[PATCH 3.8 18/81] compiler-gcc.h: Add gcc-recommended GCC_VERSION macro

[Kamal Mostafa]

3.8.13.12 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel Santos <daniel.santos@xxxxxxxxx>

commit 3f3f8d2f48acfd8ed3b8e6b7377935da57b27b16 upstream.

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 <daniel.santos@xxxxxxxxx>
Acked-by: Borislav Petkov <bp@xxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Joe Perches <joe@xxxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
[ kamal: 3.8-stable prereq for
  3f0116c "compiler/gcc4: Add quirk for 'asm goto' miscompilation bug" ]
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
 include/linux/compiler-gcc.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 6a6d7ae..24545cd 100644
--- 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 */
-- 
1.8.1.2

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