Turn off fast stepping for ARM till the MC's MayAffectControlFlow gets more accurate.

rdar://problem/14488761


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@186646 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/source/Target/ThreadPlanStepRange.cpp b/source/Target/ThreadPlanStepRange.cpp
index 1af567c..e282079 100644
--- a/source/Target/ThreadPlanStepRange.cpp
+++ b/source/Target/ThreadPlanStepRange.cpp
@@ -54,7 +54,11 @@
     m_first_run_event (true),
     m_use_fast_step(false)
 {
-    m_use_fast_step = GetTarget().GetUseFastStepping();
+    llvm::Triple::ArchType arch_type = GetTarget().GetArchitecture().GetMachine();
+    if (arch_type == llvm::Triple::arm || arch_type == llvm::Triple::thumb)
+        m_use_fast_step = false;
+    else
+        m_use_fast_step = GetTarget().GetUseFastStepping();
     AddRange(range);
     m_stack_id = m_thread.GetStackFrameAtIndex(0)->GetStackID();
 }