From 82ee84ad39c67f7bdf3cad1547871f02fa6bce5b Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Thu, 23 May 2024 17:17:21 +0200
Subject: [PATCH] Optimize Development builds to use SSE2 by default on Windows
 and use SSE4.1 when targeting Windows 11

---
 Source/Tools/Flax.Build/Build/Target.cs       |  4 +--
 .../Platforms/Windows/WindowsToolchain.cs     | 36 +++++++++++++------
 .../Platforms/Windows/WindowsToolchainBase.cs |  7 ++--
 3 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/Source/Tools/Flax.Build/Build/Target.cs b/Source/Tools/Flax.Build/Build/Target.cs
index 90523b5ef..bc56254b6 100644
--- a/Source/Tools/Flax.Build/Build/Target.cs
+++ b/Source/Tools/Flax.Build/Build/Target.cs
@@ -281,10 +281,10 @@ namespace Flax.Build
                 options.CompileEnv.IntrinsicFunctions = true;
                 options.CompileEnv.BufferSecurityCheck = true;
                 options.CompileEnv.Inlining = true;
-                options.CompileEnv.WholeProgramOptimization = false;
+                options.CompileEnv.WholeProgramOptimization = true;
 
                 options.LinkEnv.DebugInformation = true;
-                options.LinkEnv.LinkTimeCodeGeneration = false;
+                options.LinkEnv.LinkTimeCodeGeneration = true;
                 options.LinkEnv.UseIncrementalLinking = true;
                 options.LinkEnv.Optimization = true;
                 break;
diff --git a/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchain.cs b/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchain.cs
index e7354442b..121a7b367 100644
--- a/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchain.cs
+++ b/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchain.cs
@@ -27,6 +27,8 @@ namespace Flax.Build.Platforms
     /// <seealso cref="Flax.Build.Platforms.WindowsToolchainBase" />
     public sealed class WindowsToolchain : WindowsToolchainBase
     {
+        private Version _minVersion;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="WindowsToolchain"/> class.
         /// </summary>
@@ -35,6 +37,14 @@ namespace Flax.Build.Platforms
         public WindowsToolchain(WindowsPlatform platform, TargetArchitecture architecture)
         : base(platform, architecture, WindowsPlatformToolset.Latest, WindowsPlatformSDK.Latest)
         {
+            // Select minimum Windows version
+            if (!Version.TryParse(Configuration.WindowsMinVer, out _minVersion))
+            {
+                if (int.TryParse(Configuration.WindowsMinVer, out var winMinVerMajor))
+                    _minVersion = new Version(winMinVerMajor, 0);
+                else
+                    _minVersion = new Version(7, 0);
+            }
         }
 
         /// <inheritdoc />
@@ -44,20 +54,12 @@ namespace Flax.Build.Platforms
 
             options.CompileEnv.PreprocessorDefinitions.Add("PLATFORM_WINDOWS");
 
-            // Select minimum Windows version
-            if (!Version.TryParse(Configuration.WindowsMinVer, out var winMinVer))
-            {
-                if (int.TryParse(Configuration.WindowsMinVer, out var winMinVerMajor))
-                    winMinVer = new Version(winMinVerMajor, 0);
-                else
-                    winMinVer = new Version(7, 0);
-            }
             int winVer;
-            if (winMinVer.Major >= 10)
+            if (_minVersion.Major >= 10)
                 winVer = 0x0A00; // Windows 10
-            else if (winMinVer.Major == 8 && winMinVer.Minor >= 1)
+            else if (_minVersion.Major == 8 && _minVersion.Minor >= 1)
                 winVer = 0x0603; // Windows 8.1
-            else if (winMinVer.Major == 8)
+            else if (_minVersion.Major == 8)
                 winVer = 0x0602; // Windows 8
             else
                 winVer = 0x0601; // Windows 7
@@ -74,6 +76,18 @@ namespace Flax.Build.Platforms
             options.LinkEnv.InputLibraries.Add("delayimp.lib");
         }
 
+        /// <inheritdoc />
+        protected override void SetupCompileCppFilesArgs(TaskGraph graph, BuildOptions options, List<string> args)
+        {
+            base.SetupCompileCppFilesArgs(graph, options, args);
+
+            if (Toolset >= WindowsPlatformToolset.v142 && _minVersion.Major >= 11)
+            {
+                // Windows 11 requires SSE4.2
+                args.Add("/d2archSSE42");
+            }
+        }
+
         /// <inheritdoc />
         public override void LinkFiles(TaskGraph graph, BuildOptions options, string outputFilePath)
         {
diff --git a/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchainBase.cs b/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchainBase.cs
index c1cdcb0ee..3693595ea 100644
--- a/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchainBase.cs
+++ b/Source/Tools/Flax.Build/Platforms/Windows/WindowsToolchainBase.cs
@@ -511,16 +511,13 @@ namespace Flax.Build.Platforms
                     commonArgs.Add("/Os");
                 if (compileEnvironment.Optimization)
                 {
-                    // Enable Most Speed Optimizations
-                    // Commented out due to /Og causing slow build times without /GL in development builds
-                    //commonArgs.Add("/Ox");
-
                     // Generate Intrinsic Functions
                     commonArgs.Add("/Oi");
 
                     // Frame-Pointer Omission
                     commonArgs.Add("/Oy");
 
+                    // Only use /Ox with /GL to prevent too long build times
                     if (compileEnvironment.WholeProgramOptimization)
                     {
                         // Enable Most Speed Optimizations
@@ -889,7 +886,7 @@ namespace Flax.Build.Platforms
                     }
 
                     // Link Incrementally
-                    if (linkEnvironment.UseIncrementalLinking)
+                    if (linkEnvironment.UseIncrementalLinking && !linkEnvironment.LinkTimeCodeGeneration)
                     {
                         args.Add("/INCREMENTAL");
                     }