Similar to 806761a7629df268c8aed49657aeccffa6bca449
-mtriple= specifies the full target triple while -march= merely sets the
architecture part of the default target triple (e.g. Windows, macOS),
leaving a target triple which may not make sense.
Therefore, -march= is error-prone and not recommended for tests without
a target triple. The issue has been benign as we recognize
bpf*-apple-darwin as ELF instead of rejecting it outrightly.
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
