Fix for a jit liveness bug.

`fgRemoveDeadStore` has special logic for removing dead assignments
whose rhs was of type `TYP_STRUCT`:

https://github.com/dotnet/coreclr/blob/311b5e2fe413c6c74a2a3680ab54d8a978651472/src/jit/liveness.cpp#L2264-L2274

That logic was applied to "normal"
assignments (i.e., direct children of `GT_STMT`) but not to "internal"
assignments (e.g., children of `GT_COMMA`).
The test case has an internal assignment and, because this logic wasn't
applied, we ended up with a standalone `GT_IND` of type `TYP_STRUCT`
that the register allocator can't handle.

This change apples the missing logic to "internal" assignments.

Fixes #24253.

2 files changed, 90 insertions, 0 deletions

diff --git a/tests/src/JIT/Regression/JitBlue/GitHub_24253/GitHub_24253.cs b/tests/src/JIT/Regression/JitBlue/GitHub_24253/GitHub_24253.cs
new file mode 100644
index 0000000000..65110fe401
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/GitHub_24253/GitHub_24253.cs
@@ -0,0 +1,57 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using System.Runtime.CompilerServices;
+
+// Test removal of a dead struct assignment when the assignment is "internal"
+// i.e., is not a direct child of a statement node.
+// In this example, the statement is STMT(COMMA(CALL HELPER.CORINFO_HELP_GETSHARED_NONGCSTATIC_BASE, ASG)).
+
+namespace GitHub_24253
+{
+    struct TestStruct
+    {
+        public static readonly TestStruct ZeroStruct = new TestStruct(0);
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        public TestStruct(int i)
+        {
+            this.i = i;
+            this.j = 5;
+            this.k = 5;
+            this.l = 5;
+        }
+
+        int i;
+        int j;
+        short k;
+        short l;
+    }
+
+    class Program
+    {
+        static int Main(string[] args)
+        {
+            GetStruct(1);
+            return 100;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private static TestStruct GetStruct(int i)
+        {
+            // This is the dead assignment that is causing the bug assert.
+            TestStruct result = TestStruct.ZeroStruct;
+            try
+            {
+                result = new TestStruct(i);
+            }
+            catch
+            {
+                throw new ArgumentException();
+            }
+            return result;
+        }
+    }
+}
diff --git a/tests/src/JIT/Regression/JitBlue/GitHub_24253/GitHub_24253.csproj b/tests/src/JIT/Regression/JitBlue/GitHub_24253/GitHub_24253.csproj
new file mode 100644
index 0000000000..95052d9884
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/GitHub_24253/GitHub_24253.csproj
@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" />
+  <PropertyGroup>
+    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
+    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
+    <SchemaVersion>2.0</SchemaVersion>
+    <ProjectGuid>{95DFC527-4DC1-495E-97D7-E94EE1F7140D}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
+  </PropertyGroup>
+  <!-- Default configurations to help VS understand the configurations -->
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' "></PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' " />
+  <ItemGroup>
+    <CodeAnalysisDependentAssemblyPaths Condition=" '$(VS100COMNTOOLS)' != '' " Include="$(VS100COMNTOOLS)..\IDE\PrivateAssemblies">
+      <Visible>False</Visible>
+    </CodeAnalysisDependentAssemblyPaths>
+  </ItemGroup>
+  <PropertyGroup>
+    <DebugType>None</DebugType>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
+  <PropertyGroup Condition=" '$(MsBuildProjectDirOverride)' != '' "></PropertyGroup>
+</Project>