[llvm] [SystemZ] Fix bitwidth problem in FindReplicatedImm() (NFC). (PR #115383)

[Ulrich Weigand via llvm-commits]

uweigand wrote:

> As SystemZVectorConstantInfo() does not really care about the bitwidth of its initial APInt

I don't think this is quite true.   It does use the initial bitwidth to decide whether the value can be generated as a splat in some cases.  For example, it would appear that the value 0x01010101 can be created via VREPIB if the initial bitwidth is 32 (because then it is a splat), but not if the initial bitwidth is 64 (then it is not).


https://github.com/llvm/llvm-project/pull/115383