Subject: bug#47237: closed (Re: bug#47237: [PATCH] gnu: metis: Use 64-bit floating pointer numbers on 64-bit architectures.)

From: [email-masked] (GNU bug Tracking System)
Date: Thu, 25 Mar 2021 17:43:02 +0000

Your bug report

#47237: [PATCH] gnu: metis: Use 64-bit floating pointer numbers on 64-bit architectures.

which was filed against the guix-patches package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to [email-masked].

-- 
47237: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=47237
GNU Bug Tracking System
Contact [email-masked] with problems

Subject: Re: bug#47237: [PATCH] gnu: metis: Use 64-bit floating pointer numbers on 64-bit architectures.
From: Ludovic Courtès <[email-masked]>
To: Paul Garlick <[email-masked]>
Cc: [email-masked], [email-masked], [email-masked]
Date: Thu, 25 Mar 2021 18:42:39 +0100
List-Id: <debbugs-submit.debbugs.gnu.org>

Hi again,

For now I’ve added a ‘metis-r64’ package with 64-bit reals to the
‘guix-hpc’ channel:

  https://gitlab.inria.fr/guix-hpc/guix-hpc/-/commit/f4a77fe95f0286bd63b07af6b9fbef25f3262682

Let’s see later if we can come up with a more generic solution in Guix
proper.

Ludo’.

Subject: [PATCH] gnu: metis: Use 64-bit floating pointer numbers on 64-bit architectures.
From: Ludovic Courtès <[email-masked]>
To: [email-masked]
Cc: Emmanuel Agullo <[email-masked]>,Ludovic Courtès <[email-masked]>, Eric Bavier <[email-masked]>, Paul Garlick <[email-masked]>
Date: Thu, 18 Mar 2021 16:02:46 +0100
List-Id: <debbugs-submit.debbugs.gnu.org>

From: Ludovic Courtès <[email-masked]>

* gnu/packages/maths.scm (metis)[arguments]: Add #:modules and #:phases.
---
 gnu/packages/maths.scm | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

Hi!

Metis defaults to 32-bit floating point numbers.  However, on 64-bit
platforms, users probably expect 64-bit floating point numbers, hence
this patch.

We could make it configurable through different variants or via package
parameters when they’re available, but I wonder about the usefulness of
a variant that uses 32-bit floats on 64-bit architectures.  Can we keep
just this one variant?

Thanks,
Ludo’.

diff --git a/gnu/packages/maths.scm b/gnu/packages/maths.scm
index 565f109f47..4cd9112be9 100644
--- a/gnu/packages/maths.scm
+++ b/gnu/packages/maths.scm
@@ -12,7 +12,7 @@
 ;;; Copyright © 2015 Fabian Harfert <[email-masked]>
 ;;; Copyright © 2016 Roel Janssen <[email-masked]>
 ;;; Copyright © 2016, 2018, 2020 Kei Kebreau <[email-masked]>
-;;; Copyright © 2016, 2017, 2018, 2019, 2020 Ludovic Courtès <[email-masked]>
+;;; Copyright © 2016, 2017, 2018, 2019, 2020, 2021 Ludovic Courtès <[email-masked]>
 ;;; Copyright © 2016 Leo Famulari <[email-masked]>
 ;;; Copyright © 2016, 2017 Thomas Danckaert <[email-masked]>
 ;;; Copyright © 2017, 2018, 2019, 2020 Paul Garlick <[email-masked]>
@@ -3312,7 +3312,26 @@ YACC = bison -pscotchyy -y -b y
      `(#:tests? #f                      ;no tests
        #:configure-flags `("-DSHARED=ON"
                            ,(string-append "-DGKLIB_PATH=" (getcwd)
-                                           "/metis-" ,version "/GKlib"))))
+                                           "/metis-" ,version "/GKlib"))
+
+       #:modules ((system base target)
+                  (guix build cmake-build-system)
+                  (guix build utils))
+       #:phases (modify-phases %standard-phases
+                  (add-after 'unpack 'set-real-type-width
+                    (lambda* (#:key build target #:allow-other-keys)
+                      ;; Enable 64-bit floating point numbers on 64-bit
+                      ;; architectures.  Leave the default 32-bit width on
+                      ;; other architectures.
+                      (let ((word-size
+                             (with-target (or target build %host-type)
+                               (lambda ()
+                                 (target-word-size)))))
+                        (when (= 8 word-size)
+                          (display "setting REALTYPEWIDTH to 64...\n")
+                          (substitute* "include/metis.h"
+                            (("define REALTYPEWIDTH.*$")
+                             "define REALTYPEWIDTH 64\n")))))))))
     (home-page "http://glaros.dtc.umn.edu/gkhome/metis/metis/overview")
     (synopsis "Graph partitioning and fill-reducing matrix ordering library")
     (description
-- 
2.30.2