emit_library_call help

[Stephen Biggs]

On Mon, 2003-06-23 at 11:54, Stephen Biggs wrote:
> On Sun, 2003-06-22 at 18:00, Stephen Biggs wrote:
> > Greetings,
> > 
> > I am trying to unravel the many varied puzzles of emitting custom insns
> > and am making progress, but am stuck on an issue:
> > 
> > I have an internal library function that I wish to generate an insn for
> > which has the prototype:
> > void bar(void *);
> > 
> > ... and I have a function in <machine>.c thus:
> > 
> > void
> > foo(rtx val) /* val is possibly a pseudo-register */
> > {
> > 	rtx val_ptr = force_reg(Pmode,val);
> > 	emit_library_call(gen_rtx_SYMBOL_REF(Pmode,"bar"),LCT_NORMAL,VOIDmode,1,val_ptr,Pmode);
> > }
> > 
> > The argument val_ptr is created in the recognized insn as an integer
> > instead of a pointer, even though I think I am forcing it to be a
> > pointer. What magic is needed here to have this argument be a pointer
> > argument instead of an integer argument?  Thanks for any help.
> > 
> > 
> 
> I also tried:
> void
> foo(rtx val) /* val is possibly a pseudo-register */
> {
> 	mark_reg_pointer(val,0);
> 	emit_library_call(gen_rtx_SYMBOL_REF(Pmode,"bar"),LCT_NORMAL,VOIDmode,1,val,Pmode);
> }
> ... but no soap.  How do I force this register to be a pointer register?
> 
> I finally got it to work by copying code from emit_library_call_value_1
> in gcc/calls.c since I can't define FUNCTION_ARG_PASS_BY_REFERENCE in my
> port, thusly:
> 
> void
> foo(rtx val) /* val is possibly a pseudo-register */
> {
> 	tree type = type_for_mode (Pmode, 0);
> 	rtx val_ptr,slot = gen_rtx_MEM(Pmode,
> 		expand_expr(build1(ADDR_EXPR,build_pointer_type(type),
> 			make_tree(type, val)),NULL_RTX, VOIDmode, 0));
> 
> 	val_ptr = force_operand(XEXP(slot, 0),NULL_RTX);
> 
> 	emit_library_call(gen_rtx_SYMBOL_REF(Pmode,"bar"),
> 		LCT_NORMAL,VOIDmode,1,val_ptr,Pmode);
> }
>  
> ... a gross, horrid, sleazy hack, overkill, IMHO, but I couldn't figure out any other way to do this... any suggestions?

Actually (and excuse my replying two times to my own post!), the above
gross, horrid, sleazy hack did NOT work, but the following, much cleaner
version, albeit still gross, horrid, and sleazy, DOES work:

void
foo(rtx val) /* val is possibly a pseudo-register */
{
	emit_library_call(gen_rtx_SYMBOL_REF(Pmode,"bar"),
		LCT_NORMAL,VOIDmode,1,
		force_operand(XEXP(gen_rtx_MEM(Pmode,val),0),NULL_RTX),
		Pmode);
}


Is this the right way to do what I want to do, or did I just get lucky?