Don't enforce ABI stack alignment rules on the sigtramp frame --
its stack frame is a constructed, fake thing that may not conform
correctly to these rules. This fixes a problem where lldb couldn't
backtrace past an asynchronous signal handler (_sigtramp) frame on
a stack on Mac OS X.
<rdar://problem/15035673>
llvm-svn: 198450
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
index b258f7f..f5f499f 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
@@ -949,6 +949,12 @@
return m_frame_type != eNotAValidFrame;
}
+bool
+RegisterContextLLDB::IsSigtrampFrame () const
+{
+ return m_frame_type == eSigtrampFrame;
+}
+
// A skip frame is a bogus frame on the stack -- but one where we're likely to find a real frame farther
// up the stack if we keep looking. It's always the second frame in an unwind (i.e. the first frame after
// frame zero) where unwinding can be the trickiest. Ideally we'll mark up this frame in some way so the
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
index dc6d8c6..368cd65 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.h
@@ -73,6 +73,9 @@
IsValid () const;
bool
+ IsSigtrampFrame () const;
+
+ bool
GetCFA (lldb::addr_t& cfa);
bool
diff --git a/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp b/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
index 203d4c1..ddded5a 100644
--- a/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
+++ b/lldb/source/Plugins/Process/Utility/UnwindLLDB.cpp
@@ -171,12 +171,18 @@
}
if (abi && !abi->CallFrameAddressIsValid(cursor_sp->cfa))
{
- if (log)
+ // On Mac OS X, the _sigtramp asynchronous signal trampoline frame may not have
+ // its (constructed) CFA aligned correctly -- don't do the abi alignment check for
+ // these.
+ if (reg_ctx_sp->IsSigtrampFrame() == false)
{
- 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 did not get a valid CFA for this frame, stopping stack walk",
+ cur_idx < 100 ? cur_idx : 100, "", cur_idx);
+ }
+ goto unwind_done;
}
- goto unwind_done;
}
if (!reg_ctx_sp->ReadPC (cursor_sp->start_pc))
{