X-Git-Url: https://git.karo-electronics.de/?a=blobdiff_plain;f=include%2Flinux%2Fcompiler-gcc.h;h=22ab246feed34c104038d3f94e1401ea9a587f8f;hb=ccf27814a63fc122dc5980453a18847dc5d8429f;hp=8efb40e61d6e48021d68f93635eea8d3ab3e8c0b;hpb=c2a75885ff15c6ed1bc6e6b0652f4107ced671ff;p=karo-tx-linux.git

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 8efb40e61d6e..22ab246feed3 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -205,11 +205,31 @@
 
 #if GCC_VERSION >= 40600
 /*
- * Tell the optimizer that something else uses this function or variable.
+ * When used with Link Time Optimization, gcc can optimize away C functions or
+ * variables which are referenced only from assembly code.  __visible tells the
+ * optimizer that something else uses this function or variable, thus preventing
+ * this.
  */
 #define __visible	__attribute__((externally_visible))
 #endif
 
+
+#if GCC_VERSION >= 40900 && !defined(__CHECKER__)
+/*
+ * __assume_aligned(n, k): Tell the optimizer that the returned
+ * pointer can be assumed to be k modulo n. The second argument is
+ * optional (default 0), so we use a variadic macro to make the
+ * shorthand.
+ *
+ * Beware: Do not apply this to functions which may return
+ * ERR_PTRs. Also, it is probably unwise to apply it to functions
+ * returning extra information in the low bits (but in that case the
+ * compiler should see some alignment anyway, when the return value is
+ * massaged by 'flags = ptr & 3; ptr &= ~3;').
+ */
+#define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
+#endif
+
 /*
  * GCC 'asm goto' miscompiles certain code sequences:
  *