Re: [PATCH] Use more gcc extensions in the Linux headers

From: Rusty Russell
Date: Fri Mar 09 2007 - 17:58:45 EST


On Fri, 2007-03-09 at 16:56 +1100, Rusty Russell wrote:
> __builtin_types_compatible_p() has been around since gcc 2.95, and we
> don't use it anywhere. This patch quietly fixes that.

OK, many people complained that it needed a comment. Good point!
==
Add comment to ARRAY_SIZE macro.

Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

diff -r 933e410f204f include/linux/kernel.h
--- a/include/linux/kernel.h Sat Mar 10 09:55:31 2007 +1100
+++ b/include/linux/kernel.h Sat Mar 10 09:55:53 2007 +1100
@@ -35,6 +35,7 @@ extern const char linux_proc_banner[];
#define ALIGN(x,a) __ALIGN_MASK(x,(typeof(x))(a)-1)
#define __ALIGN_MASK(x,mask) (((x)+(mask))&~(mask))

+/* GCC is awesome. */
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) \
+ sizeof(typeof(int[1 - 2*!!__builtin_types_compatible_p(typeof(arr), \
typeof(&arr[0]))]))*0)



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