gcc: backport patch to fix miscompilation on mips64

Backport a patch to fix miscompilation on mips64.

We've observed strange behaviour of `systemctl status <xxx> on qemumips64.
The output of the command is like `systemctl show <xxx>', which is incorrect.

The problem is due to the miscompilation of gcc for mips64 platform, thus
backporting patch from upstream to fix this problem.

[YOCTO #12266]

(From OE-Core rev: 6264b4afe6962d37eeb918e062568dee811ef231)

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
(cherry picked from commit cfa13e5c756849820644d86d1882602649db6a9c)
Signed-off-by: Armin Kuster <akuster@mvista.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 53 insertions, 0 deletions

diff --git a/meta/recipes-devtools/gcc/gcc-7.2.inc b/meta/recipes-devtools/gcc/gcc-7.2.inc
index a2cb288ba0..1d40cba731 100644
--- a/meta/recipes-devtools/gcc/gcc-7.2.inc
+++ b/meta/recipes-devtools/gcc/gcc-7.2.inc
@@ -79,6 +79,7 @@ SRC_URI = "\
 "
 BACKPORTS = "\
            file://0051-ARM-PR-82445-suppress-32-bit-aligned-ldrd-strd-peeph.patch \
+           file://0001-PR-rtl-optimization-81803.patch \
 "
 SRC_URI[md5sum] = "ff370482573133a7fcdd96cd2f552292"
 SRC_URI[sha256sum] = "1cf7adf8ff4b5aa49041c8734bbcf1ad18cc4c94d0029aae0f4e48841088479a"
diff --git a/meta/recipes-devtools/gcc/gcc-7.2/0001-PR-rtl-optimization-81803.patch b/meta/recipes-devtools/gcc/gcc-7.2/0001-PR-rtl-optimization-81803.patch
new file mode 100644
index 0000000000..292e734a2f
--- /dev/null
+++ b/meta/recipes-devtools/gcc/gcc-7.2/0001-PR-rtl-optimization-81803.patch
@@ -0,0 +1,52 @@
+From 5cbb8e6b1122092b3eaabd4270b2f316aa40407c Mon Sep 17 00:00:00 2001
+From: ebotcazou <ebotcazou@138bc75d-0d04-0410-961f-82ee72b054a4>
+Date: Tue, 31 Oct 2017 18:27:52 +0000
+Subject: [PATCH]        PR rtl-optimization/81803       * lra-constraints.c
+ (curr_insn_transform): Also reload the whole   register for a strict subreg
+ no wider than a word if this is for    a WORD_REGISTER_OPERATIONS target.
+
+git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@254275 138bc75d-0d04-0410-961f-82ee72b054a4
+
+Upstream-Status: Backport
+
+This patch removes changes to Changelog from the original patch upstream. This is
+because we are backporting a patch to a stable version, making changes to Changelog,
+especially up '* GCC 7.2.0 released.', feels a little weird.
+
+Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
+---
+ gcc/lra-constraints.c | 11 ++++++++---
+ 2 files changed, 16 insertions(+), 3 deletions(-)
+
+diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
+index a423f069836..3758409bb9c 100644
+--- a/gcc/lra-constraints.c
++++ b/gcc/lra-constraints.c
+@@ -4207,8 +4207,9 @@ curr_insn_transform (bool check_only_p)
+              reg = SUBREG_REG (*loc);
+              byte = SUBREG_BYTE (*loc);
+              if (REG_P (reg)
+-                 /* Strict_low_part requires reload the register not
+-                    the sub-register.  */
++                 /* Strict_low_part requires reloading the register and not
++                    just the subreg.  Likewise for a strict subreg no wider
++                    than a word for WORD_REGISTER_OPERATIONS targets.  */
+                  && (curr_static_id->operand[i].strict_low
+                      || (!paradoxical_subreg_p (mode, GET_MODE (reg))
+                          && (hard_regno
+@@ -4219,7 +4220,11 @@ curr_insn_transform (bool check_only_p)
+                          && (goal_alt[i] == NO_REGS
+                              || (simplify_subreg_regno
+                                  (ira_class_hard_regs[goal_alt[i]][0],
+-                                  GET_MODE (reg), byte, mode) >= 0)))))
++                                  GET_MODE (reg), byte, mode) >= 0)))
++                     || (GET_MODE_PRECISION (mode)
++                         < GET_MODE_PRECISION (GET_MODE (reg))
++                         && GET_MODE_SIZE (GET_MODE (reg)) <= UNITS_PER_WORD
++                         && WORD_REGISTER_OPERATIONS)))
+                {
+                  /* An OP_INOUT is required when reloading a subreg of a
+                     mode wider than a word to ensure that data beyond the
+-- 
+2.13.0
+