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

[Jan Patrick Lehr via cfe-commits]

jplehr wrote:

Given this is in the `preopt` IR, the change would occur in an even earlier stage, right? I'll see if I can get some IR out of whatever stage that may be.

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