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[PATCH v2] configure.ac: add detection of symver gcc attribute
From: |
Giulio Benetti |
Subject: |
[PATCH v2] configure.ac: add detection of symver gcc attribute |
Date: |
Sun, 18 Feb 2024 00:50:06 +0100 |
From: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
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
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
[Giulio: rework #if nesting]
Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
---
V1->V2:
* rework syscalls #if nesting as suggested by Andreas Grünbacher
---
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