Revert "Revert the Metal Experiment (#701)"

This reverts commit fe1617ffea.

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

@@ -0,0 +1,60 @@
+using Ryujinx.Graphics.Shader.StructuredIr;
+
+using static Ryujinx.Graphics.Shader.CodeGen.Msl.Instructions.InstGenHelper;
+
+namespace Ryujinx.Graphics.Shader.CodeGen.Msl.Instructions
+{
+    static class InstGenCall
+    {
+        public static string Call(CodeGenContext context, AstOperation operation)
+        {
+            AstOperand funcId = (AstOperand)operation.GetSource(0);
+
+            StructuredFunction function = context.GetFunction(funcId.Value);
+
+            int argCount = operation.SourcesCount - 1;
+            int additionalArgCount = CodeGenContext.AdditionalArgCount + (context.Definitions.Stage != ShaderStage.Compute ? 1 : 0);
+            bool needsThreadIndex = false;
+
+            // TODO: Replace this with a proper flag
+            if (function.Name.Contains("Shuffle"))
+            {
+                needsThreadIndex = true;
+                additionalArgCount++;
+            }
+
+            string[] args = new string[argCount + additionalArgCount];
+
+            // Additional arguments
+            if (context.Definitions.Stage != ShaderStage.Compute)
+            {
+                args[0] = "in";
+                args[1] = "constant_buffers";
+                args[2] = "storage_buffers";
+
+                if (needsThreadIndex)
+                {
+                    args[3] = "thread_index_in_simdgroup";
+                }
+            }
+            else
+            {
+                args[0] = "constant_buffers";
+                args[1] = "storage_buffers";
+
+                if (needsThreadIndex)
+                {
+                    args[2] = "thread_index_in_simdgroup";
+                }
+            }
+
+            int argIndex = additionalArgCount;
+            for (int i = 0; i < argCount; i++)
+            {
+                args[argIndex++] = GetSourceExpr(context, operation.GetSource(i + 1), function.GetArgumentType(i));
+            }
+
+            return $"{function.Name}({string.Join(", ", args)})";
+        }
+    }
+}