52b1b342ab
This PR implements zero cost `BaseIO` by erasing the `IO.RealWorld` parameter from argument lists and structures. This is a **major breaking change for FFI**. Concretely: - `BaseIO` is defined in terms of `ST IO.RealWorld` - `EIO` (and thus `IO`) is defined in terms of `EST IO.RealWorld` - The opaque `Void` type is introduced and the trivial structure optimization updated to account for it. Furthermore, arguments of type `Void s` are removed from the argument lists of the C functions. - `ST` is redefined as `Void s -> ST.Out s a` where `ST.Out` is a pair of `Void s` and `a` This together has the following major effects on our generated code: - Functions that return `BaseIO`/`ST`/`EIO`/`IO`/`EST` now do not take the dummy world parameter anymore. To account for this FFI code needs to delete the dummy world parameter from the argument lists. - Functions that return `BaseIO`/`ST` now return their wrapped value directly. In particular `BaseIO UInt32` now returns a `uint32_t` instead of a `lean_object*`. To account for this FFI code might have to change the return type and does not need to call `lean_io_result_mk_ok` anymore but can instead just `return` values right away (same with extracting values from `BaseIO` computations. - Functions that return `EIO`/`IO`/`EST` now only return the equivalent of an `Except` node which reduces the allocation size. The `lean_io_result_mk_ok`/`lean_io_result_mk_error` functions were updated to account for this already so no change is required. Besides improving performance by dropping allocation (sizes) we can now also do fun new things such as: ```lean @[extern "malloc"] opaque malloc (size : USize) : BaseIO USize ```
71 lines
2.4 KiB
Text
71 lines
2.4 KiB
Text
/-
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Copyright (c) 2025 Lean FRO, LLC. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Henrik Böving
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-/
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module
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prelude
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public import Lean.Compiler.LCNF.CompilerM
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import Lean.Compiler.LCNF.BaseTypes
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import Lean.Compiler.LCNF.Util
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namespace Lean.Compiler.LCNF
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/--
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Given a constructor, return a bitmask `m` s.t. `m[i]` is true if field `i` is
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computationally relevant.
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-/
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def getRelevantCtorFields (ctorName : Name) (trivialType : Expr → MetaM Bool) :
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CoreM (Array Bool) := do
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let .ctorInfo info ← getConstInfo ctorName | unreachable!
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Meta.MetaM.run' do
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Meta.forallTelescopeReducing info.type fun xs _ => do
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let mut result := #[]
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for x in xs[info.numParams...*] do
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let type ← Meta.inferType x
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result := result.push !(← trivialType type)
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return result
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/--
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We say a structure has a trivial structure if it has not builtin support in the runtime,
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it has only one constructor, and this constructor has only one relevant field.
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-/
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public structure TrivialStructureInfo where
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ctorName : Name
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numParams : Nat
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fieldIdx : Nat
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deriving Inhabited, Repr
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/--
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Return `some fieldIdx` if `declName` is the name of an inductive datatype s.t.
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- It does not have builtin support in the runtime.
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- It has only one constructor.
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- This constructor has only one computationally relevant field.
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-/
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public def Irrelevant.hasTrivialStructure?
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(cacheExt : CacheExtension Name (Option TrivialStructureInfo))
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(trivialType : Expr → MetaM Bool) (declName : Name) : CoreM (Option TrivialStructureInfo) := do
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match (← cacheExt.find? declName) with
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| some info? => return info?
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| none =>
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let info? ← fillCache
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cacheExt.insert declName info?
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return info?
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where fillCache : CoreM (Option TrivialStructureInfo) := do
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if isRuntimeBuiltinType declName then return none
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let .inductInfo info ← getConstInfo declName | return none
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if info.isUnsafe || info.isRec then return none
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let [ctorName] := info.ctors | return none
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let ctorType ← getOtherDeclBaseType ctorName []
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if ctorType.isErased then return none
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let mask ← getRelevantCtorFields ctorName trivialType
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let mut result := none
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for h : i in *...mask.size do
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if mask[i] then
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if result.isSome then return none
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result := some { ctorName, fieldIdx := i, numParams := info.numParams }
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return result
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end Lean.Compiler.LCNF
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