[Bug tree-optimization/102872] If statement is always false but not figured out at gimple level
rguenth at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Thu Oct 21 08:58:21 GMT 2021
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102872
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Ever confirmed|0 |1
Status|UNCONFIRMED |NEW
Last reconfirmed| |2021-10-21
CC| |amacleod at redhat dot com,
| |rguenth at gcc dot gnu.org
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed. I wonder if the relation oracle could be extended to handle this
though there's the usual caveat that _9 and d_10 are not dependent on each
other but only are indirectly related through a.3_5.
d_10 = (short unsigned int) a.3_5;
_9 = a.3_5 & 65535;
if (_9 == 0)
Here VN could be teached to look for (short unsigned int) a.3_5 when
seeing a.3_5 & 65535 and CSE it as (short signed int) d_10 (but then
I think we might fold that back).
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