compiler-gcc.h: Add gcc-recommended GCC_VERSION macro

Throughout compiler*.h, many version checks are made.  These can be
simplified by using the macro that gcc's documentation recommends.
However, my primary reason for adding this is that I need bug-check
macros that are enabled at certain gcc versions and it's cleaner to use
this macro than the tradition method:

  #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ => 2)

If you add patch level, it gets this ugly:

  #if __GNUC__ > 4 || (__GNUC__ == 4 && (__GNUC_MINOR__ > 2 || \
      __GNUC_MINOR__ == 2 __GNUC_PATCHLEVEL__ >= 1))

As opposed to:

  #if GCC_VERSION >= 40201

While having separate headers for gcc 3 & 4 eliminates some of this
verbosity, they can still be cleaned up by this.

See also:

  http://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html

Signed-off-by: Daniel Santos <[email protected]>
Acked-by: Borislav Petkov <[email protected]>
Acked-by: David Rientjes <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Josh Triplett <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 6a6d7aefe12d6e61cae9e44b13aea1ed74ebedda..24545cd90a252b8dea0a9eec462b97a03b86adaa 100644 (file)
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -5,6 +5,9 @@
 /*
  * Common definitions for all gcc versions go here.
  */
+#define GCC_VERSION (__GNUC__ * 10000 \
+                  + __GNUC_MINOR__ * 100 \
+                  + __GNUC_PATCHLEVEL__)
 
 
 /* Optimization barrier */