Subject: [bug#49896] [PATCH core-updates-frozen] gnu: gcc-5: Fix powerpc64le-linux build

From: Thiago Jung Bauermann <[email-masked]>
Date: Thu, 5 Aug 2021 13:19:43 -0300

GCC 5 has a misaligned access to a vector pointer which causes a build
failure when using GCC 8 and later. Backport upstream fix that was applied
on the GCC 6 branch.

* gnu/packages/gcc.scm (gcc-5)[source]: Apply
gcc-5-fix-powerpc64le-build.patch.
* gnu/packages/patches/gcc-5-fix-powerpc64le-build.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add new file.
---

Hi,

Even though gcc-5-fix-powerpc64le-build.patch modifies a file which is
used by all architectures, it only affects powerpc64le because the code
it touches is guarded by:

  #elif defined(_ARCH_PWR8) && defined(__ALTIVEC__)

Also, this problem doesn't affect the master branch because GCC 7.5 is
able to build GCC 5.

Thanks,
Thiago

 gnu/local.mk                                  |  1 +
 gnu/packages/gcc.scm                          |  4 +-
 .../patches/gcc-5-fix-powerpc64le-build.patch | 64 +++++++++++++++++++
 3 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 gnu/packages/patches/gcc-5-fix-powerpc64le-build.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index 5e5dd0bad3ec..7562b54d14e4 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -1068,6 +1068,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/gcc-4.9.3-mingw-gthr-default.patch	\
   %D%/packages/patches/gcc-5-hurd.patch				\
   %D%/packages/patches/gcc-5.0-libvtv-runpath.patch		\
+  %D%/packages/patches/gcc-5-fix-powerpc64le-build.patch	\
   %D%/packages/patches/gcc-5-source-date-epoch-1.patch		\
   %D%/packages/patches/gcc-5-source-date-epoch-2.patch		\
   %D%/packages/patches/gcc-6-arm-none-eabi-multilib.patch	\
diff --git a/gnu/packages/gcc.scm b/gnu/packages/gcc.scm
index 79994cc19116..ddc5af3cedf9 100644
--- a/gnu/packages/gcc.scm
+++ b/gnu/packages/gcc.scm
@@ -490,7 +490,9 @@ Go.  It also includes runtime support libraries for these languages.")
                                        "gcc-5-source-date-epoch-2.patch"
                                        "gcc-6-libsanitizer-mode-size.patch"
                                        "gcc-fix-texi2pod.patch"
-                                       "gcc-5-hurd.patch"))
+                                       "gcc-5-hurd.patch"
+                                       ;; See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86162
+                                       "gcc-5-fix-powerpc64le-build.patch"))
               (modules '((guix build utils)))
               (snippet gcc-canadian-cross-objdump-snippet)))
     (inputs
diff --git a/gnu/packages/patches/gcc-5-fix-powerpc64le-build.patch b/gnu/packages/patches/gcc-5-fix-powerpc64le-build.patch
new file mode 100644
index 000000000000..289d64887539
--- /dev/null
+++ b/gnu/packages/patches/gcc-5-fix-powerpc64le-build.patch
@@ -0,0 +1,64 @@
+From ee6c0081c03330045b3d4cde8421cd1d3a459609 Mon Sep 17 00:00:00 2001
+From: Martin Liska <[email-masked]>
+Date: Fri, 15 Jun 2018 10:51:28 +0200
+Subject: [PATCH] Partial backport r256656
+
+2018-06-15  Martin Liska  <[email-masked]>
+
+	Backport from mainline
+	2018-01-10  Kelvin Nilsen  <[email-masked]>
+
+	* lex.c (search_line_fast): Remove illegal coercion of an
+	unaligned pointer value to vector pointer type and replace with
+	use of __builtin_vec_vsx_ld () built-in function, which operates
+	on unaligned pointer values.
+
+From-SVN: r261621
+---
+
+Obtained from:
+
+https://gcc.gnu.org/git/?p=gcc.git;a=patch;h=ee6c0081c03330045b3d4cde8421cd1d3a459609
+
+The libcpp/ChangeLog hunk was modified to apply on top of gcc-5's libcpp/ChangeLog.
+
+ libcpp/ChangeLog | 12 ++++++++++++
+ libcpp/lex.c     |  2 +-
+ 2 files changed, 13 insertions(+), 1 deletion(-)
+
+diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
+index c920a05d438..a63abb04f5e 100644
+--- a/libcpp/ChangeLog
++++ b/libcpp/ChangeLog
+@@ -1,3 +1,15 @@
++2018-06-15  Martin Liska  <[email-masked]>
++
++	PR bootstrap/86162
++
++	Backport from mainline
++	2018-01-10  Kelvin Nilsen  <[email-masked]>
++
++	* lex.c (search_line_fast): Remove illegal coercion of an
++	unaligned pointer value to vector pointer type and replace with
++	use of __builtin_vec_vsx_ld () built-in function, which operates
++	on unaligned pointer values.
++
+ 2017-10-10  Release Manager
+ 
+ 	* GCC 5.5.0 released.
+diff --git a/libcpp/lex.c b/libcpp/lex.c
+index e5a0397f309..b789686f1c4 100644
+--- a/libcpp/lex.c
++++ b/libcpp/lex.c
+@@ -568,7 +568,7 @@ search_line_fast (const uchar *s, const uchar *end ATTRIBUTE_UNUSED)
+     {
+       vc m_nl, m_cr, m_bs, m_qm;
+ 
+-      data = *((const vc *)s);
++      data = __builtin_vec_vsx_ld (0, s);
+       s += 16;
+ 
+       m_nl = (vc) __builtin_vec_cmpeq(data, repl_nl);
+-- 
+2.27.0
+