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

[Fabian Ritter via llvm-commits]

ritter-x2a wrote:

PR to fix the AMDGPUPromoteAlloca issue: #157682
I'm still observing crashes in different tests, `libc.test.src.math.smoke.ufromfpf_test` and similar variants, but I see those with and without my fix, and with and without the patch from this PR reverted, so they are probably caused by a separate problem.

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