Make ARCH_HAS_FAST_MULTIPLIER a real config variable

It used to be an ad-hoc hack defined by the x86 version of
<asm/bitops.h> that enabled a couple of library routines to know whether
an integer multiply is faster than repeated shifts and additions.

This just makes it use the real Kconfig system instead, and makes x86
(which was the only architecture that did this) select the option.

NOTE! Even for x86, this really is kind of wrong.  If we cared, we would
probably not enable this for builds optimized for netburst (P4), where
shifts-and-adds are generally faster than multiplies.  This patch does
*not* change that kind of logic, though, it is purely a syntactic change
with no code changes.

This was triggered by the fact that we have other places that really
want to know "do I want to expand multiples by constants by hand or
not", particularly the hash generation code.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 1 insertions, 2 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 778178f4c7d1..36327438caf0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -23,6 +23,7 @@ config X86
         def_bool y
         select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
         select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS
+        select ARCH_HAS_FAST_MULTIPLIER
         select ARCH_MIGHT_HAVE_PC_PARPORT
         select ARCH_MIGHT_HAVE_PC_SERIO
         select HAVE_AOUT if X86_32
diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h
index afcd35d331de..cfe3b954d5e4 100644
--- a/arch/x86/include/asm/bitops.h
+++ b/arch/x86/include/asm/bitops.h
@@ -497,8 +497,6 @@ static __always_inline int fls64(__u64 x)
 
 #include <asm-generic/bitops/sched.h>
 
-#define ARCH_HAS_FAST_MULTIPLIER 1
-
 #include <asm/arch_hweight.h>
 
 #include <asm-generic/bitops/const_hweight.h>