lean4-htt/src/Lean/Compiler/Specialize.lean
2025-10-16 20:27:46 +00:00

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/-
Copyright (c) 2019 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Leonardo de Moura
-/
module
prelude
public import Lean.Meta.Basic
public section
namespace Lean.Compiler
inductive SpecializeAttributeKind where
| specialize | nospecialize
deriving Inhabited, BEq
/--
Marks a definition to never be specialized during code generation.
-/
@[builtin_doc]
builtin_initialize nospecializeAttr : TagAttribute ←
registerTagAttribute `nospecialize "mark definition to never be specialized"
private def elabSpecArgs (declName : Name) (args : Array Syntax) : MetaM (Array Nat) := do
if args.isEmpty then return #[]
let info ← getConstInfo declName
Meta.forallTelescopeReducing info.type fun xs _ => do
let argNames ← xs.mapM fun x => x.fvarId!.getUserName
let mut result := #[]
for arg in args do
if let some idx := arg.isNatLit? then
if idx == 0 then throwErrorAt arg "Invalid specialization argument index `0`: Index must be greater than 0"
let idx := idx - 1
if h : idx >= argNames.size then
throwErrorAt arg "Invalid argument index `{idx}`: `{.ofConstName declName}` has only {argNames.size} arguments"
else
if result.contains idx then throwErrorAt arg "Invalid specialization argument index `{idx + 1}`: \
The argument at this index (`{argNames[idx]}`) has already been specified as a specialization candidate"
result := result.push idx
else
let argName := arg.getId
if let some idx := argNames.idxOf? argName then
if result.contains idx then throwErrorAt arg "Invalid specialization argument name `{argName}`: \
It has already been specified as a specialization candidate"
result := result.push idx
else
throwErrorAt arg "Invalid specialization argument name `{argName}`: `{.ofConstName declName}` does not have an argument with this name"
return result.qsort (·<·)
/--
Marks a definition to always be specialized during code generation.
Specialization is an optimization in the code generator for generating variants of a function that
are specialized to specific parameter values. This is in particular useful for functions that take
other functions as parameters: Usually when passing functions as parameters, a closure needs to be
allocated that will then be called. Using `@[specialize]` prevents both of these operations by
using the provided function directly in the specialization of the inner function.
`@[specialize]` can take additional arguments for the parameter names or indices (starting at 1) of
the parameters that should be specialized. By default, instance and function parameters are
specialized.
-/
@[builtin_doc]
builtin_initialize specializeAttr : ParametricAttribute (Array Nat) ←
registerParametricAttribute {
name := `specialize
descr := "mark definition to always be specialized"
getParam := fun declName stx => do
let args := stx[1].getArgs
elabSpecArgs declName args |>.run'
}
def getSpecializationArgs? (env : Environment) (declName : Name) : Option (Array Nat) :=
specializeAttr.getParam? env declName
def hasSpecializeAttribute (env : Environment) (declName : Name) : Bool :=
getSpecializationArgs? env declName |>.isSome
def hasNospecializeAttribute (env : Environment) (declName : Name) : Bool :=
nospecializeAttr.hasTag env declName
end Lean.Compiler