Replace __attribute_pure__ with __pure

To be consistent with the use of attributes in the rest of the kernel
replace all use of __attribute_pure__ with __pure and delete the definition
of __attribute_pure__.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Acked-by: Mauro Carvalho Chehab <mchehab@infradead.org>
Cc: Bryan Wu <bryan.wu@analog.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index acd5833..fe23792 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -36,10 +36,20 @@
 #define __weak				__attribute__((weak))
 #define __naked				__attribute__((naked))
 #define __noreturn			__attribute__((noreturn))
+
+/*
+ * From the GCC manual:
+ *
+ * Many functions have no effects except the return value and their
+ * return value depends only on the parameters and/or global
+ * variables.  Such a function can be subject to common subexpression
+ * elimination and loop optimization just as an arithmetic operator
+ * would be.
+ * [...]
+ */
 #define __pure				__attribute__((pure))
 #define __aligned(x)			__attribute__((aligned(x)))
 #define __printf(a,b)			__attribute__((format(printf,a,b)))
 #define  noinline			__attribute__((noinline))
-#define __attribute_pure__		__attribute__((pure))
 #define __attribute_const__		__attribute__((__const__))
 #define __maybe_unused			__attribute__((unused))