summaryrefslogtreecommitdiff
path: root/libc
diff options
context:
space:
mode:
authorThomas Petazzoni <thomas.petazzoni@free-electrons.com>2016-03-20 16:58:35 (GMT)
committerWaldemar Brodkorb <wbx@openadk.org>2016-03-31 17:35:13 (GMT)
commitfeb9f08cfe8ddd1fd4fb62265e17ee35147ab268 (patch)
treeda452e5e8aa09cd6ef0c9d9d83033a8d4f3d623c /libc
parent4ab024d22980cf493dc95a089353df6ebc743f46 (diff)
arm: simplify handling of Thumb related options
Currently, the Thumb support on ARM has three related Config.in options, which are not trivial for users to understand, and are in fact not needed: - The USE_BX option is not needed: knowing whether BX is available or not is easy. If you have an ARM > v4 or ARMv4T, then BX is available, otherwise it's not. This is the logic used in glibc. - The USE_LDREXSTREX option is not needed: whenever Thumb2 is available, ldrex/strex are available, so we can simply rely on __thumb2__ to determine whether ldrex/strex should be used, without requiring a Config.in option. - Once USE_BX and USE_LDREXSTREX are removed, the only thing left that COMPILE_IN_THUMB does is to set -mthumb. This makes the option unnecessary, as on ARM at least, the user is already supposed to pass -march=<foo> or other compiler options tuning the library for a specific ARM variant. There is no reason to do otherwise for Thumb, which allows to get rid of the COMPILE_IN_THUMB option. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Diffstat (limited to 'libc')
-rw-r--r--libc/sysdeps/linux/arm/bits/arm_bx.h10
-rw-r--r--libc/sysdeps/linux/arm/clone.S2
2 files changed, 5 insertions, 7 deletions
diff --git a/libc/sysdeps/linux/arm/bits/arm_bx.h b/libc/sysdeps/linux/arm/bits/arm_bx.h
index 2c29089..1c775b6 100644
--- a/libc/sysdeps/linux/arm/bits/arm_bx.h
+++ b/libc/sysdeps/linux/arm/bits/arm_bx.h
@@ -23,13 +23,11 @@
#error Please include features.h first
#endif /* features.h not yet included */
-#if defined(__USE_BX__)
-# if (__ARM_ARCH <= 4 && !defined __ARM_ARCH_4T__)
-# error Use of BX was requested, but is not available on the target processor.
-# endif /* ARCH level */
-#endif /* __USE_BX__ */
+#if __ARM_ARCH > 4 || defined (__ARM_ARCH_4T__)
+# define ARCH_HAS_BX
+#endif
-#if defined(__USE_BX__) && (__ARM_ARCH > 4 || (__ARM_ARCH == 4 && defined __ARM_ARCH_4T__))
+#if defined(ARCH_HAS_BX)
# define BX(reg) bx reg
# define BXC(cond, reg) bx##cond reg
#else
diff --git a/libc/sysdeps/linux/arm/clone.S b/libc/sysdeps/linux/arm/clone.S
index b4c7d8a..fd7590d 100644
--- a/libc/sysdeps/linux/arm/clone.S
+++ b/libc/sysdeps/linux/arm/clone.S
@@ -69,7 +69,7 @@ __clone:
@ pick the function arg and call address off the stack and execute
ldr r0, [sp, #4]
-#if defined(__USE_BX__)
+#if defined(ARCH_HAS_BX)
ldr r1, [sp]
bl 2f @ blx r1
#else