Fix for TestNoreturnUnwind.py on i386

Authored by ravitheja on Jan 12 2016, 2:08 AM.


Fix for TestNoreturnUnwind.py on i386

The testcase TestNoreturnUnwind.py was failing
because the unwind from the vdso library was not
successful for clang compiler while it was passing
for gcc. It was passing for gcc since the unwind plan
used was the assembly plan and the ebp register was
set by the main function in case of gcc and was not
used by the functions in the call flow to the vdso, whereas
clang did not emit assembly prologue for main and so
the assembly unwind was failing. Normally in case of
failure of assembly unwind, lldb switches to EH CFI frame
based unwinding, but this was not happening for
the first frame. This patch tries to fix this behaviour by
falling to EH CFI frame based unwinding in case of assembly
unwind failure even for the first frame.
The test is still marked as XFAIL since it relys on the fix
of another bug.

Reviewers: lldb-commits, jingham, zturner, tberghammer, jasonmolenda

Subscribers: jasonmolenda

Differential Revision: http://reviews.llvm.org/D15046

llvm-svn: 257465