[llvm] Calculate KnownBits from Metadata correctly for vector loads (PR #128908)

[Augie Fackler via llvm-commits]

durin42 wrote:

This is causing rustc to no longer be able to build its stage 2 compiler: instead it gets a SIGSEGV partway through. Search for SEGV in https://buildkite.com/llvm-project/rust-llvm-integrate-prototype/builds/35748#0195ce08-82ac-45e8-9161-ae441a1939bd - I'll try and do more debugging to figure out what's going on.

https://github.com/llvm/llvm-project/pull/128908