Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754537AbdFWGp3 (ORCPT ); Fri, 23 Jun 2017 02:45:29 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:57740 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754417AbdFWGp2 (ORCPT ); Fri, 23 Jun 2017 02:45:28 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 22 Jun 2017 23:45:26 -0700 From: Sodagudi Prasad To: Mark Rutland Cc: David Rientjes , will.deacon@arm.com, catalin.marinas@arm.com, mingo@kernel.org, peterz@infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] compiler, clang: Add always_inline attribute to inline In-Reply-To: <20170622094333.GB25967@leverpostej> References: <20170615155440.GC26471@leverpostej> <1497887596-8731-1-git-send-email-psodagud@codeaurora.org> <47bd7df20466d5f7f557ca087b0189cf@codeaurora.org> <20170620105937.GD28157@leverpostej> <20170622094333.GB25967@leverpostej> Message-ID: User-Agent: Roundcube Webmail/1.2.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3836 Lines: 103 On 2017-06-22 02:43, Mark Rutland wrote: > On Tue, Jun 20, 2017 at 04:12:32PM -0700, David Rientjes wrote: >> On Tue, 20 Jun 2017, Mark Rutland wrote: >> >> > As with my reply to David, my preference would be that we: >> > >> > 1) Align compiler-clang.h with the compiler-gcc.h inlining behaviour, so >> > that things work by default. >> > >> > 2) Fix up the arm64 core code (and drivers for architected / common >> > peripherals) to use __always_inline where we always require inlining. >> > >> > 3) Have arm64 select CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING, and have >> > people test-build configurations with CONFIG_OPTIMIZE_INLINING, with >> > both GCC and clang. >> > >> > 4) Fix up drivers, etc, as appropriate. >> > >> > 5) Once that's largely stable, and if there's a benefit, have arm64 >> > select CONFIG_OPTIMIZE_INLINING by default. >> > >> > That should avoid undue breakage, while enabling this ASAP. >> > >> >> Sounds good, but I think we should simply deal with the >> __attribute__((unused)) needed for clang as part of compiler-gcc.h by >> simply adding it to the inline override there to avoid duplicated >> code. > > Agreed. That looks much better. > > Thanks, > Mark. > >> >> diff --git a/include/linux/compiler-clang.h >> b/include/linux/compiler-clang.h >> --- a/include/linux/compiler-clang.h >> +++ b/include/linux/compiler-clang.h >> @@ -15,11 +15,3 @@ >> * with any version that can compile the kernel >> */ >> #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), >> __COUNTER__) >> - >> -/* >> - * GCC does not warn about unused static inline functions for >> - * -Wunused-function. This turns out to avoid the need for complex >> #ifdef >> - * directives. Suppress the warning in clang as well. >> - */ >> -#undef inline >> -#define inline inline __attribute__((unused)) notrace >> diff --git a/include/linux/compiler-gcc.h >> b/include/linux/compiler-gcc.h >> index 0efef9cf014f..71fe0994cf1a 100644 >> --- a/include/linux/compiler-gcc.h >> +++ b/include/linux/compiler-gcc.h >> @@ -66,18 +66,22 @@ >> >> /* >> * Force always-inline if the user requests it so via the .config, >> - * or if gcc is too old: >> + * or if gcc is too old. >> + * GCC does not warn about unused static inline functions for >> + * -Wunused-function. This turns out to avoid the need for complex >> #ifdef >> + * directives. Suppress the warning in clang as well by using >> "unused" >> + * function attribute, which is redundant but not harmful for gcc. >> */ >> #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ >> !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) >> -#define inline inline __attribute__((always_inline)) notrace >> -#define __inline__ __inline__ __attribute__((always_inline)) notrace >> -#define __inline __inline __attribute__((always_inline)) notrace >> +#define inline inline __attribute__((always_inline,unused)) notrace >> +#define __inline__ __inline__ __attribute__((always_inline,unused)) >> notrace >> +#define __inline __inline __attribute__((always_inline,unused)) >> notrace >> #else >> /* A lot of inline functions can cause havoc with function tracing */ >> -#define inline inline notrace >> -#define __inline__ __inline__ notrace >> -#define __inline __inline notrace >> +#define inline inline __attribute__((unused)) notrace >> +#define __inline__ __inline__ __attribute__((unused)) notrace >> +#define __inline __inline __attribute__((unused)) notrace >> #endif >> >> #define __always_inline inline __attribute__((always_inline)) Hi David, I just want to cross check with you. Do you want me to update this change in next patch set ? Or are you going to add this ? -Thanks, Prasad -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, Linux Foundation Collaborative Project