ByteBuffer uses ArrayPool to prevent LOH allocations

eng/Versions.props

@@ -103,6 +103,7 @@
     <SystemThreadingTasksDataflow>4.11.1</SystemThreadingTasksDataflow>
     <SystemThreadingThreadVersion>4.3.0</SystemThreadingThreadVersion>
     <SystemThreadingThreadPoolVersion>4.3.0</SystemThreadingThreadPoolVersion>
+    <SystemRuntimeCompilerServicesUnsafeVersion>4.7.1</SystemRuntimeCompilerServicesUnsafeVersion>
     <!-- Roslyn packages -->
     <RoslynVersion>3.8.0-5.20570.14</RoslynVersion>
     <MicrosoftCodeAnalysisEditorFeaturesVersion>$(RoslynVersion)</MicrosoftCodeAnalysisEditorFeaturesVersion>

src/fsharp/CompilerImports.fs

@@ -90,9 +90,11 @@ let PickleToResource inMem file (g: TcGlobals) scope rName p x =
     let bytes = pickleObjWithDanglingCcus inMem file g scope p x
     let byteStorage =
         if inMem then
-            ByteStorage.FromByteArrayAndCopy(bytes, useBackingMemoryMappedFile = true)
+            ByteStorage.FromMemoryAndCopy(bytes.AsMemory(), useBackingMemoryMappedFile = true)
         else
-            ByteStorage.FromByteArray(bytes)
+            ByteStorage.FromByteArray(bytes.AsMemory().ToArray())
+
+    (bytes :> IDisposable).Dispose()
 
     { Name = rName
       Location = ILResourceLocation.Local(byteStorage)

src/fsharp/FSharp.Compiler.Service/FSharp.Compiler.Service.fsproj

@@ -59,6 +59,7 @@
     <NuspecProperty Include="SystemThreadingTasksParallelPackageVersion=$(SystemThreadingTasksParallelVersion)" />
     <NuspecProperty Include="SystemThreadingThreadPackageVersion=$(SystemThreadingThreadVersion)" />
     <NuspecProperty Include="SystemThreadingThreadPoolPackageVersion=$(SystemThreadingThreadPoolVersion)" />
+    <NuspecProperty Include="SystemRuntimeCompilerServicesUnsafePackageVersion=$(SystemRuntimeCompilerServicesUnsafeVersion)" />
   </ItemGroup>
 
   <ItemGroup>
@@ -987,6 +988,7 @@
     <PackageReference Include="Microsoft.Build.Framework" Version="$(MicrosoftBuildVersion)" />
     <PackageReference Include="Microsoft.Build.Tasks.Core" Version="$(MicrosoftBuildVersion)" />
     <PackageReference Include="Microsoft.Build.Utilities.Core" Version="$(MicrosoftBuildVersion)" />
+    <PackageReference Include="System.Runtime.CompilerServices.Unsafe" Version="$(SystemRuntimeCompilerServicesUnsafeVersion)" />
   </ItemGroup>
 
 </Project>

src/fsharp/FSharp.Compiler.Service/FSharp.Compiler.Service.nuspec

@@ -30,6 +30,7 @@
             <dependency id="System.Threading.Tasks.Parallel" version="$SystemThreadingTasksParallelPackageVersion$" exclude="Build,Analyzers" />
             <dependency id="System.Threading.Thread" version="$SystemThreadingThreadPackageVersion$" exclude="Build,Analyzers" />
             <dependency id="System.Threading.ThreadPool" version="$SystemThreadingThreadPoolPackageVersion$" exclude="Build,Analyzers" />
+            <dependency id="System.Runtime.CompilerServices.Unsafe" version="$SystemRuntimeCompilerServicesUnsafePackageVersion$" exclude="Build,Analyzers" />
           </group>
         </dependencies>
     </metadata>

src/fsharp/IlxGen.fs

@@ -2027,9 +2027,9 @@ let GenString cenv cgbuf s =
 
 let GenConstArray cenv (cgbuf: CodeGenBuffer) eenv ilElementType (data:'a[]) (write: ByteBuffer -> 'a -> unit) =
     let g = cenv.g
-    let buf = ByteBuffer.Create data.Length
+    use buf = ByteBuffer.Create data.Length
     data |> Array.iter (write buf)
-    let bytes = buf.Close()
+    let bytes = buf.AsMemory().ToArray()
     let ilArrayType = mkILArr1DTy ilElementType
     if data.Length = 0 then
         CG.EmitInstrs cgbuf (pop 0) (Push [ilArrayType]) [ mkLdcInt32 0; I_newarr (ILArrayShape.SingleDimensional, ilElementType); ]

src/fsharp/QuotationPickler.fs

@@ -2,6 +2,7 @@
 
 module internal FSharp.Compiler.QuotationPickler
 
+open System
 open System.Text
 open FSharp.Compiler.IO
 open Internal.Utilities
@@ -245,6 +246,10 @@ let SerializedReflectedDefinitionsResourceNameBase = "ReflectedDefinitions"
 
 let freshVar (n, ty, mut) = { vText=n; vType=ty; vMutable=mut }
 
+/// Arbitrary value
+[<Literal>]
+let PickleBufferCapacity = 100000
+
 module SimplePickle =
 
     type Table<'T> =
@@ -311,6 +316,11 @@ module SimplePickle =
         p_int32 (len) st
         st.os.EmitBytes s
 
+    let p_memory (s:ReadOnlyMemory<byte>) st =
+        let len = s.Length
+        p_int32 (len) st
+        st.os.EmitMemory s
+
     let prim_pstring (s:string) st =
         let bytes = Encoding.UTF8.GetBytes s
         let len = bytes.Length
@@ -363,20 +373,26 @@ module SimplePickle =
         | h :: t -> p_byte 1 st; f h st; p_list f t st
 
     let pickle_obj p x =
+        let st1 =
+            { os = ByteBuffer.Create(PickleBufferCapacity, useArrayPool = true)
+              ostrings=Table<_>.Create() }
         let stringTab, phase1bytes =
-            let st1 =
-                { os = ByteBuffer.Create 100000
-                  ostrings=Table<_>.Create() }
             p x st1
-            st1.ostrings.AsList, st1.os.Close()
+            st1.ostrings.AsList, st1.os.AsMemory()
+
         let phase2data = (stringTab, phase1bytes)
+
+        let st2 =
+           { os = ByteBuffer.Create(PickleBufferCapacity, useArrayPool = true)
+             ostrings=Table<_>.Create() }
         let phase2bytes =
-            let st2 =
-               { os = ByteBuffer.Create 100000
-                 ostrings=Table<_>.Create() }
-            p_tup2 (p_list prim_pstring) p_bytes phase2data st2
-            st2.os.Close()
-        phase2bytes
+            p_tup2 (p_list prim_pstring) p_memory phase2data st2
+            st2.os.AsMemory()
+
+        let finalBytes = phase2bytes.ToArray()
+        (st1.os :> IDisposable).Dispose()
+        (st2.os :> IDisposable).Dispose()
+        finalBytes
 
 open SimplePickle
 

src/fsharp/TypedTree.fs

@@ -4637,7 +4637,7 @@ type TOp =
     | Array
 
     /// Constant byte arrays (used for parser tables and other embedded data)
-    | Bytes of byte[] 
+    | Bytes of byte[]
 
     /// Constant uint16 arrays (used for parser tables)
     | UInt16s of uint16[] 

src/fsharp/TypedTreePickle.fs

@@ -213,6 +213,11 @@ let p_bytes (s: byte[]) st =
     p_int32 len st
     st.os.EmitBytes s
 
+let p_memory (s: System.ReadOnlyMemory<byte>) st =
+    let len = s.Length
+    p_int32 len st
+    st.os.EmitMemory s
+
 let p_prim_string (s: string) st =
     let bytes = Encoding.UTF8.GetBytes s
     let len = bytes.Length
@@ -775,10 +780,13 @@ let p_encoded_simpletyp x st = p_int x st
 let p_encoded_anoninfo x st = p_int x st
 let p_simpletyp x st = p_int (encode_simpletyp st.occus st.ostrings st.onlerefs st.osimpletys st.oscope x) st
 
+/// Arbitrary value
+[<Literal>]
+let PickleBufferCapacity = 100000
+
 let pickleObjWithDanglingCcus inMem file g scope p x =
-  let ccuNameTab, (ntycons, ntypars, nvals, nanoninfos), stringTab, pubpathTab, nlerefTab, simpleTyTab, phase1bytes =
-    let st1 =
-      { os = ByteBuffer.Create 100000
+  let st1 =
+      { os = ByteBuffer.Create(PickleBufferCapacity, useArrayPool = true)
         oscope=scope
         occus= Table<_>.Create "occus"
         oentities=NodeOutTable<_, _>.Create((fun (tc: Tycon) -> tc.Stamp), (fun tc -> tc.LogicalName), (fun tc -> tc.Range), (fun osgn -> osgn), "otycons")
@@ -793,31 +801,32 @@ let pickleObjWithDanglingCcus inMem file g scope p x =
         ofile=file
         oInMem=inMem
         isStructThisArgPos = false}
+  let ccuNameTab, (ntycons, ntypars, nvals, nanoninfos), stringTab, pubpathTab, nlerefTab, simpleTyTab, phase1bytes =
     p x st1
     let sizes =
       st1.oentities.Size,
       st1.otypars.Size,
       st1.ovals.Size,
       st1.oanoninfos.Size
-    st1.occus, sizes, st1.ostrings, st1.opubpaths, st1.onlerefs, st1.osimpletys, st1.os.Close()
-
+    st1.occus, sizes, st1.ostrings, st1.opubpaths, st1.onlerefs, st1.osimpletys, st1.os.AsMemory()
+
+  let st2 =
+   { os = ByteBuffer.Create(PickleBufferCapacity, useArrayPool = true)
+     oscope=scope
+     occus= Table<_>.Create "occus (fake)"
+     oentities=NodeOutTable<_, _>.Create((fun (tc: Tycon) -> tc.Stamp), (fun tc -> tc.LogicalName), (fun tc -> tc.Range), (fun osgn -> osgn), "otycons")
+     otypars=NodeOutTable<_, _>.Create((fun (tp: Typar) -> tp.Stamp), (fun tp -> tp.DisplayName), (fun tp -> tp.Range), (fun osgn -> osgn), "otypars")
+     ovals=NodeOutTable<_, _>.Create((fun (v: Val) -> v.Stamp), (fun v -> v.LogicalName), (fun v -> v.Range), (fun osgn -> osgn), "ovals")
+     oanoninfos=NodeOutTable<_, _>.Create((fun (v: AnonRecdTypeInfo) -> v.Stamp), (fun v -> string v.Stamp), (fun _ -> range0), id, "oanoninfos")
+     ostrings=Table<_>.Create "ostrings (fake)"
+     opubpaths=Table<_>.Create "opubpaths (fake)"
+     onlerefs=Table<_>.Create "onlerefs (fake)"
+     osimpletys=Table<_>.Create "osimpletys (fake)"
+     oglobals=g
+     ofile=file
+     oInMem=inMem
+     isStructThisArgPos = false }
   let phase2bytes =
-    let st2 =
-     { os = ByteBuffer.Create 100000
-       oscope=scope
-       occus= Table<_>.Create "occus (fake)"
-       oentities=NodeOutTable<_, _>.Create((fun (tc: Tycon) -> tc.Stamp), (fun tc -> tc.LogicalName), (fun tc -> tc.Range), (fun osgn -> osgn), "otycons")
-       otypars=NodeOutTable<_, _>.Create((fun (tp: Typar) -> tp.Stamp), (fun tp -> tp.DisplayName), (fun tp -> tp.Range), (fun osgn -> osgn), "otypars")
-       ovals=NodeOutTable<_, _>.Create((fun (v: Val) -> v.Stamp), (fun v -> v.LogicalName), (fun v -> v.Range), (fun osgn -> osgn), "ovals")
-       oanoninfos=NodeOutTable<_, _>.Create((fun (v: AnonRecdTypeInfo) -> v.Stamp), (fun v -> string v.Stamp), (fun _ -> range0), id, "oanoninfos")
-       ostrings=Table<_>.Create "ostrings (fake)"
-       opubpaths=Table<_>.Create "opubpaths (fake)"
-       onlerefs=Table<_>.Create "onlerefs (fake)"
-       osimpletys=Table<_>.Create "osimpletys (fake)"
-       oglobals=g
-       ofile=file
-       oInMem=inMem
-       isStructThisArgPos = false }
     p_array p_encoded_ccuref ccuNameTab.AsArray st2
     // Add a 4th integer indicated by a negative 1st integer
     let z1 = if nanoninfos > 0 then  -ntycons-1 else ntycons
@@ -830,11 +839,14 @@ let pickleObjWithDanglingCcus inMem file g scope p x =
         (p_array p_encoded_pubpath)
         (p_array p_encoded_nleref)
         (p_array p_encoded_simpletyp)
-        p_bytes
+        p_memory
         (stringTab.AsArray, pubpathTab.AsArray, nlerefTab.AsArray, simpleTyTab.AsArray, phase1bytes)
         st2
-    st2.os.Close()
-  phase2bytes
+    st2.os
+
+  let finalBytes = phase2bytes
+  (st1.os :> System.IDisposable).Dispose()
+  finalBytes
 
 let check (ilscope: ILScopeRef) (inMap : NodeInTable<_, _>) =
     for i = 0 to inMap.Count - 1 do

src/fsharp/TypedTreePickle.fsi

@@ -84,7 +84,7 @@ val internal p_ty : pickler<TType>
 val internal pickleCcuInfo : pickler<PickledCcuInfo>
 
 /// Serialize an arbitrary object using the given pickler
-val pickleObjWithDanglingCcus : inMem: bool -> file: string -> TcGlobals -> scope:CcuThunk -> pickler<'T> -> 'T -> byte[]
+val pickleObjWithDanglingCcus : inMem: bool -> file: string -> TcGlobals -> scope:CcuThunk -> pickler<'T> -> 'T -> ByteBuffer
 
 /// The type of state unpicklers read from
 type ReaderState

src/fsharp/absil/ilsupp.fs

@@ -91,15 +91,15 @@ type IMAGE_FILE_HEADER (m: int16, secs: int16, tds: int32, ptst: int32, nos: int
             with get() = 20
 
         member x.toBytes () =
-            let buf = ByteBuffer.Create IMAGE_FILE_HEADER.Width
+            use buf = ByteBuffer.Create IMAGE_FILE_HEADER.Width
             buf.EmitUInt16 (uint16 machine)
             buf.EmitUInt16 (uint16 numberOfSections)
             buf.EmitInt32 timeDateStamp
             buf.EmitInt32 pointerToSymbolTable
             buf.EmitInt32 numberOfSymbols
             buf.EmitUInt16 (uint16 sizeOfOptionalHeader)
             buf.EmitUInt16 (uint16 characteristics)
-            buf.Close()
+            buf.AsMemory().ToArray()
 
 let bytesToIFH (buffer: byte[]) (offset: int) =
     if (buffer.Length - offset) < IMAGE_FILE_HEADER.Width then
@@ -172,7 +172,7 @@ type IMAGE_SECTION_HEADER(n: int64, ai: int32, va: int32, srd: int32, prd: int32
             with get() = 40
 
         member x.toBytes () =
-            let buf = ByteBuffer.Create IMAGE_SECTION_HEADER.Width
+            use buf = ByteBuffer.Create IMAGE_SECTION_HEADER.Width
             buf.EmitInt64 name
             buf.EmitInt32 addressInfo
             buf.EmitInt32 virtualAddress
@@ -183,7 +183,7 @@ type IMAGE_SECTION_HEADER(n: int64, ai: int32, va: int32, srd: int32, prd: int32
             buf.EmitUInt16 (uint16 numberOfRelocations)
             buf.EmitUInt16 (uint16 numberOfLineNumbers)
             buf.EmitInt32 characteristics
-            buf.Close()
+            buf.AsMemory().ToArray()
 
 
 let bytesToISH (buffer: byte[]) (offset: int) =
@@ -236,14 +236,14 @@ type IMAGE_SYMBOL(n: int64, v: int32, sn: int16, t: int16, sc: byte, nas: byte)
             with get() = 18
 
         member x.toBytes() =
-            let buf = ByteBuffer.Create IMAGE_SYMBOL.Width
+            use buf = ByteBuffer.Create IMAGE_SYMBOL.Width
             buf.EmitInt64 name
             buf.EmitInt32 value
             buf.EmitUInt16 (uint16 sectionNumber)
             buf.EmitUInt16 (uint16 stype)
             buf.EmitByte storageClass
             buf.EmitByte numberOfAuxSymbols
-            buf.Close()
+            buf.AsMemory().ToArray()
 
 let bytesToIS (buffer: byte[]) (offset: int) =
     if (buffer.Length - offset) < IMAGE_SYMBOL.Width then
@@ -280,11 +280,11 @@ type IMAGE_RELOCATION(va: int32, sti: int32, t: int16) =
         with get() = 10
 
     member x.toBytes() =
-        let buf = ByteBuffer.Create IMAGE_RELOCATION.Width
+        use buf = ByteBuffer.Create IMAGE_RELOCATION.Width
         buf.EmitInt32 virtualAddress
         buf.EmitInt32 symbolTableIndex
         buf.EmitUInt16 (uint16 ty)
-        buf.Close()
+        buf.AsMemory().ToArray()
 
 let bytesToIR (buffer: byte[]) (offset: int) =
     if (buffer.Length - offset) < IMAGE_RELOCATION.Width then
@@ -328,14 +328,14 @@ type IMAGE_RESOURCE_DIRECTORY(c: int32, tds: int32, mjv: int16, mnv: int16, nne:
     static member Width = 16
 
     member x.toBytes () =
-        let buf = ByteBuffer.Create IMAGE_RESOURCE_DIRECTORY.Width
+        use buf = ByteBuffer.Create IMAGE_RESOURCE_DIRECTORY.Width
         buf.EmitInt32 characteristics
         buf.EmitInt32 timeDateStamp
         buf.EmitUInt16 (uint16 majorVersion)
         buf.EmitUInt16 (uint16 minorVersion)
         buf.EmitUInt16 (uint16 numberOfNamedEntries)
         buf.EmitUInt16 (uint16 numberOfIdEntries)
-        buf.Close()
+        buf.AsMemory().ToArray()
 
 let bytesToIRD (buffer: byte[]) (offset: int) =
     if (buffer.Length - offset) < IMAGE_RESOURCE_DIRECTORY.Width then
@@ -368,10 +368,10 @@ type IMAGE_RESOURCE_DIRECTORY_ENTRY(n: int32, o: int32) =
     static member Width = 8
 
     member x.toBytes () =
-        let buf = ByteBuffer.Create IMAGE_RESOURCE_DIRECTORY_ENTRY.Width
+        use buf = ByteBuffer.Create IMAGE_RESOURCE_DIRECTORY_ENTRY.Width
         buf.EmitInt32 name
         buf.EmitInt32 offset
-        buf.Close()
+        buf.AsMemory().ToArray()
 
 let bytesToIRDE (buffer: byte[]) (offset: int) =
     if (buffer.Length - offset) < IMAGE_RESOURCE_DIRECTORY_ENTRY.Width then
@@ -401,7 +401,7 @@ type IMAGE_RESOURCE_DATA_ENTRY(o: int32, s: int32, c: int32, r: int32) =
     static member Width = 16
 
     member x.toBytes() =
-        let buf = ByteBuffer.Create IMAGE_RESOURCE_DATA_ENTRY.Width
+        use buf = ByteBuffer.Create IMAGE_RESOURCE_DATA_ENTRY.Width
         buf.EmitInt32 offsetToData
         buf.EmitInt32 size
         buf.EmitInt32 codePage
@@ -466,7 +466,7 @@ type ResFormatHeader() =
     static member Width = 32
 
     member x.toBytes() =
-        let buf = ByteBuffer.Create ResFormatHeader.Width
+        use buf = ByteBuffer.Create ResFormatHeader.Width
         buf.EmitInt32 dwDataSize
         buf.EmitInt32 dwHeaderSize
         buf.EmitInt32 dwTypeID
@@ -476,7 +476,7 @@ type ResFormatHeader() =
         buf.EmitUInt16 (uint16 wLangID)
         buf.EmitInt32 dwVersion
         buf.EmitInt32 dwCharacteristics
-        buf.Close()
+        buf.AsMemory().ToArray()
 
 type ResFormatNode(tid: int32, nid: int32, lid: int32, dataOffset: int32, pbLinkedResource: byte[]) =
     let mutable resHdr = ResFormatHeader()