compiler, runtime: call gcWriteBarrier instead of writebarrierptr

[official-gcc.git] / gcc / rtl.def

/* This file contains the definitions and documentation for the
   Register Transfer Expressions (rtx's) that make up the
   Register Transfer Language (rtl) used in the Back End of the GNU compiler.
   Copyright (C) 1987-2018 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */


/* Expression definitions and descriptions for all targets are in this file.
   Some will not be used for some targets.

   The fields in the cpp macro call "DEF_RTL_EXPR()"
   are used to create declarations in the C source of the compiler.

   The fields are:

   1.  The internal name of the rtx used in the C source.
   It is a tag in the enumeration "enum rtx_code" defined in "rtl.h".
   By convention these are in UPPER_CASE.

   2.  The name of the rtx in the external ASCII format read by
   read_rtx(), and printed by print_rtx().
   These names are stored in rtx_name[].
   By convention these are the internal (field 1) names in lower_case.

   3.  The print format, and type of each rtx->u.fld[] (field) in this rtx.
   These formats are stored in rtx_format[].
   The meaning of the formats is documented in front of this array in rtl.c

   4.  The class of the rtx.  These are stored in rtx_class and are accessed
   via the GET_RTX_CLASS macro.  They are defined as follows:

     RTX_CONST_OBJ
         an rtx code that can be used to represent a constant object
         (e.g, CONST_INT)
     RTX_OBJ
         an rtx code that can be used to represent an object (e.g, REG, MEM)
     RTX_COMPARE
         an rtx code for a comparison (e.g, LT, GT)
     RTX_COMM_COMPARE
         an rtx code for a commutative comparison (e.g, EQ, NE, ORDERED)
     RTX_UNARY
         an rtx code for a unary arithmetic expression (e.g, NEG, NOT)
     RTX_COMM_ARITH
         an rtx code for a commutative binary operation (e.g,, PLUS, MULT)
     RTX_TERNARY
         an rtx code for a non-bitfield three input operation (IF_THEN_ELSE)
     RTX_BIN_ARITH
         an rtx code for a non-commutative binary operation (e.g., MINUS, DIV)
     RTX_BITFIELD_OPS
         an rtx code for a bit-field operation (ZERO_EXTRACT, SIGN_EXTRACT)
     RTX_INSN
         an rtx code for a machine insn (INSN, JUMP_INSN, CALL_INSN) or
         data that will be output as assembly pseudo-ops (DEBUG_INSN)
     RTX_MATCH
         an rtx code for something that matches in insns (e.g, MATCH_DUP)
     RTX_AUTOINC
         an rtx code for autoincrement addressing modes (e.g. POST_DEC)
     RTX_EXTRA
         everything else

   All of the expressions that appear only in machine descriptions,
   not in RTL used by the compiler itself, are at the end of the file.  */

/* Unknown, or no such operation; the enumeration constant should have
   value zero.  */
DEF_RTL_EXPR(UNKNOWN, "UnKnown", "*", RTX_EXTRA)

/* Used in the cselib routines to describe a value.  Objects of this
   kind are only allocated in cselib.c, in an alloc pool instead of in
   GC memory.  The only operand of a VALUE is a cselib_val.
   var-tracking requires this to have a distinct integral value from
   DECL codes in trees.  */
DEF_RTL_EXPR(VALUE, "value", "0", RTX_OBJ)

/* The RTL generated for a DEBUG_EXPR_DECL.  It links back to the
   DEBUG_EXPR_DECL in the first operand.  */
DEF_RTL_EXPR(DEBUG_EXPR, "debug_expr", "0", RTX_OBJ)

/* ---------------------------------------------------------------------
   Expressions used in constructing lists.
   --------------------------------------------------------------------- */

/* A linked list of expressions.  */
DEF_RTL_EXPR(EXPR_LIST, "expr_list", "ee", RTX_EXTRA)

/* A linked list of instructions.
   The insns are represented in print by their uids.  */
DEF_RTL_EXPR(INSN_LIST, "insn_list", "ue", RTX_EXTRA)

/* A linked list of integers.  */
DEF_RTL_EXPR(INT_LIST, "int_list", "ie", RTX_EXTRA)

/* SEQUENCE is used in late passes of the compiler to group insns for
   one reason or another.

   For example, after delay slot filling, branch instructions with filled
   delay slots are represented as a SEQUENCE of length 1 + n_delay_slots,
   with the branch instruction in XEXPVEC(seq, 0, 0) and the instructions
   occupying the delay slots in the remaining XEXPVEC slots.

   Another place where a SEQUENCE may appear, is in REG_FRAME_RELATED_EXPR
   notes, to express complex operations that are not obvious from the insn
   to which the REG_FRAME_RELATED_EXPR note is attached.  In this usage of
   SEQUENCE, the sequence vector slots do not hold real instructions but
   only pseudo-instructions that can be translated to DWARF CFA expressions.

   Some back ends also use SEQUENCE to group insns in bundles.

   Much of the compiler infrastructure is not prepared to handle SEQUENCE
   objects.  Only passes after pass_free_cfg are expected to handle them.  */
DEF_RTL_EXPR(SEQUENCE, "sequence", "E", RTX_EXTRA)

/* Represents a non-global base address.  This is only used in alias.c.  */
DEF_RTL_EXPR(ADDRESS, "address", "i", RTX_EXTRA)

/* ----------------------------------------------------------------------
   Expression types used for things in the instruction chain.

   All formats must start with "uu" to handle the chain.
   Each insn expression holds an rtl instruction and its semantics
   during back-end processing.
   See macros in "rtl.h" for the meaning of each rtx->u.fld[].

   ---------------------------------------------------------------------- */

/* An annotation for variable assignment tracking.  */
DEF_RTL_EXPR(DEBUG_INSN, "debug_insn", "uuBeiie", RTX_INSN)

/* An instruction that cannot jump.  */
DEF_RTL_EXPR(INSN, "insn", "uuBeiie", RTX_INSN)

/* An instruction that can possibly jump.
   Fields ( rtx->u.fld[] ) have exact same meaning as INSN's.  */
DEF_RTL_EXPR(JUMP_INSN, "jump_insn", "uuBeiie0", RTX_INSN)

/* An instruction that can possibly call a subroutine
   but which will not change which instruction comes next
   in the current function.
   Field ( rtx->u.fld[8] ) is CALL_INSN_FUNCTION_USAGE.
   All other fields ( rtx->u.fld[] ) have exact same meaning as INSN's.  */
DEF_RTL_EXPR(CALL_INSN, "call_insn", "uuBeiiee", RTX_INSN)

/* Placeholder for tablejump JUMP_INSNs.  The pattern of this kind
   of rtx is always either an ADDR_VEC or an ADDR_DIFF_VEC.  These
   placeholders do not appear as real instructions inside a basic
   block, but are considered active_insn_p instructions for historical
   reasons, when jump table data was represented with JUMP_INSNs.  */
DEF_RTL_EXPR(JUMP_TABLE_DATA, "jump_table_data", "uuBe0000", RTX_INSN)

/* A marker that indicates that control will not flow through.  */
DEF_RTL_EXPR(BARRIER, "barrier", "uu00000", RTX_EXTRA)

/* Holds a label that is followed by instructions.
   Operand:
   3: is used in jump.c for the use-count of the label.
   4: is used in the sh backend.
   5: is a number that is unique in the entire compilation.
   6: is the user-given name of the label, if any.  */
DEF_RTL_EXPR(CODE_LABEL, "code_label", "uuB00is", RTX_EXTRA)

/* Say where in the code a source line starts, for symbol table's sake.
   Operand:
   3: note-specific data
   4: enum insn_note
   5: unique number if insn_note == note_insn_deleted_label.  */
DEF_RTL_EXPR(NOTE, "note", "uuB0ni", RTX_EXTRA)

/* ----------------------------------------------------------------------
   Top level constituents of INSN, JUMP_INSN and CALL_INSN.
   ---------------------------------------------------------------------- */

/* Conditionally execute code.
   Operand 0 is the condition that if true, the code is executed.
   Operand 1 is the code to be executed (typically a SET).

   Semantics are that there are no side effects if the condition
   is false.  This pattern is created automatically by the if_convert
   pass run after reload or by target-specific splitters.  */
DEF_RTL_EXPR(COND_EXEC, "cond_exec", "ee", RTX_EXTRA)

/* Several operations to be done in parallel (perhaps under COND_EXEC).  */
DEF_RTL_EXPR(PARALLEL, "parallel", "E", RTX_EXTRA)

/* A string that is passed through to the assembler as input.
     One can obviously pass comments through by using the
     assembler comment syntax.
     These occur in an insn all by themselves as the PATTERN.
     They also appear inside an ASM_OPERANDS
     as a convenient way to hold a string.  */
DEF_RTL_EXPR(ASM_INPUT, "asm_input", "si", RTX_EXTRA)

/* An assembler instruction with operands.
   1st operand is the instruction template.
   2nd operand is the constraint for the output.
   3rd operand is the number of the output this expression refers to.
     When an insn stores more than one value, a separate ASM_OPERANDS
     is made for each output; this integer distinguishes them.
   4th is a vector of values of input operands.
   5th is a vector of modes and constraints for the input operands.
     Each element is an ASM_INPUT containing a constraint string
     and whose mode indicates the mode of the input operand.
   6th is a vector of labels that may be branched to by the asm.
   7th is the source line number.  */
DEF_RTL_EXPR(ASM_OPERANDS, "asm_operands", "ssiEEEi", RTX_EXTRA)

/* A machine-specific operation.
   1st operand is a vector of operands being used by the operation so that
     any needed reloads can be done.
   2nd operand is a unique value saying which of a number of machine-specific
     operations is to be performed.
   (Note that the vector must be the first operand because of the way that
   genrecog.c record positions within an insn.)

   UNSPEC can occur all by itself in a PATTERN, as a component of a PARALLEL,
   or inside an expression.
   UNSPEC by itself or as a component of a PARALLEL
   is currently considered not deletable.

   FIXME: Replace all uses of UNSPEC that appears by itself or as a component
   of a PARALLEL with USE.
   */
DEF_RTL_EXPR(UNSPEC, "unspec", "Ei", RTX_EXTRA)

/* Similar, but a volatile operation and one which may trap.  */
DEF_RTL_EXPR(UNSPEC_VOLATILE, "unspec_volatile", "Ei", RTX_EXTRA)

/* ----------------------------------------------------------------------
   Table jump addresses.
   ---------------------------------------------------------------------- */

/* Vector of addresses, stored as full words.
   Each element is a LABEL_REF to a CODE_LABEL whose address we want.  */
DEF_RTL_EXPR(ADDR_VEC, "addr_vec", "E", RTX_EXTRA)

/* Vector of address differences X0 - BASE, X1 - BASE, ...
   First operand is BASE; the vector contains the X's.
   The machine mode of this rtx says how much space to leave
   for each difference and is adjusted by branch shortening if
   CASE_VECTOR_SHORTEN_MODE is defined.
   The third and fourth operands store the target labels with the
   minimum and maximum addresses respectively.
   The fifth operand stores flags for use by branch shortening.
  Set at the start of shorten_branches:
   min_align: the minimum alignment for any of the target labels.
   base_after_vec: true iff BASE is after the ADDR_DIFF_VEC.
   min_after_vec: true iff minimum addr target label is after the ADDR_DIFF_VEC.
   max_after_vec: true iff maximum addr target label is after the ADDR_DIFF_VEC.
   min_after_base: true iff minimum address target label is after BASE.
   max_after_base: true iff maximum address target label is after BASE.
  Set by the actual branch shortening process:
   offset_unsigned: true iff offsets have to be treated as unsigned.
   scale: scaling that is necessary to make offsets fit into the mode.

   The third, fourth and fifth operands are only valid when
   CASE_VECTOR_SHORTEN_MODE is defined, and only in an optimizing
   compilation.  */
DEF_RTL_EXPR(ADDR_DIFF_VEC, "addr_diff_vec", "eEee0", RTX_EXTRA)

/* Memory prefetch, with attributes supported on some targets.
   Operand 1 is the address of the memory to fetch.
   Operand 2 is 1 for a write access, 0 otherwise.
   Operand 3 is the level of temporal locality; 0 means there is no
   temporal locality and 1, 2, and 3 are for increasing levels of temporal
   locality.

   The attributes specified by operands 2 and 3 are ignored for targets
   whose prefetch instructions do not support them.  */
DEF_RTL_EXPR(PREFETCH, "prefetch", "eee", RTX_EXTRA)

/* ----------------------------------------------------------------------
   At the top level of an instruction (perhaps under PARALLEL).
   ---------------------------------------------------------------------- */

/* Assignment.
   Operand 1 is the location (REG, MEM, PC, CC0 or whatever) assigned to.
   Operand 2 is the value stored there.
   ALL assignment must use SET.
   Instructions that do multiple assignments must use multiple SET,
   under PARALLEL.  */
DEF_RTL_EXPR(SET, "set", "ee", RTX_EXTRA)

/* Indicate something is used in a way that we don't want to explain.
   For example, subroutine calls will use the register
   in which the static chain is passed.

   USE can not appear as an operand of other rtx except for PARALLEL.
   USE is not deletable, as it indicates that the operand
   is used in some unknown way.  */
DEF_RTL_EXPR(USE, "use", "e", RTX_EXTRA)

/* Indicate something is clobbered in a way that we don't want to explain.
   For example, subroutine calls will clobber some physical registers
   (the ones that are by convention not saved).

   CLOBBER can not appear as an operand of other rtx except for PARALLEL.
   CLOBBER of a hard register appearing by itself (not within PARALLEL)
   is considered undeletable before reload.  */
DEF_RTL_EXPR(CLOBBER, "clobber", "e", RTX_EXTRA)

/* Indicate that the upper parts of something are clobbered in a way that we
   don't want to explain.  The MODE references the lower bits that will be
   preserved.  Anything above that size will be clobbered.

   CLOBBER_HIGH only occurs as the operand of a PARALLEL rtx.  It cannot appear
   in other contexts, and unlike CLOBBER, it cannot appear on its own.
   CLOBBER_HIGH can only be used with fixed register rtxes.  */

DEF_RTL_EXPR(CLOBBER_HIGH, "clobber_high", "e", RTX_EXTRA)

/* Call a subroutine.
   Operand 1 is the address to call.
   Operand 2 is the number of arguments.  */

DEF_RTL_EXPR(CALL, "call", "ee", RTX_EXTRA)

/* Return from a subroutine.  */

DEF_RTL_EXPR(RETURN, "return", "", RTX_EXTRA)

/* Like RETURN, but truly represents only a function return, while
   RETURN may represent an insn that also performs other functions
   of the function epilogue.  Like RETURN, this may also occur in
   conditional jumps.  */
DEF_RTL_EXPR(SIMPLE_RETURN, "simple_return", "", RTX_EXTRA)

/* Special for EH return from subroutine.  */

DEF_RTL_EXPR(EH_RETURN, "eh_return", "", RTX_EXTRA)

/* Conditional trap.
   Operand 1 is the condition.
   Operand 2 is the trap code.
   For an unconditional trap, make the condition (const_int 1).  */
DEF_RTL_EXPR(TRAP_IF, "trap_if", "ee", RTX_EXTRA)

/* ----------------------------------------------------------------------
   Primitive values for use in expressions.
   ---------------------------------------------------------------------- */

/* numeric integer constant */
DEF_RTL_EXPR(CONST_INT, "const_int", "w", RTX_CONST_OBJ)

/* numeric integer constant */
DEF_RTL_EXPR(CONST_WIDE_INT, "const_wide_int", "", RTX_CONST_OBJ)

/* An rtx representation of a poly_wide_int.  */
DEF_RTL_EXPR(CONST_POLY_INT, "const_poly_int", "", RTX_CONST_OBJ)

/* fixed-point constant */
DEF_RTL_EXPR(CONST_FIXED, "const_fixed", "www", RTX_CONST_OBJ)

/* numeric floating point or integer constant.  If the mode is
   VOIDmode it is an int otherwise it has a floating point mode and a
   floating point value.  Operands hold the value.  They are all 'w'
   and there may be from 2 to 6; see real.h.  */
DEF_RTL_EXPR(CONST_DOUBLE, "const_double", CONST_DOUBLE_FORMAT, RTX_CONST_OBJ)

/* Describes a vector constant.  */
DEF_RTL_EXPR(CONST_VECTOR, "const_vector", "E", RTX_CONST_OBJ)

/* String constant.  Used for attributes in machine descriptions and
   for special cases in DWARF2 debug output.  NOT used for source-
   language string constants.  */
DEF_RTL_EXPR(CONST_STRING, "const_string", "s", RTX_OBJ)

/* This is used to encapsulate an expression whose value is constant
   (such as the sum of a SYMBOL_REF and a CONST_INT) so that it will be
   recognized as a constant operand rather than by arithmetic instructions.  */

DEF_RTL_EXPR(CONST, "const", "e", RTX_CONST_OBJ)

/* program counter.  Ordinary jumps are represented
   by a SET whose first operand is (PC).  */
DEF_RTL_EXPR(PC, "pc", "", RTX_OBJ)

/* A register.  The "operand" is the register number, accessed with
   the REGNO macro.  If this number is less than FIRST_PSEUDO_REGISTER
   than a hardware register is being referred to.  The second operand
   points to a reg_attrs structure.
   This rtx needs to have as many (or more) fields as a MEM, since we
   can change REG rtx's into MEMs during reload.  */
DEF_RTL_EXPR(REG, "reg", "r", RTX_OBJ)

/* A scratch register.  This represents a register used only within a
   single insn.  It will be replaced by a REG during register allocation
   or reload unless the constraint indicates that the register won't be
   needed, in which case it can remain a SCRATCH.  */
DEF_RTL_EXPR(SCRATCH, "scratch", "", RTX_OBJ)

/* A reference to a part of another value.  The first operand is the
   complete value and the second is the byte offset of the selected part.   */
DEF_RTL_EXPR(SUBREG, "subreg", "ep", RTX_EXTRA)

/* This one-argument rtx is used for move instructions
   that are guaranteed to alter only the low part of a destination.
   Thus, (SET (SUBREG:HI (REG...)) (MEM:HI ...))
   has an unspecified effect on the high part of REG,
   but (SET (STRICT_LOW_PART (SUBREG:HI (REG...))) (MEM:HI ...))
   is guaranteed to alter only the bits of REG that are in HImode.

   The actual instruction used is probably the same in both cases,
   but the register constraints may be tighter when STRICT_LOW_PART
   is in use.  */

DEF_RTL_EXPR(STRICT_LOW_PART, "strict_low_part", "e", RTX_EXTRA)

/* (CONCAT a b) represents the virtual concatenation of a and b
   to make a value that has as many bits as a and b put together.
   This is used for complex values.  Normally it appears only
   in DECL_RTLs and during RTL generation, but not in the insn chain.  */
DEF_RTL_EXPR(CONCAT, "concat", "ee", RTX_OBJ)

/* (CONCATN [a1 a2 ... an]) represents the virtual concatenation of
   all An to make a value.  This is an extension of CONCAT to larger
   number of components.  Like CONCAT, it should not appear in the
   insn chain.  Every element of the CONCATN is the same size.  */
DEF_RTL_EXPR(CONCATN, "concatn", "E", RTX_OBJ)

/* A memory location; operand is the address.  The second operand is the
   alias set to which this MEM belongs.  We use `0' instead of `w' for this
   field so that the field need not be specified in machine descriptions.  */
DEF_RTL_EXPR(MEM, "mem", "e0", RTX_OBJ)

/* Reference to an assembler label in the code for this function.
   The operand is a CODE_LABEL found in the insn chain.  */
DEF_RTL_EXPR(LABEL_REF, "label_ref", "u", RTX_CONST_OBJ)

/* Reference to a named label:
   Operand 0: label name
   Operand 1: tree from which this symbol is derived, or null.
   This is either a DECL node, or some kind of constant.  */
DEF_RTL_EXPR(SYMBOL_REF, "symbol_ref", "s0", RTX_CONST_OBJ)

/* The condition code register is represented, in our imagination,
   as a register holding a value that can be compared to zero.
   In fact, the machine has already compared them and recorded the
   results; but instructions that look at the condition code
   pretend to be looking at the entire value and comparing it.  */
DEF_RTL_EXPR(CC0, "cc0", "", RTX_OBJ)

/* ----------------------------------------------------------------------
   Expressions for operators in an rtl pattern
   ---------------------------------------------------------------------- */

/* if_then_else.  This is used in representing ordinary
   conditional jump instructions.
     Operand:
     0:  condition
     1:  then expr
     2:  else expr */
DEF_RTL_EXPR(IF_THEN_ELSE, "if_then_else", "eee", RTX_TERNARY)

/* Comparison, produces a condition code result.  */
DEF_RTL_EXPR(COMPARE, "compare", "ee", RTX_BIN_ARITH)

/* plus */
DEF_RTL_EXPR(PLUS, "plus", "ee", RTX_COMM_ARITH)

/* Operand 0 minus operand 1.  */
DEF_RTL_EXPR(MINUS, "minus", "ee", RTX_BIN_ARITH)

/* Minus operand 0.  */
DEF_RTL_EXPR(NEG, "neg", "e", RTX_UNARY)

DEF_RTL_EXPR(MULT, "mult", "ee", RTX_COMM_ARITH)

/* Multiplication with signed saturation */
DEF_RTL_EXPR(SS_MULT, "ss_mult", "ee", RTX_COMM_ARITH)
/* Multiplication with unsigned saturation */
DEF_RTL_EXPR(US_MULT, "us_mult", "ee", RTX_COMM_ARITH)

/* Operand 0 divided by operand 1.  */
DEF_RTL_EXPR(DIV, "div", "ee", RTX_BIN_ARITH)
/* Division with signed saturation */
DEF_RTL_EXPR(SS_DIV, "ss_div", "ee", RTX_BIN_ARITH)
/* Division with unsigned saturation */
DEF_RTL_EXPR(US_DIV, "us_div", "ee", RTX_BIN_ARITH)

/* Remainder of operand 0 divided by operand 1.  */
DEF_RTL_EXPR(MOD, "mod", "ee", RTX_BIN_ARITH)

/* Unsigned divide and remainder.  */
DEF_RTL_EXPR(UDIV, "udiv", "ee", RTX_BIN_ARITH)
DEF_RTL_EXPR(UMOD, "umod", "ee", RTX_BIN_ARITH)

/* Bitwise operations.  */
DEF_RTL_EXPR(AND, "and", "ee", RTX_COMM_ARITH)
DEF_RTL_EXPR(IOR, "ior", "ee", RTX_COMM_ARITH)
DEF_RTL_EXPR(XOR, "xor", "ee", RTX_COMM_ARITH)
DEF_RTL_EXPR(NOT, "not", "e", RTX_UNARY)

/* Operand:
     0:  value to be shifted.
     1:  number of bits.  */
DEF_RTL_EXPR(ASHIFT, "ashift", "ee", RTX_BIN_ARITH) /* shift left */
DEF_RTL_EXPR(ROTATE, "rotate", "ee", RTX_BIN_ARITH) /* rotate left */
DEF_RTL_EXPR(ASHIFTRT, "ashiftrt", "ee", RTX_BIN_ARITH) /* arithmetic shift right */
DEF_RTL_EXPR(LSHIFTRT, "lshiftrt", "ee", RTX_BIN_ARITH) /* logical shift right */
DEF_RTL_EXPR(ROTATERT, "rotatert", "ee", RTX_BIN_ARITH) /* rotate right */

/* Minimum and maximum values of two operands.  We need both signed and
   unsigned forms.  (We cannot use MIN for SMIN because it conflicts
   with a macro of the same name.)   The signed variants should be used
   with floating point.  Further, if both operands are zeros, or if either
   operand is NaN, then it is unspecified which of the two operands is
   returned as the result.  */

DEF_RTL_EXPR(SMIN, "smin", "ee", RTX_COMM_ARITH)
DEF_RTL_EXPR(SMAX, "smax", "ee", RTX_COMM_ARITH)
DEF_RTL_EXPR(UMIN, "umin", "ee", RTX_COMM_ARITH)
DEF_RTL_EXPR(UMAX, "umax", "ee", RTX_COMM_ARITH)

/* These unary operations are used to represent incrementation
   and decrementation as they occur in memory addresses.
   The amount of increment or decrement are not represented
   because they can be understood from the machine-mode of the
   containing MEM.  These operations exist in only two cases:
   1. pushes onto the stack.
   2. created automatically by the auto-inc-dec pass.  */
DEF_RTL_EXPR(PRE_DEC, "pre_dec", "e", RTX_AUTOINC)
DEF_RTL_EXPR(PRE_INC, "pre_inc", "e", RTX_AUTOINC)
DEF_RTL_EXPR(POST_DEC, "post_dec", "e", RTX_AUTOINC)
DEF_RTL_EXPR(POST_INC, "post_inc", "e", RTX_AUTOINC)

/* These binary operations are used to represent generic address
   side-effects in memory addresses, except for simple incrementation
   or decrementation which use the above operations.  They are
   created automatically by the life_analysis pass in flow.c.
   The first operand is a REG which is used as the address.
   The second operand is an expression that is assigned to the
   register, either before (PRE_MODIFY) or after (POST_MODIFY)
   evaluating the address.
   Currently, the compiler can only handle second operands of the
   form (plus (reg) (reg)) and (plus (reg) (const_int)), where
   the first operand of the PLUS has to be the same register as
   the first operand of the *_MODIFY.  */
DEF_RTL_EXPR(PRE_MODIFY, "pre_modify", "ee", RTX_AUTOINC)
DEF_RTL_EXPR(POST_MODIFY, "post_modify", "ee", RTX_AUTOINC)

/* Comparison operations.  The ordered comparisons exist in two
   flavors, signed and unsigned.  */
DEF_RTL_EXPR(NE, "ne", "ee", RTX_COMM_COMPARE)
DEF_RTL_EXPR(EQ, "eq", "ee", RTX_COMM_COMPARE)
DEF_RTL_EXPR(GE, "ge", "ee", RTX_COMPARE)
DEF_RTL_EXPR(GT, "gt", "ee", RTX_COMPARE)
DEF_RTL_EXPR(LE, "le", "ee", RTX_COMPARE)
DEF_RTL_EXPR(LT, "lt", "ee", RTX_COMPARE)
DEF_RTL_EXPR(GEU, "geu", "ee", RTX_COMPARE)
DEF_RTL_EXPR(GTU, "gtu", "ee", RTX_COMPARE)
DEF_RTL_EXPR(LEU, "leu", "ee", RTX_COMPARE)
DEF_RTL_EXPR(LTU, "ltu", "ee", RTX_COMPARE)

/* Additional floating point unordered comparison flavors.  */
DEF_RTL_EXPR(UNORDERED, "unordered", "ee", RTX_COMM_COMPARE)
DEF_RTL_EXPR(ORDERED, "ordered", "ee", RTX_COMM_COMPARE)

/* These are equivalent to unordered or ...  */
DEF_RTL_EXPR(UNEQ, "uneq", "ee", RTX_COMM_COMPARE)
DEF_RTL_EXPR(UNGE, "unge", "ee", RTX_COMPARE)
DEF_RTL_EXPR(UNGT, "ungt", "ee", RTX_COMPARE)
DEF_RTL_EXPR(UNLE, "unle", "ee", RTX_COMPARE)
DEF_RTL_EXPR(UNLT, "unlt", "ee", RTX_COMPARE)

/* This is an ordered NE, ie !UNEQ, ie false for NaN.  */
DEF_RTL_EXPR(LTGT, "ltgt", "ee", RTX_COMM_COMPARE)

/* Represents the result of sign-extending the sole operand.
   The machine modes of the operand and of the SIGN_EXTEND expression
   determine how much sign-extension is going on.  */
DEF_RTL_EXPR(SIGN_EXTEND, "sign_extend", "e", RTX_UNARY)

/* Similar for zero-extension (such as unsigned short to int).  */
DEF_RTL_EXPR(ZERO_EXTEND, "zero_extend", "e", RTX_UNARY)

/* Similar but here the operand has a wider mode.  */
DEF_RTL_EXPR(TRUNCATE, "truncate", "e", RTX_UNARY)

/* Similar for extending floating-point values (such as SFmode to DFmode).  */
DEF_RTL_EXPR(FLOAT_EXTEND, "float_extend", "e", RTX_UNARY)
DEF_RTL_EXPR(FLOAT_TRUNCATE, "float_truncate", "e", RTX_UNARY)

/* Conversion of fixed point operand to floating point value.  */
DEF_RTL_EXPR(FLOAT, "float", "e", RTX_UNARY)

/* With fixed-point machine mode:
   Conversion of floating point operand to fixed point value.
   Value is defined only when the operand's value is an integer.
   With floating-point machine mode (and operand with same mode):
   Operand is rounded toward zero to produce an integer value
   represented in floating point.  */
DEF_RTL_EXPR(FIX, "fix", "e", RTX_UNARY)

/* Conversion of unsigned fixed point operand to floating point value.  */
DEF_RTL_EXPR(UNSIGNED_FLOAT, "unsigned_float", "e", RTX_UNARY)

/* With fixed-point machine mode:
   Conversion of floating point operand to *unsigned* fixed point value.
   Value is defined only when the operand's value is an integer.  */
DEF_RTL_EXPR(UNSIGNED_FIX, "unsigned_fix", "e", RTX_UNARY)

/* Conversions involving fractional fixed-point types without saturation,
   including:
     fractional to fractional (of different precision),
     signed integer to fractional,
     fractional to signed integer,
     floating point to fractional,
     fractional to floating point.
   NOTE: fractional can be either signed or unsigned for conversions.  */
DEF_RTL_EXPR(FRACT_CONVERT, "fract_convert", "e", RTX_UNARY)

/* Conversions involving fractional fixed-point types and unsigned integer
   without saturation, including:
     unsigned integer to fractional,
     fractional to unsigned integer.
   NOTE: fractional can be either signed or unsigned for conversions.  */
DEF_RTL_EXPR(UNSIGNED_FRACT_CONVERT, "unsigned_fract_convert", "e", RTX_UNARY)

/* Conversions involving fractional fixed-point types with saturation,
   including:
     fractional to fractional (of different precision),
     signed integer to fractional,
     floating point to fractional.
   NOTE: fractional can be either signed or unsigned for conversions.  */
DEF_RTL_EXPR(SAT_FRACT, "sat_fract", "e", RTX_UNARY)

/* Conversions involving fractional fixed-point types and unsigned integer
   with saturation, including:
     unsigned integer to fractional.
   NOTE: fractional can be either signed or unsigned for conversions.  */
DEF_RTL_EXPR(UNSIGNED_SAT_FRACT, "unsigned_sat_fract", "e", RTX_UNARY)

/* Absolute value */
DEF_RTL_EXPR(ABS, "abs", "e", RTX_UNARY)

/* Square root */
DEF_RTL_EXPR(SQRT, "sqrt", "e", RTX_UNARY)

/* Swap bytes.  */
DEF_RTL_EXPR(BSWAP, "bswap", "e", RTX_UNARY)

/* Find first bit that is set.
   Value is 1 + number of trailing zeros in the arg.,
   or 0 if arg is 0.  */
DEF_RTL_EXPR(FFS, "ffs", "e", RTX_UNARY)

/* Count number of leading redundant sign bits (number of leading
   sign bits minus one).  */
DEF_RTL_EXPR(CLRSB, "clrsb", "e", RTX_UNARY)

/* Count leading zeros.  */
DEF_RTL_EXPR(CLZ, "clz", "e", RTX_UNARY)

/* Count trailing zeros.  */
DEF_RTL_EXPR(CTZ, "ctz", "e", RTX_UNARY)

/* Population count (number of 1 bits).  */
DEF_RTL_EXPR(POPCOUNT, "popcount", "e", RTX_UNARY)

/* Population parity (number of 1 bits modulo 2).  */
DEF_RTL_EXPR(PARITY, "parity", "e", RTX_UNARY)

/* Reference to a signed bit-field of specified size and position.
   Operand 0 is the memory unit (usually SImode or QImode) which
   contains the field's first bit.  Operand 1 is the width, in bits.
   Operand 2 is the number of bits in the memory unit before the
   first bit of this field.
   If BITS_BIG_ENDIAN is defined, the first bit is the msb and
   operand 2 counts from the msb of the memory unit.
   Otherwise, the first bit is the lsb and operand 2 counts from
   the lsb of the memory unit.
   This kind of expression can not appear as an lvalue in RTL.  */
DEF_RTL_EXPR(SIGN_EXTRACT, "sign_extract", "eee", RTX_BITFIELD_OPS)

/* Similar for unsigned bit-field.
   But note!  This kind of expression _can_ appear as an lvalue.  */
DEF_RTL_EXPR(ZERO_EXTRACT, "zero_extract", "eee", RTX_BITFIELD_OPS)

/* For RISC machines.  These save memory when splitting insns.  */

/* HIGH are the high-order bits of a constant expression.  */
DEF_RTL_EXPR(HIGH, "high", "e", RTX_CONST_OBJ)

/* LO_SUM is the sum of a register and the low-order bits
   of a constant expression.  */
DEF_RTL_EXPR(LO_SUM, "lo_sum", "ee", RTX_OBJ)

/* Describes a merge operation between two vector values.
   Operands 0 and 1 are the vectors to be merged, operand 2 is a bitmask
   that specifies where the parts of the result are taken from.  Set bits
   indicate operand 0, clear bits indicate operand 1.  The parts are defined
   by the mode of the vectors.  */
DEF_RTL_EXPR(VEC_MERGE, "vec_merge", "eee", RTX_TERNARY)

/* Describes an operation that selects parts of a vector.
   Operands 0 is the source vector, operand 1 is a PARALLEL that contains
   a CONST_INT for each of the subparts of the result vector, giving the
   number of the source subpart that should be stored into it.  */
DEF_RTL_EXPR(VEC_SELECT, "vec_select", "ee", RTX_BIN_ARITH)

/* Describes a vector concat operation.  Operands 0 and 1 are the source
   vectors, the result is a vector that is as long as operands 0 and 1
   combined and is the concatenation of the two source vectors.  */
DEF_RTL_EXPR(VEC_CONCAT, "vec_concat", "ee", RTX_BIN_ARITH)

/* Describes an operation that converts a small vector into a larger one by
   duplicating the input values.  The output vector mode must have the same
   submodes as the input vector mode, and the number of output parts must be
   an integer multiple of the number of input parts.  */
DEF_RTL_EXPR(VEC_DUPLICATE, "vec_duplicate", "e", RTX_UNARY)

/* Creation of a vector in which element I has the value BASE + I * STEP,
   where BASE is the first operand and STEP is the second.  The result
   must have a vector integer mode.  */
DEF_RTL_EXPR(VEC_SERIES, "vec_series", "ee", RTX_BIN_ARITH)

/* Addition with signed saturation */
DEF_RTL_EXPR(SS_PLUS, "ss_plus", "ee", RTX_COMM_ARITH)

/* Addition with unsigned saturation */
DEF_RTL_EXPR(US_PLUS, "us_plus", "ee", RTX_COMM_ARITH)

/* Operand 0 minus operand 1, with signed saturation.  */
DEF_RTL_EXPR(SS_MINUS, "ss_minus", "ee", RTX_BIN_ARITH)

/* Negation with signed saturation.  */
DEF_RTL_EXPR(SS_NEG, "ss_neg", "e", RTX_UNARY)
/* Negation with unsigned saturation.  */
DEF_RTL_EXPR(US_NEG, "us_neg", "e", RTX_UNARY)

/* Absolute value with signed saturation.  */
DEF_RTL_EXPR(SS_ABS, "ss_abs", "e", RTX_UNARY)

/* Shift left with signed saturation.  */
DEF_RTL_EXPR(SS_ASHIFT, "ss_ashift", "ee", RTX_BIN_ARITH)

/* Shift left with unsigned saturation.  */
DEF_RTL_EXPR(US_ASHIFT, "us_ashift", "ee", RTX_BIN_ARITH)

/* Operand 0 minus operand 1, with unsigned saturation.  */
DEF_RTL_EXPR(US_MINUS, "us_minus", "ee", RTX_BIN_ARITH)

/* Signed saturating truncate.  */
DEF_RTL_EXPR(SS_TRUNCATE, "ss_truncate", "e", RTX_UNARY)

/* Unsigned saturating truncate.  */
DEF_RTL_EXPR(US_TRUNCATE, "us_truncate", "e", RTX_UNARY)

/* Floating point multiply/add combined instruction.  */
DEF_RTL_EXPR(FMA, "fma", "eee", RTX_TERNARY)

/* Information about the variable and its location.  */
DEF_RTL_EXPR(VAR_LOCATION, "var_location", "te", RTX_EXTRA)

/* Used in VAR_LOCATION for a pointer to a decl that is no longer
   addressable.  */
DEF_RTL_EXPR(DEBUG_IMPLICIT_PTR, "debug_implicit_ptr", "t", RTX_OBJ)

/* Represents value that argument had on function entry.  The
   single argument is the DECL_INCOMING_RTL of the corresponding
   parameter.  */
DEF_RTL_EXPR(ENTRY_VALUE, "entry_value", "0", RTX_OBJ)

/* Used in VAR_LOCATION for a reference to a parameter that has
   been optimized away completely.  */
DEF_RTL_EXPR(DEBUG_PARAMETER_REF, "debug_parameter_ref", "t", RTX_OBJ)

/* Used in marker DEBUG_INSNs to avoid being recognized as an insn.  */
DEF_RTL_EXPR(DEBUG_MARKER, "debug_marker", "", RTX_EXTRA)

/* All expressions from this point forward appear only in machine
   descriptions.  */
#ifdef GENERATOR_FILE

/* Pattern-matching operators:  */

/* Use the function named by the second arg (the string)
   as a predicate; if matched, store the structure that was matched
   in the operand table at index specified by the first arg (the integer).
   If the second arg is the null string, the structure is just stored.

   A third string argument indicates to the register allocator restrictions
   on where the operand can be allocated.

   If the target needs no restriction on any instruction this field should
   be the null string.

   The string is prepended by:
   '=' to indicate the operand is only written to.
   '+' to indicate the operand is both read and written to.

   Each character in the string represents an allocable class for an operand.
   'g' indicates the operand can be any valid class.
   'i' indicates the operand can be immediate (in the instruction) data.
   'r' indicates the operand can be in a register.
   'm' indicates the operand can be in memory.
   'o' a subset of the 'm' class.  Those memory addressing modes that
       can be offset at compile time (have a constant added to them).

   Other characters indicate target dependent operand classes and
   are described in each target's machine description.

   For instructions with more than one operand, sets of classes can be
   separated by a comma to indicate the appropriate multi-operand constraints.
   There must be a 1 to 1 correspondence between these sets of classes in
   all operands for an instruction.
   */
DEF_RTL_EXPR(MATCH_OPERAND, "match_operand", "iss", RTX_MATCH)

/* Match a SCRATCH or a register.  When used to generate rtl, a
   SCRATCH is generated.  As for MATCH_OPERAND, the mode specifies
   the desired mode and the first argument is the operand number.
   The second argument is the constraint.  */
DEF_RTL_EXPR(MATCH_SCRATCH, "match_scratch", "is", RTX_MATCH)

/* Apply a predicate, AND match recursively the operands of the rtx.
   Operand 0 is the operand-number, as in match_operand.
   Operand 1 is a predicate to apply (as a string, a function name).
   Operand 2 is a vector of expressions, each of which must match
   one subexpression of the rtx this construct is matching.  */
DEF_RTL_EXPR(MATCH_OPERATOR, "match_operator", "isE", RTX_MATCH)

/* Match a PARALLEL of arbitrary length.  The predicate is applied
   to the PARALLEL and the initial expressions in the PARALLEL are matched.
   Operand 0 is the operand-number, as in match_operand.
   Operand 1 is a predicate to apply to the PARALLEL.
   Operand 2 is a vector of expressions, each of which must match the
   corresponding element in the PARALLEL.  */
DEF_RTL_EXPR(MATCH_PARALLEL, "match_parallel", "isE", RTX_MATCH)

/* Match only something equal to what is stored in the operand table
   at the index specified by the argument.  Use with MATCH_OPERAND.  */
DEF_RTL_EXPR(MATCH_DUP, "match_dup", "i", RTX_MATCH)

/* Match only something equal to what is stored in the operand table
   at the index specified by the argument.  Use with MATCH_OPERATOR.  */
DEF_RTL_EXPR(MATCH_OP_DUP, "match_op_dup", "iE", RTX_MATCH)

/* Match only something equal to what is stored in the operand table
   at the index specified by the argument.  Use with MATCH_PARALLEL.  */
DEF_RTL_EXPR(MATCH_PAR_DUP, "match_par_dup", "iE", RTX_MATCH)

/* Appears only in define_predicate/define_special_predicate
   expressions.  Evaluates true only if the operand has an RTX code
   from the set given by the argument (a comma-separated list).  If the
   second argument is present and nonempty, it is a sequence of digits
   and/or letters which indicates the subexpression to test, using the
   same syntax as genextract/genrecog's location strings: 0-9 for
   XEXP (op, n), a-z for XVECEXP (op, 0, n); each character applies to
   the result of the one before it.  */
DEF_RTL_EXPR(MATCH_CODE, "match_code", "ss", RTX_MATCH)

/* Used to inject a C conditional expression into an .md file.  It can
   appear in a predicate definition or an attribute expression.  */
DEF_RTL_EXPR(MATCH_TEST, "match_test", "s", RTX_MATCH)

/* Insn (and related) definitions.  */

/* Definition of the pattern for one kind of instruction.
   Operand:
   0: names this instruction.
      If the name is the null string, the instruction is in the
      machine description just to be recognized, and will never be emitted by
      the tree to rtl expander.
   1: is the pattern.
   2: is a string which is a C expression
      giving an additional condition for recognizing this pattern.
      A null string means no extra condition.
   3: is the action to execute if this pattern is matched.
      If this assembler code template starts with a * then it is a fragment of
      C code to run to decide on a template to use.  Otherwise, it is the
      template to use.
   4: optionally, a vector of attributes for this insn.
     */
DEF_RTL_EXPR(DEFINE_INSN, "define_insn", "sEsTV", RTX_EXTRA)

/* Definition of a peephole optimization.
   1st operand: vector of insn patterns to match
   2nd operand: C expression that must be true
   3rd operand: template or C code to produce assembler output.
   4: optionally, a vector of attributes for this insn.

   This form is deprecated; use define_peephole2 instead.  */
DEF_RTL_EXPR(DEFINE_PEEPHOLE, "define_peephole", "EsTV", RTX_EXTRA)

/* Definition of a split operation.
   1st operand: insn pattern to match
   2nd operand: C expression that must be true
   3rd operand: vector of insn patterns to place into a SEQUENCE
   4th operand: optionally, some C code to execute before generating the
        insns.  This might, for example, create some RTX's and store them in
        elements of `recog_data.operand' for use by the vector of
        insn-patterns.
        (`operands' is an alias here for `recog_data.operand').  */
DEF_RTL_EXPR(DEFINE_SPLIT, "define_split", "EsES", RTX_EXTRA)

/* Definition of an insn and associated split.
   This is the concatenation, with a few modifications, of a define_insn
   and a define_split which share the same pattern.
   Operand:
   0: names this instruction.
      If the name is the null string, the instruction is in the
      machine description just to be recognized, and will never be emitted by
      the tree to rtl expander.
   1: is the pattern.
   2: is a string which is a C expression
      giving an additional condition for recognizing this pattern.
      A null string means no extra condition.
   3: is the action to execute if this pattern is matched.
      If this assembler code template starts with a * then it is a fragment of
      C code to run to decide on a template to use.  Otherwise, it is the
      template to use.
   4: C expression that must be true for split.  This may start with "&&"
      in which case the split condition is the logical and of the insn
      condition and what follows the "&&" of this operand.
   5: vector of insn patterns to place into a SEQUENCE
   6: optionally, some C code to execute before generating the
        insns.  This might, for example, create some RTX's and store them in
        elements of `recog_data.operand' for use by the vector of
        insn-patterns.
        (`operands' is an alias here for `recog_data.operand').
   7: optionally, a vector of attributes for this insn.  */
DEF_RTL_EXPR(DEFINE_INSN_AND_SPLIT, "define_insn_and_split", "sEsTsESV", RTX_EXTRA)

/* Definition of an RTL peephole operation.
   Follows the same arguments as define_split.  */
DEF_RTL_EXPR(DEFINE_PEEPHOLE2, "define_peephole2", "EsES", RTX_EXTRA)

/* Define how to generate multiple insns for a standard insn name.
   1st operand: the insn name.
   2nd operand: vector of insn-patterns.
        Use match_operand to substitute an element of `recog_data.operand'.
   3rd operand: C expression that must be true for this to be available.
        This may not test any operands.
   4th operand: Extra C code to execute before generating the insns.
        This might, for example, create some RTX's and store them in
        elements of `recog_data.operand' for use by the vector of
        insn-patterns.
        (`operands' is an alias here for `recog_data.operand').
   5th: optionally, a vector of attributes for this expand.  */
DEF_RTL_EXPR(DEFINE_EXPAND, "define_expand", "sEssV", RTX_EXTRA)

/* Define a requirement for delay slots.
   1st operand: Condition involving insn attributes that, if true,
                indicates that the insn requires the number of delay slots
                shown.
   2nd operand: Vector whose length is the three times the number of delay
                slots required.
                Each entry gives three conditions, each involving attributes.
                The first must be true for an insn to occupy that delay slot
                location.  The second is true for all insns that can be
                annulled if the branch is true and the third is true for all
                insns that can be annulled if the branch is false.

   Multiple DEFINE_DELAYs may be present.  They indicate differing
   requirements for delay slots.  */
DEF_RTL_EXPR(DEFINE_DELAY, "define_delay", "eE", RTX_EXTRA)

/* Define attribute computation for `asm' instructions.  */
DEF_RTL_EXPR(DEFINE_ASM_ATTRIBUTES, "define_asm_attributes", "V", RTX_EXTRA)

/* Definition of a conditional execution meta operation.  Automatically
   generates new instances of DEFINE_INSN, selected by having attribute
   "predicable" true.  The new pattern will contain a COND_EXEC and the
   predicate at top-level.

   Operand:
   0: The predicate pattern.  The top-level form should match a
      relational operator.  Operands should have only one alternative.
   1: A C expression giving an additional condition for recognizing
      the generated pattern.
   2: A template or C code to produce assembler output.
   3: A vector of attributes to append to the resulting cond_exec insn.  */
DEF_RTL_EXPR(DEFINE_COND_EXEC, "define_cond_exec", "EssV", RTX_EXTRA)

/* Definition of an operand predicate.  The difference between
   DEFINE_PREDICATE and DEFINE_SPECIAL_PREDICATE is that genrecog will
   not warn about a match_operand with no mode if it has a predicate
   defined with DEFINE_SPECIAL_PREDICATE.

   Operand:
   0: The name of the predicate.
   1: A boolean expression which computes whether or not the predicate
      matches.  This expression can use IOR, AND, NOT, MATCH_OPERAND,
      MATCH_CODE, and MATCH_TEST.  It must be specific enough that genrecog
      can calculate the set of RTX codes that can possibly match.
   2: A C function body which must return true for the predicate to match.
      Optional.  Use this when the test is too complicated to fit into a
      match_test expression.  */
DEF_RTL_EXPR(DEFINE_PREDICATE, "define_predicate", "ses", RTX_EXTRA)
DEF_RTL_EXPR(DEFINE_SPECIAL_PREDICATE, "define_special_predicate", "ses", RTX_EXTRA)

/* Definition of a register operand constraint.  This simply maps the
   constraint string to a register class.

   Operand:
   0: The name of the constraint (often, but not always, a single letter).
   1: A C expression which evaluates to the appropriate register class for
      this constraint.  If this is not just a constant, it should look only
      at -m switches and the like.
   2: A docstring for this constraint, in Texinfo syntax; not currently
      used, in future will be incorporated into the manual's list of
      machine-specific operand constraints.  */
DEF_RTL_EXPR(DEFINE_REGISTER_CONSTRAINT, "define_register_constraint", "sss", RTX_EXTRA)

/* Definition of a non-register operand constraint.  These look at the
   operand and decide whether it fits the constraint.

   DEFINE_CONSTRAINT gets no special treatment if it fails to match.
   It is appropriate for constant-only constraints, and most others.

   DEFINE_MEMORY_CONSTRAINT tells reload that this constraint can be made
   to match, if it doesn't already, by converting the operand to the form
   (mem (reg X)) where X is a base register.  It is suitable for constraints
   that describe a subset of all memory references.

   DEFINE_ADDRESS_CONSTRAINT tells reload that this constraint can be made
   to match, if it doesn't already, by converting the operand to the form
   (reg X) where X is a base register.  It is suitable for constraints that
   describe a subset of all address references.

   When in doubt, use plain DEFINE_CONSTRAINT.

   Operand:
   0: The name of the constraint (often, but not always, a single letter).
   1: A docstring for this constraint, in Texinfo syntax; not currently
      used, in future will be incorporated into the manual's list of
      machine-specific operand constraints.
   2: A boolean expression which computes whether or not the constraint
      matches.  It should follow the same rules as a define_predicate
      expression, including the bit about specifying the set of RTX codes
      that could possibly match.  MATCH_TEST subexpressions may make use of
      these variables:
        `op'    - the RTL object defining the operand.
        `mode'  - the mode of `op'.
        `ival'  - INTVAL(op), if op is a CONST_INT.
        `hval'  - CONST_DOUBLE_HIGH(op), if op is an integer CONST_DOUBLE.
        `lval'  - CONST_DOUBLE_LOW(op), if op is an integer CONST_DOUBLE.
        `rval'  - CONST_DOUBLE_REAL_VALUE(op), if op is a floating-point
                  CONST_DOUBLE.
      Do not use ival/hval/lval/rval if op is not the appropriate kind of
      RTL object.  */
DEF_RTL_EXPR(DEFINE_CONSTRAINT, "define_constraint", "sse", RTX_EXTRA)
DEF_RTL_EXPR(DEFINE_MEMORY_CONSTRAINT, "define_memory_constraint", "sse", RTX_EXTRA)
DEF_RTL_EXPR(DEFINE_SPECIAL_MEMORY_CONSTRAINT, "define_special_memory_constraint", "sse", RTX_EXTRA)
DEF_RTL_EXPR(DEFINE_ADDRESS_CONSTRAINT, "define_address_constraint", "sse", RTX_EXTRA)


/* Constructions for CPU pipeline description described by NDFAs.  */

/* (define_cpu_unit string [string]) describes cpu functional
   units (separated by comma).

   1st operand: Names of cpu functional units.
   2nd operand: Name of automaton (see comments for DEFINE_AUTOMATON).

   All define_reservations, define_cpu_units, and
   define_query_cpu_units should have unique names which may not be
   "nothing".  */
DEF_RTL_EXPR(DEFINE_CPU_UNIT, "define_cpu_unit", "sS", RTX_EXTRA)

/* (define_query_cpu_unit string [string]) describes cpu functional
   units analogously to define_cpu_unit.  The reservation of such
   units can be queried for automaton state.  */
DEF_RTL_EXPR(DEFINE_QUERY_CPU_UNIT, "define_query_cpu_unit", "sS", RTX_EXTRA)

/* (exclusion_set string string) means that each CPU functional unit
   in the first string can not be reserved simultaneously with any
   unit whose name is in the second string and vise versa.  CPU units
   in the string are separated by commas.  For example, it is useful
   for description CPU with fully pipelined floating point functional
   unit which can execute simultaneously only single floating point
   insns or only double floating point insns.  All CPU functional
   units in a set should belong to the same automaton.  */
DEF_RTL_EXPR(EXCLUSION_SET, "exclusion_set", "ss", RTX_EXTRA)

/* (presence_set string string) means that each CPU functional unit in
   the first string can not be reserved unless at least one of pattern
   of units whose names are in the second string is reserved.  This is
   an asymmetric relation.  CPU units or unit patterns in the strings
   are separated by commas.  Pattern is one unit name or unit names
   separated by white-spaces.

   For example, it is useful for description that slot1 is reserved
   after slot0 reservation for a VLIW processor.  We could describe it
   by the following construction

      (presence_set "slot1" "slot0")

   Or slot1 is reserved only after slot0 and unit b0 reservation.  In
   this case we could write

      (presence_set "slot1" "slot0 b0")

   All CPU functional units in a set should belong to the same
   automaton.  */
DEF_RTL_EXPR(PRESENCE_SET, "presence_set", "ss", RTX_EXTRA)

/* (final_presence_set string string) is analogous to `presence_set'.
   The difference between them is when checking is done.  When an
   instruction is issued in given automaton state reflecting all
   current and planned unit reservations, the automaton state is
   changed.  The first state is a source state, the second one is a
   result state.  Checking for `presence_set' is done on the source
   state reservation, checking for `final_presence_set' is done on the
   result reservation.  This construction is useful to describe a
   reservation which is actually two subsequent reservations.  For
   example, if we use

      (presence_set "slot1" "slot0")

   the following insn will be never issued (because slot1 requires
   slot0 which is absent in the source state).

      (define_reservation "insn_and_nop" "slot0 + slot1")

   but it can be issued if we use analogous `final_presence_set'.  */
DEF_RTL_EXPR(FINAL_PRESENCE_SET, "final_presence_set", "ss", RTX_EXTRA)

/* (absence_set string string) means that each CPU functional unit in
   the first string can be reserved only if each pattern of units
   whose names are in the second string is not reserved.  This is an
   asymmetric relation (actually exclusion set is analogous to this
   one but it is symmetric).  CPU units or unit patterns in the string
   are separated by commas.  Pattern is one unit name or unit names
   separated by white-spaces.

   For example, it is useful for description that slot0 can not be
   reserved after slot1 or slot2 reservation for a VLIW processor.  We
   could describe it by the following construction

      (absence_set "slot2" "slot0, slot1")

   Or slot2 can not be reserved if slot0 and unit b0 are reserved or
   slot1 and unit b1 are reserved .  In this case we could write

      (absence_set "slot2" "slot0 b0, slot1 b1")

   All CPU functional units in a set should to belong the same
   automaton.  */
DEF_RTL_EXPR(ABSENCE_SET, "absence_set", "ss", RTX_EXTRA)

/* (final_absence_set string string) is analogous to `absence_set' but
   checking is done on the result (state) reservation.  See comments
   for `final_presence_set'.  */
DEF_RTL_EXPR(FINAL_ABSENCE_SET, "final_absence_set", "ss", RTX_EXTRA)

/* (define_bypass number out_insn_names in_insn_names) names bypass
   with given latency (the first number) from insns given by the first
   string (see define_insn_reservation) into insns given by the second
   string.  Insn names in the strings are separated by commas.  The
   third operand is optional name of function which is additional
   guard for the bypass.  The function will get the two insns as
   parameters.  If the function returns zero the bypass will be
   ignored for this case.  Additional guard is necessary to recognize
   complicated bypasses, e.g. when consumer is load address.  If there
   are more one bypass with the same output and input insns, the
   chosen bypass is the first bypass with a guard in description whose
   guard function returns nonzero.  If there is no such bypass, then
   bypass without the guard function is chosen.  */
DEF_RTL_EXPR(DEFINE_BYPASS, "define_bypass", "issS", RTX_EXTRA)

/* (define_automaton string) describes names of automata generated and
   used for pipeline hazards recognition.  The names are separated by
   comma.  Actually it is possibly to generate the single automaton
   but unfortunately it can be very large.  If we use more one
   automata, the summary size of the automata usually is less than the
   single one.  The automaton name is used in define_cpu_unit and
   define_query_cpu_unit.  All automata should have unique names.  */
DEF_RTL_EXPR(DEFINE_AUTOMATON, "define_automaton", "s", RTX_EXTRA)

/* (automata_option string) describes option for generation of
   automata.  Currently there are the following options:

   o "no-minimization" which makes no minimization of automata.  This
     is only worth to do when we are debugging the description and
     need to look more accurately at reservations of states.

   o "time" which means printing additional time statistics about
      generation of automata.

   o "v" which means generation of file describing the result
     automata.  The file has suffix `.dfa' and can be used for the
     description verification and debugging.

   o "w" which means generation of warning instead of error for
     non-critical errors.

   o "ndfa" which makes nondeterministic finite state automata.

   o "progress" which means output of a progress bar showing how many
     states were generated so far for automaton being processed.  */
DEF_RTL_EXPR(AUTOMATA_OPTION, "automata_option", "s", RTX_EXTRA)

/* (define_reservation string string) names reservation (the first
   string) of cpu functional units (the 2nd string).  Sometimes unit
   reservations for different insns contain common parts.  In such
   case, you can describe common part and use its name (the 1st
   parameter) in regular expression in define_insn_reservation.  All
   define_reservations, define_cpu_units, and define_query_cpu_units
   should have unique names which may not be "nothing".  */
DEF_RTL_EXPR(DEFINE_RESERVATION, "define_reservation", "ss", RTX_EXTRA)

/* (define_insn_reservation name default_latency condition regexpr)
   describes reservation of cpu functional units (the 3nd operand) for
   instruction which is selected by the condition (the 2nd parameter).
   The first parameter is used for output of debugging information.
   The reservations are described by a regular expression according
   the following syntax:

       regexp = regexp "," oneof
              | oneof

       oneof = oneof "|" allof
             | allof

       allof = allof "+" repeat
             | repeat

       repeat = element "*" number
              | element

       element = cpu_function_unit_name
               | reservation_name
               | result_name
               | "nothing"
               | "(" regexp ")"

       1. "," is used for describing start of the next cycle in
       reservation.

       2. "|" is used for describing the reservation described by the
       first regular expression *or* the reservation described by the
       second regular expression *or* etc.

       3. "+" is used for describing the reservation described by the
       first regular expression *and* the reservation described by the
       second regular expression *and* etc.

       4. "*" is used for convenience and simply means sequence in
       which the regular expression are repeated NUMBER times with
       cycle advancing (see ",").

       5. cpu functional unit name which means its reservation.

       6. reservation name -- see define_reservation.

       7. string "nothing" means no units reservation.  */

DEF_RTL_EXPR(DEFINE_INSN_RESERVATION, "define_insn_reservation", "sies", RTX_EXTRA)

/* Expressions used for insn attributes.  */

/* Definition of an insn attribute.
   1st operand: name of the attribute
   2nd operand: comma-separated list of possible attribute values
   3rd operand: expression for the default value of the attribute.  */
DEF_RTL_EXPR(DEFINE_ATTR, "define_attr", "sse", RTX_EXTRA)

/* Definition of an insn attribute that uses an existing enumerated type.
   1st operand: name of the attribute
   2nd operand: the name of the enumerated type
   3rd operand: expression for the default value of the attribute.  */
DEF_RTL_EXPR(DEFINE_ENUM_ATTR, "define_enum_attr", "sse", RTX_EXTRA)

/* Marker for the name of an attribute.  */
DEF_RTL_EXPR(ATTR, "attr", "s", RTX_EXTRA)

/* For use in the last (optional) operand of DEFINE_INSN or DEFINE_PEEPHOLE and
   in DEFINE_ASM_INSN to specify an attribute to assign to insns matching that
   pattern.

   (set_attr "name" "value") is equivalent to
   (set (attr "name") (const_string "value"))  */
DEF_RTL_EXPR(SET_ATTR, "set_attr", "ss", RTX_EXTRA)

/* In the last operand of DEFINE_INSN and DEFINE_PEEPHOLE, this can be used to
   specify that attribute values are to be assigned according to the
   alternative matched.

   The following three expressions are equivalent:

   (set (attr "att") (cond [(eq_attrq "alternative" "1") (const_string "a1")
                            (eq_attrq "alternative" "2") (const_string "a2")]
                           (const_string "a3")))
   (set_attr_alternative "att" [(const_string "a1") (const_string "a2")
                                 (const_string "a3")])
   (set_attr "att" "a1,a2,a3")
 */
DEF_RTL_EXPR(SET_ATTR_ALTERNATIVE, "set_attr_alternative", "sE", RTX_EXTRA)

/* A conditional expression true if the value of the specified attribute of
   the current insn equals the specified value.  The first operand is the
   attribute name and the second is the comparison value.  */
DEF_RTL_EXPR(EQ_ATTR, "eq_attr", "ss", RTX_EXTRA)

/* A special case of the above representing a set of alternatives.  The first
   operand is bitmap of the set, the second one is the default value.  */
DEF_RTL_EXPR(EQ_ATTR_ALT, "eq_attr_alt", "ii", RTX_EXTRA)

/* A conditional expression which is true if the specified flag is
   true for the insn being scheduled in reorg.

   genattr.c defines the following flags which can be tested by
   (attr_flag "foo") expressions in eligible_for_delay: forward, backward.  */

DEF_RTL_EXPR (ATTR_FLAG, "attr_flag", "s", RTX_EXTRA)

/* General conditional. The first operand is a vector composed of pairs of
   expressions.  The first element of each pair is evaluated, in turn.
   The value of the conditional is the second expression of the first pair
   whose first expression evaluates nonzero.  If none of the expressions is
   true, the second operand will be used as the value of the conditional.  */
DEF_RTL_EXPR(COND, "cond", "Ee", RTX_EXTRA)

/* Definition of a pattern substitution meta operation on a DEFINE_EXPAND
   or a DEFINE_INSN.  Automatically generates new instances of DEFINE_INSNs
   that match the substitution pattern.

   Operand:
   0: The name of the substitition template.
   1: Input template to match to see if a substitution is applicable.
   2: A C expression giving an additional condition for the generated
      new define_expand or define_insn.
   3: Output tempalate to generate via substitution.

   Within a DEFINE_SUBST template, the meaning of some RTL expressions is
   different from their usual interpretation: a MATCH_OPERAND matches any
   expression tree with matching machine mode or with VOIDmode.  Likewise,
   MATCH_OP_DUP and MATCH_DUP match more liberally in a DEFINE_SUBST than
   in other RTL expressions.  MATCH_OPERATOR matches all common operators
   but also UNSPEC, UNSPEC_VOLATILE, and MATCH_OPERATORS from the input
   DEFINE_EXPAND or DEFINE_INSN.  */
DEF_RTL_EXPR(DEFINE_SUBST, "define_subst", "sEsE", RTX_EXTRA)

/* Substitution attribute to apply a DEFINE_SUBST to a pattern.

   Operand:
   0: The name of the subst-attribute.
   1: The name of the DEFINE_SUBST to be applied for this attribute.
   2: String to substitute for the subst-attribute name in the pattern
      name, for the case that the DEFINE_SUBST is not applied (i.e. the
      unmodified version of the pattern).
   3: String to substitute for the subst-attribute name in the pattern
      name, for the case that the DEFINE_SUBST is applied to the patten.
      
   The use of DEFINE_SUBST and DEFINE_SUBST_ATTR is explained in the
   GCC internals manual, under "RTL Templates Transformations".  */
DEF_RTL_EXPR(DEFINE_SUBST_ATTR, "define_subst_attr", "ssss", RTX_EXTRA)

#endif /* GENERATOR_FILE */

/*
Local variables:
mode:c
End:
*/