[Bug tree-optimization/108199] Bitfields, unions and SRA and storage_order_attribute

pinskia at gcc dot gnu.org gcc-bugzilla@gcc.gnu.org
Mon Jan 9 20:26:15 GMT 2023


Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
             Status|WAITING                     |NEW

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Here is a testcase for the trunk on x86_64-linux-gnu:
#define BITFIELD_ENDIAN "big-endian"

#define SRC_ENDIAN "big-endian"
#define DST_ENDIAN "big-endian"

typedef unsigned long long u64;

union DST {
  unsigned long val;

  struct {
    u64 x : 1;
    u64 y : 1;
    u64 r: 62;
  } __attribute__((scalar_storage_order("big-endian")));
} __attribute__((scalar_storage_order("big-endian")));

struct SRC {
  u64 a;
} __attribute__((scalar_storage_order("big-endian")));

void foo (){__builtin_abort();}
int bar(struct SRC *src)
  union DST dst;

  dst.val = src->a;

  if (dst.y) {
  return 0;
int main(void)
    struct SRC t = {-1ull & (~(0x01ull<<62))};
    return 0;
It does not cause an abort at -O0 but does at -O2.

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