nlopes added a comment. In D134410#3895077 <https://reviews.llvm.org/D134410#3895077>, @nikic wrote:
> In D134410#3894995 <https://reviews.llvm.org/D134410#3894995>, @nlopes wrote: > >> 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. > > Can you elaborate on this? I don't see how this is necessary for switching > uninitialized loads to poison. It's not mandatory, it's a simple way of achieving it as !noundef already exists. We cannot change the default behavior of load as it would break BC. An alternative is to introduce a new !poison_on_unint for loads. Clang could use that on all loads except those for bit-fields. Our suggestion is to jump straight to !noundef. To fully remove undef, then we need to swtich loads to return `freeze poison` rather than undef on uninitialized access, but only after we are able to yield poison in the common case. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D134410/new/ https://reviews.llvm.org/D134410 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
