[llvm] [PowerPC] using milicode call for strcmp instead of lib call (PR #177009)

[zhijian lin via llvm-commits]

diggerlin wrote:

For easier review, and because the following functionality is not strongly tied to` using a milicode call for strcmp instead of a library call`, I have split the changes into two patches.

I will add the following items in a subsequent patch:

1. A new parameter, AttributeSet ResultAttrs = {}, added to
`CallLoweringInfo &setLibCallee(CallingConv::ID CC, Type *ResultType, SDValue Target, ArgListTy &&ArgsList, AttributeSet ResultAttrs = {}).`

2. A new function,
`CallLoweringInfo &setLibCallee(CallingConv::ID CC, Type *ResultType, SDValue Target, ArgListTy &&ArgsList, const CallBase &Call).`



https://github.com/llvm/llvm-project/pull/177009