toolchain: add BR2_TOOLCHAIN_SUPPORTS_ALWAYS_LOCKFREE_ATOMIC_INTS hidden option
Add BR2_TOOLCHAIN_SUPPORTS_ALWAYS_LOCKFREE_ATOMIC_INTS variable and
use it in BR2_TOOLCHAIN_HAS_GCC_BUG_64735.
This new variable will be used to select boost atomic when lock-free
atomic ints are not available
Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
diff --git a/toolchain/Config.in b/toolchain/Config.in
index 3a53a32..ad02af5 100644
--- a/toolchain/Config.in
+++ b/toolchain/Config.in
@@ -69,18 +69,35 @@
config BR2_TOOLCHAIN_HAS_BINUTILS_BUG_19615
bool
-# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64735
-# exception_ptr, nested_exception, and future from libstdc++ are not
-# available for architectures not supporting always lock-free atomic
-# ints before GCC 7
+# Atomic types can be:
+# - never lock-free
+# - sometimes lock-free
+# - always lock-free
+# see https://en.cppreference.com/w/c/atomic/ATOMIC_LOCK_FREE_consts
+#
+# On most architectures, gcc provides "always lock-free" atomic types,
+# but a few architectures are limited to "sometimes lock-free"
+# types. This hidden option allows to know if the architecture
+# provides "always lock-free" atomic types.
+config BR2_TOOLCHAIN_SUPPORTS_ALWAYS_LOCKFREE_ATOMIC_INTS
+ bool
+ default y
+ depends on !BR2_nios2
+ depends on !BR2_ARM_CPU_ARMV4
+ depends on !BR2_ARM_CPU_ARMV5
+ depends on !BR2_sparc_v8
+ depends on !BR2_m68k_cf5208
+
+# Prior to gcc 7.x, exception_ptr, nested_exception and future from
+# libstdc++ would only be provided on architectures that support
+# always lock-free atomic ints. See
+# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64735. This issue has
+# been removed in GCC 7.x, where exception propagation is now
+# supported without lock-free atomic int.
config BR2_TOOLCHAIN_HAS_GCC_BUG_64735
bool
- default y if BR2_nios2
- default y if BR2_ARM_CPU_ARMV4
- default y if BR2_ARM_CPU_ARMV5
- default y if BR2_sparc_v8
- default y if BR2_m68k_cf5208
- depends on !BR2_TOOLCHAIN_GCC_AT_LEAST_7
+ default y if !BR2_TOOLCHAIN_SUPPORTS_ALWAYS_LOCKFREE_ATOMIC_INTS && \
+ !BR2_TOOLCHAIN_GCC_AT_LEAST_7
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85180. This bug no
# longer exists in gcc 8.x.