Fix for bug 12398: Lowering is inconsistent in checking safety of RegOptional. (#19740)

This fixes an inconsistency in lowering where it fails to make an
operand contained because IsSafeToContainMem() returns false yet
it marks it regOptional, which may cause a problem if the operand
will be loaded at the point of use.

I also fixed a case where an operand was marked RegOptional even though
there is a type size mismatch.

There are 7 places that are affected, I added repro cases for 4 of them.
I wasn't able to construct repros for the 3 places that deal with
floating point operands but decided to fix those places anyway.

Fixes #12398.

2 files changed, 118 insertions, 0 deletions

diff --git a/tests/src/JIT/Regression/JitBlue/GitHub_12398/Github_12398.cs b/tests/src/JIT/Regression/JitBlue/GitHub_12398/Github_12398.cs
new file mode 100644
index 0000000000..69057f33a3
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/GitHub_12398/Github_12398.cs
@@ -0,0 +1,84 @@
+// 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.
+//
+// GitHub12398: Lowering is inconsistent in checking safety of RegOptional.
+
+using System;
+using System.Runtime.CompilerServices;
+
+struct S0
+{
+    public sbyte F1;
+    public sbyte F2;
+}
+
+class GitHub_12398
+{
+    static int Main()
+    {
+        int result = 100;
+        if (TestBinary() != 0) {
+            Console.WriteLine("Failed TestBinary");
+            result = -1;
+        }
+
+        if (TestCompare()) {
+            Console.WriteLine("Failed TestCompare");
+            result = -1;
+        }
+
+        if (TestMul() != 1) {
+            Console.WriteLine("Failed TestMul");
+            result = -1;
+        }
+
+        if (TestMulTypeSize() != 0) {
+            Console.WriteLine ("Failed TestMulTypeSize");
+            result = -1;
+        }
+
+        if (result == 100) {
+            Console.WriteLine("PASSED");
+        }
+        else {
+            Console.WriteLine("FAILED");
+        }
+
+        return result;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    static long TestBinary()
+    {
+        long l = 0;
+        long result = l ^ System.Threading.Interlocked.Exchange(ref l, 1);
+        return result;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    public static bool TestCompare()
+    {
+        long l = 0;
+        bool result = l > System.Threading.Interlocked.Exchange(ref l, 1);
+        return result;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    public static long TestMul()
+    {
+        long l = 1;
+        long result = l * System.Threading.Interlocked.Exchange(ref l, 0);
+        return result;
+    }
+
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    public static int TestMulTypeSize()
+    {
+        S0 s = new S0();
+        s.F2--;
+        int i = System.Threading.Volatile.Read(ref s.F1) * 100;
+        return i;
+    }
+}
+
diff --git a/tests/src/JIT/Regression/JitBlue/GitHub_12398/Github_12398.csproj b/tests/src/JIT/Regression/JitBlue/GitHub_12398/Github_12398.csproj
new file mode 100644
index 0000000000..67d0b29edb
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/GitHub_12398/Github_12398.csproj
@@ -0,0 +1,34 @@
+<?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>
+    <AssemblyName>$(MSBuildProjectName)</AssemblyName>
+    <SchemaVersion>2.0</SchemaVersion>
+    <ProjectGuid>{ADEEA3D1-B67B-456E-8F2B-6DCCACC2D34C}</ProjectGuid>
+    <OutputType>Exe</OutputType>
+    <ProjectTypeGuids>{786C830F-07A1-408B-BD7F-6EE04809D6DB};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
+    <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
+  </PropertyGroup>
+  <!-- Default configurations to help VS understand the configurations -->
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' "></PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' "></PropertyGroup>
+  <ItemGroup>
+    <CodeAnalysisDependentAssemblyPaths Condition=" '$(VS100COMNTOOLS)' != '' " Include="$(VS100COMNTOOLS)..\IDE\PrivateAssemblies">
+      <Visible>False</Visible>
+    </CodeAnalysisDependentAssemblyPaths>
+  </ItemGroup>
+  <PropertyGroup>
+    <DebugType></DebugType>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
+  <PropertyGroup Condition=" '$(MsBuildProjectDirOverride)' != '' "></PropertyGroup>
+</Project>