This adds a test for the bug
https://bugs.llvm.org/show_bug.cgi?id=47591
Previously, selection dag has a bug which may incorrectly
assume no alias when crossing a lifetime boundary and this
may generate incorrect code as demonstrated in the above bug.
It looks the bug is fixed by https://reviews.llvm.org/D91833.
Basically, when comparing two potential memory access dag nodes,
a store and a lifetime.start,
with the same frame index.
Previously, it may be decided no alias. With the above fix,
these two will be considered aliasing which will prevent
incorrect code scheduling.
Differential Revision: https://reviews.llvm.org/D92451
Yonghong Song