[LLVMdev] Flag output used by two other nodes in DAG

[Edmund Grimley-Evans]

Anton Korobeynikov:

> > Is it, or should it be legal for a Flag output to be used as input by
> > more than one other node?
> It's illegal. Multiple uses of the flag output do not make any sense,
> this breaks the semantics of flag operands.

All right. Then what should the Selection DAG look like in a case where the
flag value generated by one instruction is to be used as input to two other
instructions?

For a concrete example, consider:

int f(int x)
{
  return x < 0 ? 11 : x == 0 ? 22 : 33;
}

I'd like this to turn into something like what I've seen from other compilers:

	cmp	r0, #0
	movlt	r0, #11
	bxlt	lr
	movne	r0, #33
	moveq	r0, #22
	bx	lr
-- 
IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium.  Thank you.