tree-ssa-forwprop.c (associate_plusminus): For widening conversions check for undefined overflow in (T)(P + A) - (T)P -> (T)A.

2014-06-25  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * tree-ssa-forwprop.c (associate_plusminus): For widening conversions
        check for undefined overflow in (T)(P + A) - (T)P -> (T)A.
        Issue a strict overflow warning if appropriate.

testsuite:
2014-06-25  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * gcc.c-torture/execute/20140622-1.c: New test.

From-SVN: r211988