Revert "Simplify and document entrypoint toggling in instrumentation."

This reverts commit 76ec6f6562229033b2fecc08c01bef58a9488c92.

Reason for revert: Test failure

Change-Id: Ibb14e7a2830276b4f0a68b7025f9c394041e52d6
diff --git a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
index bd392f6..3488cef 100644
--- a/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
+++ b/runtime/entrypoints/quick/quick_trampoline_entrypoints.cc
@@ -1036,21 +1036,24 @@
       << "Proxy method " << method->PrettyMethod()
       << " (declaring class: " << method->GetDeclaringClass()->PrettyClass() << ")"
       << " should not hit instrumentation entrypoint.";
-  DCHECK(!instrumentation->IsDeoptimized(method));
-  // This will get the entry point either from the oat file, the JIT or the appropriate bridge
-  // method if none of those can be found.
-  result = instrumentation->GetCodeForInvoke(method);
-  jit::Jit* jit = Runtime::Current()->GetJit();
-  DCHECK_NE(result, GetQuickInstrumentationEntryPoint()) << method->PrettyMethod();
-  DCHECK(jit == nullptr ||
-         // Native methods come through here in Interpreter entrypoints. We might not have
-         // disabled jit-gc but that is fine since we won't return jit-code for native methods.
-         method->IsNative() ||
-         !jit->GetCodeCache()->GetGarbageCollectCode());
-  DCHECK(!method->IsNative() ||
-         jit == nullptr ||
-         !jit->GetCodeCache()->ContainsPc(result))
-      << method->PrettyMethod() << " code will jump to possibly cleaned up jit code!";
+  if (instrumentation->IsDeoptimized(method)) {
+    result = GetQuickToInterpreterBridge();
+  } else {
+    // This will get the entry point either from the oat file, the JIT or the appropriate bridge
+    // method if none of those can be found.
+    result = instrumentation->GetCodeForInvoke(method);
+    jit::Jit* jit = Runtime::Current()->GetJit();
+    DCHECK_NE(result, GetQuickInstrumentationEntryPoint()) << method->PrettyMethod();
+    DCHECK(jit == nullptr ||
+           // Native methods come through here in Interpreter entrypoints. We might not have
+           // disabled jit-gc but that is fine since we won't return jit-code for native methods.
+           method->IsNative() ||
+           !jit->GetCodeCache()->GetGarbageCollectCode());
+    DCHECK(!method->IsNative() ||
+           jit == nullptr ||
+           !jit->GetCodeCache()->ContainsPc(result))
+        << method->PrettyMethod() << " code will jump to possibly cleaned up jit code!";
+  }
 
   bool interpreter_entry = (result == GetQuickToInterpreterBridge());
   bool is_static = method->IsStatic();
diff --git a/runtime/instrumentation.cc b/runtime/instrumentation.cc
index 78a77a3..8ef5ef4 100644
--- a/runtime/instrumentation.cc
+++ b/runtime/instrumentation.cc
@@ -47,7 +47,6 @@
 #include "mirror/object-inl.h"
 #include "mirror/object_array-inl.h"
 #include "nth_caller_visitor.h"
-#include "oat_file_manager.h"
 #include "oat_quick_method_header.h"
 #include "runtime-inl.h"
 #include "thread.h"
@@ -217,13 +216,15 @@
   method->SetEntryPointFromQuickCompiledCode(quick_code);
 }
 
-bool Instrumentation::InterpretOnly(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_) {
-  if (method->IsNative()) {
-    return false;
-  }
-  return InterpretOnly() ||
-      IsDeoptimized(method) ||
-      Runtime::Current()->GetRuntimeCallbacks()->MethodNeedsDebugVersion(method);
+bool Instrumentation::NeedDebugVersionFor(ArtMethod* method) const
+    REQUIRES_SHARED(Locks::mutator_lock_) {
+  art::Runtime* runtime = Runtime::Current();
+  // If anything says we need the debug version or we are debuggable we will need the debug version
+  // of the method.
+  return (runtime->GetRuntimeCallbacks()->MethodNeedsDebugVersion(method) ||
+          runtime->IsJavaDebuggable()) &&
+         !method->IsNative() &&
+         !method->IsProxyMethod();
 }
 
 bool Instrumentation::CodeNeedsEntryExitStub(const void* code, ArtMethod* method) {
@@ -233,17 +234,6 @@
     return true;
   }
 
-  // If the methods needs an initialization check, we need to keep the current
-  // entrypoint.
-  if (!method->GetDeclaringClass()->IsInitialized() && NeedsClinitCheckBeforeCall(method)) {
-    return false;
-  }
-
-  // Code running in the interpreter doesn't need entry/exit stubs.
-  if (Runtime::Current()->GetClassLinker()->IsQuickToInterpreterBridge(code)) {
-    return false;
-  }
-
   // When jiting code for debuggable apps we generate the code to call method
   // entry / exit hooks when required. Hence it is not required to update
   // to instrumentation entry point for JITed code in debuggable mode.
@@ -265,39 +255,6 @@
   return true;
 }
 
-static bool IsProxyInit(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_) {
-  // Annoyingly this can be called before we have actually initialized WellKnownClasses so therefore
-  // we also need to check this based on the declaring-class descriptor. The check is valid because
-  // Proxy only has a single constructor.
-  ArtMethod* well_known_proxy_init = jni::DecodeArtMethod(
-      WellKnownClasses::java_lang_reflect_Proxy_init);
-  if (well_known_proxy_init == method) {
-    return true;
-  }
-
-  if (well_known_proxy_init != nullptr) {
-    return false;
-  }
-
-  return method->IsConstructor() &&
-      method->GetDeclaringClass()->DescriptorEquals("Ljava/lang/reflect/Proxy;");
-}
-
-static const void* GetOptimizedCodeFor(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_) {
-  DCHECK(!Runtime::Current()->GetInstrumentation()->InterpretOnly(method));
-  // We need to have the resolution stub still if the class is not initialized.
-  if (NeedsClinitCheckBeforeCall(method) && !method->GetDeclaringClass()->IsInitialized()) {
-    return GetQuickResolutionStub();
-  }
-  // TODO We could have JIT compiled native entrypoints. It might be worth it to find these.
-  if (!method->IsNative() && Runtime::Current()->IsJavaDebuggable()) {
-    // TODO: Return nterp.
-    return GetQuickToInterpreterBridge();
-  }
-  return Runtime::Current()->GetClassLinker()->GetQuickOatCodeFor(method);
-}
-
-
 void Instrumentation::InstallStubsForMethod(ArtMethod* method) {
   if (!method->IsInvokable() || method->IsProxyMethod()) {
     // Do not change stubs for these methods.
@@ -306,28 +263,60 @@
   // Don't stub Proxy.<init>. Note that the Proxy class itself is not a proxy class.
   // TODO We should remove the need for this since it means we cannot always correctly detect calls
   // to Proxy.<init>
-  if (IsProxyInit(method)) {
+  // Annoyingly this can be called before we have actually initialized WellKnownClasses so therefore
+  // we also need to check this based on the declaring-class descriptor. The check is valid because
+  // Proxy only has a single constructor.
+  ArtMethod* well_known_proxy_init = jni::DecodeArtMethod(
+      WellKnownClasses::java_lang_reflect_Proxy_init);
+  if ((LIKELY(well_known_proxy_init != nullptr) && UNLIKELY(method == well_known_proxy_init)) ||
+      UNLIKELY(method->IsConstructor() &&
+               method->GetDeclaringClass()->DescriptorEquals("Ljava/lang/reflect/Proxy;"))) {
     return;
   }
-
-  // If the instrumentation needs to go through the interpreter, just update the
-  // entrypoint to interpreter.
-  if (InterpretOnly(method)) {
-    UpdateEntrypoints(method, GetQuickToInterpreterBridge());
-    return;
-  }
-
-  if (EntryExitStubsInstalled()) {
-    // Install the instrumentation entry point if needed.
-    if (CodeNeedsEntryExitStub(method->GetEntryPointFromQuickCompiledCode(), method)) {
-      UpdateEntrypoints(method, GetQuickInstrumentationEntryPoint());
+  const void* new_quick_code;
+  bool uninstall = (instrumentation_level_ == InstrumentationLevel::kInstrumentNothing);
+  Runtime* const runtime = Runtime::Current();
+  ClassLinker* const class_linker = runtime->GetClassLinker();
+  bool is_class_initialized = method->GetDeclaringClass()->IsInitialized();
+  if (uninstall) {
+    if ((forced_interpret_only_ || IsDeoptimized(method)) && !method->IsNative()) {
+      new_quick_code = GetQuickToInterpreterBridge();
+    } else if (is_class_initialized || !method->IsStatic() || method->IsConstructor()) {
+      new_quick_code = GetCodeForInvoke(method);
+    } else {
+      new_quick_code = GetQuickResolutionStub();
     }
-    return;
+  } else {  // !uninstall
+    if ((InterpretOnly() || IsDeoptimized(method)) && !method->IsNative()) {
+      new_quick_code = GetQuickToInterpreterBridge();
+    } else {
+      // Do not overwrite resolution trampoline. When the trampoline initializes the method's
+      // class, all its static methods code will be set to the instrumentation entry point.
+      // For more details, see ClassLinker::FixupStaticTrampolines.
+      if (is_class_initialized || !method->IsStatic() || method->IsConstructor()) {
+        if (EntryExitStubsInstalled()) {
+          // This needs to be checked first since the instrumentation entrypoint will be able to
+          // find the actual JIT compiled code that corresponds to this method.
+          const void* code = method->GetEntryPointFromQuickCompiledCodePtrSize(kRuntimePointerSize);
+          if (CodeNeedsEntryExitStub(code, method)) {
+            new_quick_code = GetQuickInstrumentationEntryPoint();
+          } else {
+            new_quick_code = code;
+          }
+        } else if (NeedDebugVersionFor(method)) {
+          // It would be great to search the JIT for its implementation here but we cannot due to
+          // the locks we hold. Instead just set to the interpreter bridge and that code will search
+          // the JIT when it gets called and replace the entrypoint then.
+          new_quick_code = GetQuickToInterpreterBridge();
+        } else {
+          new_quick_code = class_linker->GetQuickOatCodeFor(method);
+        }
+      } else {
+        new_quick_code = GetQuickResolutionStub();
+      }
+    }
   }
-
-  // We're being asked to restore the entrypoints after instrumentation.
-  CHECK_EQ(instrumentation_level_, InstrumentationLevel::kInstrumentNothing);
-  UpdateEntrypoints(method, GetOptimizedCodeFor(method));
+  UpdateEntrypoints(method, new_quick_code);
 }
 
 // Places the instrumentation exit pc as the return PC for every quick frame. This also allows
@@ -936,77 +925,44 @@
   }
 }
 
-static std::string EntrypointString(const void* code) {
-  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
-  jit::Jit* jit = Runtime::Current()->GetJit();
-  if (class_linker->IsQuickToInterpreterBridge(code)) {
-    return "interpreter";
-  } else if (class_linker->IsQuickResolutionStub(code)) {
-    return "resolution";
-  } else if (code == GetQuickInstrumentationEntryPoint()) {
-    return "instrumentation";
-  } else if (jit != nullptr && jit->GetCodeCache()->ContainsPc(code)) {
-    return "jit";
-  } else if (code == GetInvokeObsoleteMethodStub()) {
-    return "obsolete";
-  } else if (code == interpreter::GetNterpEntryPoint()) {
-    return "nterp";
-  } else if (class_linker->IsQuickGenericJniStub(code)) {
-    return "generic jni";
-  } else if (Runtime::Current()->GetOatFileManager().ContainsPc(code)) {
-    return "oat";
-  }
-  return "unknown";
-}
-
 void Instrumentation::UpdateMethodsCodeImpl(ArtMethod* method, const void* quick_code) {
-  if (!AreExitStubsInstalled()) {
-    // Fast path: no instrumentation.
-    DCHECK(!EntryExitStubsInstalled());
-    DCHECK(!IsDeoptimized(method));
-    UpdateEntrypoints(method, quick_code);
-    return;
-  }
-
-  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
-  if (class_linker->IsQuickResolutionStub(quick_code) ||
-      class_linker->IsQuickToInterpreterBridge(quick_code)) {
-    // It's always OK to update to these entrypoints.
-    UpdateEntrypoints(method, quick_code);
-    return;
-  }
-
-  if (IsDeoptimized(method)) {
-    DCHECK(class_linker->IsQuickToInterpreterBridge(method->GetEntryPointFromQuickCompiledCode()));
-    // Don't update, stay deoptimized.
-    return;
-  }
-
-  if (EntryExitStubsInstalled()) {
-    if (CodeNeedsEntryExitStub(quick_code, method)) {
-      DCHECK(method->GetEntryPointFromQuickCompiledCode() == GetQuickInstrumentationEntryPoint() ||
-          class_linker->IsQuickGenericJniStub(method->GetEntryPointFromQuickCompiledCode()) ||
-          class_linker->IsQuickToInterpreterBridge(method->GetEntryPointFromQuickCompiledCode()) ||
-          class_linker->IsQuickResolutionStub(method->GetEntryPointFromQuickCompiledCode()))
-              << EntrypointString(method->GetEntryPointFromQuickCompiledCode());
-      // If the code we want to update the method with still needs entry/exit stub, just skip.
-      return;
+  const void* new_quick_code;
+  if (LIKELY(!instrumentation_stubs_installed_)) {
+    new_quick_code = quick_code;
+  } else {
+    if ((InterpreterStubsInstalled() || IsDeoptimized(method)) && !method->IsNative()) {
+      new_quick_code = GetQuickToInterpreterBridge();
+    } else {
+      ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+      if (class_linker->IsQuickResolutionStub(quick_code) ||
+          class_linker->IsQuickToInterpreterBridge(quick_code)) {
+        new_quick_code = quick_code;
+      } else if (EntryExitStubsInstalled() &&
+                 // We need to make sure not to replace anything that InstallStubsForMethod
+                 // wouldn't. Specifically we cannot stub out Proxy.<init> since subtypes copy the
+                 // implementation directly and this will confuse the instrumentation trampolines.
+                 // TODO We should remove the need for this since it makes it impossible to profile
+                 // Proxy.<init> correctly in all cases.
+                 method != jni::DecodeArtMethod(WellKnownClasses::java_lang_reflect_Proxy_init) &&
+                 CodeNeedsEntryExitStub(quick_code, method)) {
+        new_quick_code = GetQuickInstrumentationEntryPoint();
+      } else {
+        new_quick_code = quick_code;
+      }
     }
   }
-
-  // At this point, we can update as asked.
-  UpdateEntrypoints(method, quick_code);
+  UpdateEntrypoints(method, new_quick_code);
 }
 
 void Instrumentation::UpdateNativeMethodsCodeToJitCode(ArtMethod* method, const void* quick_code) {
   // We don't do any read barrier on `method`'s declaring class in this code, as the JIT might
   // enter here on a soon-to-be deleted ArtMethod. Updating the entrypoint is OK though, as
   // the ArtMethod is still in memory.
-  if (EntryExitStubsInstalled()) {
-    // If stubs are installed don't update.
-    return;
+  const void* new_quick_code = quick_code;
+  if (UNLIKELY(instrumentation_stubs_installed_) && EntryExitStubsInstalled()) {
+    new_quick_code = GetQuickInstrumentationEntryPoint();
   }
-  UpdateEntrypoints(method, quick_code);
+  UpdateEntrypoints(method, new_quick_code);
 }
 
 void Instrumentation::UpdateMethodsCode(ArtMethod* method, const void* quick_code) {
@@ -1075,7 +1031,7 @@
         << " is already deoptimized";
   }
   if (!InterpreterStubsInstalled()) {
-    UpdateEntrypoints(method, GetQuickToInterpreterBridge());
+    UpdateEntrypoints(method, GetQuickInstrumentationEntryPoint());
 
     // Install instrumentation exit stub and instrumentation frames. We may already have installed
     // these previously so it will only cover the newly created frames.
@@ -1108,10 +1064,15 @@
   // Restore code and possibly stack only if we did not deoptimize everything.
   if (!InterpreterStubsInstalled()) {
     // Restore its code or resolution trampoline.
-    if (InterpretOnly(method)) {
-      UpdateEntrypoints(method, GetQuickToInterpreterBridge());
+    ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+    if (method->IsStatic() && !method->IsConstructor() &&
+        !method->GetDeclaringClass()->IsInitialized()) {
+      UpdateEntrypoints(method, GetQuickResolutionStub());
     } else {
-      UpdateEntrypoints(method, GetOptimizedCodeFor(method));
+      const void* quick_code = NeedDebugVersionFor(method)
+          ? GetQuickToInterpreterBridge()
+          : class_linker->GetQuickOatCodeFor(method);
+      UpdateEntrypoints(method, quick_code);
     }
 
     // If there is no deoptimized method left, we can restore the stack of each thread.
@@ -1192,26 +1153,46 @@
   ConfigureStubs(key, InstrumentationLevel::kInstrumentNothing);
 }
 
-const void* Instrumentation::GetCodeForInvoke(ArtMethod* method) {
+const void* Instrumentation::GetCodeForInvoke(ArtMethod* method) const {
   // This is called by instrumentation entry only and that should never be getting proxy methods.
   DCHECK(!method->IsProxyMethod()) << method->PrettyMethod();
   ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
-  const void* code = method->GetEntryPointFromQuickCompiledCodePtrSize(kRuntimePointerSize);
-  // If we don't have the instrumentation, the resolution stub, or the
-  // interpreter as entrypoint, just return the current entrypoint, assuming
-  // it's the most optimized.
-  if (code != GetQuickInstrumentationEntryPoint() &&
-      !class_linker->IsQuickResolutionStub(code) &&
-      !class_linker->IsQuickToInterpreterBridge(code)) {
-    return code;
+  if (LIKELY(!InterpreterStubsInstalled())) {
+    // In general we just return whatever the method thinks its entrypoint is here. The only
+    // exception is if it still has the instrumentation entrypoint. That means we are racing another
+    // thread getting rid of instrumentation which is unexpected but possible. In that case we want
+    // to wait and try to get it from the oat file or jit.
+    const void* code = method->GetEntryPointFromQuickCompiledCodePtrSize(kRuntimePointerSize);
+    DCHECK(code != nullptr);
+    if (code != GetQuickInstrumentationEntryPoint()) {
+      return code;
+    }
+    // We don't know what it is. Fallthough to try to find the code from the JIT or Oat file.
   }
 
-  if (InterpretOnly(method)) {
-    // If we're forced into interpreter just use it.
+  if (method->IsNative()) {
+    // TODO We could have JIT compiled native entrypoints. It might be worth it to find these.
+    return class_linker->GetQuickOatCodeFor(method);
+  } else if (!NeedDebugVersionFor(method) && !InterpreterStubsInstalled()) {
+    return class_linker->GetQuickOatCodeFor(method);
+  } else {
     return GetQuickToInterpreterBridge();
   }
+}
 
-  return GetOptimizedCodeFor(method);
+const void* Instrumentation::GetQuickCodeFor(ArtMethod* method, PointerSize pointer_size) const {
+  ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
+  if (LIKELY(!instrumentation_stubs_installed_)) {
+    const void* code = method->GetEntryPointFromQuickCompiledCodePtrSize(pointer_size);
+    DCHECK(code != nullptr);
+    if (LIKELY(!class_linker->IsQuickResolutionStub(code) &&
+               !class_linker->IsQuickToInterpreterBridge(code)) &&
+               !class_linker->IsQuickResolutionStub(code) &&
+               !class_linker->IsQuickToInterpreterBridge(code)) {
+      return code;
+    }
+  }
+  return class_linker->GetQuickOatCodeFor(method);
 }
 
 void Instrumentation::MethodEnterEventImpl(Thread* thread, ArtMethod* method) const {
diff --git a/runtime/instrumentation.h b/runtime/instrumentation.h
index 2f0594f..a505ce3 100644
--- a/runtime/instrumentation.h
+++ b/runtime/instrumentation.h
@@ -322,7 +322,14 @@
       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!GetDeoptimizedMethodsLock());
 
   // Return the code that we can execute for an invoke including from the JIT.
-  const void* GetCodeForInvoke(ArtMethod* method) REQUIRES_SHARED(Locks::mutator_lock_);
+  const void* GetCodeForInvoke(ArtMethod* method) const
+      REQUIRES_SHARED(Locks::mutator_lock_);
+
+  // Get the quick code for the given method. More efficient than asking the class linker as it
+  // will short-cut to GetCode if instrumentation and static method resolution stubs aren't
+  // installed.
+  const void* GetQuickCodeFor(ArtMethod* method, PointerSize pointer_size) const
+      REQUIRES_SHARED(Locks::mutator_lock_);
 
   void ForceInterpretOnly() {
     forced_interpret_only_ = true;
@@ -342,12 +349,15 @@
     return forced_interpret_only_ || InterpreterStubsInstalled();
   }
 
-  bool InterpretOnly(ArtMethod* m) REQUIRES_SHARED(Locks::mutator_lock_);
-
   bool IsForcedInterpretOnly() const {
     return forced_interpret_only_;
   }
 
+  // Code is in boot image oat file which isn't compiled as debuggable.
+  // Need debug version (interpreter or jitted) if that's the case.
+  bool NeedDebugVersionFor(ArtMethod* method) const
+      REQUIRES_SHARED(Locks::mutator_lock_);
+
   bool AreExitStubsInstalled() const {
     return instrumentation_stubs_installed_;
   }
@@ -574,8 +584,7 @@
 
   // Returns true if we need entry exit stub to call entry hooks. JITed code
   // directly call entry / exit hooks and don't need the stub.
-  bool CodeNeedsEntryExitStub(const void* code, ArtMethod* method)
-      REQUIRES_SHARED(Locks::mutator_lock_);
+  bool CodeNeedsEntryExitStub(const void* code, ArtMethod* method);
 
   // Update the current instrumentation_level_.
   void UpdateInstrumentationLevel(InstrumentationLevel level);
diff --git a/runtime/oat_file_manager.cc b/runtime/oat_file_manager.cc
index 3bcd9bb..3449919 100644
--- a/runtime/oat_file_manager.cc
+++ b/runtime/oat_file_manager.cc
@@ -849,15 +849,4 @@
   }
 }
 
-bool OatFileManager::ContainsPc(const void* code) {
-  ReaderMutexLock mu(Thread::Current(), *Locks::oat_file_manager_lock_);
-  std::vector<const OatFile*> boot_oat_files = GetBootOatFiles();
-  for (const std::unique_ptr<const OatFile>& oat_file : oat_files_) {
-    if (oat_file->Contains(code)) {
-      return true;
-    }
-  }
-  return false;
-}
-
 }  // namespace art
diff --git a/runtime/oat_file_manager.h b/runtime/oat_file_manager.h
index b73ac58..0c1a69b 100644
--- a/runtime/oat_file_manager.h
+++ b/runtime/oat_file_manager.h
@@ -140,8 +140,6 @@
   // Maximum number of anonymous vdex files kept in the process' data folder.
   static constexpr size_t kAnonymousVdexCacheSize = 8u;
 
-  bool ContainsPc(const void* pc) REQUIRES(!Locks::oat_file_manager_lock_);
-
  private:
   std::vector<std::unique_ptr<const DexFile>> OpenDexFilesFromOat_Impl(
       std::vector<MemMap>&& dex_mem_maps,
diff --git a/runtime/stack.cc b/runtime/stack.cc
index 7f1f47f..eb0fe56 100644
--- a/runtime/stack.cc
+++ b/runtime/stack.cc
@@ -787,7 +787,8 @@
   DCHECK(method->IsNative());
   if (kIsDebugBuild && !method->IsCriticalNative()) {
     ClassLinker* class_linker = runtime->GetClassLinker();
-    const void* entry_point = runtime->GetInstrumentation()->GetCodeForInvoke(method);
+    const void* entry_point = runtime->GetInstrumentation()->GetQuickCodeFor(method,
+                                                                             kRuntimePointerSize);
     CHECK(class_linker->IsQuickGenericJniStub(entry_point) ||
           // The current entrypoint (after filtering out trampolines) may have changed
           // from GenericJNI to JIT-compiled stub since we have entered this frame.