[Target] Generalize language-specific behavior in ThreadPlanStepThrough

Summary:
When creating a ThreadPlan to step through a trampoline, we ask the
ObjC language runtime and the CPP language runtime to come up with such a thread
plan if the dynamic loader fails to give us one. I don't see why this behavior
can't be language agnostic.

Differential Revision: https://reviews.llvm.org/D61921

llvm-svn: 362164
diff --git a/lldb/include/lldb/Target/CPPLanguageRuntime.h b/lldb/include/lldb/Target/CPPLanguageRuntime.h
index a144a48..8de8853 100644
--- a/lldb/include/lldb/Target/CPPLanguageRuntime.h
+++ b/lldb/include/lldb/Target/CPPLanguageRuntime.h
@@ -61,7 +61,7 @@
   /// \return
   ///      A ThreadPlan Shared pointer
   lldb::ThreadPlanSP GetStepThroughTrampolinePlan(Thread &thread,
-                                                  bool stop_others);
+                                                  bool stop_others) override;
 
   bool IsRuntimeSupportValue(ValueObject &valobj) override;
 protected:
diff --git a/lldb/include/lldb/Target/LanguageRuntime.h b/lldb/include/lldb/Target/LanguageRuntime.h
index 43fcf52..105a004 100644
--- a/lldb/include/lldb/Target/LanguageRuntime.h
+++ b/lldb/include/lldb/Target/LanguageRuntime.h
@@ -143,6 +143,9 @@
     return false;
   }
 
+  virtual lldb::ThreadPlanSP GetStepThroughTrampolinePlan(Thread &thread,
+                                                          bool stop_others) = 0;
+
   /// Identify whether a value is a language implementation detaul
   /// that should be hidden from the user interface by default.
   virtual bool IsRuntimeSupportValue(ValueObject &valobj) { return false; }
diff --git a/lldb/include/lldb/Target/ObjCLanguageRuntime.h b/lldb/include/lldb/Target/ObjCLanguageRuntime.h
index e8fd897..c31d725 100644
--- a/lldb/include/lldb/Target/ObjCLanguageRuntime.h
+++ b/lldb/include/lldb/Target/ObjCLanguageRuntime.h
@@ -216,9 +216,6 @@
 
   virtual bool HasReadObjCLibrary() = 0;
 
-  virtual lldb::ThreadPlanSP GetStepThroughTrampolinePlan(Thread &thread,
-                                                          bool stop_others) = 0;
-
   lldb::addr_t LookupInMethodCache(lldb::addr_t class_addr, lldb::addr_t sel);
 
   void AddToMethodCache(lldb::addr_t class_addr, lldb::addr_t sel,
diff --git a/lldb/source/Target/ThreadPlanStepThrough.cpp b/lldb/source/Target/ThreadPlanStepThrough.cpp
index d08d779..e46eba0 100644
--- a/lldb/source/Target/ThreadPlanStepThrough.cpp
+++ b/lldb/source/Target/ThreadPlanStepThrough.cpp
@@ -8,9 +8,8 @@
 
 #include "lldb/Target/ThreadPlanStepThrough.h"
 #include "lldb/Breakpoint/Breakpoint.h"
-#include "lldb/Target/CPPLanguageRuntime.h"
 #include "lldb/Target/DynamicLoader.h"
-#include "lldb/Target/ObjCLanguageRuntime.h"
+#include "lldb/Target/LanguageRuntime.h"
 #include "lldb/Target/Process.h"
 #include "lldb/Target/RegisterContext.h"
 #include "lldb/Target/Target.h"
@@ -85,22 +84,17 @@
     m_sub_plan_sp =
         loader->GetStepThroughTrampolinePlan(m_thread, m_stop_others);
 
-  // If that didn't come up with anything, try the ObjC runtime plugin:
-  if (!m_sub_plan_sp.get()) {
-    ObjCLanguageRuntime *objc_runtime =
-        m_thread.GetProcess()->GetObjCLanguageRuntime();
-    if (objc_runtime)
+  // If the DynamicLoader was unable to provide us with a ThreadPlan, then we
+  // try the LanguageRuntimes.
+  if (!m_sub_plan_sp) {
+    for (LanguageRuntime *runtime :
+         m_thread.GetProcess()->GetLanguageRuntimes()) {
       m_sub_plan_sp =
-          objc_runtime->GetStepThroughTrampolinePlan(m_thread, m_stop_others);
+          runtime->GetStepThroughTrampolinePlan(m_thread, m_stop_others);
 
-    CPPLanguageRuntime *cpp_runtime =
-        m_thread.GetProcess()->GetCPPLanguageRuntime();
-
-    // If the ObjC runtime did not provide us with a step though plan then if we
-    // have it check the C++ runtime for a step though plan.
-    if (!m_sub_plan_sp.get() && cpp_runtime)
-      m_sub_plan_sp =
-          cpp_runtime->GetStepThroughTrampolinePlan(m_thread, m_stop_others);
+      if (m_sub_plan_sp)
+        break;
+    }
   }
 
   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));