http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56478



Jakub Jelinek <jakub at gcc dot gnu.org> changed:



           What    |Removed                     |Added

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                 CC|                            |dehao at gcc dot gnu.org



--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-28 
08:05:03 UTC ---

loop_bound = compare_bound = 0

base = -9223372036854775808

so

HOST_WIDE_INT loop_count = (loop_bound - base) / compare_step;

first invokes undefined behavior (loop_bound - base) computation and then

-LONG_LONG_MIN / -1 SIGFPEs.

That and the following code is just full of many potential undefined behaviors.

Even the compare_count++ or loop_count++ could trigger that.

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