Annotation of gcc/rtl.def, revision 1.1.1.2

1.1       root        1: /* This file contains the definitions and documentation for the
                      2:    Register Transfer Expressions (rtx's) that make up the
                      3:    Register Transfer Language (rtl) used in the Back End of the GNU compiler.
                      4:    Copyright (C) 1987-1991 Free Software Foundation, Inc.
                      5: 
                      6: This file is part of GNU CC.
                      7: 
                      8: GNU CC is free software; you can redistribute it and/or modify
                      9: it under the terms of the GNU General Public License as published by
                     10: the Free Software Foundation; either version 2, or (at your option)
                     11: any later version.
                     12: 
                     13: GNU CC is distributed in the hope that it will be useful,
                     14: but WITHOUT ANY WARRANTY; without even the implied warranty of
                     15: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
                     16: GNU General Public License for more details.
                     17: 
                     18: You should have received a copy of the GNU General Public License
                     19: along with GNU CC; see the file COPYING.  If not, write to
                     20: the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
                     21: 
                     22: 
                     23: /* Expression definitions and descriptions for all targets are in this file.
                     24:    Some will not be used for some targets.
                     25: 
                     26:    The fields in the cpp macro call "DEF_RTL_EXPR()"
                     27:    are used to create declarations in the C source of the compiler.
                     28: 
                     29:    The fields are:
                     30: 
                     31:    1.  The internal name of the rtx used in the C source.
                     32:    It is a tag in the enumeration "enum rtx_code" defined in "rtl.h".
                     33:    By convention these are in UPPER_CASE.
                     34: 
                     35:    2.  The name of the rtx in the external ASCII format read by
                     36:    read_rtx(), and printed by print_rtx().
                     37:    These names are stored in rtx_name[].
                     38:    By convention these are the internal (field 1) names in lower_case.
                     39: 
                     40:    3.  The print format, and type of each rtx->fld[] (field) in this rtx.
                     41:    These formats are stored in rtx_format[].
                     42:    The meaning of the formats is documented in front of this array in rtl.c
                     43:    
                     44:    4.  The class of the rtx.  These are stored in rtx_class and are accessed
                     45:    via the GET_RTX_CLASS macro.  They are defined as follows:
                     46: 
                     47:      "o" an rtx code that can be used to represent an object (e.g, REG, MEM)
                     48:      "<" an rtx code for a comparison (e.g, EQ, NE, LT)
                     49:      "1" an rtx code for a unary arithmetic expression (e.g, NEG, NOT)
                     50:      "c" an rtx code for a commutative binary operation (e.g,, PLUS, MULT)
                     51:      "3" an rtx code for a non-bitfield three input operation (IF_THEN_ELSE)
                     52:      "2" an rtx code for a non-commutative binary operation (e.g., MINUS, DIV)
                     53:      "b" an rtx code for a bit-field operation (ZERO_EXTRACT, SIGN_EXTRACT)
                     54:      "i" an rtx code for a machine insn (INSN, JUMP_INSN, CALL_INSN)
                     55:      "m" an rtx code for something that matches in insns (e.g, MATCH_DUP)
                     56:      "x" everything else
                     57:      
                     58:    */
                     59: 
                     60: /* ---------------------------------------------------------------------
                     61:    Expressions (and "meta" expressions) used for structuring the
                     62:    rtl representation of a program.
                     63:    --------------------------------------------------------------------- */
                     64: 
                     65: /* an expression code name unknown to the reader */
                     66: DEF_RTL_EXPR(UNKNOWN, "UnKnown", "*", 'x')
                     67: 
                     68: /* (NIL) is used by rtl reader and printer to represent a null pointer.  */
                     69: 
                     70: DEF_RTL_EXPR(NIL, "nil", "*", 'x')
                     71: 
                     72: /* ---------------------------------------------------------------------
                     73:    Expressions used in constructing lists.
                     74:    --------------------------------------------------------------------- */
                     75: 
                     76: /* a linked list of expressions */
                     77: DEF_RTL_EXPR(EXPR_LIST, "expr_list", "ee", 'x')
                     78: 
                     79: /* a linked list of instructions.
                     80:    The insns are represented in print by their uids.  */
                     81: DEF_RTL_EXPR(INSN_LIST, "insn_list", "ue", 'x')
                     82: 
                     83: /* ----------------------------------------------------------------------
1.1.1.2 ! root       84:    Expression types for machine descriptions.
1.1       root       85:    These do not appear in actual rtl code in the compiler.
                     86:    ---------------------------------------------------------------------- */
                     87: 
                     88: /* Appears only in machine descriptions.
                     89:    Means use the function named by the second arg (the string)
                     90:    as a predicate; if matched, store the structure that was matched
                     91:    in the operand table at index specified by the first arg (the integer).
                     92:    If the second arg is the null string, the structure is just stored.
                     93: 
                     94:    A third string argument indicates to the register allocator restrictions
                     95:    on where the operand can be allocated.
                     96: 
                     97:    If the target needs no restriction on any instruction this field should
                     98:    be the null string.
                     99: 
                    100:    The string is prepended by:
                    101:    '=' to indicate the operand is only written to.
                    102:    '+' to indicate the operand is both read and written to.
                    103: 
                    104:    Each character in the string represents an allocatable class for an operand.
                    105:    'g' indicates the operand can be any valid class.
                    106:    'i' indicates the operand can be immediate (in the instruction) data.
                    107:    'r' indicates the operand can be in a register.
                    108:    'm' indicates the operand can be in memory.
                    109:    'o' a subset of the 'm' class.  Those memory addressing modes that
                    110:        can be offset at compile time (have a constant added to them).
                    111: 
                    112:    Other characters indicate target dependent operand classes and
                    113:    are described in each target's machine description.
                    114: 
                    115:    For instructions with more than one operand, sets of classes can be
                    116:    separated by a comma to indicate the appropriate multi-operand constraints.
                    117:    There must be a 1 to 1 correspondence between these sets of classes in
                    118:    all operands for an instruction.
                    119:    */
                    120: DEF_RTL_EXPR(MATCH_OPERAND, "match_operand", "iss", 'm')
                    121: 
                    122: /* Appears only in machine descriptions.
                    123:    Means match a SCRATCH or a register.  When used to generate rtl, a
                    124:    SCRATCH is generated.  As for MATCH_OPERAND, the mode specifies
                    125:    the desired mode and the first argument is the operand number.
                    126:    The second argument is the constraint.  */
                    127: DEF_RTL_EXPR(MATCH_SCRATCH, "match_scratch", "is", 'm')
                    128: 
                    129: /* Appears only in machine descriptions.
                    130:    Means match only something equal to what is stored in the operand table
                    131:    at the index specified by the argument.  */
                    132: DEF_RTL_EXPR(MATCH_DUP, "match_dup", "i", 'm')
                    133: 
                    134: /* Appears only in machine descriptions.
                    135:    Means apply a predicate, AND match recursively the operands of the rtx.
                    136:    Operand 0 is the operand-number, as in match_operand.
                    137:    Operand 1 is a predicate to apply (as a string, a function name).
                    138:    Operand 2 is a vector of expressions, each of which must match
                    139:    one subexpression of the rtx this construct is matching.  */
                    140: DEF_RTL_EXPR(MATCH_OPERATOR, "match_operator", "isE", 'm')
                    141: 
                    142: /* Appears only in machine descriptions.
                    143:    Means to match a PARALLEL of arbitrary length.  The predicate is applied
                    144:    to the PARALLEL and the initial expressions in the PARALLEL are matched.
                    145:    Operand 0 is the operand-number, as in match_operand.
                    146:    Operand 1 is a predicate to apply to the PARALLEL.
                    147:    Operand 2 is a vector of expressions, each of which must match the 
                    148:    corresponding element in the PARALLEL.  */
                    149: DEF_RTL_EXPR(MATCH_PARALLEL, "match_parallel", "isE", 'm')
                    150: 
                    151: /* Appears only in machine descriptions.
                    152:    Means match only something equal to what is stored in the operand table
                    153:    at the index specified by the argument.  For MATCH_OPERATOR.  */
                    154: DEF_RTL_EXPR(MATCH_OP_DUP, "match_op_dup", "iE", 'm')
                    155: 
                    156: /* Appears only in machine descriptions.
                    157:    Defines the pattern for one kind of instruction.
                    158:    Operand:
                    159:    0: names this instruction.
                    160:       If the name is the null string, the instruction is in the
                    161:       machine description just to be recognized, and will never be emitted by
                    162:       the tree to rtl expander.
                    163:    1: is the pattern.
                    164:    2: is a string which is a C expression
                    165:       giving an additional condition for recognizing this pattern.
                    166:       A null string means no extra condition.
                    167:    3: is the action to execute if this pattern is matched.
                    168:       If this assembler code template starts with a * then it is a fragment of
                    169:       C code to run to decide on a template to use.  Otherwise, it is the
                    170:       template to use.
                    171:    4: optionally, a vector of attributes for this insn.
                    172:      */
                    173: DEF_RTL_EXPR(DEFINE_INSN, "define_insn", "sEssV", 'x')
                    174: 
                    175: /* Definition of a peephole optimization.
                    176:    1st operand: vector of insn patterns to match
                    177:    2nd operand: C expression that must be true
                    178:    3rd operand: template or C code to produce assembler output.
                    179:    4: optionally, a vector of attributes for this insn.
                    180:      */
                    181: DEF_RTL_EXPR(DEFINE_PEEPHOLE, "define_peephole", "EssV", 'x')
                    182: 
                    183: /* Definition of a split operation.
                    184:    1st operand: insn pattern to match
                    185:    2nd operand: C expression that must be true
                    186:    3rd operand: vector of insn patterns to place into a SEQUENCE
                    187:    4th operand: optionally, some C code to execute before generating the
                    188:        insns.  This might, for example, create some RTX's and store them in
                    189:        elements of `recog_operand' for use by the vector of insn-patterns.
                    190:        (`operands' is an alias here for `recog_operand').   */
                    191: DEF_RTL_EXPR(DEFINE_SPLIT, "define_split", "EsES", 'x')
                    192: 
                    193: /* Definition of a combiner pattern.
                    194:    Operands not defined yet.  */
                    195: DEF_RTL_EXPR(DEFINE_COMBINE, "define_combine", "Ess", 'x')
                    196: 
                    197: /* Define how to generate multiple insns for a standard insn name.
                    198:    1st operand: the insn name.
                    199:    2nd operand: vector of insn-patterns.
                    200:        Use match_operand to substitute an element of `recog_operand'.
                    201:    3rd operand: C expression that must be true for this to be available.
                    202:        This may not test any operands.
                    203:    4th operand: Extra C code to execute before generating the insns.
                    204:        This might, for example, create some RTX's and store them in
                    205:        elements of `recog_operand' for use by the vector of insn-patterns.
                    206:        (`operands' is an alias here for `recog_operand').  */
                    207: DEF_RTL_EXPR(DEFINE_EXPAND, "define_expand", "sEss", 'x')
                    208:    
                    209: /* Define a requirement for delay slots.
                    210:    1st operand: Condition involving insn attributes that, if true,
                    211:                indicates that the insn requires the number of delay slots
                    212:                shown.
                    213:    2nd operand: Vector whose length is the three times the number of delay
                    214:                slots required.
                    215:                Each entry gives three conditions, each involving attributes.
                    216:                The first must be true for an insn to occupy that delay slot
                    217:                location.  The second is true for all insns that can be
                    218:                annulled if the branch is true and the third is true for all
                    219:                insns that can be annulled if the branch is false. 
                    220: 
                    221:    Multiple DEFINE_DELAYs may be present.  They indicate differing
                    222:    requirements for delay slots.  */
                    223: DEF_RTL_EXPR(DEFINE_DELAY, "define_delay", "eE", 'x')
                    224: 
                    225: /* Define a set of insns that requires a function unit.  This means that
                    226:    these insns produce their result after a delay and that there may be
                    227:    restrictions on the number of insns of this type that can be scheduled
                    228:    simultaneously.
                    229: 
                    230:    More than one DEFINE_FUNCTION_UNIT can be specified for a function unit.
                    231:    Each gives a set of operations and associated delays.  The first three
                    232:    operands must be the same for each operation for the same function unit.
                    233: 
                    234:    All delays are specified in units of COST_PER_CYCLE.
                    235: 
                    236:    1st operand: Name of function unit (mostly for documentation)
                    237:    2nd operand: Number of identical function units in CPU
                    238:    3rd operand: Total number of simultaneous insns that can execute on this
                    239:                function unit; 0 if unlimited.
                    240:    4th operand: Condition involving insn attribute, that, if true, specifies
                    241:                those insns that this expression applies to.
                    242:    5th operand: Constant delay after which insn result will be
                    243:                available.
                    244:    6th operand: Delay until next insn can be scheduled on the function unit
                    245:                executing this operation.  The meaning depends on whether or
                    246:                not the next operand is supplied.
                    247:    7th operand: If this operand is not specified, the 6th operand gives the
                    248:                cost of scheduling another operation on this unit while a
                    249:                previous one is active.  A value of zero should be used for a
                    250:                pipelined unit.  If only one operation can be executed a time
                    251:                and the unit is busy for the entire time, the 3rd operand
                    252:                should be specified as 1 and the 6th and 7th operands will
                    253:                be ignored.
                    254: 
                    255:                If this operand is specified, it is a list of attribute
                    256:                expressions.  If an insn for which any of these expressions
                    257:                is true is currently executing on the function unit, the
                    258:                delay will be given by the 6th operand.  Otherwise, the
                    259:                insn can be immediately scheduled (subject to the limit on
                    260:                the number of simultaneous operations executing on the
                    261:                unit.)  */
                    262: DEF_RTL_EXPR(DEFINE_FUNCTION_UNIT, "define_function_unit", "siieiiV", 'x')
                    263: 
                    264: /* Define attribute computation for `asm' instructions.  */
                    265: DEF_RTL_EXPR(DEFINE_ASM_ATTRIBUTES, "define_asm_attributes", "V", 'x' )
                    266: 
                    267: /* SEQUENCE appears in the result of a `gen_...' function
                    268:    for a DEFINE_EXPAND that wants to make several insns.
                    269:    Its elements are the bodies of the insns that should be made.
                    270:    `emit_insn' takes the SEQUENCE apart and makes separate insns.  */
                    271: DEF_RTL_EXPR(SEQUENCE, "sequence", "E", 'x')
                    272: 
                    273: /* Refers to the address of its argument.
                    274:    This appears only in machine descriptions, indicating that
                    275:    any expression that would be acceptable as the operand of MEM
                    276:    should be matched.  */
                    277: DEF_RTL_EXPR(ADDRESS, "address", "e", 'm')
                    278: 
                    279: /* ----------------------------------------------------------------------
                    280:    Expressions used for insn attributes.  These also do not appear in
                    281:    actual rtl code in the compiler.
                    282:    ---------------------------------------------------------------------- */
                    283: 
                    284: /* Definition of an insn attribute.
                    285:    1st operand: name of the attribute
                    286:    2nd operand: comma-separated list of possible attribute values
                    287:    3rd operand: expression for the default value of the attribute. */
                    288: DEF_RTL_EXPR(DEFINE_ATTR, "define_attr", "sse", 'x')
                    289: 
                    290: /* Marker for the name of an attribute. */
                    291: DEF_RTL_EXPR(ATTR, "attr", "s", 'x')
                    292: 
                    293: /* For use in the last (optional) operand of DEFINE_INSN or DEFINE_PEEPHOLE and
                    294:    in DEFINE_ASM_INSN to specify an attribute to assign to insns matching that
                    295:    pattern.
                    296: 
                    297:    (set_attr "name" "value") is equivalent to
                    298:    (set (attr "name") (const_string "value"))  */
                    299: DEF_RTL_EXPR(SET_ATTR, "set_attr", "ss", 'x')
                    300: 
                    301: /* In the last operand of DEFINE_INSN and DEFINE_PEEPHOLE, this can be used to
                    302:    specify that attribute values are to be assigned according to the
                    303:    alternative matched.
                    304: 
                    305:    The following three expressions are equivalent:
                    306: 
                    307:    (set (attr "att") (cond [(eq_attrq "alternative" "1") (const_string "a1")
                    308:                            (eq_attrq "alternative" "2") (const_string "a2")]
                    309:                           (const_string "a3")))
                    310:    (set_attr_alternative "att" [(const_string "a1") (const_string "a2")
                    311:                                 (const_string "a3")])
                    312:    (set_attr "att" "a1,a2,a3")
                    313:  */
                    314: DEF_RTL_EXPR(SET_ATTR_ALTERNATIVE, "set_attr_alternative", "sE", 'x')
                    315: 
                    316: /* A conditional expression true if the value of the specified attribute of
                    317:    the current insn equals the specified value.  The first operand is the
                    318:    attribute name and the second is the comparison value.  */
                    319: DEF_RTL_EXPR(EQ_ATTR, "eq_attr", "ss", 'x')
                    320: 
                    321: /* ----------------------------------------------------------------------
                    322:    Expression types used for things in the instruction chain.
                    323: 
                    324:    All formats must start with "iuu" to handle the chain.
                    325:    Each insn expression holds an rtl instruction and its semantics
                    326:    during back-end processing.
                    327:    See macros's in "rtl.h" for the meaning of each rtx->fld[].
                    328: 
                    329:    ---------------------------------------------------------------------- */
                    330: 
                    331: /* An instruction that cannot jump.  */
                    332: DEF_RTL_EXPR(INSN, "insn", "iuueiee", 'i')
                    333: 
                    334: /* An instruction that can possibly jump.
                    335:    Fields ( rtx->fld[] ) have exact same meaning as INSN's.  */
                    336: DEF_RTL_EXPR(JUMP_INSN, "jump_insn", "iuueiee0", 'i')
                    337: 
                    338: /* An instruction that can possibly call a subroutine
                    339:    but which will not change which instruction comes next
                    340:    in the current function.
                    341:    Fields ( rtx->fld[] ) have exact same meaning as INSN's.  */
                    342: DEF_RTL_EXPR(CALL_INSN, "call_insn", "iuueiee", 'i')
                    343: 
                    344: /* A marker that indicates that control will not flow through.  */
                    345: DEF_RTL_EXPR(BARRIER, "barrier", "iuu", 'x')
                    346: 
                    347: /* Holds a label that is followed by instructions.
                    348:    Operand:
                    349:    3: is a number that is unique in the entire compilation.
                    350:    4: is the user-given name of the label, if any.
                    351:    5: is used in jump.c for the use-count of the label.
                    352:    and in flow.c to point to the chain of label_ref's to this label.  */
                    353: DEF_RTL_EXPR(CODE_LABEL, "code_label", "iuuis0", 'x')
                    354:      
                    355: /* Say where in the code a source line starts, for symbol table's sake.
                    356:    Contains a filename and a line number.  Line numbers <= 0 are special:
                    357:    0 is used in a dummy placed at the front of every function
                    358:       just so there will never be a need to delete the first insn;
                    359:    -1 indicates a dummy; insns to be deleted by flow analysis and combining
                    360:       are really changed to NOTEs with a number of -1.
                    361:    -2 means beginning of a name binding contour; output N_LBRAC.
                    362:    -3 means end of a contour; output N_RBRAC.  */
                    363: DEF_RTL_EXPR(NOTE, "note", "iuusn", 'x')
                    364: 
                    365: /* INLINE_HEADER is use by inline function machinery.  The information
                    366:    it contains helps to build the mapping function between the rtx's of
                    367:    the function to be inlined and the current function being expanded.  */
                    368: 
                    369: DEF_RTL_EXPR(INLINE_HEADER, "inline_header", "iuuuiiiiiieiiEe", 'x')
                    370: 
                    371: /* ----------------------------------------------------------------------
                    372:    Top level constituents of INSN, JUMP_INSN and CALL_INSN.
                    373:    ---------------------------------------------------------------------- */
                    374:    
                    375: /* Several operations to be done in parallel.  */
                    376: DEF_RTL_EXPR(PARALLEL, "parallel", "E", 'x')
                    377: 
                    378: /* A string that is passed through to the assembler as input.
                    379:      One can obviously pass comments through by using the
                    380:      assembler comment syntax.
                    381:      These occur in an insn all by themselves as the PATTERN.
                    382:      They also appear inside an ASM_OPERANDS
                    383:      as a convenient way to hold a string.  */
                    384: DEF_RTL_EXPR(ASM_INPUT, "asm_input", "s", 'x')
                    385: 
                    386: /* An assembler instruction with operands.
                    387:    1st operand is the instruction template.
                    388:    2nd operand is the constraint for the output.
                    389:    3rd operand is the number of the output this expression refers to.
                    390:      When an insn stores more than one value, a separate ASM_OPERANDS
                    391:      is made for each output; this integer distinguishes them.
                    392:    4th is a vector of values of input operands.
                    393:    5th is a vector of modes and constraints for the input operands.
                    394:      Each element is an ASM_INPUT containing a constraint string
                    395:      and whose mode indicates the mode of the input operand.
                    396:    6th is the name of the containing source file.
                    397:    7th is the source line number.  */
                    398: DEF_RTL_EXPR(ASM_OPERANDS, "asm_operands", "ssiEEsi", 'x')
                    399: 
                    400: /* A machine-specific operation.
                    401:    1st operand is a vector of operands being used by the operation so that
                    402:      any needed reloads can be done.
                    403:    2nd operand is a unique value saying which of a number of machine-specific
                    404:      operations is to be performed.
                    405:    (Note that the vector must be the first operand because of the way that
                    406:    genrecog.c record positions within an insn.)
                    407:    This can occur all by itself in a PATTERN, as a component of a PARALLEL,
                    408:    or inside an expression.  */
                    409: DEF_RTL_EXPR(UNSPEC, "unspec", "Ei", 'x')
                    410: 
1.1.1.2 ! root      411: /* Similar, but a volatile operation and one which may trap.  */
1.1       root      412: DEF_RTL_EXPR(UNSPEC_VOLATILE, "unspec_volatile", "Ei", 'x')
                    413: 
                    414: /* Vector of addresses, stored as full words.  */
                    415: /* Each element is a LABEL_REF to a CODE_LABEL whose address we want.  */
                    416: DEF_RTL_EXPR(ADDR_VEC, "addr_vec", "E", 'x')
                    417: 
                    418: /* Vector of address differences X0 - BASE, X1 - BASE, ...
                    419:    First operand is BASE; the vector contains the X's.
                    420:    The machine mode of this rtx says how much space to leave
                    421:    for each difference.  */
                    422: DEF_RTL_EXPR(ADDR_DIFF_VEC, "addr_diff_vec", "eE", 'x')
                    423: 
                    424: /* ----------------------------------------------------------------------
                    425:    At the top level of an instruction (perhaps under PARALLEL).
                    426:    ---------------------------------------------------------------------- */
                    427: 
                    428: /* Assignment.
                    429:    Operand 1 is the location (REG, MEM, PC, CC0 or whatever) assigned to.
                    430:    Operand 2 is the value stored there.
                    431:    ALL assignment must use SET.
                    432:    Instructions that do multiple assignments must use multiple SET,
                    433:    under PARALLEL.  */
                    434: DEF_RTL_EXPR(SET, "set", "ee", 'x')
                    435: 
                    436: /* Indicate something is used in a way that we don't want to explain.
                    437:    For example, subroutine calls will use the register
                    438:    in which the static chain is passed.  */
                    439: DEF_RTL_EXPR(USE, "use", "e", 'x')
                    440: 
                    441: /* Indicate something is clobbered in a way that we don't want to explain.
                    442:    For example, subroutine calls will clobber some physical registers
                    443:    (the ones that are by convention not saved).  */
                    444: DEF_RTL_EXPR(CLOBBER, "clobber", "e", 'x')
                    445: 
                    446: /* Call a subroutine.
                    447:    Operand 1 is the address to call.
                    448:    Operand 2 is the number of arguments.  */
                    449: 
                    450: DEF_RTL_EXPR(CALL, "call", "ee", 'x')
                    451: 
                    452: /* Return from a subroutine.  */
                    453: 
                    454: DEF_RTL_EXPR(RETURN, "return", "", 'x')
                    455: 
                    456: /* Conditional trap.
                    457:    Operand 1 is the condition.
                    458:    Operand 2 is the trap code.
                    459:    For an unconditional trap, make the condition (const_int 1).  */
                    460: DEF_RTL_EXPR(TRAP_IF, "trap_if", "ei", 'x')
                    461: 
                    462: /* ----------------------------------------------------------------------
                    463:    Primitive values for use in expressions.
                    464:    ---------------------------------------------------------------------- */
                    465: 
                    466: /* numeric integer constant */
                    467: DEF_RTL_EXPR(CONST_INT, "const_int", "i", 'o')
                    468: 
                    469: /* numeric double constant.
                    470:    Operand 0 is the MEM that stores this constant in memory,
                    471:    or various other things (see comments at immed_double_const in varasm.c).
                    472:    Operand 1 is a chain of all CONST_DOUBLEs in use in the current function.
                    473:    Remaining operands hold the actual value.
                    474:    The number of operands may be more than 2 if cross-compiling;
                    475:    see init_rtl.  */
                    476: DEF_RTL_EXPR(CONST_DOUBLE, "const_double", "e0ii", 'o')
                    477: 
                    478: /* String constant.  Used only for attributes right now.  */
                    479: DEF_RTL_EXPR(CONST_STRING, "const_string", "s", 'o')
                    480: 
                    481: /* This is used to encapsulate an expression whose value is constant
                    482:    (such as the sum of a SYMBOL_REF and a CONST_INT) so that it will be
                    483:    recognized as a constant operand rather than by arithmetic instructions.  */
                    484: 
                    485: DEF_RTL_EXPR(CONST, "const", "e", 'o')
                    486: 
                    487: /* program counter.  Ordinary jumps are represented
                    488:    by a SET whose first operand is (PC).  */
                    489: DEF_RTL_EXPR(PC, "pc", "", 'o')
                    490: 
                    491: /* A register.  The "operand" is the register number, accessed
                    492:    with the REGNO macro.  If this number is less than FIRST_PSEUDO_REGISTER
                    493:    than a hardware register is being referred to.  */
                    494: DEF_RTL_EXPR(REG, "reg", "i", 'o')
                    495: 
                    496: /* A scratch register.  This represents a register used only within a
                    497:    single insn.  It will be turned into a REG during register allocation
                    498:    or reload unless the constraint indicates that the register won't be
                    499:    needed, in which case it can remain a SCRATCH.  This code is
                    500:    marked as having one operand so it can be turned into a REG.  */
                    501: DEF_RTL_EXPR(SCRATCH, "scratch", "0", 'o')
                    502: 
                    503: /* One word of a multi-word value.
                    504:    The first operand is the complete value; the second says which word.
                    505:    The WORDS_BIG_ENDIAN flag controls whether word number 0
                    506:    (as numbered in a SUBREG) is the most or least significant word.
                    507: 
                    508:    This is also used to refer to a value in a different machine mode.
                    509:    For example, it can be used to refer to a SImode value as if it were
                    510:    Qimode, or vice versa.  Then the word number is always 0.  */
                    511: DEF_RTL_EXPR(SUBREG, "subreg", "ei", 'x')
                    512: 
                    513: /* This one-argument rtx is used for move instructions
                    514:    that are guaranteed to alter only the low part of a destination.
                    515:    Thus, (SET (SUBREG:HI (REG...)) (MEM:HI ...))
                    516:    has an unspecified effect on the high part of REG,
                    517:    but (SET (STRICT_LOW_PART (SUBREG:HI (REG...))) (MEM:HI ...))
                    518:    is guaranteed to alter only the bits of REG that are in HImode.
                    519: 
                    520:    The actual instruction used is probably the same in both cases,
                    521:    but the register constraints may be tighter when STRICT_LOW_PART
                    522:    is in use.  */
                    523: 
                    524: DEF_RTL_EXPR(STRICT_LOW_PART, "strict_low_part", "e", 'x')
                    525: 
                    526: /* A memory location; operand is the address.
                    527:    Can be nested inside a VOLATILE.  */
                    528: DEF_RTL_EXPR(MEM, "mem", "e", 'o')
                    529: 
                    530: /* Reference to an assembler label in the code for this function.
                    531:    The operand is a CODE_LABEL found in the insn chain.
                    532:    The unprinted fields 1 and 2 are used in flow.c for the
                    533:    LABEL_NEXTREF and CONTAINING_INSN.  */
                    534: DEF_RTL_EXPR(LABEL_REF, "label_ref", "u00", 'o')
                    535: 
                    536: /* Reference to a named label: the string that is the first operand,
                    537:    with `_' added implicitly in front.
                    538:    Exception: if the first character explicitly given is `*',
                    539:    to give it to the assembler, remove the `*' and do not add `_'.  */
                    540: DEF_RTL_EXPR(SYMBOL_REF, "symbol_ref", "s", 'o')
                    541: 
                    542: /* The condition code register is represented, in our imagination,
                    543:    as a register holding a value that can be compared to zero.
                    544:    In fact, the machine has already compared them and recorded the
                    545:    results; but instructions that look at the condition code
                    546:    pretend to be looking at the entire value and comparing it.  */
                    547: DEF_RTL_EXPR(CC0, "cc0", "", 'o')
                    548: 
                    549: /* =====================================================================
                    550:    A QUEUED expression really points to a member of the queue of instructions
                    551:    to be output later for postincrement/postdecrement.
                    552:    QUEUED expressions never become part of instructions.
                    553:    When a QUEUED expression would be put into an instruction,
                    554:    instead either the incremented variable or a copy of its previous
                    555:    value is used.
                    556:    
                    557:    Operands are:
                    558:    0. the variable to be incremented (a REG rtx).
                    559:    1. the incrementing instruction, or 0 if it hasn't been output yet.
                    560:    2. A REG rtx for a copy of the old value of the variable, or 0 if none yet.
                    561:    3. the body to use for the incrementing instruction
                    562:    4. the next QUEUED expression in the queue.
                    563:    ====================================================================== */
                    564: 
                    565: DEF_RTL_EXPR(QUEUED, "queued", "eeeee", 'x')
                    566: 
                    567: /* ----------------------------------------------------------------------
                    568:    Expressions for operators in an rtl pattern
                    569:    ---------------------------------------------------------------------- */
                    570: 
                    571: /* if_then_else.  This is used in representing ordinary
                    572:    conditional jump instructions.
                    573:      Operand:
                    574:      0:  condition
                    575:      1:  then expr
                    576:      2:  else expr */
                    577: DEF_RTL_EXPR(IF_THEN_ELSE, "if_then_else", "eee", '3')
                    578: 
                    579: /* General conditional. The first operand is a vector composed of pairs of
                    580:    expressions.  The first element of each pair is evaluated, in turn.
                    581:    The value of the conditional is the second expression of the first pair
                    582:    whose first expression evaluates non-zero.  If none of the expressions is
                    583:    true, the second operand will be used as the value of the conditional.
                    584: 
                    585:    This should be replaced with use of IF_THEN_ELSE.  */
                    586: DEF_RTL_EXPR(COND, "cond", "Ee", 'x')
                    587: 
                    588: /* Comparison, produces a condition code result.  */
                    589: DEF_RTL_EXPR(COMPARE, "compare", "ee", '2')
                    590: 
                    591: /* plus */
                    592: DEF_RTL_EXPR(PLUS, "plus", "ee", 'c')
                    593: 
                    594: /* Operand 0 minus operand 1.  */
                    595: DEF_RTL_EXPR(MINUS, "minus", "ee", '2')
                    596: 
                    597: /* Minus operand 0.  */
                    598: DEF_RTL_EXPR(NEG, "neg", "e", '1')
                    599: 
                    600: DEF_RTL_EXPR(MULT, "mult", "ee", 'c')
                    601: 
                    602: /* Operand 0 divided by operand 1.  */
                    603: DEF_RTL_EXPR(DIV, "div", "ee", '2')
                    604: /* Remainder of operand 0 divided by operand 1.  */
                    605: DEF_RTL_EXPR(MOD, "mod", "ee", '2')
                    606: 
                    607: /* Unsigned divide and remainder.  */
                    608: DEF_RTL_EXPR(UDIV, "udiv", "ee", '2')
                    609: DEF_RTL_EXPR(UMOD, "umod", "ee", '2')
                    610: 
                    611: /* Bitwise operations.  */
                    612: DEF_RTL_EXPR(AND, "and", "ee", 'c')
                    613: 
                    614: DEF_RTL_EXPR(IOR, "ior", "ee", 'c')
                    615: 
                    616: DEF_RTL_EXPR(XOR, "xor", "ee", 'c')
                    617: 
                    618: DEF_RTL_EXPR(NOT, "not", "e", '1')
                    619: 
                    620: /* Operand:
                    621:      0:  value to be shifted.
                    622:      1:  number of bits.
                    623:    ASHIFT and LSHIFT are distinguished because on some machines
                    624:    these allow a negative operand and shift right in that case.  */
                    625: DEF_RTL_EXPR(LSHIFT, "lshift", "ee", '2')
                    626: DEF_RTL_EXPR(ASHIFT, "ashift", "ee", '2')
                    627: DEF_RTL_EXPR(ROTATE, "rotate", "ee", '2')
                    628: 
                    629: /* Right shift operations, for machines where these are not the same
                    630:    as left shifting with a negative argument.  */
                    631: 
                    632: DEF_RTL_EXPR(ASHIFTRT, "ashiftrt", "ee", '2')
                    633: DEF_RTL_EXPR(LSHIFTRT, "lshiftrt", "ee", '2')
                    634: DEF_RTL_EXPR(ROTATERT, "rotatert", "ee", '2')
                    635: 
                    636: /* Minimum and maximum values of two operands.  We need both signed and
                    637:    unsigned forms.  (We cannot use MIN for SMIN because it conflicts
                    638:    with a macro of the same name.) */
                    639: 
                    640: DEF_RTL_EXPR(SMIN, "smin", "ee", 'c')
                    641: DEF_RTL_EXPR(SMAX, "smax", "ee", 'c')
                    642: DEF_RTL_EXPR(UMIN, "umin", "ee", 'c')
                    643: DEF_RTL_EXPR(UMAX, "umax", "ee", 'c')
                    644: 
                    645: /* These unary operations are used to represent incrementation
                    646:    and decrementation as they occur in memory addresses.
                    647:    The amount of increment or decrement are not represented
                    648:    because they can be understood from the machine-mode of the
                    649:    containing MEM.  These operations exist in only two cases:
                    650:    1. pushes onto the stack.
                    651:    2. created automatically by the life_analysis pass in flow.c.  */
                    652: DEF_RTL_EXPR(PRE_DEC, "pre_dec", "e", 'x')
                    653: DEF_RTL_EXPR(PRE_INC, "pre_inc", "e", 'x')
                    654: DEF_RTL_EXPR(POST_DEC, "post_dec", "e", 'x')
                    655: DEF_RTL_EXPR(POST_INC, "post_inc", "e", 'x')
                    656: 
                    657: /* Comparison operations.  The ordered comparisons exist in two
                    658:    flavors, signed and unsigned.  */
                    659: DEF_RTL_EXPR(NE, "ne", "ee", '<')
                    660: DEF_RTL_EXPR(EQ, "eq", "ee", '<')
                    661: DEF_RTL_EXPR(GE, "ge", "ee", '<')
                    662: DEF_RTL_EXPR(GT, "gt", "ee", '<')
                    663: DEF_RTL_EXPR(LE, "le", "ee", '<')
                    664: DEF_RTL_EXPR(LT, "lt", "ee", '<')
                    665: DEF_RTL_EXPR(GEU, "geu", "ee", '<')
                    666: DEF_RTL_EXPR(GTU, "gtu", "ee", '<')
                    667: DEF_RTL_EXPR(LEU, "leu", "ee", '<')
                    668: DEF_RTL_EXPR(LTU, "ltu", "ee", '<')
                    669: 
                    670: /* Represents the result of sign-extending the sole operand.
                    671:    The machine modes of the operand and of the SIGN_EXTEND expression
                    672:    determine how much sign-extension is going on.  */
                    673: DEF_RTL_EXPR(SIGN_EXTEND, "sign_extend", "e", '1')
                    674: 
                    675: /* Similar for zero-extension (such as unsigned short to int).  */
                    676: DEF_RTL_EXPR(ZERO_EXTEND, "zero_extend", "e", '1')
                    677: 
                    678: /* Similar but here the operand has a wider mode.  */
                    679: DEF_RTL_EXPR(TRUNCATE, "truncate", "e", '1')
                    680: 
                    681: /* Similar for extending floating-point values (such as SFmode to DFmode).  */
                    682: DEF_RTL_EXPR(FLOAT_EXTEND, "float_extend", "e", '1')
                    683: DEF_RTL_EXPR(FLOAT_TRUNCATE, "float_truncate", "e", '1')
                    684: 
                    685: /* Conversion of fixed point operand to floating point value.  */
                    686: DEF_RTL_EXPR(FLOAT, "float", "e", '1')
                    687: 
                    688: /* With fixed-point machine mode:
                    689:    Conversion of floating point operand to fixed point value.
                    690:    Value is defined only when the operand's value is an integer.
                    691:    With floating-point machine mode (and operand with same mode):
                    692:    Operand is rounded toward zero to produce an integer value
                    693:    represented in floating point.  */
                    694: DEF_RTL_EXPR(FIX, "fix", "e", '1')
                    695: 
                    696: /* Conversion of unsigned fixed point operand to floating point value.  */
                    697: DEF_RTL_EXPR(UNSIGNED_FLOAT, "unsigned_float", "e", '1')
                    698: 
                    699: /* With fixed-point machine mode:
                    700:    Conversion of floating point operand to *unsigned* fixed point value.
                    701:    Value is defined only when the operand's value is an integer.  */
                    702: DEF_RTL_EXPR(UNSIGNED_FIX, "unsigned_fix", "e", '1')
                    703: 
                    704: /* Absolute value */
                    705: DEF_RTL_EXPR(ABS, "abs", "e", '1')
                    706: 
                    707: /* Square root */
                    708: DEF_RTL_EXPR(SQRT, "sqrt", "e", '1')
                    709: 
                    710: /* Find first bit that is set.
                    711:    Value is 1 + number of trailing zeros in the arg.,
                    712:    or 0 if arg is 0.  */
                    713: DEF_RTL_EXPR(FFS, "ffs", "e", '1')
                    714: 
                    715: /* Reference to a signed bit-field of specified size and position.
                    716:    Operand 0 is the memory unit (usually SImode or QImode) which
                    717:    contains the field's first bit.  Operand 1 is the width, in bits.
                    718:    Operand 2 is the number of bits in the memory unit before the
                    719:    first bit of this field.
                    720:    If BITS_BIG_ENDIAN is defined, the first bit is the msb and
                    721:    operand 2 counts from the msb of the memory unit.
                    722:    Otherwise, the first bit is the lsb and operand 2 counts from
                    723:    the lsb of the memory unit.  */
                    724: DEF_RTL_EXPR(SIGN_EXTRACT, "sign_extract", "eee", 'b')
                    725: 
                    726: /* Similar for unsigned bit-field.  */
                    727: DEF_RTL_EXPR(ZERO_EXTRACT, "zero_extract", "eee", 'b')
                    728: 
                    729: /* For RISC machines.  These save memory when splitting insns.  */
                    730: 
                    731: /* HIGH are the high-order bits of a constant expression.  */
                    732: DEF_RTL_EXPR(HIGH, "high", "e", 'o')
                    733: 
                    734: /* LO_SUM is the sum of a register and the low-order bits
                    735:    of a constant expression.  */
                    736: DEF_RTL_EXPR(LO_SUM, "lo_sum", "ee", 'o')
                    737: 
                    738: /*
                    739: Local variables:
                    740: mode:c
                    741: version-control: t
                    742: End:
                    743: */

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