nlopes added a comment.

In D134410#3893918 <https://reviews.llvm.org/D134410#3893918>, @nikic wrote:

> I think adding this under a default-disabled flag is fine for evaluation 
> purposes, but I have doubts that we will ever be able to enable this by 
> default. There is a lot of code out there assuming that copying uninitialized 
> data around is fine.

Well, I think that flags that are disabled by default don't exist and they are 
not useful.
We wanted this patch to make us switch uninitialized loads to poison at will, 
since they become UB. In practice, this helps us fixing bugs in SROA and etc 
without perf degradation.
As long as ubsan/valgrind can detect these uninitialized loads, I think we 
should be ok to deploy this change. We are touching memcpys yet, at least, as 
those may be susceptible to handling uninit memory.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D134410/new/

https://reviews.llvm.org/D134410

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