[PATCH] D50233: [InstCombine] Transform str(n)cmp to memcmp

[Adam Reichold via Phabricator via llvm-commits]

adamreichold added a comment.

In https://reviews.llvm.org/D50233#1223683, @efriedma wrote:

> > Does LLVM's implementation somehow guarantee that no later optimization pass comes along, sees the program reading uninitialized memory and declares UB?
>
> In LLVM IR, reading uninitialized memory isn't itself UB; it's only UB if you perform certain operations on the result.  Granted, a naive LLVM IR implementation of memcmp might involve operations which lead to UB.


But that also implies that you have to emit an inline implementation since you might not control what the implementation of `memcmp` supplied by `libc` does?


Repository:
  rL LLVM

https://reviews.llvm.org/D50233