avr32: Work around byteswap bug in gcc < 4.2
gcc versions earlier than 4.2 sign-extends the result of le16_to_cpu()
and friends when we implement __arch__swabX() using
__builtin_bswap_X(). Disable our arch-specific optimizations when those
gcc versions are being used.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
diff --git a/include/asm-avr32/byteorder.h b/include/asm-avr32/byteorder.h
index 402ff41..d77b48b 100644
--- a/include/asm-avr32/byteorder.h
+++ b/include/asm-avr32/byteorder.h
@@ -12,8 +12,14 @@
extern unsigned short __builtin_bswap_16(unsigned short x);
#endif
+/*
+ * avr32-linux-gcc versions earlier than 4.2 improperly sign-extends
+ * the result.
+ */
+#if !(__GNUC__ == 4 && __GNUC_MINOR__ < 2)
#define __arch__swab32(x) __builtin_bswap_32(x)
#define __arch__swab16(x) __builtin_bswap_16(x)
+#endif
#if !defined(__STRICT_ANSI__) || defined(__KERNEL__)
# define __BYTEORDER_HAS_U64__