From bf95049818f3eb968345945192e9ab341429bc27 Mon Sep 17 00:00:00 2001
From: Jakob Botsch Nielsen <jakob.botsch.nielsen@gmail.com>
Date: Thu, 1 Aug 2024 19:34:39 +0200
Subject: [PATCH 1/2] Diagnose beginInlining problem

---
 .../JitInterface/CorInfoImpl.ReadyToRun.cs    | 32 ++++++++++++++++---
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs b/src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs
index cecfbe0e5d5854..2d704b4037c687 100644
--- a/src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs
+++ b/src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs
@@ -3174,14 +3174,36 @@ private void setEHinfo(uint EHnumber, ref CORINFO_EH_CLAUSE clause)
         }
 
         private readonly Stack<List<ISymbolNode>> _stashedPrecodeFixups = new Stack<List<ISymbolNode>>();
-        private readonly Stack<HashSet<MethodDesc>> _stashedInlinedMethods = new Stack<HashSet<MethodDesc>>();
+        private readonly Stack<HashSet<MethodDesc>> _stashedInlinedMethods = FailFastIfNull(new Stack<HashSet<MethodDesc>>());
 
         private void beginInlining(CORINFO_METHOD_STRUCT_* inlinerHnd, CORINFO_METHOD_STRUCT_* inlineeHnd)
         {
-            _stashedPrecodeFixups.Push(_precodeFixups);
-            _precodeFixups = null;
-            _stashedInlinedMethods.Push(_inlinedMethods);
-            _inlinedMethods = null;
+            try
+            {
+                _stashedPrecodeFixups.Push(_precodeFixups);
+                _precodeFixups = null;
+                _stashedInlinedMethods.Push(_inlinedMethods);
+                _inlinedMethods = null;
+            }
+            catch
+            {
+                Environment.FailFast("Caught exception in beginInlining");
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private static Stack<HashSet<MethodDesc>> FailFastIfNull(Stack<HashSet<MethodDesc>> s)
+        {
+            var array = Accessor<HashSet<MethodDesc>>.GetArray(s);
+            if (array == null)
+                Environment.FailFast("Got null array");
+            return s;
+        }
+
+        class Accessor<T>
+        {
+            [UnsafeAccessor(UnsafeAccessorKind.Field, Name = "_array")]
+            public extern static ref T[] GetArray(Stack<T> stack);
         }
 
         private void reportInliningDecision(CORINFO_METHOD_STRUCT_* inlinerHnd, CORINFO_METHOD_STRUCT_* inlineeHnd, CorInfoInline inlineResult, byte* reason)

From dcdb784aa32887c88bfdfba67e16a6dd07b1f92f Mon Sep 17 00:00:00 2001
From: Jakob Botsch Nielsen <jakob.botsch.nielsen@gmail.com>
Date: Fri, 2 Aug 2024 11:42:00 +0200
Subject: [PATCH 2/2] Force inlining, do for both stacks

---
 .../JitInterface/CorInfoImpl.ReadyToRun.cs                | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs b/src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs
index 2d704b4037c687..99f051e079ef9c 100644
--- a/src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs
+++ b/src/coreclr/tools/aot/ILCompiler.ReadyToRun/JitInterface/CorInfoImpl.ReadyToRun.cs
@@ -3173,7 +3173,7 @@ private void setEHinfo(uint EHnumber, ref CORINFO_EH_CLAUSE clause)
             _ehClauses[EHnumber] = clause;
         }
 
-        private readonly Stack<List<ISymbolNode>> _stashedPrecodeFixups = new Stack<List<ISymbolNode>>();
+        private readonly Stack<List<ISymbolNode>> _stashedPrecodeFixups = FailFastIfNull(new Stack<List<ISymbolNode>>());
         private readonly Stack<HashSet<MethodDesc>> _stashedInlinedMethods = FailFastIfNull(new Stack<HashSet<MethodDesc>>());
 
         private void beginInlining(CORINFO_METHOD_STRUCT_* inlinerHnd, CORINFO_METHOD_STRUCT_* inlineeHnd)
@@ -3191,10 +3191,10 @@ private void beginInlining(CORINFO_METHOD_STRUCT_* inlinerHnd, CORINFO_METHOD_ST
             }
         }
 
-        [MethodImpl(MethodImplOptions.NoInlining)]
-        private static Stack<HashSet<MethodDesc>> FailFastIfNull(Stack<HashSet<MethodDesc>> s)
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static Stack<T> FailFastIfNull<T>(Stack<T> s)
         {
-            var array = Accessor<HashSet<MethodDesc>>.GetArray(s);
+            var array = Accessor<T>.GetArray(s);
             if (array == null)
                 Environment.FailFast("Got null array");
             return s;