From 54ef3eb3ceae91719330d052c502441994fde228 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20Strehovsk=C3=BD?=
 <MichalStrehovsky@users.noreply.github.com>
Date: Tue, 17 Oct 2023 13:21:49 +0200
Subject: [PATCH 1/2] Add a test for determinism

Resolves #73931. This checks that the result of parallel build is the same as the result of single-threaded build.

I'd like to add some more code to this so that there's more junk to compile but don't have a good idea of what to add. `XmlSerializer`? Suggestions welcome.
---
 .../SmokeTests/Determinism/Determinism.cs     | 22 +++++++++++
 .../SmokeTests/Determinism/Determinism.csproj | 37 +++++++++++++++++++
 2 files changed, 59 insertions(+)
 create mode 100644 src/tests/nativeaot/SmokeTests/Determinism/Determinism.cs
 create mode 100644 src/tests/nativeaot/SmokeTests/Determinism/Determinism.csproj

diff --git a/src/tests/nativeaot/SmokeTests/Determinism/Determinism.cs b/src/tests/nativeaot/SmokeTests/Determinism/Determinism.cs
new file mode 100644
index 0000000000000..8409645d31bc7
--- /dev/null
+++ b/src/tests/nativeaot/SmokeTests/Determinism/Determinism.cs
@@ -0,0 +1,22 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.IO;
+
+using var baseline = File.OpenRead("baseline.object");
+using var compare = File.OpenRead("compare.object");
+
+Console.WriteLine($"Baseline size: {baseline.Length}");
+Console.WriteLine($"Compare size: {compare.Length}");
+
+if (baseline.Length != compare.Length)
+    throw new Exception("Different sizes");
+
+for (int i = 0; i < baseline.Length; i++)
+{
+    if (baseline.ReadByte() != compare.ReadByte())
+        throw new Exception($"Different at byte {i}");
+}
+
+return 100;
diff --git a/src/tests/nativeaot/SmokeTests/Determinism/Determinism.csproj b/src/tests/nativeaot/SmokeTests/Determinism/Determinism.csproj
new file mode 100644
index 0000000000000..725a7dff99fd6
--- /dev/null
+++ b/src/tests/nativeaot/SmokeTests/Determinism/Determinism.csproj
@@ -0,0 +1,37 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <CLRTestPriority>0</CLRTestPriority>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="Determinism.cs" />
+  </ItemGroup>
+
+  <Target Name="IlcCompileSingleThreaded"
+      Inputs="$(NativeIntermediateOutputPath)%(ManagedBinary.Filename)$(IlcOutputFileExt)"
+      Outputs="$(NativeIntermediateOutputPath)%(ManagedBinary.Filename)$(IlcOutputFileExt)-singlethreaded"
+      AfterTargets="IlcCompile">
+
+    <PropertyGroup>
+      <OldObjectFileName>$(NativeIntermediateOutputPath)%(ManagedBinary.Filename)$(IlcOutputFileExt)</OldObjectFileName>
+      <NewObjectFileName>$(NativeIntermediateOutputPath)%(ManagedBinary.Filename)$(IlcOutputFileExt)-singlethreaded</NewObjectFileName>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <IlcArg Remove="-o:$(OldObjectFileName)" />
+      <IlcArg Include="-o:$(NewObjectFileName)" />
+      <IlcArg Include="--parallelism:1" />
+    </ItemGroup>
+
+    <WriteLinesToFile File="%(ManagedBinary.IlcRspFile)-singlethreaded" Lines="@(IlcArg)" Overwrite="true" WriteOnlyWhenDifferent="true" />
+
+    <Message Text="Compiling single-threaded baseline" Importance="High" />
+
+    <Exec Command="&quot;$(IlcToolsPath)\ilc&quot; @&quot;%(ManagedBinary.IlcRspFile)-singlethreaded&quot;"
+          EnvironmentVariables="$(_IlcEnvironmentVariables)" />
+
+    <Copy SourceFiles="$(OldObjectFileName)" DestinationFiles="$(OutDir)\baseline.object" />
+    <Copy SourceFiles="$(NewObjectFileName)" DestinationFiles="$(OutDir)\compare.object" />
+  </Target>
+</Project>

From 561baefcb97ab1d2117481182d238df2846e83e4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Michal=20Strehovsk=C3=BD?=
 <MichalStrehovsky@users.noreply.github.com>
Date: Thu, 19 Oct 2023 10:06:26 +0200
Subject: [PATCH 2/2] Call into the other test

---
 .../nativeaot/SmokeTests/Determinism/Determinism.cs  | 12 +++++++++++-
 .../SmokeTests/Determinism/Determinism.csproj        |  5 +++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/tests/nativeaot/SmokeTests/Determinism/Determinism.cs b/src/tests/nativeaot/SmokeTests/Determinism/Determinism.cs
index 8409645d31bc7..bd2361ddf0e8b 100644
--- a/src/tests/nativeaot/SmokeTests/Determinism/Determinism.cs
+++ b/src/tests/nativeaot/SmokeTests/Determinism/Determinism.cs
@@ -13,10 +13,20 @@
 if (baseline.Length != compare.Length)
     throw new Exception("Different sizes");
 
-for (int i = 0; i < baseline.Length; i++)
+long length = baseline.Length;
+for (int i = 0; i < length; i++)
 {
     if (baseline.ReadByte() != compare.ReadByte())
         throw new Exception($"Different at byte {i}");
 }
 
+// We're not interested in running this, we just want some junk to compile
+if (Environment.GetEnvironmentVariable("Never") == "Ever")
+{
+    Delegates.Run();
+    Devirtualization.Run();
+    Generics.Run();
+    Interfaces.Run();
+}
+
 return 100;
diff --git a/src/tests/nativeaot/SmokeTests/Determinism/Determinism.csproj b/src/tests/nativeaot/SmokeTests/Determinism/Determinism.csproj
index 725a7dff99fd6..5601b0480c7ff 100644
--- a/src/tests/nativeaot/SmokeTests/Determinism/Determinism.csproj
+++ b/src/tests/nativeaot/SmokeTests/Determinism/Determinism.csproj
@@ -6,6 +6,11 @@
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="Determinism.cs" />
+    <Compile Include="../UnitTests/Delegates.cs" />
+    <Compile Include="../UnitTests/Devirtualization.cs" />
+    <Compile Include="../UnitTests/Generics.cs" />
+    <Compile Include="../UnitTests/Interfaces.cs" />
+
   </ItemGroup>
 
   <Target Name="IlcCompileSingleThreaded"