #endif
        !           161: 
        !           162: #ifndef GENERIC_PTR
        !           163: #if defined (USE_PROTOTYPES) ? USE_PROTOTYPES : defined (__STDC__)
        !           164: #define GENERIC_PTR void *
        !           165: #else
        !           166: #define GENERIC_PTR char *
        !           167: #endif
        !           168: #endif
        !           169: 
        !           170: #ifndef NULL_PTR
        !           171: #define NULL_PTR ((GENERIC_PTR)0)
        !           172: #endif
        !           173: 
        !           174: /* Define macros to access the `code' field of the rtx.  */
        !           175: 
        !           176: #ifdef SHORT_ENUM_BUG
        !           177: #define GET_CODE(RTX)          ((enum rtx_code) ((RTX)->code))
        !           178: #define PUT_CODE(RTX, CODE)    ((RTX)->code = ((short) (CODE)))
        !           179: #else
        !           180: #define GET_CODE(RTX)          ((RTX)->code)
        !           181: #define PUT_CODE(RTX, CODE)    ((RTX)->code = (CODE))
        !           182: #endif
        !           183: 
        !           184: #define GET_MODE(RTX)          ((RTX)->mode)
        !           185: #define PUT_MODE(RTX, MODE)    ((RTX)->mode = (MODE))
        !           186: 
        !           187: #define RTX_INTEGRATED_P(RTX) ((RTX)->integrated)
        !           188: #define RTX_UNCHANGING_P(RTX) ((RTX)->unchanging)
        !           189: 
        !           190: /* RTL vector.  These appear inside RTX's when there is a need
        !           191:    for a variable number of things.  The principle use is inside
        !           192:    PARALLEL expressions.  */
        !           193: 
        !           194: typedef struct rtvec_def{
        !           195:   unsigned num_elem;           /* number of elements */
        !           196:   rtunion elem[1];
        !           197: } *rtvec;
        !           198: 
        !           199: #define NULL_RTVEC (rtvec) 0
        !           200: 
        !           201: #define GET_NUM_ELEM(RTVEC)            ((RTVEC)->num_elem)
        !           202: #define PUT_NUM_ELEM(RTVEC, NUM)       ((RTVEC)->num_elem = (unsigned) NUM)
        !           203: 
        !           204: #define RTVEC_ELT(RTVEC, I)  ((RTVEC)->elem[(I)].rtx)
        !           205: 
        !           206: /* 1 if X is a REG.  */
        !           207: 
        !           208: #define REG_P(X) (GET_CODE (X) == REG)
        !           209: 
        !           210: /* 1 if X is a constant value that is an integer.  */
        !           211: 
        !           212: #define CONSTANT_P(X)   \
        !           213:   (GET_CODE (X) == LABEL_REF || GET_CODE (X) == SYMBOL_REF             \
        !           214:    || GET_CODE (X) == CONST_INT || GET_CODE (X) == CONST_DOUBLE                \
        !           215:    || GET_CODE (X) == CONST || GET_CODE (X) == HIGH)
        !           216: 
        !           217: /* General accessor macros for accessing the fields of an rtx.  */
        !           218: 
        !           219: #define XEXP(RTX, N)   ((RTX)->fld[N].rtx)
        !           220: #define XINT(RTX, N)   ((RTX)->fld[N].rtint)
        !           221: #define XWINT(RTX, N)  ((RTX)->fld[N].rtwint)
        !           222: #define XSTR(RTX, N)   ((RTX)->fld[N].rtstr)
        !           223: #define XVEC(RTX, N)   ((RTX)->fld[N].rtvec)
        !           224: #define XVECLEN(RTX, N)        ((RTX)->fld[N].rtvec->num_elem)
        !           225: #define XVECEXP(RTX,N,M)((RTX)->fld[N].rtvec->elem[M].rtx)
        !           226: 
        !           227: /* ACCESS MACROS for particular fields of insns.  */
        !           228: 
        !           229: /* Holds a unique number for each insn.
        !           230:    These are not necessarily sequentially increasing.  */
        !           231: #define INSN_UID(INSN) ((INSN)->fld[0].rtint)
        !           232: 
        !           233: /* Chain insns together in sequence.  */
        !           234: #define PREV_INSN(INSN)        ((INSN)->fld[1].rtx)
        !           235: #define NEXT_INSN(INSN)        ((INSN)->fld[2].rtx)
        !           236: 
        !           237: /* The body of an insn.  */
        !           238: #define PATTERN(INSN)  ((INSN)->fld[3].rtx)
        !           239: 
        !           240: /* Code number of instruction, from when it was recognized.
        !           241:    -1 means this instruction has not been recognized yet.  */
        !           242: #define INSN_CODE(INSN) ((INSN)->fld[4].rtint)
        !           243: 
        !           244: /* Set up in flow.c; empty before then.
        !           245:    Holds a chain of INSN_LIST rtx's whose first operands point at
        !           246:    previous insns with direct data-flow connections to this one.
        !           247:    That means that those insns set variables whose next use is in this insn.
        !           248:    They are always in the same basic block as this insn.  */
        !           249: #define LOG_LINKS(INSN)                ((INSN)->fld[5].rtx)
        !           250: 
        !           251: /* 1 if insn has been deleted.  */
        !           252: #define INSN_DELETED_P(INSN) ((INSN)->volatil)
        !           253: 
        !           254: /* 1 if insn is a call to a const function.  */
        !           255: #define CONST_CALL_P(INSN) ((INSN)->unchanging)
        !           256: 
        !           257: /* 1 if insn is a branch that should not unconditionally execute its
        !           258:    delay slots, i.e., it is an annulled branch.   */
        !           259: #define INSN_ANNULLED_BRANCH_P(INSN) ((INSN)->unchanging)
        !           260: 
        !           261: /* 1 if insn is in a delay slot and is from the target of the branch.  If
        !           262:    the branch insn has INSN_ANNULLED_BRANCH_P set, this insn should only be
        !           263:    executed if the branch is taken.  For annulled branches with this bit
        !           264:    clear, the insn should be executed only if the branch is not taken.  */
        !           265: #define INSN_FROM_TARGET_P(INSN) ((INSN)->in_struct)
        !           266: 
        !           267: /* Holds a list of notes on what this insn does to various REGs.
        !           268:    It is a chain of EXPR_LIST rtx's, where the second operand
        !           269:    is the chain pointer and the first operand is the REG being described.
        !           270:    The mode field of the EXPR_LIST contains not a real machine mode
        !           271:    but a value that says what this note says about the REG:
        !           272:      REG_DEAD means that the value in REG dies in this insn (i.e., it is
        !           273:    not needed past this insn).  If REG is set in this insn, the REG_DEAD
        !           274:    note may, but need not, be omitted.
        !           275:      REG_INC means that the REG is autoincremented or autodecremented.
        !           276:      REG_EQUIV describes the insn as a whole; it says that the
        !           277:    insn sets a register to a constant value or to be equivalent to
        !           278:    a memory address.  If the
        !           279:    register is spilled to the stack then the constant value
        !           280:    should be substituted for it.  The contents of the REG_EQUIV
        !           281:    is the constant value or memory address, which may be different
        !           282:    from the source of the SET although it has the same value. 
        !           283:      REG_EQUAL is like REG_EQUIV except that the destination
        !           284:    is only momentarily equal to the specified rtx.  Therefore, it
        !           285:    cannot be used for substitution; but it can be used for cse.
        !           286:      REG_RETVAL means that this insn copies the return-value of
        !           287:    a library call out of the hard reg for return values.  This note
        !           288:    is actually an INSN_LIST and it points to the first insn involved
        !           289:    in setting up arguments for the call.  flow.c uses this to delete
        !           290:    the entire library call when its result is dead.
        !           291:      REG_LIBCALL is the inverse of REG_RETVAL: it goes on the first insn
        !           292:    of the library call and points at the one that has the REG_RETVAL.
        !           293:      REG_WAS_0 says that the register set in this insn held 0 before the insn.
        !           294:    The contents of the note is the insn that stored the 0.
        !           295:    If that insn is deleted or patched to a NOTE, the REG_WAS_0 is inoperative.
        !           296:    The REG_WAS_0 note is actually an INSN_LIST, not an EXPR_LIST.
        !           297:      REG_NONNEG means that the register is always nonnegative during
        !           298:    the containing loop.  This is used in branches so that decrement and
        !           299:    branch instructions terminating on zero can be matched.  There must be
        !           300:    an insn pattern in the md file named `decrement_and_branch_until_zero'
        !           301:    or else this will never be added to any instructions.
        !           302:      REG_NO_CONFLICT means there is no conflict *after this insn*
        !           303:    between the register in the note and the destination of this insn.
        !           304:      REG_UNUSED identifies a register set in this insn and never used.
        !           305:      REG_CC_SETTER and REG_CC_USER link a pair of insns that set and use
        !           306:    CC0, respectively.  Normally, these are required to be consecutive insns,
        !           307:    but we permit putting a cc0-setting insn in the delay slot of a branch
        !           308:    as long as only one copy of the insn exists.  In that case, these notes
        !           309:    point from one to the other to allow code generation to determine what
        !           310:    any require information and to properly update CC_STATUS.
        !           311:      REG_LABEL points to a CODE_LABEL.  Used by non-JUMP_INSNs to
        !           312:    say that the CODE_LABEL contained in the REG_LABEL note is used
        !           313:    by the insn.
        !           314:      REG_DEP_ANTI is used in LOG_LINKS which represent anti (write after read)
        !           315:    dependencies.  REG_DEP_OUTPUT is used in LOG_LINKS which represent output
        !           316:    (write after write) dependencies.  Data dependencies, which are the only
        !           317:    type of LOG_LINK created by flow, are represented by a 0 reg note kind.  */
        !           318: 
        !           319: #define REG_NOTES(INSN)        ((INSN)->fld[6].rtx)
        !           320: 
        !           321: /* Don't forget to change reg_note_name in rtl.c.  */
        !           322: enum reg_note { REG_DEAD = 1, REG_INC = 2, REG_EQUIV = 3, REG_WAS_0 = 4,
        !           323:                REG_EQUAL = 5, REG_RETVAL = 6, REG_LIBCALL = 7,
        !           324:                REG_NONNEG = 8, REG_NO_CONFLICT = 9, REG_UNUSED = 10,
        !           325:                REG_CC_SETTER = 11, REG_CC_USER = 12, REG_LABEL = 13,
        !           326:                REG_DEP_ANTI = 14, REG_DEP_OUTPUT = 15 };
        !           327: 
        !           328: /* Define macros to extract and insert the reg-note kind in an EXPR_LIST.  */
        !           329: #define REG_NOTE_KIND(LINK) ((enum reg_note) GET_MODE (LINK))
        !           330: #define PUT_REG_NOTE_KIND(LINK,KIND) PUT_MODE(LINK, (enum machine_mode) (KIND))
        !           331: 
        !           332: /* Names for REG_NOTE's in EXPR_LIST insn's.  */
        !           333: 
        !           334: extern char *reg_note_name[];
        !           335: #define GET_REG_NOTE_NAME(MODE) (reg_note_name[(int)(MODE)])
        !           336: 
        !           337: /* The label-number of a code-label.  The assembler label
        !           338:    is made from `L' and the label-number printed in decimal.
        !           339:    Label numbers are unique in a compilation.  */
        !           340: #define CODE_LABEL_NUMBER(INSN)        ((INSN)->fld[3].rtint)
        !           341: 
        !           342: #define LINE_NUMBER NOTE
        !           343: 
        !           344: /* In a NOTE that is a line number, this is a string for the file name
        !           345:    that the line is in.  We use the same field to record block numbers
        !           346:    temporarily in NOTE_INSN_BLOCK_BEG and NOTE_INSN_BLOCK_END notes.
        !           347:    (We avoid lots of casts between ints and pointers if we use a
        !           348:    different macro for the bock number.)  */
        !           349: 
        !           350: #define NOTE_SOURCE_FILE(INSN)  ((INSN)->fld[3].rtstr)
        !           351: #define NOTE_BLOCK_NUMBER(INSN) ((INSN)->fld[3].rtint)
        !           352: 
        !           353: /* In a NOTE that is a line number, this is the line number.
        !           354:    Other kinds of NOTEs are identified by negative numbers here.  */
        !           355: #define NOTE_LINE_NUMBER(INSN) ((INSN)->fld[4].rtint)
        !           356: 
        !           357: /* Codes that appear in the NOTE_LINE_NUMBER field
        !           358:    for kinds of notes that are not line numbers.
        !           359: 
        !           360:    Notice that we do not try to use zero here for any of
        !           361:    the special note codes because sometimes the source line
        !           362:    actually can be zero!  This happens (for example) when we
        !           363:    are generating code for the per-translation-unit constructor
        !           364:    and destructor routines for some C++ translation unit.
        !           365: 
        !           366:    If you should change any of the following values, or if you
        !           367:    should add a new value here, don't forget to change the
        !           368:    note_insn_name array in rtl.c.  */
        !           369: 
        !           370: /* This note is used to get rid of an insn
        !           371:    when it isn't safe to patch the insn out of the chain.  */
        !           372: #define NOTE_INSN_DELETED -1
        !           373: #define NOTE_INSN_BLOCK_BEG -2
        !           374: #define NOTE_INSN_BLOCK_END -3
        !           375: #define NOTE_INSN_LOOP_BEG -4
        !           376: #define NOTE_INSN_LOOP_END -5
        !           377: /* This kind of note is generated at the end of the function body,
        !           378:    just before the return insn or return label.
        !           379:    In an optimizing compilation it is deleted by the first jump optimization,
        !           380:    after enabling that optimizer to determine whether control can fall
        !           381:    off the end of the function body without a return statement.  */
        !           382: #define NOTE_INSN_FUNCTION_END -6
        !           383: /* This kind of note is generated just after each call to `setjmp', et al.  */
        !           384: #define NOTE_INSN_SETJMP -7
        !           385: /* Generated at the place in a loop that `continue' jumps to.  */
        !           386: #define NOTE_INSN_LOOP_CONT -8
        !           387: /* Generated at the start of a duplicated exit test.  */
        !           388: #define NOTE_INSN_LOOP_VTOP -9
        !           389: /* This marks the point immediately after the last prologue insn.  */
        !           390: #define NOTE_INSN_PROLOGUE_END -10
        !           391: /* This marks the point immediately prior to the first epilogue insn.  */
        !           392: #define NOTE_INSN_EPILOGUE_BEG -11
        !           393: /* Generated in place of user-declared labels when they are deleted.  */
        !           394: #define NOTE_INSN_DELETED_LABEL -12
        !           395: /* This note indicates the start of the real body of the function,
        !           396:    i.e. the point just after all of the parms have been moved into
        !           397:    their homes, etc.  */
        !           398: #define NOTE_INSN_FUNCTION_BEG -13
        !           399: 
        !           400: 
        !           401: #if 0 /* These are not used, and I don't know what they were for. --rms.  */
        !           402: #define NOTE_DECL_NAME(INSN) ((INSN)->fld[3].rtstr)
        !           403: #define NOTE_DECL_CODE(INSN) ((INSN)->fld[4].rtint)
        !           404: #define NOTE_DECL_RTL(INSN) ((INSN)->fld[5].rtx)
        !           405: #define NOTE_DECL_IDENTIFIER(INSN) ((INSN)->fld[6].rtint)
        !           406: #define NOTE_DECL_TYPE(INSN) ((INSN)->fld[7].rtint)
        !           407: #endif /* 0 */
        !           408: 
        !           409: /* Names for NOTE insn's other than line numbers.  */
        !           410: 
        !           411: extern char *note_insn_name[];
        !           412: #define GET_NOTE_INSN_NAME(NOTE_CODE) (note_insn_name[-(NOTE_CODE)])
        !           413: 
        !           414: /* The name of a label, in case it corresponds to an explicit label
        !           415:    in the input source code.  */
        !           416: #define LABEL_NAME(LABEL) ((LABEL)->fld[4].rtstr)
        !           417: 
        !           418: /* In jump.c, each label contains a count of the number
        !           419:    of LABEL_REFs that point at it, so unused labels can be deleted.  */
        !           420: #define LABEL_NUSES(LABEL) ((LABEL)->fld[5].rtint)
        !           421: 
        !           422: /* The rest is used instead of the above, in a CODE_LABEL,
        !           423:    if bytecode is being output.
        !           424:    We make the slightly klugy assumption that a LABEL has enough slots
        !           425:    to hold these things.  That happens to be true.  */
        !           426: 
        !           427: /* For static or external objects.  */
        !           428: #define BYTECODE_LABEL(X) (XEXP ((X), 0))
        !           429: 
        !           430: /* For goto labels inside bytecode functions.  */
        !           431: #define BYTECODE_BC_LABEL(X) (*(struct bc_label **) &XEXP ((X), 1))
        !           432: 
        !           433: /* In jump.c, each JUMP_INSN can point to a label that it can jump to,
        !           434:    so that if the JUMP_INSN is deleted, the label's LABEL_NUSES can
        !           435:    be decremented and possibly the label can be deleted.  */
        !           436: #define JUMP_LABEL(INSN)   ((INSN)->fld[7].rtx)
        !           437: 
        !           438: /* Once basic blocks are found in flow.c,
        !           439:    each CODE_LABEL starts a chain that goes through
        !           440:    all the LABEL_REFs that jump to that label.
        !           441:    The chain eventually winds up at the CODE_LABEL; it is circular.  */
        !           442: #define LABEL_REFS(LABEL) ((LABEL)->fld[5].rtx)
        !           443: 
        !           444: /* This is the field in the LABEL_REF through which the circular chain
        !           445:    of references to a particular label is linked.
        !           446:    This chain is set up in flow.c.  */
        !           447: 
        !           448: #define LABEL_NEXTREF(REF) ((REF)->fld[1].rtx)
        !           449: 
        !           450: /* Once basic blocks are found in flow.c,
        !           451:    Each LABEL_REF points to its containing instruction with this field.  */
        !           452: 
        !           453: #define CONTAINING_INSN(RTX) ((RTX)->fld[2].rtx)
        !           454: 
        !           455: /* For a REG rtx, REGNO extracts the register number.  */
        !           456: 
        !           457: #define REGNO(RTX) ((RTX)->fld[0].rtint)
        !           458: 
        !           459: /* For a REG rtx, REG_FUNCTION_VALUE_P is nonzero if the reg
        !           460:    is the current function's return value.  */
        !           461: 
        !           462: #define REG_FUNCTION_VALUE_P(RTX) ((RTX)->integrated)
        !           463: 
        !           464: /* 1 in a REG rtx if it corresponds to a variable declared by the user.  */
        !           465: #define REG_USERVAR_P(RTX) ((RTX)->volatil)
        !           466: 
        !           467: /* For a CONST_INT rtx, INTVAL extracts the integer.  */
        !           468: 
        !           469: #define INTVAL(RTX) ((RTX)->fld[0].rtwint)
        !           470: 
        !           471: /* For a SUBREG rtx, SUBREG_REG extracts the value we want a subreg of.
        !           472:    SUBREG_WORD extracts the word-number.  */
        !           473: 
        !           474: #define SUBREG_REG(RTX) ((RTX)->fld[0].rtx)
        !           475: #define SUBREG_WORD(RTX) ((RTX)->fld[1].rtint)
        !           476: 
        !           477: /* 1 if the REG contained in SUBREG_REG is already known to be
        !           478:    sign- or zero-extended from the mode of the SUBREG to the mode of
        !           479:    the reg.  SUBREG_PROMOTED_UNSIGNED_P gives the signedness of the
        !           480:    extension.  
        !           481: 
        !           482:    When used as a LHS, is means that this extension must be done
        !           483:    when assigning to SUBREG_REG.  */
        !           484: 
        !           485: #define SUBREG_PROMOTED_VAR_P(RTX) ((RTX)->in_struct)
        !           486: #define SUBREG_PROMOTED_UNSIGNED_P(RTX) ((RTX)->unchanging)
        !           487: 
        !           488: /* Access various components of an ASM_OPERANDS rtx.  */
        !           489: 
        !           490: #define ASM_OPERANDS_TEMPLATE(RTX) XSTR ((RTX), 0)
        !           491: #define ASM_OPERANDS_OUTPUT_CONSTRAINT(RTX) XSTR ((RTX), 1)
        !           492: #define ASM_OPERANDS_OUTPUT_IDX(RTX) XINT ((RTX), 2)
        !           493: #define ASM_OPERANDS_INPUT_VEC(RTX) XVEC ((RTX), 3)
        !           494: #define ASM_OPERANDS_INPUT_CONSTRAINT_VEC(RTX) XVEC ((RTX), 4)
        !           495: #define ASM_OPERANDS_INPUT(RTX, N) XVECEXP ((RTX), 3, (N))
        !           496: #define ASM_OPERANDS_INPUT_LENGTH(RTX) XVECLEN ((RTX), 3)
        !           497: #define ASM_OPERANDS_INPUT_CONSTRAINT(RTX, N) XSTR (XVECEXP ((RTX), 4, (N)), 0)
        !           498: #define ASM_OPERANDS_INPUT_MODE(RTX, N) GET_MODE (XVECEXP ((RTX), 4, (N)))
        !           499: #define ASM_OPERANDS_SOURCE_FILE(RTX) XSTR ((RTX), 5)
        !           500: #define ASM_OPERANDS_SOURCE_LINE(RTX) XINT ((RTX), 6)
        !           501: 
        !           502: /* For a MEM rtx, 1 if it's a volatile reference.
        !           503:    Also in an ASM_OPERANDS rtx.  */
        !           504: #define MEM_VOLATILE_P(RTX) ((RTX)->volatil)
        !           505: 
        !           506: /* For a MEM rtx, 1 if it refers to a structure or union component.  */
        !           507: #define MEM_IN_STRUCT_P(RTX) ((RTX)->in_struct)
        !           508: 
        !           509: /* For a LABEL_REF, 1 means that this reference is to a label outside the
        !           510:    loop containing the reference.  */
        !           511: #define LABEL_OUTSIDE_LOOP_P(RTX) ((RTX)->in_struct)
        !           512: 
        !           513: /* For a LABEL_REF, 1 means it is for a nonlocal label.  */
        !           514: /* Likewise in an EXPR_LIST for a REG_LABEL note.  */
        !           515: #define LABEL_REF_NONLOCAL_P(RTX) ((RTX)->volatil)
        !           516: 
        !           517: /* For a CODE_LABEL, 1 means always consider this label to be needed.  */
        !           518: #define LABEL_PRESERVE_P(RTX) ((RTX)->in_struct)
        !           519: 
        !           520: /* For a REG, 1 means the register is used only in an exit test of a loop.  */
        !           521: #define REG_LOOP_TEST_P(RTX) ((RTX)->in_struct)
        !           522: 
        !           523: /* During sched, for an insn, 1 means that the insn must be scheduled together
        !           524:    with the preceding insn.  */
        !           525: #define SCHED_GROUP_P(INSN) ((INSN)->in_struct)
        !           526: 
        !           527: /* During sched, for the LOG_LINKS of an insn, these cache the adjusted
        !           528:    cost of the dependence link.  The cost of executing an instruction
        !           529:    may vary based on how the results are used.  LINK_COST_ZERO is 1 when
        !           530:    the cost through the link varies and is unchanged (i.e., the link has
        !           531:    zero additional cost).  LINK_COST_FREE is 1 when the cost through the
        !           532:    link is zero (i.e., the link makes the cost free).  In other cases,
        !           533:    the adjustment to the cost is recomputed each time it is needed.  */
        !           534: #define LINK_COST_ZERO(X) ((X)->jump)
        !           535: #define LINK_COST_FREE(X) ((X)->call)
        !           536: 
        !           537: /* For a SET rtx, SET_DEST is the place that is set
        !           538:    and SET_SRC is the value it is set to.  */
        !           539: #define SET_DEST(RTX) ((RTX)->fld[0].rtx)
        !           540: #define SET_SRC(RTX) ((RTX)->fld[1].rtx)
        !           541: 
        !           542: /* For a TRAP_IF rtx, TRAP_CONDITION is an expression.  */
        !           543: #define TRAP_CONDITION(RTX) ((RTX)->fld[0].rtx)
        !           544: 
        !           545: /* 1 in a SYMBOL_REF if it addresses this function's constants pool.  */
        !           546: #define CONSTANT_POOL_ADDRESS_P(RTX) ((RTX)->unchanging)
        !           547: 
        !           548: /* Flag in a SYMBOL_REF for machine-specific purposes.  */
        !           549: #define SYMBOL_REF_FLAG(RTX) ((RTX)->volatil)
        !           550: 
        !           551: /* 1 means a SYMBOL_REF has been the library function in emit_library_call.  */
        !           552: #define SYMBOL_REF_USED(RTX) ((RTX)->used)
        !           553: 
        !           554: /* For an INLINE_HEADER rtx, FIRST_FUNCTION_INSN is the first insn
        !           555:    of the function that is not involved in copying parameters to
        !           556:    pseudo-registers.  FIRST_PARM_INSN is the very first insn of
        !           557:    the function, including the parameter copying.
        !           558:    We keep this around in case we must splice
        !           559:    this function into the assembly code at the end of the file.
        !           560:    FIRST_LABELNO is the first label number used by the function (inclusive).
        !           561:    LAST_LABELNO is the last label used by the function (exclusive).
        !           562:    MAX_REGNUM is the largest pseudo-register used by that function.
        !           563:    FUNCTION_ARGS_SIZE is the size of the argument block in the stack.
        !           564:    POPS_ARGS is the number of bytes of input arguments popped by the function
        !           565:    STACK_SLOT_LIST is the list of stack slots.
        !           566:    FUNCTION_FLAGS are where single-bit flags are saved.
        !           567:    OUTGOING_ARGS_SIZE is the size of the largest outgoing stack parameter list.
        !           568:    ORIGINAL_ARG_VECTOR is a vector of the original DECL_RTX values
        !           569:     for the function arguments.
        !           570:    ORIGINAL_DECL_INITIAL is a pointer to the original DECL_INITIAL for the
        !           571:     function.
        !           572: 
        !           573:    We want this to lay down like an INSN.  The PREV_INSN field
        !           574:    is always NULL.  The NEXT_INSN field always points to the
        !           575:    first function insn of the function being squirreled away.  */
        !           576: 
        !           577: #define FIRST_FUNCTION_INSN(RTX) ((RTX)->fld[2].rtx)
        !           578: #define FIRST_PARM_INSN(RTX) ((RTX)->fld[3].rtx)
        !           579: #define FIRST_LABELNO(RTX) ((RTX)->fld[4].rtint)
        !           580: #define LAST_LABELNO(RTX) ((RTX)->fld[5].rtint)
        !           581: #define MAX_PARMREG(RTX) ((RTX)->fld[6].rtint)
        !           582: #define MAX_REGNUM(RTX) ((RTX)->fld[7].rtint)
        !           583: #define FUNCTION_ARGS_SIZE(RTX) ((RTX)->fld[8].rtint)
        !           584: #define POPS_ARGS(RTX) ((RTX)->fld[9].rtint)
        !           585: #define STACK_SLOT_LIST(RTX) ((RTX)->fld[10].rtx)
        !           586: #define FUNCTION_FLAGS(RTX) ((RTX)->fld[11].rtint)
        !           587: #define OUTGOING_ARGS_SIZE(RTX) ((RTX)->fld[12].rtint)
        !           588: #define ORIGINAL_ARG_VECTOR(RTX) ((RTX)->fld[13].rtvec)
        !           589: #define ORIGINAL_DECL_INITIAL(RTX) ((RTX)->fld[14].rtx)
        !           590: 
        !           591: /* In FUNCTION_FLAGS we save some variables computed when emitting the code
        !           592:    for the function and which must be `or'ed into the current flag values when
        !           593:    insns from that function are being inlined.  */
        !           594: 
        !           595: /* These ought to be an enum, but non-ANSI compilers don't like that.  */
        !           596: #define FUNCTION_FLAGS_CALLS_ALLOCA 01
        !           597: #define FUNCTION_FLAGS_CALLS_SETJMP 02
        !           598: #define FUNCTION_FLAGS_RETURNS_STRUCT 04
        !           599: #define FUNCTION_FLAGS_RETURNS_PCC_STRUCT 010
        !           600: #define FUNCTION_FLAGS_NEEDS_CONTEXT 020
        !           601: #define FUNCTION_FLAGS_HAS_NONLOCAL_LABEL 040
        !           602: #define FUNCTION_FLAGS_RETURNS_POINTER 0100
        !           603: #define FUNCTION_FLAGS_USES_CONST_POOL 0200
        !           604: #define FUNCTION_FLAGS_CALLS_LONGJMP 0400
        !           605: #define FUNCTION_FLAGS_USES_PIC_OFFSET_TABLE 01000
        !           606: 
        !           607: /* Define a macro to look for REG_INC notes,
        !           608:    but save time on machines where they never exist.  */
        !           609: 
        !           610: /* Don't continue this line--convex cc version 4.1 would lose.  */
        !           611: #if (defined (HAVE_PRE_INCREMENT) || defined (HAVE_PRE_DECREMENT) || defined (HAVE_POST_INCREMENT) || defined (HAVE_POST_DECREMENT))
        !           612: #define FIND_REG_INC_NOTE(insn, reg) (find_reg_note ((insn), REG_INC, (reg)))
        !           613: #else
        !           614: #define FIND_REG_INC_NOTE(insn, reg) 0
        !           615: #endif
        !           616: 
        !           617: /* Indicate whether the machine has any sort of auto increment addressing.
        !           618:    If not, we can avoid checking for REG_INC notes.  */
        !           619: 
        !           620: /* Don't continue this line--convex cc version 4.1 would lose.  */
        !           621: #if (defined (HAVE_PRE_INCREMENT) || defined (HAVE_PRE_DECREMENT) || defined (HAVE_POST_INCREMENT) || defined (HAVE_POST_DECREMENT))
        !           622: #define AUTO_INC_DEC
        !           623: #endif
        !           624: 
        !           625: /* Generally useful functions.  */
        !           626: 
        !           627: /* The following functions accept a wide integer argument.  Rather than
        !           628:    having to cast on every function call, we use a macro instead, that is
        !           629:    defined here and in tree.h.  */
        !           630: 
        !           631: #ifndef exact_log2
        !           632: #define exact_log2(N) exact_log2_wide ((HOST_WIDE_INT) (N))
        !           633: #define floor_log2(N) floor_log2_wide ((HOST_WIDE_INT) (N))
        !           634: #endif
        !           635: 
        !           636: #define plus_constant(X,C) plus_constant_wide (X, (HOST_WIDE_INT) (C))
        !           637: 
        !           638: #define plus_constant_for_output(X,C)  \
        !           639:   plus_constant_for_output_wide (X, (HOST_WIDE_INT) (C))
        !           640: 
        !           641: extern rtx plus_constant_wide           PROTO((rtx, HOST_WIDE_INT));
        !           642: extern rtx plus_constant_for_output_wide PROTO((rtx, HOST_WIDE_INT));
        !           643: 
        !           644: #define GEN_INT(N) gen_rtx (CONST_INT, VOIDmode, (HOST_WIDE_INT) (N))
        !           645: 
        !           646: #if 0
        !           647: /* We cannot define prototypes for the variable argument functions,
        !           648:    since they have not been ANSI-fied, and an ANSI compiler would
        !           649:    complain when compiling the definition of these functions.  */
        !           650: 
        !           651: extern rtx gen_rtx                     PROTO((enum rtx_code, enum machine_mode, ...));
        !           652: extern rtvec gen_rtvec                 PROTO((int, ...));
        !           653: 
        !           654: #else
        !           655: extern rtx bc_gen_rtx ();
        !           656: extern rtx gen_rtx ();
        !           657: extern rtvec gen_rtvec ();
        !           658: #endif
        !           659: 
        !           660: #ifdef BUFSIZ                  /* stdio.h has been included */
        !           661: extern rtx read_rtx                    PROTO((FILE *));
        !           662: #else
        !           663: extern rtx read_rtx ();
        !           664: #endif
        !           665: 
        !           666: #if 0
        !           667: /* At present, don't prototype xrealloc, since all of the callers don't
        !           668:    cast their pointers to char *, and all of the xrealloc's don't use
        !           669:    void * yet.  */
        !           670: extern char *xmalloc                   PROTO((size_t));
        !           671: extern char *xrealloc                  PROTO((void *, size_t));
        !           672: #else
        !           673: extern char *xmalloc ();
        !           674: extern char *xrealloc ();
        !           675: #endif
        !           676: 
        !           677: extern char *oballoc                   PROTO((int));
        !           678: extern char *permalloc                 PROTO((int));
        !           679: extern void free                       PROTO((void *));
        !           680: extern rtx rtx_alloc                   PROTO((RTX_CODE));
        !           681: extern rtvec rtvec_alloc               PROTO((int));
        !           682: extern rtx find_reg_note               PROTO((rtx, enum reg_note, rtx));
        !           683: extern rtx find_regno_note             PROTO((rtx, enum reg_note, int));
        !           684: extern HOST_WIDE_INT get_integer_term  PROTO((rtx));
        !           685: extern rtx get_related_value           PROTO((rtx));
        !           686: extern rtx single_set                  PROTO((rtx));
        !           687: extern rtx find_last_value             PROTO((rtx, rtx *, rtx));
        !           688: extern rtx copy_rtx                    PROTO((rtx));
        !           689: extern rtx copy_rtx_if_shared          PROTO((rtx));
        !           690: extern rtx copy_most_rtx               PROTO((rtx, rtx));
        !           691: extern rtx replace_rtx                 PROTO((rtx, rtx, rtx));
        !           692: extern rtvec gen_rtvec_v               PROTO((int, rtx *));
        !           693: extern rtx gen_reg_rtx                 PROTO((enum machine_mode));
        !           694: extern rtx gen_label_rtx               PROTO((void));
        !           695: extern rtx gen_inline_header_rtx       PROTO((rtx, rtx, int, int, int, int, int, int, rtx, int, int, rtvec, rtx));
        !           696: extern rtx gen_lowpart_common          PROTO((enum machine_mode, rtx));
        !           697: extern rtx gen_lowpart                 PROTO((enum machine_mode, rtx));
        !           698: extern rtx gen_lowpart_if_possible     PROTO((enum machine_mode, rtx));
        !           699: extern rtx gen_highpart                        PROTO((enum machine_mode, rtx));
        !           700: extern rtx gen_realpart                        PROTO((enum machine_mode, rtx));
        !           701: extern rtx gen_imagpart                        PROTO((enum machine_mode, rtx));
        !           702: extern rtx operand_subword             PROTO((rtx, int, int, enum machine_mode));
        !           703: extern rtx operand_subword_force       PROTO((rtx, int, enum machine_mode));
        !           704: extern int subreg_lowpart_p            PROTO((rtx));
        !           705: extern rtx make_safe_from              PROTO((rtx, rtx));
        !           706: extern rtx memory_address              PROTO((enum machine_mode, rtx));
        !           707: extern rtx get_insns                   PROTO((void));
        !           708: extern rtx get_last_insn               PROTO((void));
        !           709: extern rtx get_last_insn_anywhere      PROTO((void));
        !           710: extern void start_sequence             PROTO((void));
        !           711: extern void push_to_sequence           PROTO((rtx));
        !           712: extern void end_sequence               PROTO((void));
        !           713: extern rtx gen_sequence                        PROTO((void));
        !           714: extern rtx immed_double_const          PROTO((HOST_WIDE_INT, HOST_WIDE_INT, enum machine_mode));
        !           715: extern rtx force_const_mem             PROTO((enum machine_mode, rtx));
        !           716: extern rtx force_reg                   PROTO((enum machine_mode, rtx));
        !           717: extern rtx get_pool_constant           PROTO((rtx));
        !           718: extern enum machine_mode get_pool_mode PROTO((rtx));
        !           719: extern int get_pool_offset             PROTO((rtx));
        !           720: extern rtx simplify_subtraction                PROTO((rtx));
        !           721: extern rtx assign_stack_local          PROTO((enum machine_mode, int, int));
        !           722: extern rtx assign_stack_temp           PROTO((enum machine_mode, int, int));
        !           723: extern rtx protect_from_queue          PROTO((rtx, int));
        !           724: extern void emit_queue                 PROTO((void));
        !           725: extern rtx emit_move_insn              PROTO((rtx, rtx));
        !           726: extern rtx emit_insn_before            PROTO((rtx, rtx));
        !           727: extern rtx emit_jump_insn_before       PROTO((rtx, rtx));
        !           728: extern rtx emit_call_insn_before       PROTO((rtx, rtx));
        !           729: extern rtx emit_barrier_before         PROTO((rtx));
        !           730: extern rtx emit_note_before            PROTO((int, rtx));
        !           731: extern rtx emit_insn_after             PROTO((rtx, rtx));
        !           732: extern rtx emit_jump_insn_after                PROTO((rtx, rtx));
        !           733: extern rtx emit_barrier_after          PROTO((rtx));
        !           734: extern rtx emit_label_after            PROTO((rtx, rtx));
        !           735: extern rtx emit_note_after             PROTO((int, rtx));
        !           736: extern rtx emit_line_note_after                PROTO((char *, int, rtx));
        !           737: extern rtx emit_insn                   PROTO((rtx));
        !           738: extern rtx emit_insns                  PROTO((rtx));
        !           739: extern rtx emit_insns_before           PROTO((rtx, rtx));
        !           740: extern rtx emit_jump_insn              PROTO((rtx));
        !           741: extern rtx emit_call_insn              PROTO((rtx));
        !           742: extern rtx emit_label                  PROTO((rtx));
        !           743: extern rtx emit_barrier                        PROTO((void));
        !           744: extern rtx emit_line_note              PROTO((char *, int));
        !           745: extern rtx emit_note                   PROTO((char *, int));
        !           746: extern rtx emit_line_note_force                PROTO((char *, int));
        !           747: extern rtx make_insn_raw               PROTO((rtx));
        !           748: extern rtx previous_insn               PROTO((rtx));
        !           749: extern rtx next_insn                   PROTO((rtx));
        !           750: extern rtx prev_nonnote_insn           PROTO((rtx));
        !           751: extern rtx next_nonnote_insn           PROTO((rtx));
        !           752: extern rtx prev_real_insn              PROTO((rtx));
        !           753: extern rtx next_real_insn              PROTO((rtx));
        !           754: extern rtx prev_active_insn            PROTO((rtx));
        !           755: extern rtx next_active_insn            PROTO((rtx));
        !           756: extern rtx prev_label                  PROTO((rtx));
        !           757: extern rtx next_label                  PROTO((rtx));
        !           758: extern rtx next_cc0_user               PROTO((rtx));
        !           759: extern rtx prev_cc0_setter             PROTO((rtx));
        !           760: extern rtx reg_set_last                        PROTO((rtx, rtx));
        !           761: extern rtx next_nondeleted_insn                PROTO((rtx));
        !           762: extern enum rtx_code reverse_condition PROTO((enum rtx_code));
        !           763: extern enum rtx_code swap_condition    PROTO((enum rtx_code));
        !           764: extern enum rtx_code unsigned_condition        PROTO((enum rtx_code));
        !           765: extern enum rtx_code signed_condition  PROTO((enum rtx_code));
        !           766: extern rtx find_equiv_reg              PROTO((rtx, rtx, enum reg_class, int, short *, int, enum machine_mode));
        !           767: extern rtx squeeze_notes               PROTO((rtx, rtx));
        !           768: extern rtx delete_insn                 PROTO((rtx));
        !           769: extern void delete_jump                        PROTO((rtx));
        !           770: extern rtx get_label_before            PROTO((rtx));
        !           771: extern rtx get_label_after             PROTO((rtx));
        !           772: extern rtx follow_jumps                        PROTO((rtx));
        !           773: extern rtx adj_offsettable_operand     PROTO((rtx, int));
        !           774: extern rtx try_split                   PROTO((rtx, rtx, int));
        !           775: extern rtx split_insns                 PROTO((rtx, rtx));
        !           776: extern rtx simplify_unary_operation    PROTO((enum rtx_code, enum machine_mode, rtx, enum machine_mode));
        !           777: extern rtx simplify_binary_operation   PROTO((enum rtx_code, enum machine_mode, rtx, rtx));
        !           778: extern rtx simplify_ternary_operation  PROTO((enum rtx_code, enum machine_mode, enum machine_mode, rtx, rtx, rtx));
        !           779: extern rtx simplify_relational_operation PROTO((enum rtx_code, enum machine_mode, rtx, rtx));
        !           780: extern rtx nonlocal_label_rtx_list     PROTO((void));
        !           781: extern rtx gen_move_insn               PROTO((rtx, rtx));
        !           782: extern rtx gen_jump                    PROTO((rtx));
        !           783: extern rtx gen_beq                     PROTO((rtx));
        !           784: extern rtx gen_bge                     PROTO((rtx));
        !           785: extern rtx gen_ble                     PROTO((rtx));
        !           786: extern rtx eliminate_constant_term     PROTO((rtx, rtx *));
        !           787: extern rtx expand_complex_abs          PROTO((enum machine_mode, rtx, rtx, int));
        !           788: 
        !           789: /* Maximum number of parallel sets and clobbers in any insn in this fn.
        !           790:    Always at least 3, since the combiner could put that many togetherm
        !           791:    and we want this to remain correct for all the remaining passes.  */
        !           792: 
        !           793: extern int max_parallel;
        !           794: 
        !           795: extern int asm_noperands               PROTO((rtx));
        !           796: extern char *decode_asm_operands       PROTO((rtx, rtx *, rtx **, char **, enum machine_mode *));
        !           797: 
        !           798: extern enum reg_class reg_preferred_class PROTO((int));
        !           799: extern enum reg_class reg_alternate_class PROTO((int));
        !           800: 
        !           801: extern rtx get_first_nonparm_insn      PROTO((void));
        !           802: 
        !           803: /* Standard pieces of rtx, to be substituted directly into things.  */
        !           804: extern rtx pc_rtx;
        !           805: extern rtx cc0_rtx;
        !           806: extern rtx const0_rtx;
        !           807: extern rtx const1_rtx;
        !           808: extern rtx const2_rtx;
        !           809: extern rtx constm1_rtx;
        !           810: extern rtx const_true_rtx;
        !           811: 
        !           812: extern rtx const_tiny_rtx[3][(int) MAX_MACHINE_MODE];
        !           813: 
        !           814: /* Returns a constant 0 rtx in mode MODE.  Integer modes are treated the 
        !           815:    same as VOIDmode.  */
        !           816: 
        !           817: #define CONST0_RTX(MODE) (const_tiny_rtx[0][(int) (MODE)])
        !           818: 
        !           819: /* Likewise, for the constants 1 and 2.  */
        !           820: 
        !           821: #define CONST1_RTX(MODE) (const_tiny_rtx[1][(int) (MODE)])
        !           822: #define CONST2_RTX(MODE) (const_tiny_rtx[2][(int) (MODE)])
        !           823: 
        !           824: /* All references to certain hard regs, except those created
        !           825:    by allocating pseudo regs into them (when that's possible),
        !           826:    go through these unique rtx objects.  */
        !           827: extern rtx stack_pointer_rtx;
        !           828: extern rtx frame_pointer_rtx;
        !           829: extern rtx hard_frame_pointer_rtx;
        !           830: extern rtx arg_pointer_rtx;
        !           831: extern rtx pic_offset_table_rtx;
        !           832: extern rtx struct_value_rtx;
        !           833: extern rtx struct_value_incoming_rtx;
        !           834: extern rtx static_chain_rtx;
        !           835: extern rtx static_chain_incoming_rtx;
        !           836: 
        !           837: /* If HARD_FRAME_POINTER_REGNUM is defined, then a special dummy reg
        !           838:    is used to represent the frame pointer.  This is because the
        !           839:    hard frame pointer and the automatic variables are separated by an amount
        !           840:    that cannot be determined until after register allocation.  We can assume
        !           841:    that in this case ELIMINABLE_REGS will be defined, one action of which
        !           842:    will be to eliminate FRAME_POINTER_REGNUM into HARD_FRAME_POINTER_REGNUM. */
        !           843: #ifndef HARD_FRAME_POINTER_REGNUM
        !           844: #define HARD_FRAME_POINTER_REGNUM FRAME_POINTER_REGNUM
        !           845: #endif
        !           846: 
        !           847: /* Virtual registers are used during RTL generation to refer to locations into
        !           848:    the stack frame when the actual location isn't known until RTL generation
        !           849:    is complete.  The routine instantiate_virtual_regs replaces these with
        !           850:    the proper value, which is normally {frame,arg,stack}_pointer_rtx plus
        !           851:    a constant.  */
        !           852: 
        !           853: #define FIRST_VIRTUAL_REGISTER (FIRST_PSEUDO_REGISTER)
        !           854: 
        !           855: /* This points to the first word of the incoming arguments passed on the stack,
        !           856:    either by the caller or by the callee when pretending it was passed by the
        !           857:    caller.  */
        !           858: 
        !           859: extern rtx virtual_incoming_args_rtx;
        !           860: 
        !           861: #define VIRTUAL_INCOMING_ARGS_REGNUM   (FIRST_VIRTUAL_REGISTER)
        !           862: 
        !           863: /* If FRAME_GROWS_DOWNWARD, this points to immediately above the first
        !           864:    variable on the stack.  Otherwise, it points to the first variable on
        !           865:    the stack.  */
        !           866: 
        !           867: extern rtx virtual_stack_vars_rtx;
        !           868: 
        !           869: #define VIRTUAL_STACK_VARS_REGNUM      ((FIRST_VIRTUAL_REGISTER) + 1)
        !           870: 
        !           871: /* This points to the location of dynamically-allocated memory on the stack
        !           872:    immediately after the stack pointer has been adjusted by the amount
        !           873:    desired.  */
        !           874: 
        !           875: extern rtx virtual_stack_dynamic_rtx;
        !           876: 
        !           877: #define VIRTUAL_STACK_DYNAMIC_REGNUM   ((FIRST_VIRTUAL_REGISTER) + 2)
        !           878: 
        !           879: /* This points to the location in the stack at which outgoing arguments should
        !           880:    be written when the stack is pre-pushed (arguments pushed using push
        !           881:    insns always use sp).  */
        !           882: 
        !           883: extern rtx virtual_outgoing_args_rtx;
        !           884: 
        !           885: #define VIRTUAL_OUTGOING_ARGS_REGNUM   ((FIRST_VIRTUAL_REGISTER) + 3)
        !           886: 
        !           887: #define LAST_VIRTUAL_REGISTER  ((FIRST_VIRTUAL_REGISTER) + 3)
        !           888: 
        !           889: extern rtx find_next_ref               PROTO((rtx, rtx));
        !           890: extern rtx *find_single_use            PROTO((rtx, rtx, rtx *));
        !           891: 
        !           892: /* It is hard to write the prototype for expand_expr, since it needs
        !           893:    expr.h to be included for the enumeration.  */
        !           894: 
        !           895: extern rtx expand_expr ();
        !           896: extern rtx immed_real_const_1();
        !           897: 
        !           898: #ifdef TREE_CODE
        !           899: /* rtl.h and tree.h were included.  */
        !           900: extern rtx  output_constant_def PROTO((tree));
        !           901: extern rtx  immed_real_const   PROTO((tree));
        !           902: extern rtx  immed_real_const_1 PROTO((REAL_VALUE_TYPE, enum machine_mode));
        !           903: extern tree make_tree          PROTO((tree, rtx));
        !           904: 
        !           905: #else
        !           906: extern rtx output_constant_def ();
        !           907: extern rtx immed_real_const ();
        !           908: extern rtx immed_real_const_1 ();
        !           909: #endif
        !           910: 
        !           911: /* Define a default value for STORE_FLAG_VALUE.  */
        !           912: 
        !           913: #ifndef STORE_FLAG_VALUE
        !           914: #define STORE_FLAG_VALUE 1
        !           915: #endif
        !           916: 
        !           917: /* Nonzero after end of reload pass.
        !           918:    Set to 1 or 0 by toplev.c.  */
        !           919: 
        !           920: extern int reload_completed;
        !           921: 
        !           922: /* Set to 1 while reload_as_needed is operating.
        !           923:    Required by some machines to handle any generated moves differently.  */
        !           924: 
        !           925: extern int reload_in_progress;
        !           926: 
        !           927: /* If this is nonzero, we do not bother generating VOLATILE
        !           928:    around volatile memory references, and we are willing to
        !           929:    output indirect addresses.  If cse is to follow, we reject
        !           930:    indirect addresses so a useful potential cse is generated;
        !           931:    if it is used only once, instruction combination will produce
        !           932:    the same indirect address eventually.  */
        !           933: extern int cse_not_expected;
        !           934: 
        !           935: /* Indexed by pseudo register number, gives the rtx for that pseudo.
        !           936:    Allocated in parallel with regno_pointer_flag.  */
        !           937: extern rtx *regno_reg_rtx;
        !           938: 
        !           939: /* Translates rtx code to tree code, for those codes needed by
        !           940:    REAL_ARITHMETIC.  */
        !           941: extern int rtx_to_tree_code ();

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