Optimize metadata members and custom attributes reading (#17364)

* wip

* wip

* cleanup

* formatting

* release notes

* release notes

---------

Co-authored-by: Petr <[email protected]>
Co-authored-by: Vlad Zarytovskii <[email protected]>

Author: 3 people

docs/release-notes/.FSharp.Compiler.Service/9.0.100.md

@@ -12,6 +12,7 @@
 
 * Change compiler default setting realsig+ when building assemblies ([Issue #17384](https://github.com/dotnet/fsharp/issues/17384), [PR #17378](https://github.com/dotnet/fsharp/pull/17385))
 * Change compiler default setting for compressedMetadata ([Issue #17379](https://github.com/dotnet/fsharp/issues/17379), [PR #17383](https://github.com/dotnet/fsharp/pull/17383))
+* Optimize metadata reading for type members and custom attributes. ([PR #17364](https://github.com/dotnet/fsharp/pull/17364))
 * Enforce `AttributeTargets` on unions. ([PR #17389](https://github.com/dotnet/fsharp/pull/17389))
 
 ### Breaking Changes

src/Compiler/AbstractIL/ilread.fs

@@ -883,7 +883,7 @@ let tomdCompare (TaggedIndex(t1: TypeOrMethodDefTag, idx1)) (TaggedIndex(t2: Typ
     elif idx1 > idx2 then 1
     else compare t1.Tag t2.Tag
 
-let simpleIndexCompare (idx1: int) (idx2: int) = compare idx1 idx2
+let inline simpleIndexCompare (idx1: int) (idx2: int) = compare idx1 idx2
 
 //---------------------------------------------------------------------
 // The various keys for the various caches.
@@ -2314,18 +2314,23 @@ and seekReadTypeDefAsTypeUncached ctxtH (TypeDefAsTypIdx(boxity, ginst, idx)) =
     mkILTy boxity (ILTypeSpec.Create(seekReadTypeDefAsTypeRef ctxt idx, ginst))
 
 and seekReadTypeDefAsTypeRef (ctxt: ILMetadataReader) idx =
+    let mdv = ctxt.mdfile.GetView()
+
     let enc =
         if seekIsTopTypeDefOfIdx ctxt idx then
             []
         else
             let enclIdx =
                 seekReadIndexedRow (
                     ctxt.getNumRows TableNames.Nested,
-                    seekReadNestedRow ctxt,
-                    fst,
-                    simpleIndexCompare idx,
+                    id,
+                    id,
+                    (fun i ->
+                        let mutable addr = ctxt.rowAddr TableNames.Nested i
+                        let nestedIdx = seekReadUntaggedIdx TableNames.TypeDef ctxt mdv &addr
+                        simpleIndexCompare idx nestedIdx),
                     isSorted ctxt TableNames.Nested,
-                    snd
+                    (fun i -> seekReadNestedRow ctxt i |> snd)
                 )
 
             let tref = seekReadTypeDefAsTypeRef ctxt enclIdx
@@ -3086,15 +3091,18 @@ and seekReadMethodImpls (ctxt: ILMetadataReader) numTypars tidx =
             let mimpls =
                 seekReadIndexedRows (
                     ctxt.getNumRows TableNames.MethodImpl,
-                    seekReadMethodImplRow ctxt mdv,
-                    (fun (a, _, _) -> a),
-                    simpleIndexCompare tidx,
+                    id,
+                    id,
+                    (fun i ->
+                        let mutable addr = ctxt.rowAddr TableNames.MethodImpl i
+                        let _tidx = seekReadUntaggedIdx TableNames.TypeDef ctxt mdv &addr
+                        simpleIndexCompare tidx _tidx),
                     isSorted ctxt TableNames.MethodImpl,
-                    (fun (_, b, c) -> b, c)
+                    seekReadMethodImplRow ctxt mdv
                 )
 
             mimpls
-            |> List.map (fun (b, c) ->
+            |> List.map (fun (_, b, c) ->
                 {
                     OverrideBy =
                         let (MethodData(enclTy, cc, nm, argTys, retTy, methInst)) =
@@ -3163,11 +3171,14 @@ and seekReadEvents (ctxt: ILMetadataReader) numTypars tidx =
             match
                 seekReadOptionalIndexedRow (
                     ctxt.getNumRows TableNames.EventMap,
-                    (fun i -> i, seekReadEventMapRow ctxt mdv i),
-                    (fun (_, row) -> fst row),
-                    compare tidx,
+                    id,
+                    id,
+                    (fun i ->
+                        let mutable addr = ctxt.rowAddr TableNames.EventMap i
+                        let _tidx = seekReadUntaggedIdx TableNames.TypeDef ctxt mdv &addr
+                        simpleIndexCompare tidx _tidx),
                     false,
-                    (fun (i, row) -> (i, snd row))
+                    (fun i -> i, seekReadEventMapRow ctxt mdv i |> snd)
                 )
             with
             | None -> []
@@ -3230,11 +3241,14 @@ and seekReadProperties (ctxt: ILMetadataReader) numTypars tidx =
             match
                 seekReadOptionalIndexedRow (
                     ctxt.getNumRows TableNames.PropertyMap,
-                    (fun i -> i, seekReadPropertyMapRow ctxt mdv i),
-                    (fun (_, row) -> fst row),
-                    compare tidx,
+                    id,
+                    id,
+                    (fun i ->
+                        let mutable addr = ctxt.rowAddr TableNames.PropertyMap i
+                        let _tidx = seekReadUntaggedIdx TableNames.TypeDef ctxt mdv &addr
+                        simpleIndexCompare tidx _tidx),
                     false,
-                    (fun (i, row) -> (i, snd row))
+                    (fun i -> i, seekReadPropertyMapRow ctxt mdv i |> snd)
                 )
             with
             | None -> []
@@ -3258,16 +3272,22 @@ and customAttrsReader ctxtH tag : ILAttributesStored =
         let (ctxt: ILMetadataReader) = getHole ctxtH
         let mdv = ctxt.mdfile.GetView()
 
-        let reader =
-            { new ISeekReadIndexedRowReader<CustomAttributeRow, TaggedIndex<HasCustomAttributeTag>, ILAttribute> with
-                member _.GetRow(i, row) =
-                    seekReadCustomAttributeRow ctxt mdv i &row
-
-                member _.GetKey(attrRow) = attrRow.parentIndex
-
-                member _.CompareKey(key) = hcaCompare (TaggedIndex(tag, idx)) key
+        let searchedKey = TaggedIndex(tag, idx)
 
-                member _.ConvertRow(attrRow) =
+        let reader =
+            { new ISeekReadIndexedRowReader<int, int, ILAttribute> with
+                member _.GetRow(i, rowIndex) = rowIndex <- i
+                member _.GetKey(rowIndex) = rowIndex
+
+                member _.CompareKey(rowIndex) =
+                    let mutable addr = ctxt.rowAddr TableNames.CustomAttribute rowIndex
+                    // read parentIndex
+                    let key = seekReadHasCustomAttributeIdx ctxt mdv &addr
+                    hcaCompare searchedKey key
+
+                member _.ConvertRow(rowIndex) =
+                    let mutable attrRow = Unchecked.defaultof<_>
+                    seekReadCustomAttributeRow ctxt mdv rowIndex &attrRow
                     seekReadCustomAttr ctxt (attrRow.typeIndex, attrRow.valueIndex)
             }