EXPERIMENTAL: Metal backend (#441)

This is not a continuation of the Metal backend; this is simply bringing
the branch up to date and merging it as-is behind an experiment.

---------

Co-authored-by: Isaac Marovitz <isaacryu@icloud.com>
Co-authored-by: Samuliak <samuliak77@gmail.com>
Co-authored-by: SamoZ256 <96914946+SamoZ256@users.noreply.github.com>
Co-authored-by: Isaac Marovitz <42140194+IsaacMarovitz@users.noreply.github.com>
Co-authored-by: riperiperi <rhy3756547@hotmail.com>
Co-authored-by: Gabriel A <gab.dark.100@gmail.com>

src/Ryujinx.Graphics.Shader/CodeGen/Msl/Instructions/InstGenVector.cs

@@ -0,0 +1,32 @@
+using Ryujinx.Graphics.Shader.IntermediateRepresentation;
+using Ryujinx.Graphics.Shader.StructuredIr;
+
+using static Ryujinx.Graphics.Shader.CodeGen.Msl.Instructions.InstGenHelper;
+using static Ryujinx.Graphics.Shader.StructuredIr.InstructionInfo;
+
+namespace Ryujinx.Graphics.Shader.CodeGen.Msl.Instructions
+{
+    static class InstGenVector
+    {
+        public static string VectorExtract(CodeGenContext context, AstOperation operation)
+        {
+            IAstNode vector = operation.GetSource(0);
+            IAstNode index = operation.GetSource(1);
+
+            string vectorExpr = GetSourceExpr(context, vector, OperandManager.GetNodeDestType(context, vector));
+
+            if (index is AstOperand indexOperand && indexOperand.Type == OperandType.Constant)
+            {
+                char elem = "xyzw"[indexOperand.Value];
+
+                return $"{vectorExpr}.{elem}";
+            }
+            else
+            {
+                string indexExpr = GetSourceExpr(context, index, GetSrcVarType(operation.Inst, 1));
+
+                return $"{vectorExpr}[{indexExpr}]";
+            }
+        }
+    }
+}