[PATCH] gfortran: Improve translation of POPPAR intrinsic

[Bernhard Reutner-Fischer]

On Sun, 21 Nov 2021 19:59:35 +0100
Harald Anlauf <anlauf@gmx.de> wrote:

> Let's have a look at the tree-dump of the existing testcase:
> 
> integer(kind=4) runtime_poppar (integer(kind=16) & restrict i)
> {
>    integer(kind=4) res;
> 
>    {
>      uint128_t D.4221;
> 
>      D.4221 = (uint128_t) *i;
>      res = __builtin_parityll ((unsigned long) D.4221 ^ (unsigned long)
> (D.4221 >> 64));
>    }
>    return res;
> }
> 
> My understanding is there is actually nothing left to do,
> as the middle-end(?) already handles this.

Well the whole point was ...
> 
> Am 21.11.21 um 01:22 schrieb Bernhard Reutner-Fischer via Fortran:
> > Roger pinged this on gcc-patches some time ago fwiw.
> > [The commit-hooks will likely fix or ignore s/bext/next/ in his
> > mail-addr]
> >
> >
> > On Sun, 14 Jun 2020 23:39:32 +0100
> > "Roger Sayle" <roger@nextmovesoftware.com> wrote:
> >  
> >>
> >>
> >> The following patch to gfortran's trans-instrinsic.c tweaks the generic that
> >> is produced
> >>
> >> for popcnt on integer(kind=16).  Currently, the double word popcnt is
> >> implemented as
> >>
> >> parityll(hipart(x))^parityll(lopart(x)), but with this patch this is now
> >> translated as
> >>
> >> parityll(hipart(x)^lopart(x)).  This will be just an aesthetic change once
> >> my tree-level
> >>
> >> parity optimization patch of 12th June is reviewed and accepted, but
> >> generating the
> >>
> >> more efficient form initially, avoids a tiny bit of garbage collection when
> >> the middle-end
> >>
> >> cleans this up into its preferred form.    The semantics/correctness of this

... the above, i.e. create better code in the first place.
thanks,

> >>
> >> change are tested by the run-time tests in gfortran.dg/popcnt_poppar_2.F90
> >>
> >>
> >>
> >> This patch has been tested with "make bootstrap" and "make -k check" on
> >>
> >> x86_64-pc-linux-gnu with no regressions.  If approved, I'd very much
> >>
> >> appreciate it if the (gfortran) reviewer could commit this change for me.
> >>
> >>
> >>
> >> 2020-06-14  Roger Sayle  <roger@bextmovesoftware.com>
> >>
> >>
> >>
> >>          * trans-intrinsic.c (gfc_conv_intrinsic_popcnt_poppar): Translate
> >>
> >>          poppar(kind=16) as parityll(hipart(x)^lopart(x)) instead of
> >>
> >>          parityll(hipart(x))^parityll(lopart(x)).
> >>
> >>
> >>
> >>
> >>
> >> Thanks in advance,
> >>
> >> Roger
> >>
> >> --
> >>
> >> Roger Sayle
> >>
> >> NextMove Software
> >>
> >> Cambridge, UK
> >>
> >>
> >>  
> >  
>