------- Comment #5 from gangren at google dot com 2007-06-12 17:53 ------- (In reply to comment #3) > >Do you mean that short_var + short_var is defined as > > (short)((unsigned short)short_var + (unsigned short)short_var)? > > Kinda, because it is really defined by the C standard as: > (short)((int)short_var + (int)short_var) > And then GCC's middle-end optimizes it to: > (short)((unsigned short)short_var + (unsigned short)short_var) > > *** This bug has been marked as a duplicate of 26128 *** >
I'm aware of integral promotion. But not quite understand why we can optimize (short)((int)short_var + (int)short_var) to (short)((unsigned short)short_var + (unsigned short)short_var), but not to (short)((short)short_var + (short)short_var)? Is it because unsigned short has different overflow handling? -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32309
