[PATCH] D109844: [DSE] Track earliest escape, use for loads in isReadClobber.

[Reid Kleckner via Phabricator via llvm-commits]

rnk added a comment.

Thanks for putting this together!

In D109844#3006260 <https://reviews.llvm.org/D109844#3006260>, @fhahn wrote:

> Also, @rnk mentioned seeing plenty of stores not being removed in Chrome + auto-init in PR50220. Perhaps they could let us know the impact of the change + D109907 <https://reviews.llvm.org/D109907>. And this also fixes a regression compared to legacy DSE.

I probably won't be able to do any benchmarking, but if anyone is interested, you can probably run any benchmark set you like with `-fauto-var-init=pattern` before and after this patch and check how many extra stores are removed. I strongly suspect it will help on code patterns where initialization is separate from declaration:

  struct Foo v;
  ...
  v.x = 0;
  ...
  escape(&v);

Even if this pattern isn't prevalent in common benchmark suites, I think it's pretty important to users of these security hardening flags.


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https://reviews.llvm.org/D109844