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Re: Use predicates for RTL objects


On Thu, Aug 08, 2019 at 10:42:06AM -0600, Jeff Law wrote:
> On 8/5/19 12:29 PM, Segher Boessenkool wrote:
> > On Mon, Aug 05, 2019 at 02:14:50PM -0400, Arvind Sankar wrote:
> >> On Mon, Aug 05, 2019 at 12:48:46PM -0500, Segher Boessenkool wrote:
> >>> First: do you have a copyright assignment?  See
> >>>   https://gcc.gnu.org/contribute.html
> >>> for instructions.
> >>
> >> Nope, is this really substantial enough to warrant one?
> > 
> > Some might say it is, the sheer amount of code changed :-)  If some
> > maintainer okays it without assignment, that is fine with me of course.
> > 
> > This is also easier if it is all machine-generated and nice simple
> > patches :-)
> If it's entirely machine generated and you don't want to do a copyright
> assignment, then the way to go will be for someone with an assignment to
> run the scripts and commit the change.  Then we'd only need an
> assignment if we wanted the scripts in the repo.
> 
I have just got the forms from GNU, probably a few days to actually send
it in. I am not too fussed about how to do this particular change,
whatever's easiest.
> 
> 
> > 
> >>>> -/* Predicate yielding true iff X is an rtx for a double-int.  */
> >>>> +/* Predicate yielding true iff X is an rtx for a floating point constant.  */
> >>>>  #define CONST_DOUBLE_AS_FLOAT_P(X) \
> >>>>    (GET_CODE (X) == CONST_DOUBLE && GET_MODE (X) != VOIDmode)
> >>>
> >>> Is const_double really only used for floating point these days?
> > 
> >> Are you asking if the CONST_DOUBLE_AS_INT_P possibility is dead code
> >> now? That's beyond my current level of understanding of the code,
> >> hopefully someone else will chime in.
> > 
> > I am asking if the change to this comment is correct.
> I thought we used CONST_DOUBLE for scalar constants that are wider than
> a HOST_WIDE_INT, or perhaps wider than 2 HOST_WIDE_INTs.  If that's
> still the case, then the comment change is wrong.
> 
> Jeff

Please note that this is the comment for CONST_DOUBLE_AS_FLOAT_P, not
CONST_DOUBLE_P. CONST_DOUBLE_AS_INT_P is the predicate to represent a
CONST_DOUBLE being used to store large integers, and, as I understand
it, it will be used if the target does not define TARGET_SUPPORTS_WIDE_INT.

At present, the comment for both CONST_DOUBLE_AS_INT_P and
CONST_DOUBLE_AS_FLOAT_P claim that they are the predicates for
double-int.


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