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[MicroPerf] Cache IL method parameter attributes during overload resolution #20353

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[MicroPerf] Cache IL method parameter attributes during overload resolution #20353

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963aa38
Cache IL method parameter attributes during overload resolution
T-Gro Aug 25, 2026
b77c6c6
Merge branch 'main' into t-gro-overload-meta-reimport-spike
T-Gro Aug 26, 2026
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87 changes: 55 additions & 32 deletions src/Compiler/Checking/infos.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,8 @@
module internal FSharp.Compiler.Infos

open System
open System.Collections.Generic
open System.Runtime.CompilerServices
open Internal.Utilities.Library
open Internal.Utilities.Library.Extras
open FSharp.Compiler
Expand Down Expand Up @@ -658,6 +660,56 @@ type ILMethInfo =
|> GetFSharpViewOfReturnType amap.g


// Module-level, not a local closure, so cache hits in GetParamAttribs allocate nothing.
let private ComputeILMethodParamAttribs g (ilMethInfo: ILMethInfo) amap m =
[ [ for p in ilMethInfo.ParamMetadata do
let attrs = p.CustomAttrs
let isParamArrayArg = p.CustomAttrsStored.HasWellKnownAttribute(g, WellKnownILAttributes.ParamArrayAttribute)
let reflArgInfo =
match attrs with
| ILAttribDecoded WellKnownILAttributes.ReflectedDefinitionAttribute ([ILAttribElem.Bool b ], _) -> ReflectedArgInfo.Quote b
| ILAttribDecoded WellKnownILAttributes.ReflectedDefinitionAttribute _ -> ReflectedArgInfo.Quote false
| _ -> ReflectedArgInfo.None
let isOutArg = (p.IsOut && not p.IsIn)
let isInArg = (p.IsIn && not p.IsOut)
// Note: we get default argument values from VB and other .NET language metadata
let optArgInfo = OptionalArgInfo.FromILParameter g amap m ilMethInfo.MetadataScope ilMethInfo.DeclaringTypeInst p

let isCallerLineNumberArg = p.CustomAttrsStored.HasWellKnownAttribute(g, WellKnownILAttributes.CallerLineNumberAttribute)
let isCallerFilePathArg = p.CustomAttrsStored.HasWellKnownAttribute(g, WellKnownILAttributes.CallerFilePathAttribute)
let isCallerMemberNameArg = p.CustomAttrsStored.HasWellKnownAttribute(g, WellKnownILAttributes.CallerMemberNameAttribute)

let callerInfo =
match isCallerLineNumberArg, isCallerFilePathArg, isCallerMemberNameArg with
| false, false, false -> NoCallerInfo
| true, false, false -> CallerLineNumber
| false, true, false -> CallerFilePath
| false, false, true -> CallerMemberName
| _, _, _ ->
// if multiple caller info attributes are specified, pick the "wrong" one here
// so that we get an error later
if p.Type.TypeRef.FullName = "System.Int32" then CallerFilePath
else CallerLineNumber

ParamAttribs(isParamArrayArg, isInArg, isOutArg, optArgInfo, callerInfo, reflArgInfo) ] ]

// Extension view drops the object arg from ParamMetadata, so IsILExtensionMethod is part of the key.
let private getILMethodParamAttribsTable =
WeakMap.getOrCreate (fun (amap: ImportMap) ->
MemoizationTable(
"ilMethodParamAttribs",
(fun (struct (ilMethInfo: ILMethInfo, m)) -> ComputeILMethodParamAttribs amap.g ilMethInfo amap m),
keyComparer =
{ new IEqualityComparer<struct (ILMethInfo * range)> with

@abonie abonie Aug 28, 2026

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Does dropping the range in the methods below create a risk of reporting a diagnostic with a wrong range later on?

member _.GetHashCode(struct (mi, _)) =
RuntimeHelpers.GetHashCode mi.RawMetadata ^^^ (if mi.IsILExtensionMethod then 1 else 0)

member _.Equals(struct (mi1, _), struct (mi2, _)) =
mi1.IsILExtensionMethod = mi2.IsILExtensionMethod
&& mi1.RawMetadata === mi2.RawMetadata },
canMemoize = fun (struct (mi, _)) -> mi.DeclaringTypeInst.IsEmpty))


/// Describes an F# use of a method
[<System.Diagnostics.DebuggerDisplay("{DebuggerDisplayName}")>]
[<NoComparison; NoEquality>]
Expand Down Expand Up @@ -1335,39 +1387,10 @@ type MethInfo =
#endif

/// Get the parameter attributes of a method info, which get combined with the parameter names and types
member x.GetParamAttribs(amap, m) =
member x.GetParamAttribs(amap: ImportMap, m) =
match x with
| ILMeth(g, ilMethInfo, _) ->
[ [ for p in ilMethInfo.ParamMetadata do
let attrs = p.CustomAttrs
let isParamArrayArg = p.CustomAttrsStored.HasWellKnownAttribute(g, WellKnownILAttributes.ParamArrayAttribute)
let reflArgInfo =
match attrs with
| ILAttribDecoded WellKnownILAttributes.ReflectedDefinitionAttribute ([ILAttribElem.Bool b ], _) -> ReflectedArgInfo.Quote b
| ILAttribDecoded WellKnownILAttributes.ReflectedDefinitionAttribute _ -> ReflectedArgInfo.Quote false
| _ -> ReflectedArgInfo.None
let isOutArg = (p.IsOut && not p.IsIn)
let isInArg = (p.IsIn && not p.IsOut)
// Note: we get default argument values from VB and other .NET language metadata
let optArgInfo = OptionalArgInfo.FromILParameter g amap m ilMethInfo.MetadataScope ilMethInfo.DeclaringTypeInst p

let isCallerLineNumberArg = p.CustomAttrsStored.HasWellKnownAttribute(g, WellKnownILAttributes.CallerLineNumberAttribute)
let isCallerFilePathArg = p.CustomAttrsStored.HasWellKnownAttribute(g, WellKnownILAttributes.CallerFilePathAttribute)
let isCallerMemberNameArg = p.CustomAttrsStored.HasWellKnownAttribute(g, WellKnownILAttributes.CallerMemberNameAttribute)

let callerInfo =
match isCallerLineNumberArg, isCallerFilePathArg, isCallerMemberNameArg with
| false, false, false -> NoCallerInfo
| true, false, false -> CallerLineNumber
| false, true, false -> CallerFilePath
| false, false, true -> CallerMemberName
| _, _, _ ->
// if multiple caller info attributes are specified, pick the "wrong" one here
// so that we get an error later
if p.Type.TypeRef.FullName = "System.Int32" then CallerFilePath
else CallerLineNumber

ParamAttribs(isParamArrayArg, isInArg, isOutArg, optArgInfo, callerInfo, reflArgInfo) ] ]
| ILMeth(_, ilMethInfo, _) ->
(getILMethodParamAttribsTable amap).Apply(struct (ilMethInfo, m))

| FSMeth(g, _, vref, _) ->
GetArgInfosOfMember x.IsCSharpStyleExtensionMember g vref
Expand Down
13 changes: 13 additions & 0 deletions tests/FSharp.Compiler.ComponentTests/Language/ExtensionMethodTests.fs
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Original file line number Diff line number Diff line change
Expand Up @@ -844,3 +844,16 @@ module CompiledExtensions =
"""
|> compile
|> shouldSucceed

[<Fact>]
let ``IL extension method used with both instance and static call syntax`` () =
Fsx
"""
open System.Linq
let xs : System.Collections.Generic.IEnumerable<int> = Seq.ofList [ 1; 2; 3 ]
let a = xs.Select(fun x -> x + 1) |> Seq.length
let b = System.Linq.Enumerable.Select(xs, (fun x -> x + 1)) |> Seq.length
if a <> b then failwith "unexpected"

@abonie abonie Aug 28, 2026

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This is a runtime check, but the test only asserts that compilation should succeed.

"""
|> compile
|> shouldSucceed
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