Fixed LOH byte array allocations in the IDE from metadata

src/absil/bytes.fs

@@ -3,7 +3,14 @@
 /// Byte arrays
 namespace FSharp.Compiler.AbstractIL.Internal
 
+open System
+open System.IO
+open System.IO.MemoryMappedFiles
+open System.Runtime.InteropServices
+open System.Runtime.CompilerServices
+open FSharp.NativeInterop
 
+#nowarn "9"
 
 module internal Bytes = 
     let b0 n =  (n &&& 0xFF)
@@ -26,10 +33,286 @@ module internal Bytes =
         Array.append (System.Text.Encoding.UTF8.GetBytes s) (ofInt32Array [| 0x0 |]) 
 
     let stringAsUnicodeNullTerminated (s:string) = 
-        Array.append (System.Text.Encoding.Unicode.GetBytes s) (ofInt32Array [| 0x0;0x0 |]) 
+        Array.append (System.Text.Encoding.Unicode.GetBytes s) (ofInt32Array [| 0x0;0x0 |])
+
+[<AbstractClass>]
+type ByteMemory () =
+
+    abstract Item: int -> byte with get, set
+
+    abstract Length: int
+
+    abstract ReadBytes: pos: int * count: int -> byte[]
+
+    abstract ReadInt32: pos: int -> int
+
+    abstract ReadUInt16: pos: int -> uint16
+
+    abstract ReadUtf8String: pos: int * count: int -> string
+
+    abstract Slice: pos: int * count: int -> ByteMemory
+
+    abstract CopyTo: Stream -> unit
+
+    abstract Copy: srcOffset: int * dest: byte[] * destOffset: int * count: int -> unit
+
+    abstract ToArray: unit -> byte[]
+
+    abstract AsStream: unit -> Stream
+
+    abstract AsReadOnlyStream: unit -> Stream
+
+[<Sealed>]
+type ByteArrayMemory(bytes: byte[], offset, length) =
+    inherit ByteMemory()
+
+    do
+        if length <= 0 || length > bytes.Length then
+            raise (ArgumentOutOfRangeException("length"))
+
+        if offset < 0 || (offset + length) > bytes.Length then
+            raise (ArgumentOutOfRangeException("offset"))
+
+    override _.Item 
+        with get i = bytes.[offset + i]
+        and set i v = bytes.[offset + i] <- v
+
+    override _.Length = length
+
+    override _.ReadBytes(pos, count) = 
+        Array.sub bytes (offset + pos) count
+
+    override _.ReadInt32 pos =
+        let finalOffset = offset + pos
+        (uint32 bytes.[finalOffset]) |||
+        ((uint32 bytes.[finalOffset + 1]) <<< 8) |||
+        ((uint32 bytes.[finalOffset + 2]) <<< 16) |||
+        ((uint32 bytes.[finalOffset + 3]) <<< 24)
+        |> int
+
+    override _.ReadUInt16 pos =
+        let finalOffset = offset + pos
+        (uint16 bytes.[finalOffset]) |||
+        ((uint16 bytes.[finalOffset + 1]) <<< 8)
+
+    override _.ReadUtf8String(pos, count) =
+        System.Text.Encoding.UTF8.GetString(bytes, offset + pos, count)
+
+    override _.Slice(pos, count) =
+        ByteArrayMemory(bytes, offset + pos, count) :> ByteMemory
+
+    override _.CopyTo stream =
+        stream.Write(bytes, offset, length)
+
+    override _.Copy(srcOffset, dest, destOffset, count) =
+        Array.blit bytes (offset + srcOffset) dest destOffset count
+
+    override _.ToArray() =
+        Array.sub bytes offset length
+
+    override _.AsStream() =
+        new MemoryStream(bytes, offset, length) :> Stream
+
+    override _.AsReadOnlyStream() =
+        new MemoryStream(bytes, offset, length, false) :> Stream
+
+[<Sealed>]
+type RawByteMemory(addr: nativeptr<byte>, length: int, hold: obj) =
+    inherit ByteMemory ()
+
+    let check i =
+        if i < 0 || i >= length then 
+            raise (ArgumentOutOfRangeException("i"))
+
+    do
+        if length <= 0 then
+            raise (ArgumentOutOfRangeException("length"))
+
+    override _.Item 
+        with get i = 
+            check i
+            NativePtr.add addr i
+            |> NativePtr.read 
+        and set i v =
+            check i
+            NativePtr.set addr i v
+
+    override _.Length = length
+
+    override _.ReadUtf8String(pos, count) =
+        check pos
+        check (pos + count - 1)
+        System.Text.Encoding.UTF8.GetString(NativePtr.add addr pos, count)
+
+    override _.ReadBytes(pos, count) = 
+        check pos
+        check (pos + count - 1)
+        let res = Bytes.zeroCreate count
+        Marshal.Copy(NativePtr.toNativeInt addr + nativeint pos, res, 0, count)
+        res
+
+    override _.ReadInt32 pos =
+        check pos
+        check (pos + 3)
+        Marshal.ReadInt32(NativePtr.toNativeInt addr + nativeint pos)
+
+    override _.ReadUInt16 pos =
+        check pos
+        check (pos + 1)
+        uint16(Marshal.ReadInt16(NativePtr.toNativeInt addr + nativeint pos))
+
+    override _.Slice(pos, count) =
+        check pos
+        check (pos + count - 1)
+        RawByteMemory(NativePtr.add addr pos, count, hold) :> ByteMemory
+
+    override x.CopyTo stream =
+        use stream2 = x.AsStream()
+        stream2.CopyTo stream
+
+    override x.Copy(srcOffset, dest, destOffset, count) =
+        check srcOffset
+        Marshal.Copy(NativePtr.toNativeInt addr + nativeint srcOffset, dest, destOffset, count)
+
+    override _.ToArray() =
+        let res = Array.zeroCreate<byte> length
+        Marshal.Copy(NativePtr.toNativeInt addr, res, 0, res.Length)
+        res
+
+    override _.AsStream() =
+        new UnmanagedMemoryStream(addr, int64 length) :> Stream
+
+    override _.AsReadOnlyStream() =
+        new UnmanagedMemoryStream(addr, int64 length, int64 length, FileAccess.Read) :> Stream
+
+[<Struct;NoEquality;NoComparison>]
+type ReadOnlyByteMemory(bytes: ByteMemory) =
+
+    member _.Item with [<MethodImpl(MethodImplOptions.AggressiveInlining)>] get i = bytes.[i]
+
+    member _.Length with [<MethodImpl(MethodImplOptions.AggressiveInlining)>] get () = bytes.Length
+
+    [<MethodImpl(MethodImplOptions.AggressiveInlining)>]
+    member _.ReadBytes(pos, count) = bytes.ReadBytes(pos, count)
+
+    [<MethodImpl(MethodImplOptions.AggressiveInlining)>]
+    member _.ReadInt32 pos = bytes.ReadInt32 pos
+
+    [<MethodImpl(MethodImplOptions.AggressiveInlining)>]
+    member _.ReadUInt16 pos = bytes.ReadUInt16 pos
+
+    [<MethodImpl(MethodImplOptions.AggressiveInlining)>]
+    member _.ReadUtf8String(pos, count) = bytes.ReadUtf8String(pos, count)
+
+    [<MethodImpl(MethodImplOptions.AggressiveInlining)>]
+    member _.Slice(pos, count) = bytes.Slice(pos, count) |> ReadOnlyByteMemory
+
+    [<MethodImpl(MethodImplOptions.AggressiveInlining)>]
+    member _.CopyTo stream = bytes.CopyTo stream
+
+    [<MethodImpl(MethodImplOptions.AggressiveInlining)>]
+    member _.Copy(srcOffset, dest, destOffset, count) = bytes.Copy(srcOffset, dest, destOffset, count)
+
+    [<MethodImpl(MethodImplOptions.AggressiveInlining)>]
+    member _.ToArray() = bytes.ToArray()
+
+    [<MethodImpl(MethodImplOptions.AggressiveInlining)>]
+    member _.AsStream() = bytes.AsReadOnlyStream()
+
+type ByteMemory with
+
+    member x.AsReadOnly() = ReadOnlyByteMemory x
+
+    static member CreateMemoryMappedFile(bytes: ReadOnlyByteMemory) =
+        let length = int64 bytes.Length
+        let mmf = 
+            let mmf =
+                MemoryMappedFile.CreateNew(
+                    null, 
+                    length, 
+                    MemoryMappedFileAccess.ReadWrite, 
+                    MemoryMappedFileOptions.None, 
+                    HandleInheritability.None)
+            use stream = mmf.CreateViewStream(0L, length, MemoryMappedFileAccess.ReadWrite)
+            bytes.CopyTo stream
+            mmf
+
+        let accessor = mmf.CreateViewAccessor(0L, length, MemoryMappedFileAccess.ReadWrite)
+
+        let safeHolder =
+            { new obj() with
+                override x.Finalize() =
+                    (x :?> IDisposable).Dispose()
+              interface IDisposable with
+                member x.Dispose() =
+                    GC.SuppressFinalize x
+                    accessor.Dispose()
+                    mmf.Dispose() }
+        RawByteMemory.FromUnsafePointer(accessor.SafeMemoryMappedViewHandle.DangerousGetHandle(), int length, safeHolder)
+
+    static member FromFile(path, access, ?canShadowCopy: bool) =
+        let canShadowCopy = defaultArg canShadowCopy false
+
+        let memoryMappedFileAccess =
+            match access with
+            | FileAccess.Read -> MemoryMappedFileAccess.Read
+            | FileAccess.Write -> MemoryMappedFileAccess.Write
+            | _ -> MemoryMappedFileAccess.ReadWrite
+
+        let mmf, accessor, length = 
+            let fileStream = File.Open(path, FileMode.Open, access, FileShare.Read)
+            let length = fileStream.Length
+            let mmf = 
+                if canShadowCopy then
+                    let mmf = 
+                        MemoryMappedFile.CreateNew(
+                            null, 
+                            length, 
+                            MemoryMappedFileAccess.ReadWrite, 
+                            MemoryMappedFileOptions.None, 
+                            HandleInheritability.None)
+                    use stream = mmf.CreateViewStream(0L, length, MemoryMappedFileAccess.ReadWrite)
+                    fileStream.CopyTo(stream)
+                    fileStream.Dispose()
+                    mmf
+                else
+                    MemoryMappedFile.CreateFromFile(
+                        fileStream, 
+                        null, 
+                        length, 
+                        memoryMappedFileAccess, 
+                        HandleInheritability.None, 
+                        leaveOpen=false)
+            mmf, mmf.CreateViewAccessor(0L, length, memoryMappedFileAccess), length
+
+        match access with
+        | FileAccess.Read when not accessor.CanRead -> failwith "Cannot read file"
+        | FileAccess.Write when not accessor.CanWrite -> failwith "Cannot write file"
+        | _ when not accessor.CanRead || not accessor.CanWrite -> failwith "Cannot read or write file"
+        | _ -> ()
+
+        let safeHolder =
+            { new obj() with
+                override x.Finalize() =
+                    (x :?> IDisposable).Dispose()
+              interface IDisposable with
+                member x.Dispose() =
+                    GC.SuppressFinalize x
+                    accessor.Dispose()
+                    mmf.Dispose() }
+        RawByteMemory.FromUnsafePointer(accessor.SafeMemoryMappedViewHandle.DangerousGetHandle(), int length, safeHolder)
+
+    static member FromUnsafePointer(addr, length, hold: obj) = 
+        RawByteMemory(NativePtr.ofNativeInt addr, length, hold) :> ByteMemory
+
+    static member FromArray(bytes, offset, length) =
+        ByteArrayMemory(bytes, offset, length) :> ByteMemory
+
+    static member FromArray bytes =
+        ByteArrayMemory.FromArray(bytes, 0, bytes.Length)
 
 type internal ByteStream = 
-    { bytes: byte[] 
+    { bytes: ReadOnlyByteMemory
       mutable pos: int 
       max: int }
     member b.ReadByte() = 
@@ -38,18 +321,18 @@ type internal ByteStream =
         b.pos <- b.pos + 1
         res 
     member b.ReadUtf8String n = 
-        let res = System.Text.Encoding.UTF8.GetString(b.bytes,b.pos,n)  
+        let res = b.bytes.ReadUtf8String(b.pos,n)  
         b.pos <- b.pos + n; res 
 
-    static member FromBytes (b:byte[],n,len) = 
+    static member FromBytes (b: ReadOnlyByteMemory,n,len) = 
         if n < 0 || (n+len) > b.Length then failwith "FromBytes"
         { bytes = b; pos = n; max = n+len }
 
     member b.ReadBytes n  = 
         if b.pos + n > b.max then failwith "ReadBytes: end of stream"
-        let res = Bytes.sub b.bytes b.pos n
+        let res = b.bytes.Slice(b.pos, n)
         b.pos <- b.pos + n
-        res 
+        res
 
     member b.Position = b.pos 
 #if LAZY_UNPICKLE
@@ -108,6 +391,13 @@ type internal ByteBuffer =
         Bytes.blit i 0 buf.bbArray buf.bbCurrent n
         buf.bbCurrent <- newSize 
 
+    member buf.EmitByteMemory (i:ReadOnlyByteMemory) = 
+        let n = i.Length 
+        let newSize = buf.bbCurrent + n 
+        buf.Ensure newSize
+        i.Copy(0, buf.bbArray, buf.bbCurrent, n)
+        buf.bbCurrent <- newSize 
+
     member buf.EmitInt32AsUInt16 n = 
         let newSize = buf.bbCurrent + 2 
         buf.Ensure newSize