[OE-core] [PATCH 2/2] gcc: fix miscompilation on mips64

[Khem Raj]

On Fri, Oct 27, 2017 at 2:43 AM, Chen Qi <Qi.Chen at windriver.com> wrote:
> We've observed strange behaviour of `systemctl status <xxx> on qemumips64.
> The output of the command is like `systemctl show <xxx>', which is incorrect.
>
> This patch is from gcc bugzilla's attachment.
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81803
>
> The patch hasn't been merged into gcc. But it does solve the above problem.
>

This looks ok. Can you help by providing your testing results to gcc bugzilla
so the patch can then be submitted to gcc ml.

> Signed-off-by: Chen Qi <Qi.Chen at windriver.com>
> ---
>  meta/recipes-devtools/gcc/gcc-7.2.inc              |  1 +
>  .../fix-miscompilation-for-O1-on-mips64el.patch    | 35 ++++++++++++++++++++++
>  2 files changed, 36 insertions(+)
>  create mode 100644 meta/recipes-devtools/gcc/gcc-7.2/fix-miscompilation-for-O1-on-mips64el.patch
>
> diff --git a/meta/recipes-devtools/gcc/gcc-7.2.inc b/meta/recipes-devtools/gcc/gcc-7.2.inc
> index 5883bc6..04edad7 100644
> --- a/meta/recipes-devtools/gcc/gcc-7.2.inc
> +++ b/meta/recipes-devtools/gcc/gcc-7.2.inc
> @@ -75,6 +75,7 @@ SRC_URI = "\
>             file://0048-gcc-Enable-static-PIE.patch \
>             file://fix-segmentation-fault-precompiled-hdr.patch \
>             file://0050-RISC-V-Handle-non-legitimate-address-in-riscv_legiti.patch \
> +           file://fix-miscompilation-for-O1-on-mips64el.patch \
>             ${BACKPORTS} \
>  "
>  BACKPORTS = "\
> diff --git a/meta/recipes-devtools/gcc/gcc-7.2/fix-miscompilation-for-O1-on-mips64el.patch b/meta/recipes-devtools/gcc/gcc-7.2/fix-miscompilation-for-O1-on-mips64el.patch
> new file mode 100644
> index 0000000..28020b0
> --- /dev/null
> +++ b/meta/recipes-devtools/gcc/gcc-7.2/fix-miscompilation-for-O1-on-mips64el.patch
> @@ -0,0 +1,35 @@
> +This patch comes from https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81803
> +
> +Author: mpf <mpf at 138bc75d-0d04-0410-961f-82ee72b054a4>
> +
> +This patch hasn't been merged into gcc. But it does solve the problem of
> +strange behaviour of `systemd status <xxx>' on qemumips64.
> +
> +Upstream-Status: Pending [Taken from gcc bugzilla's attachment]
> +
> +Signed-off-by: Chen Qi <Qi.Chen at windriver.com>
> +---
> + gcc/lra-constraints.c | 7 ++++++-
> + 1 file changed, 6 insertions(+), 1 deletion(-)
> +
> +diff --git a/gcc/lra-constraints.c b/gcc/lra-constraints.c
> +index c8bc9b9a66f..6d319662b09 100644
> +--- a/gcc/lra-constraints.c
> ++++ b/gcc/lra-constraints.c
> +@@ -4235,7 +4235,12 @@ 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))))
> ++                    || (type != OP_IN
> ++                        && 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
> +
> --
> 1.9.1
>
> --
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