Re: rtl_loop_init vs try_redirect_by_replacing_jump vs simple jumps

["Steven Bosscher" <stevenb dot gcc at gmail dot com>]

On 5/23/06, DJ Delorie <dj@redhat.com> wrote:
> > You're misunderstanding how this code works.  In cfglayout mode,
> > there is no "order" in the basic blocks such that
> > BLOCK_FOR_INSN(NEXT_INSN(BB_END(BB)) ) == BB->next_bb. This means
> > that you can fall through to other blocks than next_bb.
>
> Thanks for the tip, I figured out what was really happening.  Which
> leads to the next question: What's the right way to keep an asm() from
> being loop invariant?  I've got a case where an inline asm() is passed
> a pointer (the pointer is invariant) but internally dereferences it
> (the pointed-at memory is *not* invariant).  However, loop-invariant.c
> is pulling it out of the loop anyway.

Sounds like you need a memory clobber constraint on the asm... ?

Gr.
Steven