Irix calling conventions for complex numbers

[Billinghurst, David (CALCRTS)]

I have started to look at C99 complex support on mips-sgi-irix6.5,
since it is required for gfortran complex number support.

A little experimentation suggests that complex numbers are not 
beings passed or returned to IRIX libc functions such as cpow{,f,l}.
(I will put together some examples id anyone is interested)

The SGI docs state that for the N32 ABI:

Complex types (C99 and Fortran %val) are passed in multiple floating point 
registers, as available. Float complex is passed as 2 floats, double 
complex as 2 doubles, and long double complex as 2 long doubles. Because 
the size of a float complex is 8 bytes (two 4-byte floats) but two float 
argument registers take 16 bytes of space, the float complex is padded with 
an extra 8 bytes of empty space in the stack image of the argument registers. 
For example, if the float complex is passed in $f12 and $f13, with the 
next parameters in $f14, the stack home of the float complex would be at 
n($sp) ($f12 would be stored in n($sp) and $f13 into n+4(s0)) and the stack 
home of $f14 would be at n+16($sp).


Where in gcc do I look to see if this is the case?