JIT: fix non-funclet EH empty finally/fault removal (#109361)

For non-funclet EH we don't use the handler index to constrain the placement
of add code descs, but we were still recording the handler index in the ACD.

This lead to some errors in ACD maintenance if there was an EH region
being removed with an ACD in the try and an equivalent one in the handler.

Fixes #108851

src/coreclr/jit/fgehopt.cpp

@@ -233,6 +233,9 @@ PhaseStatus Compiler::fgRemoveEmptyFinally()
             AddCodeDscMap* const map = fgGetAddCodeDscMap();
             for (AddCodeDsc* const add : AddCodeDscMap::ValueIteration(map))
             {
+                JITDUMP("Considering ");
+                JITDUMPEXEC(add->Dump());
+
                 // Remember the old lookup key
                 //
                 AddCodeDscKey oldKey(add);
@@ -245,7 +248,7 @@ PhaseStatus Compiler::fgRemoveEmptyFinally()
                 {
                     bool const removed = map->Remove(oldKey);
                     assert(removed);
-                    JITDUMP("ACD%u was in EH#%u handler region: removing\n", XTnum);
+                    JITDUMP("ACD%u was in EH#%u handler region: removing\n", add->acdNum, XTnum);
                     JITDUMPEXEC(add->Dump());
                     continue;
                 }
@@ -258,6 +261,7 @@ PhaseStatus Compiler::fgRemoveEmptyFinally()
 
                 if (!inTry || ((unsigned)(add->acdTryIndex - 1) != XTnum))
                 {
+                    JITDUMP("ACD%u not affected\n", add->acdNum);
                     continue;
                 }
 

src/coreclr/jit/flowgraph.cpp

@@ -3420,9 +3420,12 @@ void Compiler::fgAddCodeRef(BasicBlock* srcBlk, SpecialCodeKind kind)
     add              = new (this, CMK_Unknown) AddCodeDsc;
     add->acdDstBlk   = nullptr;
     add->acdTryIndex = srcBlk->bbTryIndex;
-    add->acdHndIndex = srcBlk->bbHndIndex;
-    add->acdKeyDsg   = dsg;
-    add->acdKind     = kind;
+
+    // For non-funclet EH we don't constrain ACD placement via handler regions
+    add->acdHndIndex = UsesFunclets() ? srcBlk->bbHndIndex : 0;
+
+    add->acdKeyDsg = dsg;
+    add->acdKind   = kind;
 
     // This gets set true in the stack level setter
     // if there's still a need for this helper

src/tests/JIT/Regression/JitBlue/Runtime_108851/Runtime_108851.cs

@@ -0,0 +1,46 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+// Generated by Fuzzlyn v2.4 on 2024-10-14 17:25:44
+// Run on X86 Windows
+// Seed: 16789241273493732217-vectort,vector128,vector256,x86aes,x86avx,x86avx2,x86avx512bw,x86avx512bwvl,x86avx512cd,x86avx512cdvl,x86avx512dq,x86avx512dqvl,x86avx512f,x86avx512fvl,x86bmi1,x86bmi2,x86fma,x86lzcnt,x86pclmulqdq,x86popcnt,x86sse,x86sse2,x86sse3,x86sse41,x86sse42,x86ssse3,x86x86base
+// Reduced from 49.4 KiB to 0.5 KiB in 00:03:38
+// Hits JIT assert in Release:
+// Assertion failed '!fgRngChkThrowAdded' in 'Program:Main(Fuzzlyn.ExecutionServer.IRuntime)' during 'Calculate stack level slots' (IL size 59; hash 0xade6b36b; FullOpts)
+// 
+//     File: D:\a\_work\1\s\src\coreclr\jit\flowgraph.cpp Line: 3655
+// 
+using System;
+using System.Numerics;
+using System.Runtime.Intrinsics;
+using System.Runtime.Intrinsics.X86;
+using Xunit;
+
+public class Runtime_108851
+{
+    public static int[] s_21 = new int[1];
+
+    [Fact]
+    public static void Problem()
+    {
+        if (!Avx512F.IsSupported)
+        {
+            return;
+        }
+
+        var vr1 = Vector128.Create<double>(0);
+        if (Avx512F.ConvertToUInt32WithTruncation(vr1) >= 2894444111893762202L)
+        {
+            try
+            {
+                s_21[0] = 0;
+            }
+            finally
+            {
+                s_21[0] = 0;
+            }
+        }
+
+        s_21[0] = 0;
+    }
+}

src/tests/JIT/Regression/JitBlue/Runtime_108851/Runtime_108851.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <Optimize>True</Optimize>
+    <NoWarn>0652</NoWarn>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="$(MSBuildProjectName).cs" />
+  </ItemGroup>
+</Project>