Rearrange RegisterContextLLDB::SavedLocationForRegister a tiny bit

so that we will use the UnwindPlan's rule for providing the stack
pointer BEFORE we use the trick of using the callee's CFA address
as the stack pointer.  When we're in a _sigtramp frame, the CFA of
the _sigtramp stack frame is not the same as the stack pointer value
when the async interrupt occurred -- we need to use the eh_frame
rules for retrieving the correct value.

<rdar://problem/18913548> 

llvm-svn: 225427

1 files changed, 22 insertions, 18 deletions

diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
index 4535df44518..f47d687702e 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
@@ -1143,24 +1143,6 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
         }
     }
 
-    RegisterNumber sp_regnum (m_thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_SP);
-    RegisterNumber pc_regnum (m_thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
-
-    // Are we looking for the CALLER's stack pointer?  The stack pointer is defined to be the same as THIS frame's
-    // CFA so just return the CFA value.  This is true on x86-32/x86-64 at least.
-    if (sp_regnum.GetAsKind (eRegisterKindLLDB) != LLDB_INVALID_REGNUM 
-        && sp_regnum.GetAsKind (eRegisterKindLLDB) == regnum.GetAsKind (eRegisterKindLLDB))
-    {
-        // make sure we won't lose precision copying an addr_t (m_cfa) into a uint64_t (.inferred_value)
-        assert (sizeof (addr_t) <= sizeof (uint64_t));
-        regloc.type = UnwindLLDB::RegisterLocation::eRegisterValueInferred;
-        regloc.location.inferred_value = m_cfa;
-        m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = regloc;
-        UnwindLogMsg ("supplying caller's stack pointer %s (%d) value, computed from CFA", 
-                      regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
-        return UnwindLLDB::RegisterSearchResult::eRegisterFound;
-    }
-
     // Look through the available UnwindPlans for the register location.
 
     UnwindPlan::Row::RegisterLocation unwindplan_regloc;
@@ -1193,6 +1175,8 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
 
         if (m_full_unwind_plan_sp)
         {
+            RegisterNumber pc_regnum (m_thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_PC);
+
             UnwindPlan::RowSP active_row = m_full_unwind_plan_sp->GetRowForFunctionOffset (m_current_offset);
             unwindplan_registerkind = m_full_unwind_plan_sp->GetRegisterKind ();
 
@@ -1327,6 +1311,26 @@ RegisterContextLLDB::SavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
         }
     }
 
+    if (have_unwindplan_regloc == false)
+    {
+        // Did the UnwindPlan fail to give us the caller's stack pointer?  
+        // The stack pointer is defined to be the same as THIS frame's CFA, so return the CFA value as
+        // the caller's stack pointer.  This is true on x86-32/x86-64 at least.
+
+        RegisterNumber sp_regnum (m_thread, eRegisterKindGeneric, LLDB_REGNUM_GENERIC_SP);
+        if (sp_regnum.GetAsKind (eRegisterKindLLDB) != LLDB_INVALID_REGNUM 
+            && sp_regnum.GetAsKind (eRegisterKindLLDB) == regnum.GetAsKind (eRegisterKindLLDB))
+        {
+            // make sure we won't lose precision copying an addr_t (m_cfa) into a uint64_t (.inferred_value)
+            assert (sizeof (addr_t) <= sizeof (uint64_t));
+            regloc.type = UnwindLLDB::RegisterLocation::eRegisterValueInferred;
+            regloc.location.inferred_value = m_cfa;
+            m_registers[regnum.GetAsKind (eRegisterKindLLDB)] = regloc;
+            UnwindLogMsg ("supplying caller's stack pointer %s (%d) value, computed from CFA", 
+                        regnum.GetName(), regnum.GetAsKind (eRegisterKindLLDB));
+            return UnwindLLDB::RegisterSearchResult::eRegisterFound;
+        }
+    }
 
     ExecutionContext exe_ctx(m_thread.shared_from_this());
     Process *process = exe_ctx.GetProcessPtr();