Fix GCStress coverage for multi reg returns. (#24826)

* Extract ReplaceInstrAfterCall.

* Avoid GCStress when return multireg with pointers.

Determinate when we need to protect the second register and do not cause GCStress in such cases.

* Add a repro test.

* Reenable MethodImplOptionsTests.

* Extract IsGcCoveregeInterruptInstruction.

That changes how we do checks for arm32 in `IsGcCoverageInterrupt`.

* Tolerate direct call to JIT_RareDisableHelper.

x86 ILStubClass:IL_STUB_PInvoke(byref,ref,int,byref):int generates it like:
Generating: N119 (  4,  7) [000118] ------------              *  RETURNTRAP int    REG NA
IN0021:        cmp      dword ptr [0F9BF9F8H], 0
New Basic Block BB10 [0009] created.
IN0022:        je       L_M6496_BB10
                                                        Call: GCvars=00000001 {V01}, gcrefRegs=00000000 {}, byrefRegs=00000000 {}
IN0023:        call     CORINFO_HELP_STOP_FOR_GC

* Support GC stress protect return 1/2/both Unix x64.

* Fix arm64.

Do not insert GC Stress instrucitons when we can't determinate the exact return kind.

* Fix review1.

* Fix review2.

* Change the test as Andy suggested.

* Fix some typos.

* Replace all SLOT with PBYTE.

* Disable assert that can fail because of multithreading.

2 files changed, 250 insertions, 0 deletions

diff --git a/tests/src/JIT/Regression/JitBlue/GitHub_23199/GitHub_23199.cs b/tests/src/JIT/Regression/JitBlue/GitHub_23199/GitHub_23199.cs
new file mode 100644
index 0000000000..5d4983e320
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/GitHub_23199/GitHub_23199.cs
@@ -0,0 +1,201 @@
+using System;
+using System.Diagnostics;
+using System.Runtime.CompilerServices;
+
+// The test revealed some problems of GCStress infrastructure on platforms with multi reg returns (arm64, amd64 Unix).
+// It required GCStress=0xc and GcStressOnDirectCalls=1 to hit issues. The issues were with saving GC pointers in the return registers.
+// The GC infra has to correctly mark registers with pointers as alive and must not report registers without pointers.
+
+#if BIT32
+using nint = System.Int32;
+#else
+using nint = System.Int64;
+#endif
+
+namespace GitHub_23199
+{
+    public class Program
+    {
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static Object TestCrossgenedReturnWith2PointersStruct()
+        {
+            ProcessStartInfo pi = new ProcessStartInfo();
+            // pi.Environment calls crossgened HashtableEnumerator::get_Entry returning struct that we need.
+            Console.WriteLine(pi.Environment.Count);
+            return pi;
+        }
+
+        struct TwoPointers
+        {
+            public Object a;
+            public Object b;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static TwoPointers GetTwoPointersStruct()
+        {
+            var a = new TwoPointers();
+            a.a = new String("TestTwoPointers");
+            a.b = new string("Passed");
+            return a;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static Object TestTwoPointers()
+        {
+            var a = GetTwoPointersStruct(); // Report both.
+            Console.WriteLine(a.a + " " + a.b);
+            return a;
+        }
+
+        struct OnePointer
+        {
+            public Object a;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static TwoPointers GetOnePointer()
+        {
+            var a = new TwoPointers();
+            a.a = new String("TestOnePointer Passed");
+            return a;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static Object TestOnePointer()
+        {
+            var a = GetOnePointer();  // Report one.
+            Console.WriteLine(a.a);
+            return a;
+        }
+
+        struct FirstPointer
+        {
+            public Object a;
+            public nint b;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static FirstPointer GetFirstPointer()
+        {
+            var a = new FirstPointer();
+            a.a = new String("TestFirstPointer Passed");
+            a.b = 100;
+            return a;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static Object TestFirstPointer()
+        {
+            var a = GetFirstPointer();  // Report the first field, do not report the second.
+            Console.WriteLine(a.a);
+            return a;
+        }
+
+        struct SecondPointer
+        {
+            public nint a;
+            public Object b;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static SecondPointer GetSecondPointer()
+        {
+            var a = new SecondPointer();
+            a.a = 100;
+            a.b = new String("TestSecondPointer Passed");
+            return a;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static Object TestSecondPointer()
+        {
+            var a = GetSecondPointer(); // Report the second field, do not report the first.
+            Console.WriteLine(a.b);
+            return a;
+        }
+
+        struct NoPointer1
+        {
+            public nint a;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static NoPointer1 GetNoPointer1()
+        {
+            var a = new NoPointer1();
+            a.a = 100;
+            return a;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static Object TestNoPointer1()
+        {
+            var a = GetNoPointer1(); // Do not report anything.
+            Console.WriteLine("TestNoPointer1 Passed");
+            return a;
+        }
+
+        struct NoPointer2
+        {
+            public nint a;
+            public nint b;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static NoPointer2 GetNoPointer2()
+        {
+            var a = new NoPointer2();
+            a.a = 100;
+            a.b = 100;
+            return a;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static Object TestNoPointer2()
+        {
+            NoPointer2 a = GetNoPointer2();  // Do not report anything.
+            Console.WriteLine("TestNoPointer2 Passed");
+            return a;
+        }
+        
+        struct ThirdPointer
+        {
+            public nint a;
+            public nint b;
+            public Object c;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static ThirdPointer GetThirdPointer()
+        {
+            var a = new ThirdPointer();
+            a.a = 100;
+            a.b = 100;
+            a.c = new String("TestThirdPointer Passed");
+            return a;
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        static Object TestThirdPointer()
+        {
+            ThirdPointer a = GetThirdPointer();  // Do not return in registers.
+            Console.WriteLine(a.c);
+            return a;
+        }
+
+
+        static int Main(string[] args)
+        {
+            TestCrossgenedReturnWith2PointersStruct();
+            TestTwoPointers();
+            TestOnePointer();
+            TestFirstPointer();
+            TestSecondPointer();
+            TestNoPointer1();
+            TestNoPointer2();
+            TestThirdPointer();
+            return 100;
+        }
+    }
+}
diff --git a/tests/src/JIT/Regression/JitBlue/GitHub_23199/GitHub_23199.csproj b/tests/src/JIT/Regression/JitBlue/GitHub_23199/GitHub_23199.csproj
new file mode 100644
index 0000000000..273893797e
--- /dev/null
+++ b/tests/src/JIT/Regression/JitBlue/GitHub_23199/GitHub_23199.csproj
@@ -0,0 +1,49 @@
+<?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 $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
+    <CLRTestPriority>1</CLRTestPriority>
+  </PropertyGroup>
+  <PropertyGroup Condition=" '$(PointerSize)' == '32' ">
+    <DefineConstants>BIT32;$(DefineConstants)</DefineConstants>
+  </PropertyGroup>
+  <!-- Default configurations to help VS understand the configurations -->
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' "></PropertyGroup>
+  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' " />
+  <ItemGroup>
+    <CodeAnalysisDependentAssemblyPaths Condition=" '$(VS100COMNTOOLS)' != '' " Include="$(VS100COMNTOOLS)..\IDE\PrivateAssemblies">
+      <Visible>False</Visible>
+    </CodeAnalysisDependentAssemblyPaths>
+  </ItemGroup>
+  <PropertyGroup>
+    <DebugType>None</DebugType>
+    <Optimize>True</Optimize>
+  </PropertyGroup>
+  <ItemGroup>
+    <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
+  </ItemGroup>
+  <PropertyGroup>
+    <CLRTestBatchPreCommands><![CDATA[
+$(CLRTestBatchPreCommands)
+set COMPlus_GcStressOnDirectCalls=1
+set COMPlus_GcStress=0xc
+]]></CLRTestBatchPreCommands>
+  <BashCLRTestPreCommands><![CDATA[
+$(BashCLRTestPreCommands)
+export COMPlus_GcStressOnDirectCalls=1
+export COMPlus_GcStress=0xc
+]]></BashCLRTestPreCommands>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
+  <PropertyGroup Condition=" '$(MsBuildProjectDirOverride)' != '' "></PropertyGroup>
+</Project>