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; Instruction definitions.
; Copyright (C) 2000, 2009 Red Hat, Inc.
; This file is part of CGEN.
; See file COPYING.CGEN for details.
; Class to hold an insn.
; Used to explicitly specify mnemonic, now it's computed from
; syntax string.  ??? Might be useful as an override someday.
;mnemonic
; Instruction syntax string.
; The insn fields as specified in the .cpu file.
; Also contains values for constant fields.
; Lazily computed cache
; RTL source of assertions of ifield values or #f if none.
; This is used, for example, by the decoder to help
; distinguish what would otherwise be an ambiguity in the
; specification.  It is also used by decode-split support.
; ??? It could also be used the the assembler/disassembler
; some day.
; The <fmt-desc> of the insn.
; This is used to help calculate the ifmt,sfmt members.
; The <iformat> of the insn.
; The <sformat> of the insn.
; Temp slot for use by applications.
; Instruction semantics.
; This is the rtl in source form or #f if there is none.
;
; There are a few issues (ick, I hate that word) to consider
; here:
; - some apps don't need the trap checks (e.g. SIGSEGV)
; - some apps treat the pieces in different ways
; - the simulator tries to merge common fragments among insns
;   to reduce code size in a pbb simulator
;
; Some insns don't have any semantics at all, they are defined
; in another insn [akin to anonymous patterns in gcc].  wip.
;
; ??? GCC-like apps will need a new field to allow specifying
; the semantics if a different value is needed.  wip.
; ??? May wish to put this and the compiled forms in a
; separate class.
; ??? Contents of trap expressions is wip.  It will probably
; be a sequence with an #:errchk modifier or some such.
; The processed form of the above.
; This remains #f for virtual insns (FIXME: keep?).
; The mapping of the semantics onto the host.
; FIXME: Not sure what its value will be.
; Another thing that will be needed is [in some cases] a more
; simplified version of the RTL for use by apps like compilers.
; Perhaps that's what this will become.
; The function unit usage of the instruction.
; Accessor fns
; Return a boolean indicating if X is an <insn>.
; Return a list of the machs that support INSN.
; ??? wip
; Return the length of INSN in bits.
; Return the length of INSN in bytes.
; Return instruction mnemonic.
; This is computed from the syntax string.
; The mnemonic, as we define it, is everything up to, but not including, the
; first space or '$'.
; FIXME: Rename to syntax-mnemonic, and take a syntax string argument.
; FIXME: Doesn't handle \$ to indicate a $ is actually in the mnemonic.
; Return enum cgen_insn_types value for INSN.
"@ARCH@_INSN_"; Return enum for insn named INSN-NAME.
; This is needed for the `invalid' insn, there is no object for it.
; [Though obviously having such an object seems like a good idea.]
"@ARCH@_INSN_"; Insns with derived operands (see define-derived-operand).
; ??? These are [currently] recorded separately to minimize impact on existing
; code while the design is worked out.
;
; The class is called <multi-insn> because the insn has multiple variants,
; one for each combination of "anyof" alternatives.
; Internally we create one <insn> per alternative.  The theory is that this
; will remain an internal implementation issue.  When appropriate applications
; will collapse the number of insns in a way that is appropriate for them.
;
; ??? Another way to do this is with insn templates.  One problem the current
; way has is that it requires each operand's assembler syntax to be self
; contained (one way to fix this is to use "fake" operands like before).
; Insn templates needn't have this problem.  On the other hand insn templates
; [seem to] require more description file entries.
;
; ??? This doesn't use all of the members of <insn>.
; The <multi-insn> class is wip, but should eventually reorganize <insn>.
; This reorganization might also take into account real, virtual, etc. insns.
; An <insn> is created for each combination of "anyof"
; alternatives.  They are recorded with other insns, but a
; list of them is recorded here as well.
; This is #f if the sub-insns haven't been instantiated yet.
; Return a boolean indicating if X is a <multi-insn>.
; Subroutine of -sub-insn-make! to create the ifield list.
; Return encoding of {insn} with each element of {anyof-operands} replaced
; with {new-values}.
; {value-names} is a list of names of {anyof-operands}.
; (debug-repl-env insn anyof-operands value-names new-values)
; Delete ifields of {anyof-operands} and add those for {new-values}.
; Delete ifields in {anyof-operands}.
; Add ifields for {new-values}.
; Return the last ifield of OWNER in IFLD-LIST.
; OWNER is the object that owns the <ifield> we want.
; For ifields, the owner is the ifield itself.
; For operands, the owner is the operand.
; For derived operands, the owner is the "anyof" parent.
; IFLD-LIST is an unsorted list of <ifield> elements.
;(debug-repl-env ifld-list owner)
; This is the interesting case.  The instantiated choice of
; {owner} is in {ifld-list}.  We have to find it.
;(debug-repl-env ifld-list owner)
; derived operands are handled here too
"`owner' not <ifield>, <operand>, or <derived-operand>"; Resolve any `follows' specs.
; Bad worst case performance but ifield lists aren't usually that long.
; FIXME: Doesn't handle A following B following C.
; Subroutine of multi-insn-instantiate! to instantiate one insn.
; INSN is the parent insn.
; ANYOF-OPERANDS is a list of the <anyof-operand>'s of INSN.
; NEW-VALUES is a list of the value to use for each corresponding element in
; ANYOF-OPERANDS.  Each element is a <derived-operand>.
;(debug-repl-env insn anyof-operands new-values)
"Instantiating "":"" ""="" ...\n";  (if (eq? '@sib+disp8-QI-disp32-8
;	   (obj:name (car new-values)))
;      (debug-repl-env insn anyof-operands new-values))
; Don't create insn if ifield assertions fail.
; FIXME
"   instantiated.\n";; FIXME: Hack to remove differences in generated code when we
;; switched to recording insns in hash tables.
;; See similar comment in arch-analyze-insns!.
;; Make the ordinals count backwards.
;; Subtract 2 because mach.scm:-get-next-ordinal! adds 1.
"    failed ifield assertions.\n"; Instantiate all sub-insns of MULTI-INSN.
; ??? Might be better to return the list of insns, rather than add them to
; the global list, and leave it to the caller to add them.
; We shouldn't get called more than once.
; What we want to create here is the set of all "anyof" alternatives.
; From that we create one <insn> per alternative.
"  anyof: ""\n""    choices: ""\n"; Iterate over all combinations.
; TODO is a list with one element for each <anyof-operand>.
; Each element is in turn a list of all choices (<derived-operands>'s)
; for the <anyof-operand>.  Note that some of these values may be
; derived from nested <anyof-operand>'s.
; ??? anyof-all-choices should cache the results. [Still useful?]
; ??? Need to cache results of assertion processing in addition or
; instead of anyof-all-choices. [Still useful?]
"Instantiating "" multi-insns for "" ...\n"; ??? One might prefer a `do' loop here, but every time I see one I
; have to spend too long remembering its syntax.
"Derived: ""\n"; Parse an instruction description.
; This is the main routine for building an insn object from a
; description in the .cpu file.
; All arguments are in raw (non-evaluated) form.
; The result is the parsed object or #f if insn isn't for selected mach(s).
"Processing insn "" ...\n";; Pick out name first to augment the error context.
"cgen_insn"" format"; If there are no semantics, mark this as an alias.
; ??? Not sure this makes sense for multi-insns.
"Ignoring "".\n"; Read an instruction description.
; This is the main routine for analyzing instructions in the .cpu file.
; This is also used to create virtual insns by apps like simulators.
; CONTEXT is a <context> object for error messages.
; ARG-LIST is an associative list of field name and field value.
; -insn-parse is invoked to create the <insn> object.
""; Loop over each element in ARG-LIST, recording what's found.
"invalid insn arg"; Now that we've identified the elements, build the object.
; Define an instruction object, name/value pair list version.
"define-insn"; Define an instruction object, all arguments specified.
"define-full-insn"; Parsing support.
; Parse an insn syntax field.
; SYNTAX is either a string or a list of strings, each element of which may
; in turn be a list of strings.
; ??? Not sure this extra flexibility is worth it yet.
"improper syntax"; Subroutine of -parse-insn-format to parse a symbol ifield spec.
;(debug-repl-env sym)
; There is a one-to-one relationship b/w derived operands and
; the associated derived ifield.
; An insn-enum?
"bad format element, expecting symbol to be operand or insn enum"; Subroutine of -parse-insn-format to parse an (ifield-name value) ifield spec.
;
; The last element is the ifield's value.  It must be an integer.
; ??? Whether it can be negative is still unspecified.
; ??? While there might be a case where allowing floating point values is
; desirable, supporting them would require precise conversion routines.
; They should be rare enough that we instead punt.
;
; ??? May wish to support something like "(% startbit bitsize value)".
;
; ??? Error messages need improvement, but that's generally true of cgen.
"bad ifield format, should be (ifield-name value)"; ??? This use to allow (ifield-name operand-name).  That's how
; `operand-name' elements are handled, but there's no current need
; to handle (ifield-name operand-name).
"symbolic ifield value not an enum""ifield value not an integer or enum"; Subroutine of -parse-insn-format to parse an
; (ifield-name value) ifield spec.
; ??? There is room for growth in the specification syntax here.
; Possibilities are (ifield-name|operand-name [options] [value]).
"unknown ifield"; Given an insn format field from a .cpu file, replace it with a list of
; ifield objects with the values assigned.
;
; An insn format field is a list of ifields that make up the instruction.
; All bits must be specified, including reserved bits
; [at present no checking is made of this, but the rule still holds].
;
; A normal entry begins with `+' and then consist of the following:
; - operand name
; - (ifield-name [options] value)
; - (operand-name [options] [value])
; - insn ifield enum
;
; Example: (+ OP1_ADD (f-res2 0) dr src1 (f-src2 1) (f-res1 #xea))
;
; where OP1_ADD is an enum, dr and src1 are operands, and f-src2 and f-res1
; are ifield's.  The `+' allows for future extension.
;
; The other form of entry begins with `=' and is followed by an instruction
; name that has the same format.  The specified instruction must already be
; defined.  Instructions with this form typically also include an
; `ifield-assertion' spec to keep them separate.
;
; An empty field list is ok.  This means it's unspecified.
; VIRTUAL insns have this.
;
; This is one of the more important routines to be efficient.
; It's called for each instruction, and is one of the more expensive routines
; in insn parsing.
; field list unspecified
; ??? This use to allow <ifield> objects
; in the `car' position.  Checked for below.
"FIXME: <ifield> object in format spec""bad format element, neither symbol nor ifield spec""bad `=' format spec, should be `(= insn-name)'""unknown insn""format must begin with `+' or `='"; Return a boolean indicating if IFLD-LIST contains anyof operands.
; Insn utilities.
; ??? multi-insn support wip, may require changes here.
; Return a boolean indicating if INSN is an alias insn.
; Return a list of instructions that are not aliases in INSN-LIST.
; Return a boolean indicating if INSN is a "real" INSN
; (not ALIAS and not VIRTUAL and not a <multi-insn>).
; Return a list of real instructions in INSN-LIST.
; Return a boolean indicating if INSN is a virtual insn.
; Return a list of virtual instructions in INSN-LIST.
; Return a list of non-alias/non-pbb insns in INSN-LIST.
; Return a list of multi-insns in INSN-LIST.
; And the opposite:
; Filter out instructions whose ifield patterns are strict supersets of
; another, keeping the less general cousin.  Used to resolve ambiguity
; when there are no more bits to consider.
"Filtering "" instructions for non specializations.\n"; insn2: possible submatch (more mask bits)
"Instruction "" specialization-filtered by ""\n"; Filter out instructions whose ifield patterns are identical.
"Filtering "" instructions for identical variants.\n"; Helper function for above: does (m1,v1) match a STRICT superset of (m2,v2) ?
;
; eg> mask-superset? #b1100 #b1000 #b1110 #b1010 -> #t
; eg> mask-superset? #b1100 #b1000 #b1010 #b1010 -> #f
; eg> mask-superset? #b1100 #b1000 #b1110 #b1100 -> #f
; eg> mask-superset? #b1100 #b1000 #b1100 #b1000 -> #f
; 
"("","")"" contains ""("","")""\n"; Return a boolean indicating if INSN is a cti [control transfer insn].
; This includes SKIP-CTI insns even though they don't terminate a basic block.
; ??? SKIP-CTI insns are wip, waiting for more examples of how they're used.
; Return a boolean indicating if INSN can be executed in parallel.
; Such insns are required to have enum attribute PARALLEL != NO.
; This is worded specifically to allow the PARALLEL attribute to have more
; than just NO/YES values (should a target want to do so).
; This specification may not be sufficient, but the intent is explicit.
; Return a list of the insns that support parallel execution in INSN-LIST.
; Instruction field utilities.
; Return a boolean indicating if INSN has ifield named F-NAME.
; Insn opcode value utilities.
; Given INSN, return the length in bits of the base mask (insn-base-mask).
; Given INSN, return the bitmask of constant values (the opcode field)
; in the base part.
; Given INSN, return the sum of the constant values in the insn
; (i.e. the opcode field).
;
; See also (compute-insn-base-mask).
;
; Insn operand utilities.
; Lookup operand SEM-NAME in INSN.
; Insn syntax utilities.
; Create a list of syntax strings broken up into a list of characters and
; operand objects.
; ??? The style of the following could be more Scheme-like.  Later.
; Handle escaped syntax metacharacters.
"syntax-break-out: missing char after '\\' in "; Handle operand reference.
; Extract the symbol from the string, get the operand.
; FIXME: Will crash if $ is last char in string.
; Handle everything else.
; Given a list of syntax elements (e.g. the result of syntax-break-out),
; create a syntax string.
"\\""${""}"; Called before a .cpu file is read in.
"\
Define an instruction, name/value pair list version.
""\
Define an instruction, all arguments specified.
"; Called before a .cpu file is read in to install any builtins.
; Standard insn attributes.
; ??? Some of these can be combined into one.
"unconditional cti""conditional cti"; SKIP-CTI: one or more immediately following instructions are conditionally
; executed (or skipped)
"skip cti"; DELAY-SLOT: insn has one or more delay slots (wip)
"insn has a delay slot"; RELAXABLE: Insn has one or more identical but larger variants.
; The assembler tries this one first and then the relaxation phase
; switches to the larger ones as necessary.
; All insns of identical behaviour have a RELAX_FOO attribute that groups
; them together.
; FIXME: This is a case where we need one attribute with several values.
; Presently each RELAX_FOO will use up a bit.
"insn is relaxable"; RELAXED: Large relaxable variant.  Avoided by assembler in first pass.
"relaxed form of insn"; NO-DIS: For macro insns, do not use during disassembly.
"don't use for disassembly"; PBB: Virtual insn used for PBB support.
"virtual insn used for PBB support"; DECODE-SPLIT: insn resulted from decode-split processing
"insn split from another insn for decoding purposes"; Also (defined elsewhere):
; VIRTUAL: Helper insn used by the simulator.
; Called after the .cpu file has been read in.