Make TestPrintStackTraces deterministic

This test contained an incredibly complicated inferior, but in reality,
all it was testing was that we can backtrace up to main and see main's
arguments.

However, the way this was implemented (setting a breakpoint on a
separate thread) meant that each time the test would run, it would stop
in a different location on the main thread. Most of the time this
location would be deep in some libc function, which meant that the
success of this test depended on our ability to backtrace out of a
random function of the c library that the user happens to have
installed.

This makes the test unpredictable. Backtracing out of a libc function is
an important functionality, but this is not the way to test it. Often it
is not even our fault that we cannot backtrace out because the C library
contains a lot of assembly routines that may not have correct unwind
info associated with them.

For this reason the test has accumulated numerous @expectedFail/Flaky
decorators. In this patch, I replace the inferior with one that does not
depend on libc functions. Instead I create a couple of stack frames of
user code, and have the test verify that. I also simplify the test by
using lldbutil.run_to_source_breakpoint.

llvm-svn: 358266

0 files changed, 0 insertions, 0 deletions