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|
(* label.sml
*
* COPYRIGHT (c) 2001 Bell Labs, Lucent Technologies
*)
structure Label :> LABEL =
struct
datatype label_kind = GLOB of string | LOCAL of string | ANON
type label = {
id : word,
addr : int ref,
kind : label_kind
}
local
val cnt = ref 0w0
in
fun reset () = cnt := 0w0
fun mkLab k = let val id = !cnt in cnt := id+0w1; {id=id, addr=ref ~1, kind=k} end
end (* local *)
(* make a global label *)
fun global name = mkLab(GLOB name)
(* make a label generator; note that if the prefix string is "", then
* the standard prefix "L" will be used.
*)
fun label "" = label "L"
| label prefix = let
val kind = LOCAL prefix
in
fn () => mkLab kind
end
(* make an anonymous label *)
fun anon () = mkLab ANON
(* label equality, comparisons, and hashing *)
fun same (l1 : label, l2 : label) = (#id l1 = #id l2)
fun compare (l1 : label, l2 : label) = Word.compare(#id l1, #id l2)
fun hash (l : label) = #id l
(* label addresses *)
exception GlobalLabel
fun setAddr ({id, addr, kind=GLOB _}, _) = raise GlobalLabel
| setAddr ({id, addr, kind}, a) = addr := a
fun addrOf {id, addr, kind=GLOB _} = raise GlobalLabel
| addrOf {id, addr, kind} = !addr
(* return a string representation of the label; this function is meant for
* debugging; use the fmt function for assembly output.
*)
fun toString {id, addr, kind=GLOB name} = name
| toString {id, addr, kind=LOCAL prefix} = prefix ^ Word.toString id
| toString {id, addr, kind=ANON} = ".L" ^ Word.toString id
(* format a label for assembly output. The gPrefix argument is the target
* ABI's prefix for global symbols (e.g., "_" or "") and the aPrefix is
* the target assembler's prefix for anonymous labels. Local labels are
* emitted using their specified prefxix.
*)
fun fmt {gPrefix, aPrefix} = let
fun toStr {id, addr, kind=GLOB name} = gPrefix ^ name
| toStr {id, addr, kind=LOCAL prefix} = prefix ^ Word.toString id
| toStr {id, addr, kind=ANON} = aPrefix ^ Word.toString id
in
toStr
end
end
|
