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; Instruction formats.
; Copyright (C) 2000 Red Hat, Inc.
; This file is part of CGEN.
; See file COPYING.CGEN for details.
; Instruction formats are computed after the .cpu file has been read in.
; ??? May also wish to allow programmer to specify formats, but not sure this
; will complicate things more than it simplifies them, so it's defered.
;
; Two kinds of formats are defined here: iformat and sformat.
; (pronounced "I-format" and "S-format")
;
; Iformats are the instruction format as specified by the instructions' fields,
; and are the machine computed version of the generally known notion of an
; "instruction format". No semantic information is attributed to iformats.
;
; Sformats are the same as iformats except that semantics are used to
; distinguish them. For example, if an operand is refered to in one mode by
; one instruction and in a different mode by another instruction, then these
; two insns would have different sformats but the same iformat. Sformats
; are used in simulator extraction code to collapse the number of cases that
; must be handled. They can also be used to collapse the number of cases
; in the modeling code.
;
; The "base length" is the length of the insn that is initially fetched for
; decoding purposes.
; Formats are fixed in length. For variable instruction length architectures
; there are separate formats for each insn's possible length.
(define <iformat>
(class-make '<iformat>
'(<ident>)
; From <ident>:
; - NAME is derived from number, but we might have user
; specified formats someday [though I wouldn't add them
; without a clear need].
; - COMMENT is the assembler syntax of an example insn that
; uses the format.
'(
; Index into the iformat table.
number
; Sort key, used to determine insns with identical formats.
key
; List of <ifield> objects.
ifields
; min (insn-length, base-insn-size)
mask-length
; total length of insns with this format
length
; mask of base part
mask
; An example insn that uses the format.
eg-insn
)
nil)
)
; Accessor fns.
(define-getters <iformat> ifmt
(number key ifields mask-length length mask eg-insn)
)
; Traverse the ifield list to collect all base (non-derived) ifields used in it.
(define (ifields-base-ifields ifld-list)
(collect (lambda (ifld)
(ifld-base-ifields ifld))
ifld-list)
)
; Return enum cgen_fmt_type value for FMT.
; ??? Not currently used.
(define (ifmt-enum fmt)
(string-append "@CPU@_" (string-upcase (gen-sym fmt)))
)
; Given FLD-LIST, compute the length of the insn in bits.
; This is done by adding up all the field sizes.
; All bits must be represent exactly once.
(define (compute-insn-length fld-list)
(apply + (map ifld-length (collect ifld-base-ifields fld-list)))
)
; Given FLD-LIST, compute the base length in bits.
;
; For variable length instruction sets, or with cpus with multiple
; instruction sets, compute the base appropriate for this set of
; ifields. Check that ifields are not shared among isas with
; inconsistent base insn lengths.
(define (compute-insn-base-mask-length fld-list)
(let* ((isa-base-bitsizes
(remove-duplicates
(map isa-base-insn-bitsize
(map current-isa-lookup
(collect (lambda (ifld)
(bitset-attr->list (atlist-attr-value (obj-atlist ifld) 'ISA #f)))
fld-list))))))
(if (= 1 (length isa-base-bitsizes))
(min (car isa-base-bitsizes) (compute-insn-length fld-list))
(error "ifields have inconsistent isa/base-insn-size values:" isa-base-bitsizes)))
)
; Given FLD-LIST, compute the bitmask of constant values in the base part
; of the insn (i.e. the opcode field).
;
; FIXME: Need to add support for constant fields appearing outside the base
; insn. One way would be to record with each insn the value for each constant
; field. That would allow code to straightforwardly fetch it. Another would
; be to only record constant values appearing outside the base insn.
;
; See also (insn-value).
;
(define (compute-insn-base-mask fld-list)
(let* ((mask-len (compute-insn-base-mask-length fld-list))
(lsb0? (ifld-lsb0? (car fld-list)))
(mask-bitrange (make <bitrange>
0 ; word-offset
(if lsb0? (- mask-len 1) 0) ; start
mask-len ; length
mask-len ; word-length
lsb0?)))
(apply +
(map (lambda (fld) (ifld-mask fld mask-len mask-bitrange))
; Find the fields that have constant values.
(find ifld-constant? (collect ifld-base-ifields fld-list)))
)
)
)
; Return the <iformat> search key for a sorted field list.
; This determines how iformats differ from each other.
; It also speeds up searching as the search key can be anything
; (though at present searching isn't as fast as it could be).
; INSN is passed so that we can include its sanytize attribute, if present,
; so sanytized sources work (needed formats don't disappear).
(define (-ifmt-search-key insn sorted-ifld-list)
(string-map (lambda (ifld)
(string-append " ("
(or (->string (obj-attr-value insn 'sanitize))
"-nosan-")
" "
(obj:str-name ifld)
" "
(ifld-ilk ifld)
")"))
sorted-ifld-list)
)
; Create an <iformat> object for INSN.
; INDEX is the ordinal to assign to the result or -1 if unknown.
; SEARCH-KEY is the search key used to determine the iformat's uniqueness.
; IFLDS is a sorted list of INSN's ifields.
(define (ifmt-build insn index search-key iflds)
(make <iformat>
(symbol-append 'ifmt- (obj:name insn))
(string-append "e.g. " (insn-syntax insn))
atlist-empty
index
search-key
iflds
(compute-insn-base-mask-length iflds)
(compute-insn-length iflds)
(compute-insn-base-mask iflds)
insn)
)
; Sformats.
(define <sformat>
(class-make '<sformat>
'(<ident>)
; From <ident>:
; - NAME is derived from number.
; - COMMENT is the assembler syntax of an example insn that
; uses the format.
'(
; Index into the sformat table.
number
; Sort key, used to determine insns with identical formats.
key
; Non-#f if insns with this format are cti insns.
cti?
; IN-OPS is a list of input operands.
; OUT-OPS is a list of output operands.
; These are used to distinguish the format from others,
; so that the extract and read operations can be based on the
; sformat.
; The extract fns use this data to record the necessary
; information for profiling [which isn't necessarily a property
; of the field list]. We could have one extraction function
; per instruction, but there's a *lot* of duplicated code, and
; the semantic operands rarely contribute to extra formats.
; The parallel execution support uses this data to record the
; input (or output) values based on the instruction format,
; again cutting down on duplicated code.
in-ops
out-ops
; Length of all insns with this format.
; Since insns with different iformats can have the same sformat
; we need to ensure ifield extraction works among the various
; iformats. We do this by ensuring all insns with the same
; sformat have the same length.
length
; Cached list of all ifields used.
; This can be derived from IN-OPS/OUT-OPS but is computed once
; and cached here for speed.
iflds
; An example insn that uses the format.
; This is used for debugging purposes, but also to help get
; sanytization (spelled wrong on purpose) right.
eg-insn
; <sformat-argbuf> entry
; FIXME: Temporary location, to be moved elsewhere
(sbuf . #f)
)
nil)
)
; Accessor fns.
(define-getters <sformat> sfmt
(number key cti? in-ops out-ops length iflds eg-insn sbuf)
)
(define-setters <sformat> sfmt (sbuf))
(method-make-make! <sformat>
'(name comment attrs
number key cti? in-ops out-ops length iflds eg-insn)
)
; Return the <sformat> search key for a sorted field list and semantic
; operands.
; This determines how sformats differ from each other.
; It also speeds up searching as the search key can be anything
; (though at present searching isn't as fast as it could be).
;
; INSN is passed so that we can include its sanytize attribute, if present,
; so sanytized sources work (needed formats don't disappear).
; SORTED-USED-IFLDS is a sorted list of ifields used by SEM-{IN,OUT}-OPS.
; Note that it is not the complete set of ifields used by INSN.
;
; We assume INSN's <iformat> has been recorded.
;
; Note: It's important to minimize the number of created sformats. It keeps
; the generated code smaller (and sometimes faster - more usable common
; fragments in pbb simulators). Don't cause spurious differences.
(define (-sfmt-search-key insn cti? sorted-used-iflds sem-in-ops sem-out-ops)
(let ((op-key (lambda (op)
(string-append " ("
(or (->string (obj-attr-value insn 'sanitize))
"-nosan-")
" "
(obj:str-name op)
; ??? Including memory operands currently
; isn't necessary and it can account for some
; spurious differences. On the other hand
; leaving it out doesn't seem like the right
; thing to do.
(if (memory? (op:type op))
""
(string-append " "
(obj:str-name (op:mode op))))
; CGEN_OPERAND_INSTANCE_COND_REF is stored
; with the operand in the operand instance
; table thus formats must be distinguished
; by this.
(if (op:cond? op) " cond" "")
")")))
)
(list
cti?
(insn-length insn)
(string-map (lambda (ifld)
(string-append " (" (obj:str-name ifld) " " (ifld-ilk ifld) ")"))
sorted-used-iflds)
(string-map op-key
sem-in-ops)
(string-map op-key
sem-out-ops)
))
)
; Create an <sformat> object for INSN.
; INDEX is the ordinal to assign to the result or -1 if unknown.
; SEARCH-KEY is the search key used to determine the sformat's uniqueness.
; {IN,OUT}-OPS are lists of INSN's input/output operands.
; SORTED-USED-IFLDS is a sorted list of ifields used by {IN,OUT}-OPS.
; Note that it is not the complete set of ifields used by INSN.
;
; We assume INSN's <iformat> has already been recorded.
(define (sfmt-build insn index search-key cti? in-ops out-ops sorted-used-iflds)
(make <sformat>
(symbol-append 'sfmt- (obj:name insn))
(string-append "e.g. " (insn-syntax insn))
atlist-empty
index
search-key
cti?
in-ops
out-ops
(insn-length insn)
sorted-used-iflds
insn)
)
; Sort IFLDS by dependencies and then by starting bit number.
(define (-sfmt-order-iflds iflds)
(let ((up?
; ??? Something like this is preferable.
;(not (ifld-lsb0? (car ifld-list)))
(not (current-arch-insn-lsb0?))))
(let loop ((independent nil) (dependent nil) (iflds iflds))
(cond ((null? iflds)
(append (sort-ifield-list independent up?)
(sort-ifield-list dependent up?)))
; FIXME: quick hack.
((multi-ifield? (car iflds))
(loop independent (cons (car iflds) dependent) (cdr iflds)))
(else
(loop (cons (car iflds) independent) dependent (cdr iflds))))))
)
; Return a sorted list of ifields used by IN-OPS, OUT-OPS.
; The ifields are sorted by dependencies and then by start bit.
; The important points are to help distinguish sformat's by the ifields used
; and to put ifields that others depend on first.
(define (-sfmt-used-iflds in-ops out-ops)
(let ((in-iflds (map op-iflds-used in-ops))
(out-iflds (map op-iflds-used out-ops)))
(let ((all-iflds (nub (append (apply append in-iflds)
(apply append out-iflds))
obj:name)))
(-sfmt-order-iflds all-iflds)))
)
; The format descriptor is used to sort formats.
; This is a utility class internal to this file.
; There is one instance per insn.
(define <fmt-desc>
(class-make '<fmt-desc>
nil
'(
; #t if insn is a cti insn
cti?
; sorted list of insn's ifields
iflds
; computed set of input/output operands
in-ops out-ops
; set of ifields used by IN-OPS,OUT-OPS.
used-iflds
; computed set of attributes
attrs
)
nil)
)
; Accessors.
(define-getters <fmt-desc> -fmt-desc
(cti? iflds in-ops out-ops used-iflds attrs)
)
; Compute an iformat descriptor used to build an <iformat> object for INSN.
;
; If COMPUTE-SFORMAT? is #t compile the semantics and compute the semantic
; format (same as instruction format except that operands are used to
; distinguish insns).
; Attributes derivable from the semantics are also computed.
; This is all done at the same time to minimize the number of times the
; semantic code is traversed.
;
; The result is (descriptor compiled-semantics attrs).
; `descriptor' is #f for insns with an empty field list
; (this happens for virtual insns).
; `compiled-semantics' is #f if COMPUTE-SFORMAT? is #f.
; `attrs' is an <attr-list> object of attributes derived from the semantics.
;
; ??? We never traverse the semantics of virtual insns.
(define (ifmt-analyze insn compute-sformat?)
; First sort by starting bit number the list of fields in INSN.
(let ((sorted-ifields
(sort-ifield-list (insn-iflds insn)
; ??? Something like this is preferable, but
; if the first insn is a virtual insn there are
; no fields.
;(not (ifld-lsb0? (car (insn-iflds insn))))
(not (current-arch-insn-lsb0?))
)))
(if (null? sorted-ifields)
; Field list is unspecified.
(list #f #f atlist-empty)
; FIXME: error checking (e.g. missing or overlapping bits)
(let* (; A list of the various bits of semantic code.
(sems (list (insn-semantics insn)))
; Compute list of input and output operands if asked for.
(sem-ops (if compute-sformat?
(semantic-compile #f ; FIXME: context
insn sems)
(csem-make #f #f #f
(if (insn-semantics insn)
(semantic-attrs #f ; FIXME: context
insn sems)
atlist-empty))))
)
(let ((compiled-sems (csem-code sem-ops))
(in-ops (csem-inputs sem-ops))
(out-ops (csem-outputs sem-ops))
(attrs (csem-attrs sem-ops))
(cti? (or (atlist-cti? (csem-attrs sem-ops))
(insn-cti? insn))))
(list (make <fmt-desc>
cti? sorted-ifields in-ops out-ops
(if (and in-ops out-ops)
(-sfmt-used-iflds in-ops out-ops)
#f)
attrs)
compiled-sems
attrs)))))
)
; Subroutine of ifmt-compute!, to simplify it.
; Lookup INSN's iformat in IFMT-LIST and if not found add it.
; FMT-DESC is INSN's <fmt-desc> object.
; IFMT-LIST is append!'d to and the found iformat is stored in INSN.
(define (-ifmt-lookup-ifmt! insn fmt-desc ifmt-list)
(let* ((search-key (-ifmt-search-key insn (-fmt-desc-iflds fmt-desc)))
(ifmt (find-first (lambda (elm)
(equal? (ifmt-key elm) search-key))
ifmt-list)))
(if ifmt
; Format was found, use it.
(begin
(logit 3 "Using iformat " (number->string (ifmt-number ifmt)) ".\n")
(insn-set-ifmt! insn ifmt)
)
; Format wasn't found, create new entry.
(let* ((ifmt-index (length ifmt-list))
(ifmt (ifmt-build insn ifmt-index search-key
(ifields-base-ifields (-fmt-desc-iflds fmt-desc)))))
(logit 3 "Creating iformat " (number->string ifmt-index) ".\n")
(insn-set-ifmt! insn ifmt)
(append! ifmt-list (list ifmt))
)
))
*UNSPECIFIED*
)
; Subroutine of ifmt-compute!, to simplify it.
; Lookup INSN's sformat in SFMT-LIST and if not found add it.
; FMT-DESC is INSN's <fmt-desc> object.
; SFMT-LIST is append!'d to and the found sformat is stored in INSN.
;
; We assume INSN's <iformat> has already been recorded.
(define (-ifmt-lookup-sfmt! insn fmt-desc sfmt-list)
(let* ((search-key (-sfmt-search-key insn (-fmt-desc-cti? fmt-desc)
(-fmt-desc-used-iflds fmt-desc)
(-fmt-desc-in-ops fmt-desc)
(-fmt-desc-out-ops fmt-desc)))
(sfmt (find-first (lambda (elm)
(equal? (sfmt-key elm) search-key))
sfmt-list)))
(if sfmt
; Format was found, use it.
(begin
(logit 3 "Using sformat " (number->string (sfmt-number sfmt)) ".\n")
(insn-set-sfmt! insn sfmt)
)
; Format wasn't found, create new entry.
(let* ((sfmt-index (length sfmt-list))
(sfmt (sfmt-build insn sfmt-index search-key
(-fmt-desc-cti? fmt-desc)
(-fmt-desc-in-ops fmt-desc)
(-fmt-desc-out-ops fmt-desc)
(ifields-base-ifields (-fmt-desc-used-iflds fmt-desc)))))
(logit 3 "Creating sformat " (number->string sfmt-index) ".\n")
(insn-set-sfmt! insn sfmt)
(append! sfmt-list (list sfmt))
)
))
*UNSPECIFIED*
)
; Main entry point.
; Given a list of insns, compute the set of instruction formats, semantic
; formats, semantic attributes, and compiled semantics for each insn.
;
; The computed <iformat> object is stored in the `ifmt' field of each insn.
;
; Attributes derived from the semantic code are added to the insn's attributes,
; but they don't override any prespecified values.
;
; If COMPUTE-SFORMAT? is #t, the computed <sformat> object is stored in the
; `sfmt' field of each insn, and the processed semantic code is stored in the
; `compiled-semantics' field of each insn.
;
; The `fmt-desc' field of each insn is used to store an <fmt-desc> object
; which contains the search keys, sorted field list, input-operands, and
; output-operands, and is not used outside this procedure.
;
; The result is a list of two lists: the set of computed iformats, and the
; set of computed sformats.
;
; *** This is the most expensive calculation in CGEN. ***
; *** (mainly because of the detailed semantic parsing) ***
(define (ifmt-compute! insn-list compute-sformat?)
(logit 2 "Computing instruction formats and analyzing semantics ...\n")
; First analyze each insn, storing the result in fmt-desc.
; If asked to, convert the semantic code to a compiled form to simplify more
; intelligent processing of it later.
(for-each (lambda (insn)
(logit 3 "Scanning operands of " (obj:name insn) ": "
(insn-syntax insn) " ...\n")
(let ((sem-ops (ifmt-analyze insn compute-sformat?)))
(insn-set-fmt-desc! insn (car sem-ops))
(if (and compute-sformat? (cadr sem-ops))
(let ((compiled-sems (cadr sem-ops)))
(insn-set-compiled-semantics! insn (car compiled-sems))))
(obj-set-atlist! insn
(atlist-append (obj-atlist insn)
(caddr sem-ops)))
))
insn-list)
; Now for each insn, look up the ifield list in the format table (and if not
; found add it), and set the ifmt/sfmt elements of the insn.
(let* ((empty-ifmt (make <iformat>
'ifmt-empty
"empty iformat for unspecified field list"
atlist-empty ; attrs
-1 ; number
#f ; key
nil ; fields
0 ; mask-length
0 ; length
0 ; mask
#f)) ; eg-insn
(empty-sfmt (make <sformat>
'sfmt-empty
"empty sformat for unspecified field list"
atlist-empty ; attrs
-1 ; number
#f ; key
#f ; cti?
nil ; sem-in-ops
nil ; sem-out-ops
0 ; length
nil ; used iflds
#f)) ; eg-insn
(ifmt-list (list empty-ifmt))
(sfmt-list (list empty-sfmt))
)
(for-each (lambda (insn)
(logit 3 "Processing format for " (obj:name insn) ": "
(insn-syntax insn) " ...\n")
(let ((fmt-desc (insn-fmt-desc insn)))
(if fmt-desc
(begin
; Must compute <iformat> before <sformat>, the latter
; needs the former.
(-ifmt-lookup-ifmt! insn fmt-desc ifmt-list)
(if compute-sformat?
(-ifmt-lookup-sfmt! insn fmt-desc sfmt-list)))
; No field list present, use empty format.
(begin
(insn-set-ifmt! insn empty-ifmt)
(if compute-sformat?
(insn-set-sfmt! insn empty-sfmt))))))
(non-multi-insns insn-list))
; Done. Return the computed iformat and sformat lists.
(list ifmt-list sfmt-list)
)
)
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