tree 60b2c21a71a97cc4be249e985443769e5fdbd3ca
parent f6b2bc847641ea38e2655c8424fef5d2d19f35f9
author Sebastian Andrzej Siewior <bigeasy@linutronix.de> 1322649814 +0100
committer Ingo Molnar <mingo@elte.hu> 1323105371 +0100

x86/div64: Add a micro-optimization shortcut if base is power of two

In the target code I have a do_div(x, PAGE_SIZE). The x86-64
version of it was doing a shift and a mask which is clever. The
32bit version of it had a div operation in it which made me
think. After digging I noticed that x86 has an optimized version
of it. This patch adds this shift and mask optimization if base
is constant so we don't have any runtime "checking" overhead
since most users use a power of ten.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1322649814-544-1-git-send-email-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@elte.hu>