[Bug rtl-optimization/110717] Double-word sign-extension missed-optimization

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110717

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Improved testcase which shows similar behavior also with bitfields:

#ifdef __SIZEOF_INT128__
#define type __int128
#define N 59
#else
#define type long long
#define N 27
#endif

struct S { type a : sizeof (type) * __CHAR_BIT__ - N; };

unsigned type
foo (unsigned type x)
{
  x <<= N;
  return ((type) x) >> N;
}

unsigned type
bar (struct S *p)
{
  return p->a;
}