[clang] [flang] [llvm] [InstCombine] Canonicalize constant GEPs to i8 source element type (PR #68882)

[via llvm-commits]

Prabhuk wrote:

I am debugging an assertion failure regression in one of our projects that uses the FlatMap data structure implemented here: 

https://pigweed.googlesource.com/pigweed/pigweed/+/refs/heads/main/pw_containers/public/pw_containers/flat_map.h#180

The regression was that the `find` function above failed to return the value that's stored in the Map for a valid key. 

A bit of debugging and git bisect of LLVM commits pointed me to this commit https://github.com/llvm/llvm-project/commit/90ba33099cbb17e7c159e9ebc5a512037db99d6d#diff-0ffb024c6c026c4b93507d08e6d24dccf98980023130781164b71586bc747f2d as the source of failure. Reverting this commit locally fixes the regression.

I am working on generating a simple reproducer. 




https://github.com/llvm/llvm-project/pull/68882