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- From 365426c28f8bf73d34d77cc06b7d5ffeae17f13a Mon Sep 17 00:00:00 2001
- From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
- Date: Tue, 6 Feb 2024 15:33:15 +0100
- Subject: [PATCH] configure.ac: add detection of symver gcc attribute
- On non-ELF platforms, such as microblaze, builds will fail when trying
- to add symver information because __attribute__((symver ..)) is not
- supported even though __has_attribute(__symver__) returns true.
- Support for symver needs to be detected via a compile test since
- __has_attribute can report false positives [0].
- Add a configure compile check for __attribute__((symver ..)) to ensure
- it is supported and define a variable to advertise support.
- [0] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101766#c1
- Upstream: https://git.savannah.nongnu.org/cgit/attr.git/commit/?id=943c776089dbb24ebbfb7432ba9841f1845bf95a
- Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
- [Giulio: rework local patch for #if nesting]
- Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
- ---
- configure.ac | 15 +++++++++++++++
- libattr/syscalls.c | 8 ++++----
- 2 files changed, 19 insertions(+), 4 deletions(-)
- diff --git a/configure.ac b/configure.ac
- index 7e362e9..98477b5 100644
- --- a/configure.ac
- +++ b/configure.ac
- @@ -57,6 +57,21 @@ AS_CASE([$host_os],
- [linux*], [os_linux=yes])
- AM_CONDITIONAL([OS_LINUX], [test "x$os_linux" = "xyes"])
-
- +AC_CACHE_CHECK(whether __attribute__((__symver__())) is supported,
- + gcc_cv_symver_attribute,
- + [cat > conftest.c <<EOF
- +void foo (void) {}
- +__typeof(foo) foo __attribute__ ((__symver__("foo@foo")));
- +EOF
- + gcc_cv_symver_attribute=no
- + if ${CC-cc} -Werror -S conftest.c -o conftest.s >/dev/null 2>&1; then \
- + gcc_cv_symver_attribute=yes
- + fi
- + rm -f conftest.[cs]
- +])
- +AS_IF([test $gcc_cv_symver_attribute = yes],
- + [AC_DEFINE(HAVE_SYMVER_ATTRIBUTE, [], [GCC supports symver attribute])])
- +
- AC_CONFIG_COMMANDS([include/attr],
- [dnl
- rm -rf include/attr
- diff --git a/libattr/syscalls.c b/libattr/syscalls.c
- index 907560a..7ee6d39 100644
- --- a/libattr/syscalls.c
- +++ b/libattr/syscalls.c
- @@ -31,10 +31,10 @@
- * prefer symver attribute if available (since gcc 10),
- * fall back to traditional .symver asm directive otherwise.
- */
- -#ifdef __has_attribute
- -# if __has_attribute(__symver__)
- -# define SYMVER(cn, vn) __typeof(cn) cn __attribute__((__symver__(vn)))
- -# elif __has_attribute(__no_reorder__)
- +#if defined(HAVE_SYMVER_ATTRIBUTE)
- +# define SYMVER(cn, vn) __typeof(cn) cn __attribute__((__symver__(vn)))
- +#elif defined(__has_attribute)
- +# if __has_attribute(__no_reorder__)
- /*
- * Avoid wrong partitioning with older gcc and LTO. May not work reliably
- * with all versions; use -flto-partition=none if you encounter problems.
- --
- 2.34.1
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