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Improve check for a function attribute support.

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The compiler may advertise function attribute support
with __has_attribute operator even though it does
not implement the feature on some architecture.

This fixes the issue with  GCC 11 on ppc64le with
__attribute__((zero_call_used_regs("used"))).

Fixes: #959.
This commit is contained in:
Ondrej Kozina
2025-09-11 11:30:25 +02:00
parent 2b9523a1ef
commit 3a8feb8be7
3 changed files with 37 additions and 3 deletions
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21
configure.ac
View File

@@ -680,6 +680,27 @@ AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
])
CFLAGS=$saved_CFLAGS
dnl Force compiler to use zero_call_used_regs("used") to check for the function attribute support.
dnl Otherwise the compiler may falsely advertise it with __has_attribute operator, even though
dnl it does not implement it on some archs.
AC_MSG_CHECKING([for zero_call_used_regs(user)])
saved_CFLAGS=$CFLAGS
CFLAGS="-O0 -Werror"
AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
void _test_function(void);
__attribute__((zero_call_used_regs("used"))) void _test_function(void) {
volatile int *i; volatile int j = 0; if (j) *i = 0;
}
]],
[[ _test_function() ]]
)],[
AC_DEFINE([HAVE_ATTRIBUTE_ZEROCALLUSEDREGS], 1, [Define to 1 to use __attribute__((zero_call_used_regs("used")))])
AC_MSG_RESULT([yes])
], [
AC_MSG_RESULT([no])
])
CFLAGS=$saved_CFLAGS
AC_MSG_CHECKING([for systemd tmpfiles config directory])
if test "x$prefix" != "xNONE"; then
saved_PKG_CONFIG=$PKG_CONFIG

4
lib/crypto_backend/memutils.c
View File

@@ -9,11 +9,9 @@
#define ATTR_NOINLINE __attribute__ ((noinline))
#define ATTR_ZERO_REGS
#if defined __has_attribute
# if __has_attribute (zero_call_used_regs)
#if HAVE_ATTRIBUTE_ZEROCALLUSEDREGS
# undef ATTR_ZERO_REGS
# define ATTR_ZERO_REGS __attribute__ ((zero_call_used_regs("used")))
# endif
#endif
/* Workaround for https://github.com/google/sanitizers/issues/1507 */

15
meson.build
View File

@@ -697,6 +697,21 @@ if cc.links(
description: 'Define to 1 to use __attribute__((symver))')
endif
# ==========================================================================
# Check compiler support for zero_called_used_regs("used") function attribute
if cc.links(
'''void _test_fn(void);
__attribute__((zero_call_used_regs("used"))) void _test_fn(void) {
volatile int *i; volatile int j = 0; if (j) *i = 0;
}
int main(void) { _test_fn(); return 0; }''',
args: ['-O0', '-Werror' ],
name: 'for zero_call_used_regs("used") attribute support')
conf.set10('HAVE_ATTRIBUTE_ZEROCALLUSEDREGS', true,
description: 'Define to 1 to use __attribute__((zero_call_used_regs("used")))')
endif
# ==========================================================================
if get_option('dev-random')