http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56051
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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Status|NEW |ASSIGNED
AssignedTo|unassigned at gcc dot |jakub at gcc dot gnu.org
|gnu.org |
--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-01-20
16:46:04 UTC ---
Created attachment 29227
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29227
gcc48-pr56051.patch
Untested fix. As the testcase shows, also a widening conversion can be a
problem, if it extends from signed integral type to wider unsigned one, because
then for Y equal to bitsize of the narrower type - 1 we get more than one bit
set.
On the other side, the optimization doesn't hit when X isn't an ARRAY_REF, but
just an integral variable, because then arg0 and arg1 are swapped.
Guess for 4.9 we should handle those cases too.
