+;;; Define the symbol NAME to be a Virtual OPeration in the compiler.
+;;; If specified, INHERITS is the name of a VOP that we default
+;;; unspecified information from. Each SPEC is a list beginning with a
+;;; keyword indicating the interpretation of the other forms in the
+;;; SPEC:
+;;;
+;;; :Args {(Name {Key Value}*)}*
+;;; :Results {(Name {Key Value}*)}*
+;;; The Args and Results are specifications of the operand TNs passed
+;;; to the VOP. If there is an inherited VOP, any unspecified options
+;;; are defaulted from the inherited argument (or result) of the same
+;;; name. The following operand options are defined:
+;;;
+;;; :SCs (SC*)
+;;; :SCs specifies good SCs for this operand. Other SCs will be
+;;; penalized according to move costs. A load TN will be allocated if
+;;; necessary, guaranteeing that the operand is always one of the
+;;; specified SCs.
+;;;
+;;; :Load-TN Load-Name
+;;; Load-Name is bound to the load TN allocated for this operand,
+;;; or to NIL if no load TN was allocated.
+;;;
+;;; :Load-If EXPRESSION
+;;; Controls whether automatic operand loading is done.
+;;; EXPRESSION is evaluated with the fixed operand TNs bound.
+;;; If EXPRESSION is true,then loading is done and the variable
+;;; is bound to the load TN in the generator body. Otherwise,
+;;; loading is not done, and the variable is bound to the actual
+;;; operand.
+;;;
+;;; :More T-or-NIL
+;;; If specified, Name is bound to the TN-Ref for the first
+;;; argument or result following the fixed arguments or results.
+;;; A :MORE operand must appear last, and cannot be targeted or
+;;; restricted.
+;;;
+;;; :Target Operand
+;;; This operand is targeted to the named operand, indicating a
+;;; desire to pack in the same location. Not legal for results.
+;;;
+;;; :From Time-Spec
+;;; :To Time-Spec
+;;; Specify the beginning or end of the operand's lifetime.
+;;; :FROM can only be used with results, and :TO only with
+;;; arguments. The default for the N'th argument/result is
+;;; (:ARGUMENT N)/(:RESULT N). These options are necessary
+;;; primarily when operands are read or written out of order.
+;;;
+;;; :Conditional
+;;; This is used in place of :RESULTS with conditional branch VOPs.
+;;; There are no result values: the result is a transfer of control.
+;;; The target label is passed as the first :INFO arg. The second
+;;; :INFO arg is true if the sense of the test should be negated.
+;;; A side-effect is to set the PREDICATE attribute for functions
+;;; in the :TRANSLATE option.
+;;;
+;;; :Temporary ({Key Value}*) Name*
+;;; Allocate a temporary TN for each Name, binding that variable to
+;;; the TN within the body of the generators. In addition to :TARGET
+;;; (which is is the same as for operands), the following options are
+;;; defined:
+;;;
+;;; :SC SC-Name
+;;; :Offset SB-Offset
+;;; Force the temporary to be allocated in the specified SC with the
+;;; specified offset. Offset is evaluated at macroexpand time. If
+;;; Offset is emitted, the register allocator chooses a free
+;;; location in SC. If both SC and Offset are omitted, then the
+;;; temporary is packed according to its primitive type.
+;;;
+;;; :From Time-Spec
+;;; :To Time-Spec
+;;; Similar to the argument/result option, this specifies the start and
+;;; end of the temporaries' lives. The defaults are :Load and :Save,
+;;; i.e. the duration of the VOP. The other intervening phases are
+;;; :Argument,:Eval and :Result. Non-zero sub-phases can be specified
+;;; by a list, e.g. by default the second argument's life ends at
+;;; (:Argument 1).
+;;;
+;;; :Generator Cost Form*
+;;; Specifies the translation into assembly code. Cost is the
+;;; estimated cost of the code emitted by this generator. The body
+;;; is arbitrary Lisp code that emits the assembly language
+;;; translation of the VOP. An ASSEMBLE form is wrapped around
+;;; the body, so code may be emitted by using the local INST macro.
+;;; During the evaluation of the body, the names of the operands
+;;; and temporaries are bound to the actual TNs.
+;;;
+;;; :Effects Effect*
+;;; :Affected Effect*
+;;; Specifies the side effects that this VOP has and the side
+;;; effects that effect its execution. If unspecified, these
+;;; default to the worst case.
+;;;
+;;; :Info Name*
+;;; Define some magic arguments that are passed directly to the code
+;;; generator. The corresponding trailing arguments to VOP or
+;;; %PRIMITIVE are stored in the VOP structure. Within the body
+;;; of the generators, the named variables are bound to these
+;;; values. Except in the case of :Conditional VOPs, :Info arguments
+;;; cannot be specified for VOPS that are the direct translation
+;;; for a function (specified by :Translate).
+;;;
+;;; :Ignore Name*
+;;; Causes the named variables to be declared IGNORE in the
+;;; generator body.
+;;;
+;;; :Variant Thing*
+;;; :Variant-Vars Name*
+;;; These options provide a way to parameterize families of VOPs
+;;; that differ only trivially. :Variant makes the specified
+;;; evaluated Things be the "variant" associated with this VOP.
+;;; :VARIANT-VARS causes the named variables to be bound to the
+;;; corresponding Things within the body of the generator.
+;;;
+;;; :Variant-Cost Cost
+;;; Specifies the cost of this VOP, overriding the cost of any
+;;; inherited generator.
+;;;
+;;; :Note {String | NIL}
+;;; A short noun-like phrase describing what this VOP "does", i.e.
+;;; the implementation strategy. If supplied, efficiency notes will
+;;; be generated when type uncertainty prevents :TRANSLATE from
+;;; working. NIL inhibits any efficiency note.
+;;;
+;;; :Arg-Types {* | PType | (:OR PType*) | (:CONSTANT Type)}*
+;;; :Result-Types {* | PType | (:OR PType*)}*
+;;; Specify the template type restrictions used for automatic translation.
+;;; If there is a :More operand, the last type is the more type. :CONSTANT
+;;; specifies that the argument must be a compile-time constant of the
+;;; specified Lisp type. The constant values of :CONSTANT arguments are
+;;; passed as additional :INFO arguments rather than as :ARGS.
+;;;
+;;; :Translate Name*
+;;; This option causes the VOP template to be entered as an IR2
+;;; translation for the named functions.
+;;;
+;;; :Policy {:Small | :Fast | :Safe | :Fast-Safe}
+;;; Specifies the policy under which this VOP is the best translation.
+;;;
+;;; :Guard Form
+;;; Specifies a Form that is evaluated in the global environment. If
+;;; form returns NIL, then emission of this VOP is prohibited even when
+;;; all other restrictions are met.
+;;;
+;;; :VOP-Var Name
+;;; :Node-Var Name
+;;; In the generator, bind the specified variable to the VOP or
+;;; the Node that generated this VOP.
+;;;
+;;; :Save-P {NIL | T | :Compute-Only | :Force-To-Stack}
+;;; Indicates how a VOP wants live registers saved.
+;;;
+;;; :Move-Args {NIL | :Full-Call | :Local-Call | :Known-Return}
+;;; Indicates if and how the more args should be moved into a
+;;; different frame.