14 files changed, 253 insertions, 7 deletions

diff --git a/src/api/wix/WixToolset.Extensibility/BaseOptimizerExtension.cs b/src/api/wix/WixToolset.Extensibility/BaseOptimizerExtension.cs
new file mode 100644
index 00000000..5bb89272
--- /dev/null
+++ b/src/api/wix/WixToolset.Extensibility/BaseOptimizerExtension.cs
@@ -0,0 +1,26 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Extensibility
+{
+    using WixToolset.Extensibility.Data;
+
+    /// <summary>
+    /// Base class for creating an optimizer extension.
+    /// </summary>
+    public abstract class BaseOptimizerExtension : IOptimizerExtension
+    {
+        /// <summary>
+        /// Called after all files have been compiled, before built-in optimizations, and before all sections are linked into a single section.
+        /// </summary>
+        public virtual void PreOptimize(IOptimizeContext context)
+        {
+        }
+
+        /// <summary>
+        /// Called after all files have been compiled, after built-in optimizations, and before all sections are linked into a single section.
+        /// </summary>
+        public virtual void PostOptimize(IOptimizeContext context)
+        {
+        }
+    }
+}
diff --git a/src/api/wix/WixToolset.Extensibility/Data/ICompileContext.cs b/src/api/wix/WixToolset.Extensibility/Data/ICompileContext.cs
index 7006fde8..cfccd0a9 100644
--- a/src/api/wix/WixToolset.Extensibility/Data/ICompileContext.cs
+++ b/src/api/wix/WixToolset.Extensibility/Data/ICompileContext.cs
@@ -55,7 +55,7 @@ namespace WixToolset.Extensibility.Data
         XDocument Source { get; set; }
 
         /// <summary>
-        /// Cancellation token to abort cancellation.
+        /// Cancellation token.
         /// </summary>
         CancellationToken CancellationToken { get; set; }
     }
diff --git a/src/api/wix/WixToolset.Extensibility/Data/IOptimizeContext.cs b/src/api/wix/WixToolset.Extensibility/Data/IOptimizeContext.cs
new file mode 100644
index 00000000..5684ebcd
--- /dev/null
+++ b/src/api/wix/WixToolset.Extensibility/Data/IOptimizeContext.cs
@@ -0,0 +1,61 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Extensibility.Data
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Threading;
+    using WixToolset.Data;
+
+    /// <summary>
+    /// Context provided to the optimizer.
+    /// </summary>
+    public interface IOptimizeContext
+    {
+        /// <summary>
+        /// Service provider made available to the optimizer and its extensions.
+        /// </summary>
+        IServiceProvider ServiceProvider { get; }
+
+        /// <summary>
+        /// Set of extensions provided to the optimizer.
+        /// </summary>
+        IReadOnlyCollection<IOptimizerExtension> Extensions { get; set; }
+
+        /// <summary>
+        /// Intermediate folder.
+        /// </summary>
+        string IntermediateFolder { get; set; }
+
+        /// <summary>
+        /// Collection of bindpaths used to bind files.
+        /// </summary>
+        IReadOnlyCollection<IBindPath> BindPaths { get; set; }
+
+        /// <summary>
+        /// Bind variables used during optimization.
+        /// </summary>
+        IDictionary<string, string> BindVariables { get; set; }
+
+        /// <summary>
+        /// Gets or sets the platform which the optimizer will use when defaulting 64-bit symbol properties.
+        /// </summary>
+        /// <value>The platform which the optimizer will use when defaulting 64-bit symbol properties.</value>
+        Platform Platform { get; set; }
+
+        /// <summary>
+        /// Collection of intermediates to optimize.
+        /// </summary>
+        IReadOnlyCollection<Intermediate> Intermediates { get; set; }
+
+        /// <summary>
+        /// Collection of localization files to use in the optimizer.
+        /// </summary>
+        IReadOnlyCollection<Localization> Localizations { get; set; }
+
+        /// <summary>
+        /// Cancellation token.
+        /// </summary>
+        CancellationToken CancellationToken { get; set; }
+    }
+}
diff --git a/src/api/wix/WixToolset.Extensibility/IOptimizerExtension.cs b/src/api/wix/WixToolset.Extensibility/IOptimizerExtension.cs
new file mode 100644
index 00000000..589e7ecc
--- /dev/null
+++ b/src/api/wix/WixToolset.Extensibility/IOptimizerExtension.cs
@@ -0,0 +1,22 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Extensibility
+{
+    using WixToolset.Extensibility.Data;
+
+    /// <summary>
+    /// Interface that all optimizer extensions implement.
+    /// </summary>
+    public interface IOptimizerExtension
+    {
+        /// <summary>
+        /// Called after all files have been compiled, before built-in optimizations, and before all sections are linked into a single section.
+        /// </summary>
+        void PreOptimize(IOptimizeContext context);
+
+        /// <summary>
+        /// Called after all files have been compiled, after built-in optimizations, and before all sections are linked into a single section.
+        /// </summary>
+        void PostOptimize(IOptimizeContext context);
+    }
+}
diff --git a/src/wix/WixToolset.Core/CommandLine/BuildCommand.cs b/src/wix/WixToolset.Core/CommandLine/BuildCommand.cs
index 68dbd768..2ad18073 100644
--- a/src/wix/WixToolset.Core/CommandLine/BuildCommand.cs
+++ b/src/wix/WixToolset.Core/CommandLine/BuildCommand.cs
@@ -10,7 +10,6 @@ namespace WixToolset.Core.CommandLine
     using System.Threading.Tasks;
     using System.Xml.Linq;
     using WixToolset.Data;
-    using WixToolset.Data.Bind;
     using WixToolset.Extensibility;
     using WixToolset.Extensibility.Data;
     using WixToolset.Extensibility.Services;
@@ -112,6 +111,8 @@ namespace WixToolset.Core.CommandLine
                 return Task.FromResult(this.Messaging.LastErrorNumber);
             }
 
+            this.OptimizePhase(wixobjs, wxls, this.commandLine.BindPaths, this.commandLine.BindVariables, cancellationToken);
+
             if (inputsOutputs.OutputType == OutputType.Library)
             {
                 using (new IntermediateFieldContext("wix.lib"))
@@ -207,6 +208,22 @@ namespace WixToolset.Core.CommandLine
             return intermediates;
         }
 
+        private void OptimizePhase(IReadOnlyCollection<Intermediate> intermediates, IReadOnlyCollection<Localization> localizations, IReadOnlyCollection<IBindPath> bindPaths, Dictionary<string, string> bindVariables, CancellationToken cancellationToken)
+        {
+            var context = this.ServiceProvider.GetService<IOptimizeContext>();
+            context.Extensions = this.ExtensionManager.GetServices<IOptimizerExtension>();
+            context.IntermediateFolder = this.IntermediateFolder;
+            context.BindPaths = bindPaths;
+            context.BindVariables = bindVariables;
+            context.Platform = this.Platform;
+            context.Intermediates = intermediates;
+            context.Localizations = localizations;
+            context.CancellationToken = cancellationToken;
+
+            var optimizer = this.ServiceProvider.GetService<IOptimizer>();
+            optimizer.Optimize(context);
+        }
+
         private void LibraryPhase(IReadOnlyCollection<Intermediate> intermediates, IReadOnlyCollection<Localization> localizations, IEnumerable<string> libraryFiles, ISymbolDefinitionCreator creator, bool bindFiles, IReadOnlyCollection<IBindPath> bindPaths, Dictionary<string, string> bindVariables, string outputPath, CancellationToken cancellationToken)
         {
             var libraries = this.LoadLibraries(libraryFiles, creator);
diff --git a/src/wix/WixToolset.Core/IOptimizer.cs b/src/wix/WixToolset.Core/IOptimizer.cs
new file mode 100644
index 00000000..85c90b80
--- /dev/null
+++ b/src/wix/WixToolset.Core/IOptimizer.cs
@@ -0,0 +1,17 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Core
+{
+    using WixToolset.Extensibility.Data;
+
+    /// <summary>
+    /// Interface for built-in optimizer.
+    /// </summary>
+    public interface IOptimizer
+    {
+        /// <summary>
+        /// Called after all files have been compiled and before all sections are linked into a single section.
+        /// </summary>
+        void Optimize(IOptimizeContext context);
+    }
+}
diff --git a/src/wix/WixToolset.Core/OptimizeContext.cs b/src/wix/WixToolset.Core/OptimizeContext.cs
new file mode 100644
index 00000000..93b6c354
--- /dev/null
+++ b/src/wix/WixToolset.Core/OptimizeContext.cs
@@ -0,0 +1,39 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Core
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Threading;
+    using WixToolset.Data;
+    using WixToolset.Extensibility;
+    using WixToolset.Extensibility.Data;
+
+    internal class OptimizeContext : IOptimizeContext
+    {
+        internal OptimizeContext(IServiceProvider serviceProvider)
+        {
+            this.ServiceProvider = serviceProvider;
+        }
+
+        public IServiceProvider ServiceProvider { get; }
+
+        public IReadOnlyCollection<IOptimizerExtension> Extensions { get; set; }
+
+        public string IntermediateFolder { get; set; }
+
+        public IReadOnlyCollection<IBindPath> BindPaths { get; set; }
+
+        public IDictionary<string, string> BindVariables { get; set; }
+
+        public Platform Platform { get; set; }
+
+        public bool IsCurrentPlatform64Bit => this.Platform == Platform.ARM64 || this.Platform == Platform.X64;
+
+        public IReadOnlyCollection<Intermediate> Intermediates { get; set; }
+
+        public IReadOnlyCollection<Localization> Localizations { get; set; }
+
+        public CancellationToken CancellationToken { get; set; }
+    }
+}
diff --git a/src/wix/WixToolset.Core/Optimizer.cs b/src/wix/WixToolset.Core/Optimizer.cs
new file mode 100644
index 00000000..5864121e
--- /dev/null
+++ b/src/wix/WixToolset.Core/Optimizer.cs
@@ -0,0 +1,36 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Core
+{
+    using System;
+    using WixToolset.Extensibility.Data;
+    using WixToolset.Extensibility.Services;
+
+    internal class Optimizer : IOptimizer
+    {
+        internal Optimizer(IServiceProvider serviceProvider)
+        {
+            this.ServiceProvider = serviceProvider;
+            this.Messaging = this.ServiceProvider.GetService<IMessaging>();
+        }
+
+        private IServiceProvider ServiceProvider { get; }
+
+        private IMessaging Messaging { get; }
+
+        public void Optimize(IOptimizeContext context)
+        {
+            foreach (var extension in context.Extensions)
+            {
+                extension.PreOptimize(context);
+            }
+
+            // TODO: Fill with useful optimization features.
+
+            foreach (var extension in context.Extensions)
+            {
+                extension.PostOptimize(context);
+            }
+        }
+    }
+}
diff --git a/src/wix/WixToolset.Core/WixToolsetServiceProvider.cs b/src/wix/WixToolset.Core/WixToolsetServiceProvider.cs
index 5620bcd2..cb8dbd87 100644
--- a/src/wix/WixToolset.Core/WixToolsetServiceProvider.cs
+++ b/src/wix/WixToolset.Core/WixToolsetServiceProvider.cs
@@ -37,6 +37,7 @@ namespace WixToolset.Core
             this.AddService<ICommandLine>((provider, singletons) => new CommandLine.CommandLine(provider));
             this.AddService<IPreprocessContext>((provider, singletons) => new PreprocessContext(provider));
             this.AddService<ICompileContext>((provider, singletons) => new CompileContext(provider));
+            this.AddService<IOptimizeContext>((provider, singletons) => new OptimizeContext(provider));
             this.AddService<ILibraryContext>((provider, singletons) => new LibraryContext(provider));
             this.AddService<ILibraryResult>((provider, singletons) => new LibraryResult());
             this.AddService<ILinkContext>((provider, singletons) => new LinkContext(provider));
@@ -58,6 +59,7 @@ namespace WixToolset.Core
 
             this.AddService<IBinder>((provider, singletons) => new Binder(provider));
             this.AddService<ICompiler>((provider, singletons) => new Compiler(provider));
+            this.AddService<IOptimizer>((provider, singletons) => new Optimizer(provider));
             this.AddService<ILayoutCreator>((provider, singletons) => new LayoutCreator(provider));
             this.AddService<IPreprocessor>((provider, singletons) => new Preprocessor(provider));
             this.AddService<ILibrarian>((provider, singletons) => new Librarian(provider));
diff --git a/src/wix/test/Example.Extension/ExampleExtensionFactory.cs b/src/wix/test/Example.Extension/ExampleExtensionFactory.cs
index 0b0fb836..16eea6dc 100644
--- a/src/wix/test/Example.Extension/ExampleExtensionFactory.cs
+++ b/src/wix/test/Example.Extension/ExampleExtensionFactory.cs
@@ -35,6 +35,10 @@ namespace Example.Extension
             {
                 extension = new ExampleCompilerExtension();
             }
+            else if (extensionType == typeof(IOptimizerExtension))
+            {
+                extension = new ExampleOptimizerExtension();
+            }
             else if (extensionType == typeof(IExtensionData))
             {
                 extension = new ExampleExtensionData();
diff --git a/src/wix/test/Example.Extension/ExampleOptimizerExtension.cs b/src/wix/test/Example.Extension/ExampleOptimizerExtension.cs
new file mode 100644
index 00000000..6a2cb91e
--- /dev/null
+++ b/src/wix/test/Example.Extension/ExampleOptimizerExtension.cs
@@ -0,0 +1,22 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace Example.Extension
+{
+    using System.Linq;
+    using WixToolset.Extensibility;
+    using WixToolset.Extensibility.Data;
+
+    internal class ExampleOptimizerExtension : BaseOptimizerExtension
+    {
+        public override void PostOptimize(IOptimizeContext context)
+        {
+            foreach (var intermediate in context.Intermediates)
+            {
+                foreach (var symbol in intermediate.Sections.SelectMany(s=>s.Symbols).OfType<ExampleSymbol>())
+                {
+                    symbol.Value = $"{symbol.Value} <optimized>";
+                }
+            }
+        }
+    }
+}
diff --git a/src/wix/test/WixToolsetTest.CoreIntegration/ExtensionFixture.cs b/src/wix/test/WixToolsetTest.CoreIntegration/ExtensionFixture.cs
index 710f3b8d..429226f5 100644
--- a/src/wix/test/WixToolsetTest.CoreIntegration/ExtensionFixture.cs
+++ b/src/wix/test/WixToolsetTest.CoreIntegration/ExtensionFixture.cs
@@ -24,7 +24,7 @@ namespace WixToolsetTest.CoreIntegration
             var results = build.BuildAndQuery(Build, "Wix4Example");
             WixAssert.CompareLineByLine(new[]
             {
-                "Wix4Example:Foo\tfilF5_pLhBuF5b4N9XEo52g_hUM5Lo\tBar"
+                "Wix4Example:Foo\tfilF5_pLhBuF5b4N9XEo52g_hUM5Lo\tBar <optimized>"
             }, results);
         }
 
@@ -92,7 +92,7 @@ namespace WixToolsetTest.CoreIntegration
                 var example = section.Symbols.Where(t => t.Definition.Type == SymbolDefinitionType.MustBeFromAnExtension).Single();
                 WixAssert.StringEqual("Foo", example.Id?.Id);
                 WixAssert.StringEqual("filF5_pLhBuF5b4N9XEo52g_hUM5Lo", example[0].AsString());
-                WixAssert.StringEqual("Bar", example[1].AsString());
+                WixAssert.StringEqual("Bar <optimized>", example[1].AsString());
             }
         }
 
diff --git a/src/wix/test/WixToolsetTest.CoreIntegration/TestData/ExampleExtension/Decompiled-Expected.xml b/src/wix/test/WixToolsetTest.CoreIntegration/TestData/ExampleExtension/Decompiled-Expected.xml
index 42ececb1..0375b3b6 100644
--- a/src/wix/test/WixToolsetTest.CoreIntegration/TestData/ExampleExtension/Decompiled-Expected.xml
+++ b/src/wix/test/WixToolsetTest.CoreIntegration/TestData/ExampleExtension/Decompiled-Expected.xml
@@ -5,7 +5,7 @@
     <StandardDirectory Id="ProgramFilesFolder">
       <Directory Id="INSTALLFOLDER" ShortName="oekcr5lq" Name="MsiPackage">
         <Component Id="filF5_pLhBuF5b4N9XEo52g_hUM5Lo" Guid="{GUID}" Bitness="always32">
-          <Example Id="Foo" Value="Bar" xmlns="http://www.example.com/scheams/v1/wxs" />
+          <Example Id="Foo" Value="Bar &lt;optimized&gt;" xmlns="http://www.example.com/scheams/v1/wxs" />
           <File Id="filF5_pLhBuF5b4N9XEo52g_hUM5Lo" Name="example.txt" KeyPath="yes" Source="PFiles\MsiPackage\example.txt" />
         </Component>
       </Directory>
diff --git a/src/wix/test/WixToolsetTest.CoreIntegration/WixlibFixture.cs b/src/wix/test/WixToolsetTest.CoreIntegration/WixlibFixture.cs
index 76326741..0cd8a542 100644
--- a/src/wix/test/WixToolsetTest.CoreIntegration/WixlibFixture.cs
+++ b/src/wix/test/WixToolsetTest.CoreIntegration/WixlibFixture.cs
@@ -288,7 +288,7 @@ namespace WixToolsetTest.CoreIntegration
 
                 var example = section.Symbols.Where(t => t.Definition.Type == SymbolDefinitionType.MustBeFromAnExtension).Single();
                 WixAssert.StringEqual("Foo", example.Id?.Id);
-                WixAssert.StringEqual("Bar", example[1].AsString());
+                WixAssert.StringEqual("Bar <optimized>", example[1].AsString());
             }
         }
 
@@ -351,7 +351,7 @@ namespace WixToolsetTest.CoreIntegration
                 var examples = section.Symbols.Where(t => t.Definition.Type == SymbolDefinitionType.MustBeFromAnExtension).ToArray();
                 WixAssert.CompareLineByLine(new[] { "Foo", "Other" }, examples.Select(t => t.Id?.Id).ToArray());
                 WixAssert.CompareLineByLine(new[] { "filF5_pLhBuF5b4N9XEo52g_hUM5Lo", "filvxdStJhRE_M5kbpLsTZJXbs34Sg" }, examples.Select(t => t[0].AsString()).ToArray());
-                WixAssert.CompareLineByLine(new[] { "Bar", "Value" }, examples.Select(t => t[1].AsString()).ToArray());
+                WixAssert.CompareLineByLine(new[] { "Bar <optimized>", "Value <optimized>" }, examples.Select(t => t[1].AsString()).ToArray());
             }
         }
     }