private static int ILStubCache_NoGCTransition_GCTransition(int expected)
{
// This test uses a callback marked UnmanagedCallersOnly as a way to verify that
// SuppressGCTransition is taken into account when caching IL stubs.
// It calls functions with the same signature, differing only in SuppressGCTransition.
// When calling an UnmanagedCallersOnly method, the runtime validates that the GC is in
// pre-emptive mode. If not, it throws a fatal error that cannot be caught and crashes.
// If the stub for the p/invoke with the transition suppressed is incorrectly reused for
// the p/invoke without the suppression, invoking the callback would produce a fatal error.
Console.WriteLine($"{nameof(ILStubCache_NoGCTransition_GCTransition)} ({expected}) ...");
int n;
// Call function that has SuppressGCTransition
SuppressGCTransitionNative.InvokeCallbackFuncPtr_Inline_NoGCTransition(null, null);
// Call function with same (blittable) signature, but without SuppressGCTransition.
// IL stub should not be re-used, GC transition should occur, and callback should be invoked.
SuppressGCTransitionNative.InvokeCallbackFuncPtr_Inline_GCTransition(&ReturnInt, &n);
Assert.AreEqual(expected++, n);
// Call function that has SuppressGCTransition
SuppressGCTransitionNative.InvokeCallbackFuncPtr_NoInline_NoGCTransition(null, null);
// Call function with same (non-blittable) signature, but without SuppressGCTransition
// IL stub should not be re-used, GC transition should occur, and callback should be invoked.
SuppressGCTransitionNative.InvokeCallbackFuncPtr_NoInline_GCTransition(&ReturnInt, &n);
Assert.AreEqual(expected++, n);
return(n + 1);
}
