/* 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, 1988 Free Software Foundation, Inc.This file is part of GNU CC.GNU CC is free software; you can redistribute it and/or modifyit under the terms of the GNU General Public License as published bythe Free Software Foundation; either version 1, or (at your option)any later version.GNU CC is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See theGNU General Public License for more details.You should have received a copy of the GNU General Public Licensealong with GNU CC; see the file COPYING.  If not, write tothe Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  *//* 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->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      *//* ---------------------------------------------------------------------   Expressions (and "meta" expressions) used for structuring the   rtl representation of a program.   --------------------------------------------------------------------- *//* an expression code name unknown to the reader */DEF_RTL_EXPR(UNKNOWN, "UnKnown", "*")/* (NIL) is used by rtl reader and printer to represent a null pointer.  */DEF_RTL_EXPR(NIL, "nil", "*")/* ---------------------------------------------------------------------   Expressions used in constructing lists.   --------------------------------------------------------------------- *//* a linked list of expressions */DEF_RTL_EXPR(EXPR_LIST, "expr_list", "ee")/* a linked list of instructions.   The insns are represented in print by their uids.  */DEF_RTL_EXPR(INSN_LIST, "insn_list", "ue")/* ----------------------------------------------------------------------   Expression types for machine descripions.   These do not appear in actual rtl code in the compiler.   ---------------------------------------------------------------------- *//* Appears only in machine descriptions.   Means 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 allocatable class for an operand.   'g' indicates the operand can be any valid class.   'i' indicates the operand can be immeadiate (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")/* Appears only in machine descriptions.   Means match only something equal to what is stored in the operand table   at the index specified by the argument.  */DEF_RTL_EXPR(MATCH_DUP, "match_dup", "i")/* 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")/* Appears only in machine descriptions.   Defines 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 string of machine-dependant information about the insn.   */DEF_RTL_EXPR(DEFINE_INSN, "define_insn", "sEssS")/* 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 string of machine-dependant information about the insn.  */DEF_RTL_EXPR(DEFINE_PEEPHOLE, "define_peephole", "EssS")/* Definition of a combiner pattern.   Operands not defined yet.  */DEF_RTL_EXPR(DEFINE_COMBINE, "define_combine", "Ess")/* 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_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_operand' for use by the vector of insn-patterns.	(`operands' is an alias here for `recog_operand').  */DEF_RTL_EXPR(DEFINE_EXPAND, "define_expand", "sEss")   /* SEQUENCE appears in the result of a `gen_...' function   for a DEFINE_EXPAND that wants to make several insns.   Its elements are the bodies of the insns that should be made.   `emit_insn' takes the SEQUENCE apart and makes separate insns.  */DEF_RTL_EXPR(SEQUENCE, "sequence", "E")/* Refers to the address of its argument.   This appears only in machine descriptions, indicating that   any expression that would be acceptable as the operand of MEM   should be matched.  */DEF_RTL_EXPR(ADDRESS, "address", "e")/* ----------------------------------------------------------------------   Expressions types used for things in the instruction chain.   All formats must start with "iuu" to handle the chain.   Each insn expression holds an rtl instruction and its semantics   during back-end processing.   See macros's in "rtl.h" for the meaning of each rtx->fld[].   ---------------------------------------------------------------------- *//* An instruction that cannot jump.  */DEF_RTL_EXPR(INSN, "insn", "iuueiee")/* An instruction that can possibly jump.   Fields ( rtx->fld[] ) have exact same meaning as INSN's   except field 3 is also used in jump.c to point to the label jumped to.    Field 7 is used in jump.c as the JUMP_LABEL.  */DEF_RTL_EXPR(JUMP_INSN, "jump_insn", "iuueiee0")/* An instruction that can possibly call a subroutine   but which will not change which instruction comes next   in the current function.   Fields ( rtx->fld[] ) have exact same meaning as INSN's.  */DEF_RTL_EXPR(CALL_INSN, "call_insn", "iuueiee")/* A marker that indicates that control will not flow through.  */DEF_RTL_EXPR(BARRIER, "barrier", "iuu")/* Holds a label that is followed by instructions.   Operand:   3: is a number that is unique in the entire compilation.   4: is used in jump.c for the use-count of the label.   and in flow.c to point to the chain of label_ref's to this label.  */DEF_RTL_EXPR(CODE_LABEL, "code_label", "iuui0")     /* Say where in the code a source line starts, for symbol table's sake.   Contains a filename and a line number.  Line numbers <= 0 are special:   0 is used in a dummy placed at the front of every function      just so there will never be a need to delete the first insn;   -1 indicates a dummy; insns to be deleted by flow analysis and combining      are really changed to NOTEs with a number of -1.   -2 means beginning of a name binding contour; output N_LBRAC.   -3 means end of a contour; output N_RBRAC.  */DEF_RTL_EXPR(NOTE, "note", "iuusn")/* INLINE_HEADER is use by inline function machinery.  The information   it contains helps to build the mapping function between the rtx's of   the function to be inlined and the current function being expanded.  */DEF_RTL_EXPR(INLINE_HEADER, "inline_header", "iuuiiiiiiii")/* ----------------------------------------------------------------------   Top level constituents of INSN, JUMP_INSN and CALL_INSN.   ---------------------------------------------------------------------- */   /* Several operations to be done in parallel.  */DEF_RTL_EXPR(PARALLEL, "parallel", "E")/* 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", "s")/* 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 the name of the containing source file.   7th is the source line number.  */DEF_RTL_EXPR(ASM_OPERANDS, "asm_operands", "ssiEEsi")/* 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")/* 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.  */DEF_RTL_EXPR(ADDR_DIFF_VEC, "addr_diff_vec", "eE")/* ----------------------------------------------------------------------   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,