[Bug middle-end/25186] (short)(((int)short_var) <<1) should be folded so that the shift is done in the short type

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2005-12-01 12:46 -------
I.e. 6.3.1.3/3 says that conversion from type T to signed type is
implementation defined if the value doesn't fit.  And we define it to reducing
it modulo 2^N.

So, for !flag_wrapv

  (short)((int)0x8000 << 1) == 0

but
  0x8000 << 1  is undefined.

So this transformation is only ok for flag_wrapv.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25186