[Bug tree-optimization/114704] Missed optimization : eliminate store if the value is known in all predecessors

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114704

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
We're not handling "phi translation" in the lookup phase when determining if
there's a redundant store (PHI translation for the virtual operand).  In
particular value-numbering never considers whether an expression
in multiple paths into a CFG merge value-numbers the same.  This is only
done as part of PRE which figures some extra fully redundant expressions.
But the redundant store removal is something done after-the-fact using
just the VN machinery.