[Bug c/55967] rightshift an unsigned value (X) by it's number of bits does not always yield 0, when X is an unsigned that's leftshifted by it's number of bits and offset

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55967



--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-01-15 
07:55:06 UTC ---

Please google around on "undefined behavior", you'll find various FAQs about

it.  When a program triggers undefined behavior, anything can happen, the

compiler can optimize based on the fact that such behavior won't happen in a

program, as a bonus in this case you get a warning telling you your bug.  There

is no graceful/expected behavior for undefined behavior, otherwise it wouldn't

be undefined.