Import LLDB as of upstream SVN r225923 (git 2b588ecd)

This corresponds with the branchpoint for the 3.6 release.
A number of files not required for the FreeBSD build have been removed.

Sponsored by:	DARPA, AFRL

1 files changed, 36 insertions, 10 deletions

diff --git a/source/Plugins/Process/Utility/UnwindLLDB.cpp b/source/Plugins/Process/Utility/UnwindLLDB.cpp
index 37fd4f4..fc592e6 100644
--- a/source/Plugins/Process/Utility/UnwindLLDB.cpp
+++ b/source/Plugins/Process/Utility/UnwindLLDB.cpp
@@ -172,8 +172,9 @@ UnwindLLDB::AddOneMoreFrame (ABI *abi)
 
     if (!reg_ctx_sp->IsValid())
     {
-        // If the RegisterContextLLDB has a fallback UnwindPlan, it will switch to that and return
-        // true.  Subsequent calls to TryFallbackUnwindPlan() will return false.
+        // We failed to get a valid RegisterContext.
+        // See if the regctx below this on the stack has a fallback unwind plan it can use.
+        // Subsequent calls to TryFallbackUnwindPlan() will return false.
         if (m_frames[cur_idx - 1]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
         {
             return AddOneMoreFrame (abi);
@@ -207,18 +208,35 @@ UnwindLLDB::AddOneMoreFrame (ABI *abi)
         // these.
         if (reg_ctx_sp->IsTrapHandlerFrame() == false)
         {
-            // If the RegisterContextLLDB has a fallback UnwindPlan, it will switch to that and return
-            // true.  Subsequent calls to TryFallbackUnwindPlan() will return false.
-            if (m_frames[cur_idx - 1]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
+            // See if we can find a fallback unwind plan for THIS frame.  It may be
+            // that the UnwindPlan we're using for THIS frame was bad and gave us a
+            // bad CFA.  
+            // If that's not it, then see if we can change the UnwindPlan for the frame
+            // below us ("NEXT") -- see if using that other UnwindPlan gets us a better
+            // unwind state.
+            if (reg_ctx_sp->TryFallbackUnwindPlan() == false
+                || reg_ctx_sp->GetCFA (cursor_sp->cfa) == false
+                || abi->CallFrameAddressIsValid(cursor_sp->cfa) == false)
             {
-                return AddOneMoreFrame (abi);
+                if (m_frames[cur_idx - 1]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
+                {
+                    return AddOneMoreFrame (abi);
+                }
+                if (log)
+                {
+                    log->Printf("%*sFrame %d did not get a valid CFA for this frame, stopping stack walk",
+                                cur_idx < 100 ? cur_idx : 100, "", cur_idx);
+                }
+                goto unwind_done;
             }
-            if (log)
+            else
             {
-                log->Printf("%*sFrame %d did not get a valid CFA for this frame, stopping stack walk",
-                            cur_idx < 100 ? cur_idx : 100, "", cur_idx);
+                if (log)
+                {
+                    log->Printf("%*sFrame %d had a bad CFA value but we switched the UnwindPlan being used and got one that looks more realistic.",
+                                cur_idx < 100 ? cur_idx : 100, "", cur_idx);
+                }
             }
-            goto unwind_done;
         }
     }
     if (!reg_ctx_sp->ReadPC (cursor_sp->start_pc))
@@ -366,6 +384,14 @@ UnwindLLDB::SearchForSavedLocationForRegister (uint32_t lldb_regnum, lldb_privat
         UnwindLLDB::RegisterSearchResult result;
         result = m_frames[frame_num]->reg_ctx_lldb_sp->SavedLocationForRegister (lldb_regnum, regloc);
 
+        // We descended down to the live register context aka stack frame 0 and are reading the value
+        // out of a live register.
+        if (result == UnwindLLDB::RegisterSearchResult::eRegisterFound
+            && regloc.type == UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext)
+        {
+            return true;
+        }
+
         // If we have unwind instructions saying that register N is saved in register M in the middle of
         // the stack (and N can equal M here, meaning the register was not used in this function), then
         // change the register number we're looking for to M and keep looking for a concrete  location