[4.5] Doloop improvement patches, 0/7

[Zdenek Dvorak]

Hi,

> Zdenek Dvorak wrote:
> 
> > I am a bit confused by this patch -- are these changes to two version of
> > gcc?  Also, please send the changelogs separately from the patch.
> 
> Please see the followup message.  I edited an old mail I sent to our
> local mailing lists and forgot to remove the attachment.  The correct
> patch is in the first followup mail 1/7.  Sorry about the confusion.
> 
> >> + out:
> >> +  if (!CONSTANT_P (*expr))
> >> +    *expr = last_valid_expr;
> >>    FREE_REG_SET (altered);
> >> +  FREE_REG_SET (this_altered);
> >>  }
> > 
> > Why is the semantics changed to return even non-constant outcome?
> 
> That hasn't really changed - it could have happened previously as well;
> we've always modified the expression in-place.  Previously we returned
> immediately if that introduced an altered reg; now we keep scanning.
> The if statement here only makes sure that we do not return an
> expression that is invalid due to altered regs.

sorry, my fault, I misinterpreted the CONSTANT_P (*expr) shortcuts in
the original code.

> Given these explanations, is the patch OK?

Yes,

Zdenek