[bug#48825] [PATCH] gnu: Simplify the use of --with-long-double-128 on powerpc64le.

[Chris Marusich <cmmarusich@gmail.com>]

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Hi,

Currently in Guix, we explicitly specify --with-long-double-128 on
powerpc64le-linux (and potentially other powerpc64-* systems) in two
places.  It turns out that this is not necessary.  This patch simplifies
our code.

I originally authored this in order to try fixing bug 47698, but it
didn't solve that problem, and it turns out the --with-long-double-128
option is probably unrelated to that bug.  However, it's still worth
making this change to simplify our code.

If nobody has any issues with this, then in 2 weeks I will commit it.
One question is: where should I commit it?  I'd like to commit it to
master, but it causes many rebuilds on powerpc64le-linux (it does not
cause rebuilds on any other platforms), so per the guidelines ((guix)
Submitting Patches) I ought to commit it to core-updates.  However,
because the glibc upgrade from 2.31 to 2.32 on core-updates causes many
problems for powerpc64le-linux, core-updates has never once been a
viable branch for powerpc64le-linux in the time since support was first
added on master.  So if I commit this patch to core-updates, it won't
really do anyone any good right now.  With all this in mind, I think
master is the right place to commit this patch.

-- 
Chris

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From ad89f9f59d22cc10fbf7dd6f738ce15a6e79b640 Mon Sep 17 00:00:00 2001
From: Chris Marusich <cmmarusich@gmail.com>
Date: Sat, 10 Apr 2021 18:16:17 -0700
Subject: [PATCH] gnu: Simplify the use of --with-long-double-128 on
 powerpc64le.

In short, this change adds the "--with-long-double-128" configure option in
one place and removes it from two other (now-redundant) places.  It does not
cause any rebuilds on systems other than powerpc64le-linux.

* gnu/packages/gcc.scm (gcc-configure-flags-for-triplet): Add a clause for
targets starting with "powerpc64le-" which adds the "--with-long-double-128"
option.  This causes any package using this procedure to be built using this
new option on powerpc64le systems.  In particular, this affects the gcc
package and the gcc-final package, in addition to all the other versions of
GCC defined in (gnu packages gcc).
* gnu/packages/commencement.scm (gcc-boot0)[#:configure-flags]: Remove the
code that adds the "--with-long-double-128" configure option for powerpc64le,
since it is now redundant. The gcc-boot0 package uses (and adds to) the gcc
package's configure options. This means that the above change in gcc.scm is
sufficient to ensure that the gcc-boot0 package's configure options will
include "--with-long-double-128" on powerpc64le systems.
* gnu/packages/cross-base.scm (cross-gcc-arguments)[#:configure-flags]: Remove
the code that adds the "--with-long-double-128" configure option for
powerpc64le, since it is now redundant. The cross-gcc-arguments procedure
uses (and adds to) the configure options of its xgcc argument (a package).
This means that regardless of which gcc from gcc.scm is used as the xgcc, the
above change in gcc.scm is sufficient to ensure that the cross-gcc-arguments
procedure's configure options will include "--with-long-double-128" on
powerpc64le systems.
---
 gnu/packages/commencement.scm | 7 -------
 gnu/packages/cross-base.scm   | 6 ------
 gnu/packages/gcc.scm          | 3 +++
 3 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/gnu/packages/commencement.scm b/gnu/packages/commencement.scm
index d4511ed914..db564db9c4 100644
--- a/gnu/packages/commencement.scm
+++ b/gnu/packages/commencement.scm
@@ -2819,13 +2819,6 @@ exec " gcc "/bin/" program
                            "--disable-shared"
                            "--enable-languages=c,c++"
 
-                           ;; boot-triplet inserts "guix" in the triplet.
-                           ,@(if (equal? "powerpc64le-guix-linux-gnu" (boot-triplet))
-                                 ;; On POWER9 (little endian) glibc needs the
-                                 ;; 128-bit long double type.
-                                 '("--with-long-double-128")
-                                 '())
-
                            ;; libstdc++ cannot be built at this stage
                            ;; ("Link tests are not allowed after
                            ;; GCC_NO_EXECUTABLES.").
diff --git a/gnu/packages/cross-base.scm b/gnu/packages/cross-base.scm
index 180594509b..c1e5f2eb79 100644
--- a/gnu/packages/cross-base.scm
+++ b/gnu/packages/cross-base.scm
@@ -153,12 +153,6 @@ base compiler and using LIBC (which may be either a libc package or #f.)"
                                "--disable-decimal-float" ;would need libc
                                "--disable-libcilkrts"
 
-                              ,@(if (string-prefix? "powerpc64le-" target)
-                                   ;; On POWER9 (little endian) glibc needs
-                                   ;; the 128-bit long double type.
-                                   '("--with-long-double-128")
-                                   '())
-
                                ;; When target is any OS other than 'none' these
                                ;; libraries will fail if there is no libc
                                ;; present. See
diff --git a/gnu/packages/gcc.scm b/gnu/packages/gcc.scm
index a412c93c29..22a0f35422 100644
--- a/gnu/packages/gcc.scm
+++ b/gnu/packages/gcc.scm
@@ -79,6 +79,9 @@ where the OS part is overloaded to denote a specific ABI---into GCC
          ;; Cilk has been removed from GCC 8 anyway.
          '("--disable-libcilkrts"))
 
+        ((string-prefix? "powerpc64le-" target)
+         '("--with-long-double-128"))
+
         (else
          ;; TODO: Add `arm.*-gnueabi', etc.
          '())))
-- 
2.30.2


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