From e4a62fdb2a703e8eff2f6196d56ecd2261767157 Mon Sep 17 00:00:00 2001
From: Will Smith <lol.tihan@gmail.com>
Date: Wed, 11 Sep 2019 12:19:26 -0700
Subject: [PATCH] Minor cleanup, do not check assembly for string concat
 optimization (#7532)

---
 src/fsharp/Optimizer.fs | 48 +++++++++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 19 deletions(-)

diff --git a/src/fsharp/Optimizer.fs b/src/fsharp/Optimizer.fs
index cfa1a9a49..e89f3e428 100644
--- a/src/fsharp/Optimizer.fs
+++ b/src/fsharp/Optimizer.fs
@@ -1830,22 +1830,27 @@ let TryDetectQueryQuoteAndRun cenv (expr: Expr) =
         //printfn "Not eliminating because no Run found"
         None
 
-let IsILMethodRefDeclaringTypeSystemString (ilg: ILGlobals) (mref: ILMethodRef) =
-    mref.DeclaringTypeRef.Scope.IsAssemblyRef &&
-    mref.DeclaringTypeRef.Scope.AssemblyRef.Name = ilg.typ_String.TypeRef.Scope.AssemblyRef.Name &&
-    mref.DeclaringTypeRef.BasicQualifiedName = ilg.typ_String.BasicQualifiedName
-                
-let IsILMethodRefSystemStringConcatOverload (ilg: ILGlobals) (mref: ILMethodRef) =
-    IsILMethodRefDeclaringTypeSystemString ilg mref &&
+let IsILMethodRefSystemStringConcat (mref: ILMethodRef) =
     mref.Name = "Concat" &&
-    mref.ReturnType.BasicQualifiedName = ilg.typ_String.BasicQualifiedName &&
-    mref.ArgCount >= 2 && mref.ArgCount <= 4 && mref.ArgTypes |> List.forall(fun ilty -> ilty.BasicQualifiedName = ilg.typ_String.BasicQualifiedName)
-
-let IsILMethodRefSystemStringConcatArray (ilg: ILGlobals) (mref: ILMethodRef) =
-    IsILMethodRefDeclaringTypeSystemString ilg mref &&
+    mref.DeclaringTypeRef.Name = "System.String" &&
+    (mref.ReturnType.IsNominal && mref.ReturnType.TypeRef.Name = "System.String") &&
+    (mref.ArgCount >= 2 && mref.ArgCount <= 4 &&
+        mref.ArgTypes 
+        |> List.forall (fun ilTy ->
+            ilTy.IsNominal && ilTy.TypeRef.Name = "System.String"))
+
+let IsILMethodRefSystemStringConcatArray (mref: ILMethodRef) =
     mref.Name = "Concat" &&
-    mref.ReturnType.BasicQualifiedName = ilg.typ_String.BasicQualifiedName &&
-    mref.ArgCount = 1 && mref.ArgTypes.Head.BasicQualifiedName = "System.String[]"
+    mref.DeclaringTypeRef.Name = "System.String" &&
+    (mref.ReturnType.IsNominal && mref.ReturnType.TypeRef.Name = "System.String") &&
+    (mref.ArgCount = 1 && 
+        mref.ArgTypes
+        |> List.forall (fun ilTy ->          
+            match ilTy with
+            | ILType.Array (shape, ilTy) when shape = ILArrayShape.SingleDimensional &&
+                                              ilTy.IsNominal &&
+                                              ilTy.TypeRef.Name = "System.String" -> true
+            | _ -> false))
     
 /// Optimize/analyze an expression
 let rec OptimizeExpr cenv (env: IncrementalOptimizationEnv) expr =
@@ -1972,10 +1977,12 @@ and OptimizeInterfaceImpl cenv env baseValOpt (ty, overrides) =
 and MakeOptimizedSystemStringConcatCall cenv env m args =
     let rec optimizeArg argExpr accArgs =
         match argExpr, accArgs with
-        | Expr.Op(TOp.ILCall(_, _, _, _, _, _, _, methRef, _, _, _), _, [ Expr.Op(TOp.Array, _, args, _) ], _), _ when IsILMethodRefSystemStringConcatArray cenv.g.ilg methRef ->
+        | Expr.Op(TOp.ILCall(_, _, _, _, _, _, _, mref, _, _, _), _, [ Expr.Op(TOp.Array, _, args, _) ], _), _ 
+          when IsILMethodRefSystemStringConcatArray mref ->
             optimizeArgs args accArgs
 
-        | Expr.Op(TOp.ILCall(_, _, _, _, _, _, _, mref, _, _, _), _, args, _), _ when IsILMethodRefSystemStringConcatOverload cenv.g.ilg mref ->
+        | Expr.Op(TOp.ILCall(_, _, _, _, _, _, _, mref, _, _, _), _, args, _), _ 
+          when IsILMethodRefSystemStringConcat mref ->
             optimizeArgs args accArgs
 
         // Optimize string constants, e.g. "1" + "2" will turn into "12"
@@ -2005,7 +2012,8 @@ and MakeOptimizedSystemStringConcatCall cenv env m args =
             mkStaticCall_String_Concat_Array cenv.g m arg
 
     match expr with
-    | Expr.Op(TOp.ILCall(_, _, _, _, _, _, _, methRef, _, _, _) as op, tyargs, args, m) when IsILMethodRefSystemStringConcatOverload cenv.g.ilg methRef || IsILMethodRefSystemStringConcatArray cenv.g.ilg methRef ->
+    | Expr.Op(TOp.ILCall(_, _, _, _, _, _, _, mref, _, _, _) as op, tyargs, args, m) 
+      when IsILMethodRefSystemStringConcat mref || IsILMethodRefSystemStringConcatArray mref ->
         OptimizeExprOpReductions cenv env (op, tyargs, args, m)
     | _ ->
         OptimizeExpr cenv env expr
@@ -2074,9 +2082,11 @@ and OptimizeExprOp cenv env (op, tyargs, args, m) =
     | TOp.ILAsm ([], [ty]), _, [a] when typeEquiv cenv.g (tyOfExpr cenv.g a) ty -> OptimizeExpr cenv env a
 
     // Optimize calls when concatenating strings, e.g. "1" + "2" + "3" + "4" .. etc.
-    | TOp.ILCall(_, _, _, _, _, _, _, mref, _, _, _), _, [ Expr.Op(TOp.Array, _, args, _) ] when IsILMethodRefSystemStringConcatArray cenv.g.ilg mref ->
+    | TOp.ILCall(_, _, _, _, _, _, _, mref, _, _, _), _, [ Expr.Op(TOp.Array, _, args, _) ] 
+      when IsILMethodRefSystemStringConcatArray mref ->
         MakeOptimizedSystemStringConcatCall cenv env m args
-    | TOp.ILCall(_, _, _, _, _, _, _, mref, _, _, _), _, args when IsILMethodRefSystemStringConcatOverload cenv.g.ilg mref ->
+    | TOp.ILCall(_, _, _, _, _, _, _, mref, _, _, _), _, args 
+      when IsILMethodRefSystemStringConcat mref ->
         MakeOptimizedSystemStringConcatCall cenv env m args
 
     | _ -> 
-- 
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