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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/46027] (unsignedtype1)(unsignedtype2)(unsignedtype1_var) not changed into unsignedtype1_var & NNN when sizeof(type1) > sizeof(type2)
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46027

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2010-10-19 00:29:18 UTC ---
Here is a full testcase:
typedef unsigned type1;
typedef unsigned char type2;
type1 t;
void f(type1 tt)
{
  type2 t1 = t;
  type1 t2 = t1;
  t = t2 & 0xFF;
}
void f2(type1 tt)
{
  type1 t2 = (type2)t;
  t = t2 & 0xFF;
}
void f1(type1 tt)
{
  type1 t2 = t & 0xff;
  t = t2 & 0xFF;
}

---- CUT ----
Currently f does not get optimized after my patch. f1 is optimized before my
patch and f2 is optimized afterwards.  f requires some kind of forward
prop/tree combining to do the work.