[clang] [llvm] [InstCombine] Strip leading zero indices from GEP (PR #155415)

[Jan Patrick Lehr via llvm-commits]

jplehr wrote:

I finally got some IR and maybe some other info.
With `-opt-bisect-limit` it appears that the issue is coming from GVN on the function  `_ZN47LlvmLibcCharacterConverterUTF32To8Test_FourByte3RunEv`. After that the particular tests fails at runtime.

I attached the IR after the pass of LCSSA which runs before GVN. Let me know how helpful that is or what I can do to help better with this issue.
[after-lcssa.txt](https://github.com/user-attachments/files/22102637/after-lcssa.txt)


https://github.com/llvm/llvm-project/pull/155415