[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/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));