[Bug tree-optimization/85803] [9/10/11/12 Regression] DSE removes live global store

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85803

--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 52573
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52573&action=edit
prototype patch

The testcase in the description isn't very good, it instead relies on traps
being observable as opposed to EH.

The attached prototype thus doesn't fix it but it might fix cases where we run
into a function ending stmt that lacks virtual operands.

It might also help producing a region-based DSE (which suffers from "leakage"
unless exit VOPs are speficied and handled).