attribute aligned(4) ignored

[Chris Lattner <sabre at nondot dot org>]

Hi All, I'm trying to reduce the alignment of the double in this structure 
to 4 bytes (from 8) on Darwin.  The goal of doing this is to reduce the 
structure to 12 bytes in size.  Here is my testcase:

struct Test {
  double D __attribute__((aligned(4)));    // only 4 bytes, not 8!
  int X;
};

int X() {
  return sizeof(struct Test);    // Should return 12, not 16.
}

Despite my attempt above, the structure is still 16 bytes in size, due to 
the tail padding required to pad the structure to ensure 8-byte alignment.

Does anyone know how to reduce the alignment of the double, eliminating 
the tail padding?

Thanks,

-Chris

--
http://nondot.org/sabre/
http://llvm.org/