[Bug tree-optimization/45397] [5/6/7 Regression] Issues with integer narrowing conversions

rguenth at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Fri Feb 24 09:38:00 GMT 2017


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=45397

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

--- Comment #29 from Richard Biener <rguenth at gcc dot gnu.org> ---
Created attachment 40822
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40822&action=edit
patch doing this in SCCVN

This instead of in DOM implements it in SCCVN which makes the saturated ops
recognized in phiopt1.

The other testcases in this bug involve other peculiarities like having
& 255 instead of a conversion to match or having A + B + CST.  This shows
that this kind of matching is really a hack... (or well, it show for another
time that handling CSE and larger expressions that are associatable is
difficult).


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