chunkify TcSymbolUSeData

src/fsharp/NameResolution.fs

@@ -1212,7 +1212,7 @@ let GetNestedTypesOfType (ad, ncenv:NameResolver, optFilter, staticResInfo, chec
 //------------------------------------------------------------------------- 
 
 /// Represents the kind of the occurrence when reporting a name in name resolution
-[<RequireQualifiedAccess>]
+[<RequireQualifiedAccess; Struct>]
 type ItemOccurence = 
     /// This is a binding / declaration of the item
     | Binding 
@@ -1498,13 +1498,45 @@ type TcSymbolUseData =
 /// are allocated (one per file), but they are large because the allUsesOfAllSymbols array is large.
 type TcSymbolUses(g, capturedNameResolutions : ResizeArray<CapturedNameResolution>, formatSpecifierLocations: (range * int)[]) = 
 
+    let chunks (items: ResizeArray<'t>) chunkSize =
+        let itemCount = items.Count
+        let chunksCount =
+           match itemCount / chunkSize with
+           | n when itemCount % chunkSize = 0 -> n
+           | n -> n + 1 // any remainder means we need an additional chunk to store it
+
+        [| for index in 0..chunksCount-1 do
+               let startIndex = index * chunkSize
+               let takeCount =
+                   if (index + 1) * chunkSize > itemCount
+                   then itemCount - startIndex
+                   else chunkSize
+               // pre-creating the array and doing a single copy is slightly better than
+               // two copies via ResizeArray<'t>.GetRange(start, count).ToArray().
+               let holder = Array.zeroCreate takeCount
+               items.CopyTo(startIndex, holder, 0, takeCount)
+               yield holder |]
+
+    /// chunk the provided capturedNameResolutions into arrays that are smaller than the LOH limit
+    /// in order to prevent long-term storage of those values
+    let chunkedResolutions: CapturedNameResolution [] [] =
+        let structSizeBytes = sizeof<TcSymbolUseData>
+        let lohSizeThresholdBytes = 85_000
+        // rounding down here is good beacuse it ensure we don't go over
+        let maxArrayItemCount = lohSizeThresholdBytes / structSizeBytes
+        chunks capturedNameResolutions maxArrayItemCount
+
     // Make sure we only capture the information we really need to report symbol uses
-    let allUsesOfSymbols = [| for cnr in capturedNameResolutions -> { Item=cnr.Item; ItemOccurence=cnr.ItemOccurence; DisplayEnv=cnr.DisplayEnv; Range=cnr.Range } |]
+    let allUsesOfSymbols =
+        [| for capturedNameResolutionsChunk in chunkedResolutions ->
+            [| for cnr in capturedNameResolutionsChunk ->
+                { Item=cnr.Item; ItemOccurence=cnr.ItemOccurence; DisplayEnv=cnr.DisplayEnv; Range=cnr.Range } |] |]
     let capturedNameResolutions = () 
     do ignore capturedNameResolutions // don't capture this!
 
     member this.GetUsesOfSymbol(item) = 
-        [| for symbolUse in allUsesOfSymbols do
+        [| for symbolUseChunk in allUsesOfSymbols do
+                for symbolUse in symbolUseChunk do
                if protectAssemblyExploration false (fun () -> ItemsAreEffectivelyEqual g item symbolUse.Item) then
                   yield symbolUse |]
 

src/fsharp/NameResolution.fsi

@@ -240,7 +240,7 @@ type TypeNameResolutionInfo =
   static member ResolveToTypeRefs : TypeNameResolutionStaticArgsInfo -> TypeNameResolutionInfo
 
 /// Represents the kind of the occurrence when reporting a name in name resolution
-[<RequireQualifiedAccess>]
+[<RequireQualifiedAccess; Struct>]
 type internal ItemOccurence = 
     | Binding 
     | Use 
@@ -319,7 +319,7 @@ type internal TcSymbolUses =
     member GetUsesOfSymbol : Item -> TcSymbolUseData[]
 
     /// All the uses of all items within the file
-    member AllUsesOfSymbols : TcSymbolUseData[]
+    member AllUsesOfSymbols : TcSymbolUseData[][]
 
     /// Get the locations of all the printf format specifiers in the file
     member GetFormatSpecifierLocationsAndArity : unit -> (range * int)[]

src/fsharp/service/service.fs

@@ -1913,7 +1913,8 @@ type FSharpCheckProjectResults(projectFileName:string, tcConfigOption, keepAssem
         let cenv = SymbolEnv(tcGlobals, thisCcu, Some ccuSig, tcImports)
 
         [| for r in tcSymbolUses do
-             for symbolUse in r.AllUsesOfSymbols do
+             for symbolUseChunk in r.AllUsesOfSymbols do
+                for symbolUse in symbolUseChunk do
                 if symbolUse.ItemOccurence <> ItemOccurence.RelatedText then
                   let symbol = FSharpSymbol.Create(cenv, symbolUse.Item)
                   yield FSharpSymbolUse(tcGlobals, symbolUse.DisplayEnv, symbol, symbolUse.ItemOccurence, symbolUse.Range) |]
@@ -2107,7 +2108,8 @@ type FSharpCheckFileResults(filename: string, errors: FSharpErrorInfo[], scopeOp
             (fun () -> [| |])
             (fun scope ->
                 let cenv = scope.SymbolEnv
-                [| for symbolUse in scope.ScopeSymbolUses.AllUsesOfSymbols do
+                [| for symbolUseChunk in scope.ScopeSymbolUses.AllUsesOfSymbols do
+                    for symbolUse in symbolUseChunk do
                     if symbolUse.ItemOccurence <> ItemOccurence.RelatedText then
                         let symbol = FSharpSymbol.Create(cenv, symbolUse.Item)
                         yield FSharpSymbolUse(scope.TcGlobals, symbolUse.DisplayEnv, symbol, symbolUse.ItemOccurence, symbolUse.Range) |])