[llvm] [AMDGPU] SIFoldOperands check that shrunk op is valid (PR #156298)

[Jay Foad via llvm-commits]

https://github.com/jayfoad commented:

A possible alternative fix is to implement this TODO, so that the operand is legal for the e64 instruction so this code won't even try to shrink it: https://github.com/llvm/llvm-project/blob/be1e50f56af8e270a0396eef8f62626fbbb84996/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp#L133

https://github.com/llvm/llvm-project/pull/156298