JDK-8168699 introduced a special case for is_invokespecial_receiver_check() in LIRGenerator::do_CheckCast:

  } else if (x->is_invokespecial_receiver_check()) {
    assert(patching_info == NULL, "can't patch this");
    stub = new DeoptimizeStub(info_for_exception,
                              Deoptimization::Reason_class_check,
                              Deoptimization::Action_none);

but overlooked a potential bad interaction with PatchAlot. This can lead to the assertion failure as observed during testing for JDK-8200167 with Graal. The proposed fix is quite simple but needs to be applied to each of the CPU specific files:

diff --git a/src/hotspot/cpu/x86/c1_LIRGenerator_x86.cpp b/src/hotspot/cpu/x86/c1_LIRGenerator_x86.cpp
--- a/src/hotspot/cpu/x86/c1_LIRGenerator_x86.cpp
+++ b/src/hotspot/cpu/x86/c1_LIRGenerator_x86.cpp
@@ -1314,7 +1314,7 @@
    LIRItem obj(x->obj(), this);

    CodeEmitInfo* patching_info = NULL;
- if (!x->klass()->is_loaded() || (PatchALot && !x->is_incompatible_class_change_check())) {
+ if (!x->klass()->is_loaded() || (PatchALot && !x->is_incompatible_class_change_check() && !x->is_invokespecial_receiver_check())) {
      // must do this before locking the destination register as an oop register,
      // and before the obj is loaded (the latter is for deoptimization)
      patching_info = state_for(x, x->state_before());