[NativeAOT-LLVM] Workaround to align thread statics to 8 byte boundary

src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/ThreadStatics.cs

@@ -137,7 +137,13 @@ private static unsafe object AllocateThreadStaticStorageForType(TypeManagerHandl
                 gcDesc = Internal.Runtime.Augments.RuntimeAugments.TypeLoaderCallbacks.GetThreadStaticGCDescForDynamicType(typeManager, typeTlsIndex);
             }
 
+#if TARGET_WASM
+            // TODO-LLVM: Remove when there is an upstream fix.  See https://github.com/dotnet/runtimelab/issues/2606 and https://github.com/dotnet/runtime/issues/103234
+            // This is a fix for aligning to 8, thread static fields that should be aligned 8, we just conservatively align everything to 8.
+            return InternalCalls.RhpNewFastAlign8((MethodTable*)gcDesc);
+#else
             return RuntimeImports.RhNewObject((MethodTable*)gcDesc);
+#endif
         }
     }
 }

src/tests/nativeaot/SmokeTests/HelloWasm/HelloWasm.cs

@@ -429,6 +429,8 @@ private static unsafe int Main(string[] args)
 
         LSSATests.Run();
 
+        TestThreadStaticAlignment();
+
         if (OperatingSystem.IsBrowser())
         {
             EventLoopTestClass.TestEventLoopIntegration();
@@ -4251,6 +4253,49 @@ static void TestGenStructContains()
         EndTest(contains);
     }
 
+    [InlineArray(3)]
+    internal struct ReturnArea
+    {
+        private ulong buffer;
+
+        internal unsafe nint AddressOfReturnArea()
+        {
+            return (nint)Unsafe.AsPointer(ref buffer);
+        }
+    }
+
+    internal class ThreadStaticAlignCheck1
+    {
+        [ThreadStatic]
+        [FixedAddressValueType]
+        internal static ReturnArea returnArea = default;
+    }
+
+    internal class Padder
+    {
+        private object o1;
+    }
+
+    internal class ThreadStaticAlignCheck2
+    {
+        [ThreadStatic]
+        [FixedAddressValueType]
+        internal static ReturnArea returnArea = default;
+    }
+
+    static void TestThreadStaticAlignment()
+    {
+        StartTest("Test ThreadStatic Alignment");
+
+        // Assume that these are allocated sequentially, use a padding object of size 12 ( mod 8 is not 0 ) to move the alignment of the second AddressOfReturnArea in case the first is
+        // coincidentally aligned 8.
+        var ts1Addr = ThreadStaticAlignCheck1.returnArea.AddressOfReturnArea();
+        var p = new Padder();
+        var ts2Addr = ThreadStaticAlignCheck2.returnArea.AddressOfReturnArea();
+
+        EndTest((((nint)ts1Addr) % 8 == 0) && (((nint)ts2Addr) % 8 == 0));
+    }
+
     static ushort ReadUInt16()
     {
         // something with MSB set