[PATCH] D49771: CodeGen: use non-zero memset when possible for automatic variables

Mehdi AMINI via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Tue Jul 31 15:58:21 PDT 2018

mehdi_amini added a comment.

In https://reviews.llvm.org/D49771#1183380, @jfb wrote:

> In https://reviews.llvm.org/D49771#1181008, @mehdi_amini wrote:
> > I'm curious: isn't the kind of optimization we should expect LLVM to provide?
> Maybe? It seems obvious to do here since we know we'll probably want to be doing it, and I have another patch I'm working on which will make it that much more obviously useful to have here. The middle-end can definitely figure it out but it just seems like more work, later, so in the meantime we'd be looking at more stuff.

I'm not asking where is it easier to do, but where does it make the most sense :)
Doing such in LLVM in general means catching more patterns (i.e. after inlining, etc.), and also catching it from multiple frontend. So in general I'm worried when I see optimizations implemented in the frontend  instead of the middle end.



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