1. [ARM] VECTOR_REG_CAST undef -> undef (details)
  2. [X86][AVX] Reuse existing VBROADCAST(x) for SCALAR_TO_VECTOR(x) (details)
Commit 0fe64812d86ca387115d5b25eb24bfb2287c3b8a by
[ARM] VECTOR_REG_CAST undef -> undef

Propagate undef through VECTOR_REG_CAST nodes, allowing extra
simplification in some patterns.
The file was modifiedllvm/lib/Target/ARM/ARMISelLowering.cpp
The file was modifiedllvm/test/CodeGen/Thumb2/mve-be.ll
Commit ab3ea27b6fce6e57301c3e6efc96f80b5eb31ac4 by llvm-dev
[X86][AVX] Reuse existing VBROADCAST(x) for SCALAR_TO_VECTOR(x)

Similar to what we already do for BROADCASTs of different vector sizes - if we're going to broadcast it anyway might as well reuse it.
The file was modifiedllvm/test/CodeGen/X86/combine-bitselect.ll
The file was modifiedllvm/lib/Target/X86/X86ISelLowering.cpp