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Cache attributes read by compiler— replace repeated string matching with O(1) enum lookups#19394

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T-Gro wants to merge 73 commits intomainfrom
feature/attribute-imports
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Cache attributes read by compiler— replace repeated string matching with O(1) enum lookups#19394
T-Gro wants to merge 73 commits intomainfrom
feature/attribute-imports

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@T-Gro T-Gro commented Mar 6, 2026

Attribute checks in the compiler (e.g. IsStruct, IsAbstractClass, AllowNullLiteral, NoComparison, …) were implemented as linear scans + string comparisons every time they were queried. This PR replaces that with a compute-once / query-by-flag model.

Core idea

All well-known attribute information for a given compiler item is encoded into a single uint64 flags enum — one bit per attribute. This covers:

  • WellKnownILAttributes — attributes on imported IL types (e.g. IsReadOnly, IsByRefLike, Extension, Obsolete)
  • WellKnownEntityAttributes — attributes on F# types and modules (~49 flags: Sealed, AbstractClass, NoComparison, StructuralEquality, CLIMutable, AutoOpen, …)
  • WellKnownValAttributes — attributes on F# values and members (~41 flags: DllImport, Literal, InlineIfLambda, CallerMemberName, TailCall, …)
  • WellKnownAssemblyAttributes — assembly-level attributes (AutoOpen, InternalsVisibleTo, TypeProviderAssembly, …)

The flags encode two kinds of information:

  1. Attribute presence — is the attribute there or not (single bit, e.g. AbstractClassAttribute, LiteralAttribute)
  2. Low-cardinality attribute data — bool-valued attributes use two bits (_True / _False) to distinguish [<Sealed(true)>] from [<Sealed(false)>] from absent. CompilationRepresentation similarly encodes its four known flag values as separate bits.

This does not attempt to cache high-cardinality or variable-size attribute data (strings, byte arrays, arbitrary integers). Those are still extracted on demand via typed active patterns (EntityAttribString, ValAttribInt, etc.) that compose on top of the base flag check.

How it works

  • classifyEntityAttrib / classifyValAttrib / classifyILAttrib map an attribute to its enum case via multi-level namespace+name dispatch. Computed once when the attribute list is first set; after that, every check is a single bitwise AND.
  • A generic WellKnownAttribs<'TItem, 'TFlags> struct pairs the original attribute list with its precomputed flags. Bit 63 (NotComputed) acts as a lazy-init sentinel.
  • MethInfoHasWellKnownAttribute provides the same O(1) check for method infos on the overload resolution hot path.

Migration

~60 TryFindFSharpAttribute / IsMatchingFSharpAttribute / TryDecodeILAttribute call sites migrated. Dead helpers and ~18 g.attrib_* TcGlobals members deleted.

T-Gro and others added 30 commits February 20, 2026 18:29
@T-Gro
Define WellKnownILAttributes, WellKnownEntityAttributes, WellKnownVal…
495ab1c 
…Attributes flag enums

Add three [<Flags>] enums for O(1) well-known attribute lookups:
- WellKnownILAttributes (uint32) in AbstractIL/il.fs/.fsi
- WellKnownEntityAttributes (uint64) in TypedTree/TypedTree.fs/.fsi
- WellKnownValAttributes (uint64) in TypedTree/TypedTree.fs/.fsi

Each enum uses power-of-2 bit values with NotComputed at the sign bit.
Purely additive — no existing code modified.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Add computeILWellKnownFlags and migrate IL attribute check sites
27e7424 
- Add computeILWellKnownFlags function in TypedTreeOps.fs that maps
  all 19 WellKnownILAttributes enum values to their TcGlobals attrib_* fields
- Add HasWellKnownAttribute extension members on ILAttributesStored,
  ILTypeDef, ILMethodDef, and ILFieldDef
- Migrate 12 IL-domain existence-only check sites from O(N) TryFindILAttribute
  scans to O(1) HasWellKnownAttribute calls
- Fix pre-existing ILAttributesStored sealed class callers (Given -> CreateGiven,
  customAttrsReader -> CreateReader pattern in ilread.fs)
- Keep 3 data-extracting sites (ReflectedDefinition, AutoOpen, InternalsVisibleTo)
  and 2 individual-attribute iteration sites unchanged
- TypeHierarchy.fs sites use TryFindILAttribute on storedAttrs.CustomAttrs
  (scope comparison prevents full HasWellKnownAttribute migration)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Fix IL Compute And Migration: scope-safe comparison, TypeHierarchy mi…
36da613 
…gration, remove dead enums

- Fix computeILWellKnownFlags to use name+enclosing comparison (not full
  ILTypeRef equality with scope) matching isILAttrib semantics. This fixes
  silent failures when BCL reference assemblies use ILScopeRef.Local while
  TcGlobals uses ILScopeRef.Assembly.
- Migrate TypeHierarchy.fs sites #6 and #7 (IsReadOnlyAttribute,
  RequiresLocationAttribute) to use HasWellKnownAttribute.
- Remove unused WellKnownEntityAttributes and WellKnownValAttributes enums
  from TypedTree.fs/TypedTree.fsi (dead code not part of this sprint).
- Update surface area baseline.
- Run dotnet fantomas on all changed files.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Add WellKnownEntityAttribs struct and migrate Entity.entity_attribs
8d37941 
Sprint 2: Entity Container And Infrastructure

- Add WellKnownEntityAttributes flags enum (27 flags + NotComputed sentinel)
- Add WellKnownEntityAttribs struct wrapper with O(1) attribute lookup
- Change Entity.entity_attribs field type from Attribs to WellKnownEntityAttribs
- Entity.Attribs still returns Attrib list via .AsList()
- Add Entity.EntityAttribs and Entity.SetEntityAttribs members
- Fix Entity.IsLinked for struct field (null check on AsList())
- Add computeEntityWellKnownFlags and EntityHasWellKnownAttribute in TypedTreeOps
- Update TypedTreePickle.fs to pickle/unpickle through the wrapper
- Update all entity_attribs assignments across the compiler

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Migrate 30 entity-level existence checks to EntityHasWellKnownAttribute
9e52b72 
Replace O(N) HasFSharpAttribute calls with O(1) EntityHasWellKnownAttribute
bit tests for entity-level existence-only attribute checks across:
- AugmentWithHashCompare.fs (1 site)
- CheckDeclarations.fs (12 sites)
- ConstraintSolver.fs (4 sites)
- CheckExpressions.fs (1 site)
- NameResolution.fs (9 sites)
- PostInferenceChecks.fs (2 sites)
- IlxGen.fs (2 sites)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Sprint 4: Val Container And Infrastructure - WellKnownValAttribs
1566246 
- Add WellKnownValAttributes flags enum (25 flags + NotComputed sentinel)
- Add WellKnownValAttribs wrapper struct mirroring WellKnownEntityAttribs
- Change ValOptionalData.val_attribs field type to WellKnownValAttribs
- Add Val.ValAttribs property returning WellKnownValAttribs
- Add Val.SetValAttribs accepting WellKnownValAttribs
- Val.Attribs still returns Attrib list, Val.SetAttribs still accepts Attribs
- Change ArgReprInfo.Attribs field type to WellKnownValAttribs
- Add computeValWellKnownFlags covering all 25 enum flags
- Add ValHasWellKnownAttribute helper in TypedTreeOps
- Update TypedTreePickle for val_attribs and ArgReprInfo serialization
- Fix all downstream usage sites across compiler

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Sprint 05: Migrate Val/ArgReprInfo-level existence checks to well-kno…
1ccb290 
…wn attribute flags

- Add ArgReprInfoHasWellKnownAttribute helper in TypedTreeOps.fs/.fsi
- Migrate 11 Val sites to ValHasWellKnownAttribute (O(1) flag test)
- Migrate 19 ArgReprInfo sites to ArgReprInfoHasWellKnownAttribute
- Migrate 7 Attrib list sites using computeValWellKnownFlags
- Migrate 2 Entity sites to EntityHasWellKnownAttribute
- Total: 39 existence-only attribute check sites migrated

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Sprint 6: Hybrid mapping functions and TyconRef migration
acd72b0 
Add mapILFlagToEntityFlag and mapILFlagToValFlag mapping functions to
TypedTreeOps.fs for translating WellKnownILAttributes flags to their
Entity and Val equivalents.

Add TyconRefHasWellKnownAttribute unified hybrid check function that
dispatches on IL vs F# vs provided type metadata using O(1) flag tests.

Migrate 5 existence-only TyconRef hybrid sites:
- NameResolution.fs: ExtensionAttribute check
- PostInferenceChecks.fs: IsByRefLikeAttribute and IsReadOnlyAttribute checks
- TypedTreeOps.fs: IsByRefLikeAttribute (isByrefLikeTyconRef) and
  IsReadOnlyAttribute (isTyconRefReadOnly) checks

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Sprint 7: Final validation fixes - conditional compile mapILFlagToAtt…
5f5a65e 
…ribInfo

- Wrap mapILFlagToAttribInfo in #if !NO_TYPEPROVIDERS to fix FS1182
  unused value error on netstandard2.0 target
- Simplify ProvidedTypeMetadata case in TyconRefHasWellKnownAttribute
  to reuse TyconRefHasAttribute via the new helper
- All component tests pass (6630/6630)
- All import tests pass (63/63)
- All CompilerCompat cross-version tests pass (6/6)
- All service tests pass (2089/2089)
- All scripting tests pass (99/99)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Sprint 7: Fix isByrefLikeTyconRef to use name-based attribute matching
2fe9d42 
Revert isByrefLikeTyconRef from TyconRefHasWellKnownAttribute (type-identity)
back to TyconRefHasAttributeByName (name-based) to preserve RFC FS-1053
compatibility. User code can define its own IsByRefLikeAttribute, so this
function must match by attribute name, not by type identity.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Sprint 7: Fix PostInferenceChecks IsByRefLike to use name-based match…
5a99c71 
…ing per RFC FS-1053

The IsByRefLikeAttribute check in CheckEntityDefn was incorrectly changed to
type-identity matching (TyconRefHasWellKnownAttribute) during Sprint 6. This
breaks user-defined IsByRefLikeAttribute per RFC FS-1053. Reverted to
name-based matching (TyconRefHasAttributeByName) for consistency with
isByrefLikeTyconRef in TypedTreeOps.fs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Rewrite computeEntityWellKnownFlags with multi-level path dispatch
0c9e88f 
Replace flat if/elif chain of 27 tyconRefEq comparisons with a two-phase
dispatch: first check assembly identity (ccuEq), then array pattern match
on the namespace path. User-defined attributes from unrelated assemblies
are rejected in 1-2 cheap checks instead of 27 comparisons.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Rewrite computeValWellKnownFlags with multi-level path dispatch
6e4ad5d 
Replace flat if/elif chain of tyconRefEq calls with two-phase
assembly/path routing and array pattern matching, matching the
approach used in computeEntityWellKnownFlags. User attributes
are rejected in 1-2 cheap checks instead of O(N×K) comparisons.

All 25 well-known val attributes are covered.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Rewrite computeILWellKnownFlags with prefix + string match dispatch
7a42503 
Replace flat if/elif chain of nameMatch calls against 16 AttribInfo references
with a prefix-based dispatch on ILTypeRef.Name. User-defined attributes bail out
after 1-2 prefix checks instead of scanning all 16+ comparisons.

Key changes:
- Remove 16 AttribInfo extractions from TcGlobals at function top
- Remove inline nameMatch helper
- Group by StartsWith prefix: System.Runtime.CompilerServices (13),
  Microsoft.FSharp.Core (4), then remaining (3)
- Cover SetsRequiredMembersAttribute from both CompilerServices and
  CodeAnalysis namespaces

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Migrate getAugmentationAttribs to cached WellKnownEntityAttributes flags
59b64c8 
Replace 7 TryFindFSharpBoolAttribute linear scans with cached
EntityHasWellKnownAttribute lookups. Update all pattern match sites
in CheckAugmentationAttribs, TyconIsCandidateForAugmentationWithCompare,
and TyconIsCandidateForAugmentationWithEquals from bool option to bool.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Migrate remaining existence-only attribute call sites to cached flags
af7db93 
Replace TryFindFSharpBoolAttribute/HasFSharpAttribute/TryFindFSharpAttribute
calls with EntityHasWellKnownAttribute/ValHasWellKnownAttribute at 10 sites:

- CheckDeclarations.fs: StructuralComparison, StructuralEquality
- NameResolution.fs: AutoOpen (CanAutoOpenTyconRef, module auto-open)
- Optimizer.fs: CLIMutable
- IlxGen.fs: CLIMutable, ComVisible (fast negative guard), LiteralAttribute, EntryPoint
- fsi.fs: EntryPoint (fast negative guard)

GeneralizableValueAttribute site left as-is (enum case is on Entity, not Val).
ComVisible uses conservative fast negative guard to preserve exact semantics.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Add missing enum cases to WellKnownEntityAttributes and WellKnownValA…
d5358f5 
…ttributes

Add ClassAttribute, InterfaceAttribute, StructAttribute, MeasureAttribute
to WellKnownEntityAttributes enum (bits 0x8000000u-0x40000000u).

Add NoCompilerInliningAttribute to WellKnownValAttributes enum (0x2000000uL).

Update computeEntityWellKnownFlags and computeValWellKnownFlags to recognize
the new attribute names in FSharp.Core paths.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Bool TrueFalse encoding for three-state attributes
dc15745 
Add _True/_False flag pairs for attributes that carry boolean semantics:

Entity enum: DefaultAugmentationAttribute_True/_False,
  AutoSerializableAttribute_True/_False (widened enum to uint64)

Val enum: ReflectedDefinitionAttribute_True/_False,
  DefaultValueAttribute_True/_False, NoDynamicInvocationAttribute_True/_False

Compute functions now extract bool args from attribute constructors
and set the appropriate flag. Added EntityTryGetBoolAttribute and
ValTryGetBoolAttribute helpers.

Migrated all TODO WELLKNOWN_ATTRIB bool extraction call sites:
- TypedTreeOps.fs: HasDefaultAugmentationAttribute, isSealedTy
- IlxGen.fs: DefaultAugmentation, NoDynamicInvocation, AutoSerializable
- PostInferenceChecks.fs: DefaultAugmentation
- infos.fs: ReflectedDefinition on ArgReprInfo

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Fix NoDynamicInvocation/ReflectedDefinition default to false (AssumeF…
e97f7fe 
…alse semantics)

The original code used TryFindFSharpBoolAttributeAssumeFalse for these two
attributes, which defaults to false when no explicit bool argument is present.
The | _ -> fallback incorrectly set _True; corrected to _False.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Fix ReflectedDefinitionAttribute existence check to include _False flag
a978929 
The existence check at PostInferenceChecks.fs line 2122 must check both
_True and _False flags since [<ReflectedDefinition>] without explicit
bool arg sets _False (matching TryFindFSharpBoolAttributeAssumeFalse
semantics). Without this fix, bare [<ReflectedDefinition>] on struct
members would not trigger the FS1220 error.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Flatten ILAttributesStored: eliminate Computed DU case
7fa711d 
Replace the Computed(ILAttributes * WellKnownILAttributes) DU case with a
separate mutable wellKnownFlags field on ILAttributesStored. This avoids
allocating a new DU case on every GetOrComputeWellKnownFlags call, reducing
GC pressure for IL type definitions, methods, and fields.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Fast negative guards and perf improvements for attribute checks
cc91bb1 
- Add fast negative guard for StructLayoutAttribute in IlxGen.fs
- Add fast negative guard for AttributeUsageAttribute in CheckExpressions.fs
- Optimize CombineCcuContentFragments to avoid list concat when one side is empty
- Use WellKnownEntityAttribs.Add for extension attribute additions
- Remove TODO: WELLKNOWN_ATTRIB comments from guarded sites

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Use WellKnownValAttribs.Empty instead of WellKnownValAttribs.Create([])
fafa66f 
Replace WellKnownValAttribs.Create([]) with WellKnownValAttribs.Empty in NicePrint.fs,
CompilerDiagnostics.fs, Symbols.fs, and TypedTreeBasics.fs. This avoids unnecessary
list allocations. Also remove findings.yaml leftover artifact.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
deduplicate logic for bool arg attrs
1f289ab
@T-Gro
Refactor WellKnownEntityAttribs and WellKnownValAttribs into generic …
a3ba5d1 
…WellKnownAttribs<'TItem, 'TFlags>

Extract the near-identical struct implementations into a single generic
struct WellKnownAttribs<'TItem, 'TFlags> defined in a separate file
(WellKnownAttribs.fs/fsi) outside the module rec context.

The two flag enums (WellKnownEntityAttributes, WellKnownValAttributes)
are also moved to the new file to avoid FS0073 bootstrap compiler
limitations with enum<uint64> constraints in module rec.

WellKnownEntityAttribs and WellKnownValAttribs become type aliases with
companion modules for factory functions (Empty, Create, CreateWithFlags).
All instance methods (HasWellKnownAttribute, AsList, Flags, Add, Append,
WithRecomputedFlags) live on the generic struct and work through the
type aliases unchanged.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Migrate 10 additional attribute callsites to cached well-known flags
c9b08af 
- DllImport: IlxGen.IsValRefIsDllImport and TailCallChecks to ValHasWellKnownAttribute
- CLIEventAttribute: Add flag, add ValCompileAsEvent, migrate 4 val-based callers
- ComVisibleAttribute: Split into True/False flags, migrate IlxGen bool check
- ComImportAttribute: Add True flag, migrate isComInteropTy
- CompilationRepresentation: Add ModuleSuffix/PermitNull/Instance/Static entity flags,
  migrate TyconHasUseNullAsTrueValueAttribute
- ObsoleteAttribute: Add to WellKnownILAttributes + WellKnownEntityAttributes,
  add CheckILAttributesForUnseenStored using O(1) flag check,
  migrate NameResolution.IsTyconUnseenObsoleteSpec

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Remove dead TryFindFSharpBoolAttributeAssumeFalse helper
aee8ae6 
All callers migrated to decodeBoolAttribFlag in compute functions.
Inline TryFindFSharpBoolAttribute (default=true) directly.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Phase A: Use already-computed entity flags in Phase1G
c1c2173 
Replace redundant HasFSharpAttribute/TryFindFSharpBoolAttribute calls with
direct flag tests on the entityFlags that are already computed 3 lines above.

- SealedAttribute: split into _True/_False flag pair for three-state semantics
- MeasureableAttribute: add to WellKnownEntityAttributes enum
- hasMeasureAttr, hasMeasureableAttr, hasAllowNullLiteralAttr: test entityFlags bits
- structLayoutAttr: kept as TryFindFSharpInt32Attribute (needs LayoutKind int)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Phase B: Compute entity flags ad-hoc in Phase1B and early typar check
6a4701d 
Replace HasFSharpAttribute with computeEntityWellKnownFlags + bit test
in TcTyconDefnCore_Phase1B and TyparsAllHaveMeasureDeclEarlyCheck.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Phase C: Compute val flags ad-hoc in CheckExpressions
59b08f7 
Replace HasFSharpAttribute/HasFSharpAttributeOpt with computeValWellKnownFlags
+ bit tests for: LiteralAttribute (3 sites), DllImportAttribute (1 site),
NoCompilerInliningAttribute (1 site). ComputeInlineFlag computes flags once
for both NoCompilerInlining and DllImport checks.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
T-Gro and others added 16 commits March 2, 2026 16:15
@T-Gro
Add MethInfoHasWellKnownAttribute for O(1) checks on overload resolut…
3a33729 
…ion hot path

Migrate NoEagerConstraintApplicationAttribute (2 callers in MethodCalls +
CheckExpressions) and ExtensionAttribute (NameResolution) from linear-scan
MethInfoHasAttribute to cached-flag MethInfoHasWellKnownAttribute. The new
function dispatches to ILMethodDef.HasWellKnownAttribute (cached IL flags)
for ILMeth and ValHasWellKnownAttribute (cached val flags) for FSMeth, with
ProvidedMeth fallback to the old API.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Council fixes: resolveAttribPath DU, merge IL maps, private HasWellKn…
5338bf3 
…ownAttribute, cleanup

- Refactor resolveAttribPath from callback to struct(bclPath, fsharpCorePath)
  return value. Eliminates mutable-captured-by-closure in all 3 classifiers,
  removes 1 nesting level, makes control flow linear and purely functional.
- Merge mapILFlagToAttribInfo + mapILFlagToEntityFlag into single mapILFlag
  returning struct(EntityFlag * AttribInfo option). One match, no drift risk.
- Remove HasWellKnownAttribute from .fsi — callers must use CheckFlag.
- Remove dead _g parameter from CheckCompilerFeatureRequiredAttribute.
- Add NoEagerConstraintApplicationAttribute to WellKnownValAttributes for
  complete MethInfoHasWellKnownAttribute coverage on FSMeth path.
- Add comment on dual-namespace SetsRequiredMembersAttribute.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Round 2 council fixes: extract WarnOnWithoutNull helper, dedup CheckI…
f666ca4 
…LUnseen, tryGetAssemblyAttribString

- Extract tryGetWarnOnWithoutNullMessage helper from duplicated 8-line
  decode logic at two CheckExpressions.fs callsites
- CheckILAttributesForUnseen now uses ILAttributes.HasWellKnownAttribute
  (non-caching) — same logic as CheckILAttributesForUnseenStored, no decode
- Add tryGetAssemblyAttribString for single-attrib string extraction,
  eliminating [attr] singleton-list wrapping in IncrementalBuild.fs

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Final cleanup: dead code, encapsulation, AllowNullLiteral migration, …
375270b 
…IlxGen single-scan

Dead code removed:
- WellKnownAttribs.Append (zero callers)
- ILAttributesStored.CreateGiven(idx,attrs) two-arg overload (zero callers)
- ILAttributesStored.GetCustomAttrs(int32) shim (ignored arg, fix import.fs)
- MetadataIndex + GetOrComputeWellKnownFlags removed from il.fsi (no external callers)

Encapsulation:
- CheckFlag now returns needsWriteBack bool, removing need to expose .Flags
- .Flags removed from WellKnownAttribs.fsi

Migration:
- TyconRefAllowsNull replaces 5 TryFindTyconRefBoolAttribute AllowNullLiteral
  sites with cached flag path (IL: HasWellKnownAttribute, F#: EntityTryGetBoolAttribute)

Efficiency:
- GenParamAttribs: gate tryFindValAttribByFlag with flag check, merge MarshalAs
  filter into single pass, pass valFlags to GenMarshal
- GenMarshal: accept valFlags, skip all scans when MarshalAs absent
- ComputeMethodImplAttribs: compute flags once, gate attribsHave + filterOut

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Add ValueAsStaticPropertyAttribute to WellKnownValAttributes for O(1)…
90d63d5 
… lookup

Replace List.exists with string comparison on hot path in
Val.IsCompiledAsStaticPropertyWithoutField and PostInferenceChecks
with cached WellKnownValAttributes flag check.

- Add ValueAsStaticPropertyAttribute flag at bit 39 in WellKnownValAttributes
- Add classifyValAttrib entry for the attribute
- Simplify Val.IsCompiledAsStaticPropertyWithoutField to use HasWellKnownAttribute
- Replace inline string scan in PostInferenceChecks with ValHasWellKnownAttribute
- Expose HasWellKnownAttribute and Flags in WellKnownAttribs.fsi

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Add HasWellKnownAttribute members on Entity and Val for transparent c…
c779b76 
…aching

Add convenience members that encapsulate the CheckFlag + write-back
pattern directly on Entity and Val types. This eliminates the need for
callers to manually remember the write-back step when checking well-known
attribute flags.

- Entity.HasWellKnownAttribute(flag, computeFlags) encapsulates cache update
- Val.HasWellKnownAttribute(flag, computeFlags) encapsulates cache update
- EntityHasWellKnownAttribute now forwards to entity.HasWellKnownAttribute
- ValHasWellKnownAttribute now forwards to v.HasWellKnownAttribute
- EntityTryGetBoolAttribute uses entity.HasWellKnownAttribute for first check
- Both members declared in .fsi signature files

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Add WellKnownMethAttribute struct to bundle correlated attribute chec…
d37c588 
…k parameters

Introduce WellKnownMethAttribute struct that bundles ILFlag, ValFlag, and
AttribInfo for well-known attribute checks on MethInfo. Add
MethInfoHasWellKnownAttributeSpec overload that takes the bundled struct,
delegating to the original function. Update all 3 callsites to use the
new struct-based API, eliminating the risk of passing mismatched flags.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Add ValTryGetBoolAttribute for three-state bool attribute queries on Val
297f8fb 
Mirrors EntityTryGetBoolAttribute to provide symmetric API for querying
True/False/NotPresent attribute states on Val nodes. Supports flag pairs:
ReflectedDefinition, DefaultValue, NoDynamicInvocation.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Remove unused parameters from AttributeChecking functions
9d3789b 
- Remove unused _g from CheckILExperimentalAttributes (private)
- Remove unused _m from CheckILAttributesForUnseenStored and update .fsi
- Remove unused _m from CheckFSharpAttributesForUnseen and update .fsi
- Prefix newly-unused m params with _ in PropInfoIsUnseen and IsValUnseen
- Add cross-reference doc comments between CheckILAttributesForUnseen variants
- Update all callsites in NameResolution.fs and AttributeChecking.fs

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Rewrite TryFindAutoOpenAttr and TryFindInternalsVisibleToAttr to use …
3091230 
…classifyILAttrib

Replace hand-rolled isILAttribByName checks with the modern classifyILAttrib
flag-based API for consistency with the rest of the attribute classification
infrastructure. Remove unused tname_AutoOpenAttr binding.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Add well-known attribute API navigation guide comment block
54e44e0 
Add a comprehensive navigation comment block before the attribute helpers
section in TypedTreeOps.fs. The comment documents all well-known attribute
APIs organized by category: existence checks, ad-hoc checks, data extraction
active patterns, bool queries, IL-level operations, cross-metadata dispatch,
and classification functions. Notes that MethInfoHasWellKnownAttribute lives
in AttributeChecking.fs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Fix verifier issues: BSL baseline, CompilerCompat test bugs, trailing…
2830d4e 
… newlines

- Commit updated surface area baseline removing stale ILAttributesStored entries
- Fix reserved keyword 'sealed' used as variable name in CompilerCompat Program.fs
- Fully qualify StructRecord.Y field for cross-project resolution
- Add trailing newlines to Library.fs and AttributeUsage.fs

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Add TailCallAttribute to WellKnownValAttributes for O(1) flag-based l…
7da15fa 
…ookup

- Add TailCallAttribute = (1uL <<< 40) to WellKnownValAttributes enum (.fs and .fsi)
- Add TailCallAttribute classification in classifyValAttrib under Microsoft.FSharp.Core
- Remove HasTailCallAttrib from TcGlobals; replace with hasTailCallAttrib helper in TailCallChecks
- Helper uses O(1) flag lookup with fallback for user-defined shadow attributes

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Consolidate TypeProviderAssemblyAttribute detection into classifyAsse…
3bb534f 
…mblyAttrib

Add WellKnownAssemblyAttributes.TypeProviderAssemblyAttribute flag and
classify it under Microsoft.FSharp.Core.CompilerServices in
classifyAssemblyAttrib. Fold detection into the existing assembly
attribute classification loop in IncrementalBuild.fs and
TransparentCompiler.fs, eliminating a duplicate List.exists scan over
topAttrs.assemblyAttrs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Fast-path DefaultMemberAttribute in indexer resolution
99caa9d 
Extract shared tryBindTyconRefAttributeCore with WellKnownILAttributes voption
parameter. Both TryBindTyconRefAttribute and TryBindTyconRefAttributeWithILFlag
delegate to it, eliminating code duplication while preserving the O(1) flag
check fast-path on the IL metadata path.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Remove duplicate DefaultAugmentation(false) test
e31b5e4 
The test 'DefaultAugmentation(false) suppresses helpers' in AttributeUsage.fs
was a near-duplicate of the more specific 'Is* discriminated union properties
are unavailable with DefaultAugmentation(false)' test in DiscriminatedUnionTests.fs.
Remove the duplicate per TEST-CODE-QUALITY verifier feedback.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@T-Gro T-Gro added NO_RELEASE_NOTES Label for pull requests which signals, that user opted-out of providing release notes Refactoring labels Mar 6, 2026
T-Gro and others added 5 commits March 6, 2026 11:13
@T-Gro
Merge remote-tracking branch 'origin/main' into feature/attribute-imp…
82916ab 
…orts

# Conflicts:
#	src/Compiler/Checking/Expressions/CheckExpressions.fs
@T-Gro
AugmentWishHashCompare - remove 7 bools in matches
9b1ef99
@T-Gro
Fix MarshalAs regression: don't filter attribute before GenMarshal re…
d3228b6 
…ads it

GenParamAttribs was filtering MarshalAsAttribute from the attribs list
before passing it to GenMarshal, which then couldn't find the attribute
data (UnmanagedType value). Remove MarshalAs from the pre-filter mask
and let GenMarshal handle its own filtering.

Fixes: Marshal_fs IL baseline test (all platforms)
Fixes: attributes-FSC_OPTIMIZED/FSI (Windows Desktop)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Fix fantomas formatting in TypedTree.fsi and TypedTreeOps.fsi
dc294bb 
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@T-Gro
Merge branch 'main' into feature/attribute-imports
581b9b6
@T-Gro T-Gro marked this pull request as ready for review March 6, 2026 20:55
@T-Gro T-Gro requested a review from a team as a code owner March 6, 2026 20:55
@T-Gro T-Gro requested a review from abonie March 6, 2026 20:55
@T-Gro T-Gro changed the title WIP :: Idea :: Cache attributes read by compiler— replace repeated string matching with O(1) enum lookups Cache attributes read by compiler— replace repeated string matching with O(1) enum lookups Mar 6, 2026
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