Re: x86 gcc lacks simple optimization

[Jeff Law <law at redhat dot com>]

On 12/06/13 07:17, Richard Biener wrote:
> On Fri, Dec 6, 2013 at 2:52 PM, Konstantin Vladimirov
> <konstantin.vladimirov@gmail.com> wrote:
> > Hi,
> >
> > Richard, I tried to add LSHIFT_EXPR case to tree-scalar-evolution.c
> > and now it yields code like (x86 again):
> >
> > .L5:
> > movzbl 4(%esi,%eax,4), %edx
> > movb %dl, 4(%ebx,%eax,4)
> > addl $1, %eax
> > cmpl %ecx, %eax
> > jne .L5
> >
> > So, excessive lea is gone. It is great, thank you so much. But I
> > wonder what else can I do to move add upper to simplify memory
> > accesses (I am guessing, this is some arithmetical re-associations,
> > still not sure where to look). For architecture, I am working on, it
> > is important. What would you advise?
>
> You need to look at IVOPTs and how it arrives at the choice of
> induction variables.
Konstantin,

You might want to work will Ben Cheng from ARM; he's already poking in 
this code and may have some ideas.

jeff