alpha vs complex functions

[Richard Henderson <rth at twiddle dot net>]

GCC 3.4 fixed an ABI conformance problem with complex values, which
means that all functions that take single-precision complex parameters
are incompatible with previous versions of GCC.

I'm trying to figure out what I want to do about this in glibc.

I was thinking that one possibility for letting gcc 3.3 and 3.4
live together on the same machine would be to do stuff like

#if __GNUC_PREREQ(3, 4)
float cabsf (_Complex float) __asm__("__c2_cabsf");
#endif

or something, in some alpha-specific version of some math.h or
complex.h header file.

It is possible to write code by hand in gcc 3.3 that will inter-operate
with gcc 3.4 (so that we could be forward compatible),

	float __c2_cabsf (float xreal, float ximag)
	{
	  _Complex float x;
	  __real__ x = xreal;
	  __imag__ x = ximag;
	  return __cabsf (x);
	}

It *might* be possible to do the reverse, but I'm not sure.  If it's
possible the solution would look like

	float __cabsf (double junk)
	{
	  union {
	    double d;
	    float f[2];
	  } u;
	  u.d = junk;
	  return __c2_cabsf (u.f[0], u.f[1]);
	}

Thoughts?  I'm particularly interested in what to do about the
header files.  The rest should be moderately straightforward 
additions of files under sysdeps/alpha/ that include the normal
file and massage its contents with preprocessor ugliness.


r~