Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932680AbbESNhs (ORCPT ); Tue, 19 May 2015 09:37:48 -0400 Received: from terminus.zytor.com ([198.137.202.10]:37056 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932634AbbESNhn (ORCPT ); Tue, 19 May 2015 09:37:43 -0400 Date: Tue, 19 May 2015 06:37:06 -0700 From: tip-bot for Nicholas Mc Guire Message-ID: Cc: tglx@linutronix.de, ahh@google.com, hofrat@osadl.org, linux-kernel@vger.kernel.org, pjt@google.com, hpa@zytor.com, mingo@kernel.org, yamada.m@jp.panasonic.com, joe@perches.com, mmarek@suse.cz, sam@ravnborg.org, john.stultz@linaro.org Reply-To: tglx@linutronix.de, ahh@google.com, pjt@google.com, hpa@zytor.com, hofrat@osadl.org, linux-kernel@vger.kernel.org, joe@perches.com, sam@ravnborg.org, mmarek@suse.cz, mingo@kernel.org, yamada.m@jp.panasonic.com, john.stultz@linaro.org In-Reply-To: <1431951554-5563-3-git-send-email-hofrat@osadl.org> References: <1431951554-5563-3-git-send-email-hofrat@osadl.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:timers/core] time: Allow gcc to fold constants when possible Git-Commit-ID: daa67b4b70568a07fef3cffacb2055891bf42ddb X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2634 Lines: 65 Commit-ID: daa67b4b70568a07fef3cffacb2055891bf42ddb Gitweb: http://git.kernel.org/tip/daa67b4b70568a07fef3cffacb2055891bf42ddb Author: Nicholas Mc Guire AuthorDate: Mon, 18 May 2015 14:19:14 +0200 Committer: Thomas Gleixner CommitDate: Tue, 19 May 2015 15:14:16 +0200 time: Allow gcc to fold constants when possible To allow constant folding in msecs_to_jiffies() conditionally calls the HZ dependent _msecs_to_jiffies() helpers or, when gcc can not figure out constant folding, __msecs_to_jiffies which is the renamed original msecs_to_jiffies() function. Signed-off-by: Nicholas Mc Guire Cc: Masahiro Yamada Cc: Sam Ravnborg Cc: Joe Perches Cc: John Stultz Cc: Andrew Hunter Cc: Paul Turner Cc: Michal Marek Link: http://lkml.kernel.org/r/1431951554-5563-3-git-send-email-hofrat@osadl.org Signed-off-by: Thomas Gleixner --- include/linux/jiffies.h | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h index 9527ddb..5e75af6 100644 --- a/include/linux/jiffies.h +++ b/include/linux/jiffies.h @@ -343,12 +343,24 @@ static inline unsigned long _msecs_to_jiffies(const unsigned int m) * handling any 32-bit overflows. * for the details see __msecs_to_jiffies() * - * the HZ range specific helpers _msecs_to_jiffies() are called from - * __msecs_to_jiffies(). + * msecs_to_jiffies() checks for the passed in value being a constant + * via __builtin_constant_p() allowing gcc to eliminate most of the + * code, __msecs_to_jiffies() is called if the value passed does not + * allow constant folding and the actual conversion must be done at + * runtime. + * the HZ range specific helpers _msecs_to_jiffies() are called both + * directly here and from __msecs_to_jiffies() in the case where + * constant folding is not possible. */ static inline unsigned long msecs_to_jiffies(const unsigned int m) { - return __msecs_to_jiffies(m); + if (__builtin_constant_p(m)) { + if ((int)m < 0) + return MAX_JIFFY_OFFSET; + return _msecs_to_jiffies(m); + } else { + return __msecs_to_jiffies(m); + } } extern unsigned long usecs_to_jiffies(const unsigned int u); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/