JDWP: Optimized single step during debugging

For single stepping full deoptimization and undeoptimizations were
performed with significant overhead, because every code will be
executed in interpreted mode during a single step, even if it is not
strictly required.

For example, if we have a computation heavy method call and we would
like to step over it, that method (and all the methods called from it)
will run in interpreter mode. This can take so long in some cases
(e.g. multiple minutes) that it makes debugging process unusable.

The solution for this limitation is not using full deoptimizations for
single steps and force interpreter only for those methods that we are
about to step into, and require stack deoptimization before step outs.

Bug: 17750566
Bug: 18094282
Bug: https://code.google.com/p/android/issues/detail?id=77984

Change-Id: I683c52465883146c4c84ec47bf96f8efd920527f
Signed-off-by: Daniel Mihalyi <daniel.mihalyi@mattakis.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/runtime/interpreter/interpreter_common.cc b/runtime/interpreter/interpreter_common.cc
index 26ab602..a3ab026 100644
--- a/runtime/interpreter/interpreter_common.cc
+++ b/runtime/interpreter/interpreter_common.cc
@@ -18,6 +18,7 @@
 
 #include <cmath>
 
+#include "debugger.h"
 #include "mirror/array-inl.h"
 #include "unstarted_runtime.h"
 
@@ -616,8 +617,14 @@ bool DoCall(ArtMethod* called_method, Thread* self, ShadowFrame& shadow_frame,
           << PrettyMethod(new_shadow_frame->GetMethod());
       UNREACHABLE();
     }
-    (new_shadow_frame->GetMethod()->GetEntryPointFromInterpreter())(self, code_item,
-                                                                    new_shadow_frame, result);
+    // Force the use of interpreter when it is required by the debugger.
+    mirror::EntryPointFromInterpreter* entry;
+    if (UNLIKELY(Dbg::IsForcedInterpreterNeededForCalling(self, new_shadow_frame->GetMethod()))) {
+      entry = &art::artInterpreterToInterpreterBridge;
+    } else {
+      entry = new_shadow_frame->GetMethod()->GetEntryPointFromInterpreter();
+    }
+    entry(self, code_item, new_shadow_frame, result);
   } else {
     UnstartedRuntimeInvoke(self, code_item, new_shadow_frame, result, first_dest_reg);
   }