Re: complex support on alpha

[Richard Henderson <rth at cygnus dot com>]

On Sun, Oct 05, 1997 at 07:14:09PM -0400, Weiwen Liu wrote:
> On Wed, 1 Oct 1997, Richard Henderson wrote:
> 
> > Well, it is enough to compile those examples properly, but it is
> > not completely correct.  The problem is that complex numbers should
> > be treated as two distinct arguments on Alpha, which affects padding
> > of the arguments passed on the stack.
[...]
> On an alpha-dec-osf4.0, this patch correctly compiles the following test
> program with F=char, short, int, long, float, double:

No good.

(1) It is still treating complex float as an 8-byte struct not two 
    _separate_ float arguments.  I sent you f2a and f2b so that you
    could verify that their arguments wound up in the same place, but

    f2b:
	lds $f10,16($30)
	lds $f11,20($30)

    f2a:
	lds $f10,16($30)
	lds $f11,24($30)

(2) f1, the one with odd numbered arguments, is _completely_ wrong:

    f1:
	lda $30,-16($30)
	.prologue 0
	sts $f21,8($30)
	lds $f10,12($30)

Did we write to 12($30), which is below the vfp?  No.  Your program
happened to run because of this bit from main:

	sts $f3,-4($30)

which is a big no-no.   No writes may be made below $sp.  You take a
signal after that instruction and your data will be corrupted. 


r~