More ValueOption in compiler: part 2 (#16567)

* More ValueOption in complier: part 2

* Update release notes

* extra optimization

* extra optimization 2

* fantomas

Author: psfinaki

docs/release-notes/.FSharp.Compiler.Service/8.0.300.md

@@ -15,6 +15,6 @@
 * Autogenerated .Is* members for unions skipped for single-case unions. ([PR 16571](https://github.com/dotnet/fsharp/pull/16571))
 * `implicitCtorSynPats` in `SynTypeDefnSimpleRepr.General` is now `SynPat option` instead of `SynSimplePats option`. ([PR #16425](https://github.com/dotnet/fsharp/pull/16425))
 * `SyntaxVisitorBase<'T>.VisitSimplePats` now takes `SynPat` instead of `SynSimplePat list`. ([PR #16425](https://github.com/dotnet/fsharp/pull/16425))
-* Reduce allocations in compiler checking via `ValueOption` usage ([PR #16323](https://github.com/dotnet/fsharp/pull/16323))
+* Reduce allocations in compiler checking via `ValueOption` usage ([PR #16323](https://github.com/dotnet/fsharp/pull/16323), [PR #16567](https://github.com/dotnet/fsharp/pull/16567))
 * Reverted [#16348](https://github.com/dotnet/fsharp/pull/16348) `ThreadStatic` `CancellationToken` changes to improve test stability and prevent potential unwanted cancellations. ([PR #16536](https://github.com/dotnet/fsharp/pull/16536))
 * Refactored parenthesization API. ([PR #16461])(https://github.com/dotnet/fsharp/pull/16461))

src/Compiler/Optimize/DetupleArgs.fs

@@ -150,14 +150,15 @@ let DetupleRewriteStackGuardDepth = StackGuard.GetDepthOption "DetupleRewrite"
 
 
 // Merge a tyapp node and and app node.
+[<return: Struct>]
 let (|TyappAndApp|_|) e =
     match e with
     | Expr.App(f, fty, tys, args, m) ->
         match stripDebugPoints (stripExpr f) with
-        | Expr.App(f2, fty2, tys2, [], m2) -> Some(f2, fty2, tys2 @ tys, args, m2)
-        | Expr.App _ -> Some(f, fty, tys, args, m) (* has args, so not combine ty args *)
-        | f -> Some(f, fty, tys, args, m)
-    | _ -> None
+        | Expr.App(f2, fty2, tys2, [], m2) -> ValueSome(f2, fty2, tys2 @ tys, args, m2)
+        | Expr.App _ -> ValueSome(f, fty, tys, args, m) (* has args, so not combine ty args *)
+        | f -> ValueSome(f, fty, tys, args, m)
+    | _ -> ValueNone
 
 [<AutoOpen>]
 module GlobalUsageAnalysis =

src/Compiler/Optimize/LowerComputedCollections.fs

@@ -230,27 +230,30 @@ let (|OptionalCoerce|) expr =
 
 // Making 'seq' optional means this kicks in for FSharp.Core, see TcArrayOrListComputedExpression
 // which only adds a 'seq' call outside of FSharp.Core
+[<return: Struct>]
 let (|OptionalSeq|_|) g amap expr =
     match expr with
     // use 'seq { ... }' as an indicator
     | Seq g (e, elemTy) -> 
-        Some (e, elemTy)
+        ValueSome (e, elemTy)
     | _ -> 
     // search for the relevant element type
     match tyOfExpr g expr with
     | SeqElemTy g amap expr.Range elemTy ->
-        Some (expr, elemTy)
-    | _ -> None
+        ValueSome (expr, elemTy)
+    | _ -> ValueNone
 
+[<return: Struct>]
 let (|SeqToList|_|) g expr =
     match expr with
-    | ValApp g g.seq_to_list_vref (_, [seqExpr], m) -> Some (seqExpr, m)
-    | _ -> None
+    | ValApp g g.seq_to_list_vref (_, [seqExpr], m) -> ValueSome (seqExpr, m)
+    | _ -> ValueNone
 
+[<return: Struct>]
 let (|SeqToArray|_|) g expr =
     match expr with
-    | ValApp g g.seq_to_array_vref (_, [seqExpr], m) -> Some (seqExpr, m)
-    | _ -> None
+    | ValApp g g.seq_to_array_vref (_, [seqExpr], m) -> ValueSome (seqExpr, m)
+    | _ -> ValueNone
 
 let LowerComputedListOrArrayExpr tcVal (g: TcGlobals) amap overallExpr =
     // If ListCollector is in FSharp.Core then this optimization kicks in

src/Compiler/Optimize/LowerSequences.fs

@@ -74,15 +74,16 @@ let tyConfirmsToSeq g ty =
         tyconRefEq g tcref g.tcref_System_Collections_Generic_IEnumerable
     | _ -> false 
 
+[<return: Struct>]
 let (|SeqElemTy|_|) g amap m ty =
     match SearchEntireHierarchyOfType (tyConfirmsToSeq g) g amap m ty with
     | None ->
         // printfn "FAILED - yield! did not yield a sequence! %s" (stringOfRange m)
-        None
+        ValueNone
     | Some seqTy ->
         // printfn "found yield!"
         let inpElemTy = List.head (argsOfAppTy g seqTy)
-        Some inpElemTy
+        ValueSome inpElemTy
 
 /// Analyze a TAST expression to detect the elaborated form of a sequence expression.
 /// Then compile it to a state machine represented as a TAST containing goto, return and label nodes.

src/Compiler/Optimize/LowerSequences.fsi

@@ -9,7 +9,8 @@ open FSharp.Compiler.TypedTree
 open FSharp.Compiler.Text
 
 /// Detect a 'seq<int>' type
-val (|SeqElemTy|_|): TcGlobals -> ImportMap -> range -> TType -> TType option
+[<return: Struct>]
+val (|SeqElemTy|_|): TcGlobals -> ImportMap -> range -> TType -> TType voption
 
 val callNonOverloadedILMethod:
     g: TcGlobals -> amap: ImportMap -> m: range -> methName: string -> ty: TType -> args: Exprs -> Expr

src/Compiler/Optimize/LowerStateMachines.fs

@@ -377,6 +377,7 @@ type LowerStateMachine(g: TcGlobals) =
         | None -> env2, expr2
 
     // Detect a state machine with a single method override
+    [<return: Struct>]
     let (|ExpandedStateMachineInContext|_|) inputExpr = 
         // All expanded resumable code state machines e.g. 'task { .. }' begin with a bind of @builder or 'defn'
         let env, expr = BindResumableCodeDefinitions env.Empty inputExpr 
@@ -405,9 +406,9 @@ type LowerStateMachine(g: TcGlobals) =
                         (moveNextThisVar, moveNextExprR), 
                         (setStateMachineThisVar, setStateMachineStateVar, setStateMachineBodyR), 
                         (afterCodeThisVar, afterCodeBodyR))
-            Some (env, remake2, moveNextBody)
+            ValueSome (env, remake2, moveNextBody)
         | _ -> 
-            None
+            ValueNone
 
     // A utility to add a jump table an expression
     let addPcJumpTable m (pcs: int list)  (pc2lab: Map<int, ILCodeLabel>) pcExpr expr =

src/Compiler/Optimize/Optimizer.fs

@@ -703,15 +703,17 @@ let rec stripValue = function
   | SizeValue(_, details) -> stripValue details (* step through SizeValue "aliases" *) 
   | vinfo -> vinfo
 
+[<return: Struct>]
 let (|StripConstValue|_|) ev = 
   match stripValue ev with
-  | ConstValue(c, _) -> Some c
-  | _ -> None
+  | ConstValue(c, _) -> ValueSome c
+  | _ -> ValueNone
 
+[<return: Struct>]
 let (|StripLambdaValue|_|) ev = 
   match stripValue ev with 
-  | CurriedLambdaValue (id, arity, sz, expr, ty) -> Some (id, arity, sz, expr, ty)
-  | _ -> None
+  | CurriedLambdaValue (id, arity, sz, expr, ty) -> ValueSome (id, arity, sz, expr, ty)
+  | _ -> ValueNone
 
 let destTupleValue ev = 
   match stripValue ev with 
@@ -723,10 +725,11 @@ let destRecdValue ev =
   | RecdValue (_tcref, info) -> Some info
   | _ -> None
 
+[<return: Struct>]
 let (|StripUnionCaseValue|_|) ev = 
   match stripValue ev with 
-  | UnionCaseValue (c, info) -> Some (c, info)
-  | _ -> None
+  | UnionCaseValue (c, info) -> ValueSome (c, info)
+  | _ -> ValueNone
 
 let mkBoolVal (g: TcGlobals) n = ConstValue(Const.Bool n, g.bool_ty)
 
@@ -1764,26 +1767,29 @@ let TryEliminateLet cenv env bind e2 m =
     | None -> mkLetBind m bind e2, 0
 
 /// Detect the application of a value to an arbitrary number of arguments
+[<return: Struct>]
 let rec (|KnownValApp|_|) expr = 
     match stripDebugPoints expr with
-    | Expr.Val (vref, _, _) -> Some(vref, [], [])
-    | Expr.App (KnownValApp(vref, typeArgs1, otherArgs1), _, typeArgs2, otherArgs2, _) -> Some(vref, typeArgs1@typeArgs2, otherArgs1@otherArgs2)
-    | _ -> None
+    | Expr.Val (vref, _, _) -> ValueSome(vref, [], [])
+    | Expr.App (KnownValApp(vref, typeArgs1, otherArgs1), _, typeArgs2, otherArgs2, _) -> ValueSome(vref, typeArgs1@typeArgs2, otherArgs1@otherArgs2)
+    | _ -> ValueNone
 
 /// Matches boolean decision tree:
 /// check single case with bool const.
+[<return: Struct>]
 let (|TDBoolSwitch|_|) dtree =
     match dtree with
     | TDSwitch(expr, [TCase (DecisionTreeTest.Const(Const.Bool testBool), caseTree )], Some defaultTree, range) ->
-        Some (expr, testBool, caseTree, defaultTree, range)
+        ValueSome (expr, testBool, caseTree, defaultTree, range)
     | _ -> 
-        None
+        ValueNone
 
 /// Check target that have a constant bool value
+[<return: Struct>]
 let (|ConstantBoolTarget|_|) target =
     match target with
-    | TTarget([], Expr.Const (Const.Bool b, _, _), _) -> Some b
-    | _ -> None
+    | TTarget([], Expr.Const (Const.Bool b, _, _), _) -> ValueSome b
+    | _ -> ValueNone
 
 /// Is this a tree, where each decision is a two-way switch (to prevent later duplication of trees), and each branch returns or true/false,
 /// apart from one branch which defers to another expression
@@ -2053,50 +2059,59 @@ let ExpandStructuralBinding cenv expr =
         ExpandStructuralBindingRaw cenv e
 
 /// Detect a query { ... }
+[<return: Struct>]
 let (|QueryRun|_|) g expr = 
     match expr with
     | Expr.App (Expr.Val (vref, _, _), _, _, [_builder; arg], _) when valRefEq g vref g.query_run_value_vref ->  
-        Some (arg, None)
+        ValueSome (arg, None)
     | Expr.App (Expr.Val (vref, _, _), _, [ elemTy ], [_builder; arg], _) when valRefEq g vref g.query_run_enumerable_vref ->  
-        Some (arg, Some elemTy)
+        ValueSome (arg, Some elemTy)
     | _ -> 
-        None
+        ValueNone
 
 let (|MaybeRefTupled|) e = tryDestRefTupleExpr e 
 
+[<return: Struct>]
 let (|AnyInstanceMethodApp|_|) e = 
     match e with 
-    | Expr.App (Expr.Val (vref, _, _), _, tyargs, [obj; MaybeRefTupled args], _) -> Some (vref, tyargs, obj, args)
-    | _ -> None
+    | Expr.App (Expr.Val (vref, _, _), _, tyargs, [obj; MaybeRefTupled args], _) -> ValueSome (vref, tyargs, obj, args)
+    | _ -> ValueNone
 
+[<return: Struct>]
 let (|InstanceMethodApp|_|) g (expectedValRef: ValRef) e = 
     match e with 
-    | AnyInstanceMethodApp (vref, tyargs, obj, args) when valRefEq g vref expectedValRef -> Some (tyargs, obj, args)
-    | _ -> None
+    | AnyInstanceMethodApp (vref, tyargs, obj, args) when valRefEq g vref expectedValRef -> ValueSome (tyargs, obj, args)
+    | _ -> ValueNone
 
+[<return: Struct>]
 let (|QuerySourceEnumerable|_|) g = function
-    | InstanceMethodApp g g.query_source_vref ([resTy], _builder, [res]) -> Some (resTy, res)
-    | _ -> None
+    | InstanceMethodApp g g.query_source_vref ([resTy], _builder, [res]) -> ValueSome (resTy, res)
+    | _ -> ValueNone
 
+[<return: Struct>]
 let (|QueryFor|_|) g = function
-    | InstanceMethodApp g g.query_for_vref ([srcTy;qTy;resTy;_qInnerTy], _builder, [src;selector]) -> Some (qTy, srcTy, resTy, src, selector)
-    | _ -> None
+    | InstanceMethodApp g g.query_for_vref ([srcTy;qTy;resTy;_qInnerTy], _builder, [src;selector]) -> ValueSome (qTy, srcTy, resTy, src, selector)
+    | _ -> ValueNone
 
+[<return: Struct>]
 let (|QueryYield|_|) g = function
-    | InstanceMethodApp g g.query_yield_vref ([resTy;qTy], _builder, [res]) -> Some (qTy, resTy, res)
-    | _ -> None
+    | InstanceMethodApp g g.query_yield_vref ([resTy;qTy], _builder, [res]) -> ValueSome (qTy, resTy, res)
+    | _ -> ValueNone
 
+[<return: Struct>]
 let (|QueryYieldFrom|_|) g = function
-    | InstanceMethodApp g g.query_yield_from_vref ([resTy;qTy], _builder, [res]) -> Some (qTy, resTy, res)
-    | _ -> None
+    | InstanceMethodApp g g.query_yield_from_vref ([resTy;qTy], _builder, [res]) -> ValueSome (qTy, resTy, res)
+    | _ -> ValueNone
 
+[<return: Struct>]
 let (|QuerySelect|_|) g = function
-    | InstanceMethodApp g g.query_select_vref ([srcTy;qTy;resTy], _builder, [src;selector]) -> Some (qTy, srcTy, resTy, src, selector)
-    | _ -> None
+    | InstanceMethodApp g g.query_select_vref ([srcTy;qTy;resTy], _builder, [src;selector]) -> ValueSome (qTy, srcTy, resTy, src, selector)
+    | _ -> ValueNone
 
+[<return: Struct>]
 let (|QueryZero|_|) g = function
-    | InstanceMethodApp g g.query_zero_vref ([resTy;qTy], _builder, _) -> Some (qTy, resTy)
-    | _ -> None
+    | InstanceMethodApp g g.query_zero_vref ([resTy;qTy], _builder, _) -> ValueSome (qTy, resTy)
+    | _ -> ValueNone
 
 /// Look for a possible tuple and transform
 let (|AnyRefTupleTrans|) e = 
@@ -2105,11 +2120,12 @@ let (|AnyRefTupleTrans|) e =
     | _ -> [e], (function [e] -> e | _ -> assert false; failwith "unreachable")
 
 /// Look for any QueryBuilder.* operation and transform
+[<return: Struct>]
 let (|AnyQueryBuilderOpTrans|_|) g = function
     | Expr.App (Expr.Val (vref, _, _) as v, vty, tyargs, [builder; AnyRefTupleTrans( src :: rest, replaceArgs) ], m) when 
           (match vref.ApparentEnclosingEntity with Parent tcref -> tyconRefEq g tcref g.query_builder_tcref | ParentNone -> false) ->  
-         Some (src, (fun newSource -> Expr.App (v, vty, tyargs, [builder; replaceArgs(newSource :: rest)], m)))
-    | _ -> None
+         ValueSome (src, (fun newSource -> Expr.App (v, vty, tyargs, [builder; replaceArgs(newSource :: rest)], m)))
+    | _ -> ValueNone
 
 /// If this returns "Some" then the source is not IQueryable.
 //  <qexprInner> := 

src/Compiler/Service/ServiceLexing.fs

@@ -1042,8 +1042,8 @@ type FSharpLineTokenizer(lexbuf: UnicodeLexing.Lexbuf, maxLength: int option, fi
                     false, (RQUOTE(s, raw), leftc, rightc - 1)
                 | INFIX_COMPARE_OP(LexFilter.TyparsCloseOp(greaters, afterOp) as opstr) ->
                     match afterOp with
-                    | None -> ()
-                    | Some tok -> delayToken (tok, leftc + greaters.Length, rightc)
+                    | ValueNone -> ()
+                    | ValueSome tok -> delayToken (tok, leftc + greaters.Length, rightc)
 
                     for i = greaters.Length - 1 downto 1 do
                         delayToken (greaters[i]false, leftc + i, rightc - opstr.Length + i + 1)