Optimization of alloca instructions may lead to invalid alias tags.
Incorrect alias tags can result in incorrect optimization outcomes for
Fortran source code compiled by Flang with flags: `-O3 -mmlir
-local-alloc-tbaa -flto`.
This commit removes alias tags when memcpy optimization replaces two
arrays with one array, thus ensuring correct compilation of Fortran
source code using flags: `-O3 -mmlir -local-alloc-tbaa -flto`.
This commit is also a proposal to fix the reported issue:
https://github.com/llvm/llvm-project/issues/133984
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Co-authored-by: Shilei Tian <i@tianshilei.me>
716b02d8c5