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* [Bug tree-optimization/40170] redundant zero extensions
[not found] <bug-40170-4@http.gcc.gnu.org/bugzilla/>
@ 2021-07-26 5:58 ` pinskia at gcc dot gnu.org
0 siblings, 0 replies; only message in thread
From: pinskia at gcc dot gnu.org @ 2021-07-26 5:58 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=40170
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |11.0
Resolution|--- |FIXED
Component|target |tree-optimization
Status|UNCONFIRMED |RESOLVED
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed for GCC 11, in EVRP. I can't figure out which patch caused it but what
happens is the following:
We figure out the range of _3 to be [0, 255]
_3 = (int) bit_16;
While processing:
_4 = _2 >> _3;
We figure out the range of _4 is still [0, 255] as it is a right shift so we
cannot change any upper bits.
And then we match and simplify the following:
_24 = _4 & 255;
to just:
_24 = _4;
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[not found] <bug-40170-4@http.gcc.gnu.org/bugzilla/>
2021-07-26 5:58 ` [Bug tree-optimization/40170] redundant zero extensions pinskia at gcc dot gnu.org
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