Why is GCC using DI register?

[Dan Aalberg]

I am trying to get some very simple assembly code from the GCC compiler for
some testing I am doing.
For sake of this email, I will over simplify the code.

Here is some simple C code I compile with GCC:

int main(void)
{
	int a;
	a=5;
	return (a);
}


when I compile it, I get this for the machine code (with my comments):

push      bp
mov       bp,sp		; normal
sub (w)   sp,+08		;normal
mov       [di-04],0005	; what the heck is this?
add       [bx+si],al	;where did BX and SI come into play?
				;what are we adding?
mov       ax,[di-04]	;next 2 lines are stupid.
mov       [di-08],ax
mov       ax,[di-08]
leave
retn

what is with BX, DI and SI?  I am trying to compile to a flat, non specific
system and was looking for more of this:

push  bp
mov  bp,sp		; normal
mov  [bp-4],0005
mov  ax, [bp-4]

pop bp
retn


Am I missing a GCC command line switch (there are only 472 to choose from
:-)

Thanks in advance

Dan