[clang] [llvm] [X86][AVX512] rematerialize smaller predicate masks (PR #166178)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon requested changes to this pull request.

These need regenerating with update_llc_test_checks.py:
```
Failed Tests (5):
  LLVM :: CodeGen/X86/avx512-gather-scatter-intrin-deprecated.ll
  LLVM :: CodeGen/X86/avx512-gather-scatter-intrin.ll
  LLVM :: CodeGen/X86/masked_gather_scatter.ll
  LLVM :: CodeGen/X86/scatter-schedule.ll
  LLVM :: CodeGen/X86/vector-replicaton-i1-mask.ll 
```

https://github.com/llvm/llvm-project/pull/166178