From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762251AbXJYUqR (ORCPT ); Thu, 25 Oct 2007 16:46:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753124AbXJYUqE (ORCPT ); Thu, 25 Oct 2007 16:46:04 -0400 Received: from mailout.stusta.mhn.de ([141.84.69.5]:55700 "EHLO mailhub.stusta.mhn.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752948AbXJYUqB (ORCPT ); Thu, 25 Oct 2007 16:46:01 -0400 Date: Thu, 25 Oct 2007 22:46:31 +0200 From: Adrian Bunk To: Mike Frysinger Cc: "H. Peter Anvin" , Jie Zhang , bryan.wu@analog.com, linux-kernel@vger.kernel.org Subject: Re: [2.6 patch] blackfin: "extern inline" -> "static inline" Message-ID: <20071025204630.GV30533@stusta.de> References: <20071024162643.GP30533@stusta.de> <40401db90710241947i15e40e78v292e52f5229d9d35@mail.gmail.com> <8bd0f97a0710242000h7b6c97e7ia3f461c69b7d5de5@mail.gmail.com> <47200826.1060801@zytor.com> <20071025150545.GK30533@stusta.de> <8bd0f97a0710250916v5d3f0166qbfacf4abb0fc3d45@mail.gmail.com> <20071025165344.GL30533@stusta.de> <8bd0f97a0710251307m9f45f4dmf6d8cfa93af9fdf5@mail.gmail.com> <20071025201842.GT30533@stusta.de> <8bd0f97a0710251320m3490c53dpe85656a939e8536e@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8bd0f97a0710251320m3490c53dpe85656a939e8536e@mail.gmail.com> User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 25, 2007 at 04:20:20PM -0400, Mike Frysinger wrote: > On 10/25/07, Adrian Bunk wrote: > > On Thu, Oct 25, 2007 at 04:07:45PM -0400, Mike Frysinger wrote: > > > On 10/25/07, Adrian Bunk wrote: > > > > On Thu, Oct 25, 2007 at 12:16:40PM -0400, Mike Frysinger wrote: > > > > > On 10/25/07, Adrian Bunk wrote: > > > > > > On Wed, Oct 24, 2007 at 08:06:14PM -0700, H. Peter Anvin wrote: > > > > > > > Mike Frysinger wrote: > > > > > > >> we'll have to either use the gcc attributes to force old inline > > > > > > >> behavior or use the gcc flag to force it > > > > > > > > > > > > > > We should probably have an extern_inline define then, assuming this is a > > > > > > > function that does exist in a linkable version already -- otherwise "static > > > > > > > inline" is correct. > > > > > > > > > > > > Since we #define inline to be __attribute__((always_inline)) > > > > > > "extern inline" with the old semantics would only behave differently > > > > > > if someone took the address of one of these string functions. > > > > > > > > > > that isnt what we intended ;) > > > > > > > > > > > Does this happen anywhere in the blackfin port? > > > > > > > > > > gcc is also free to ignore the optimized inline in favor of an > > > > > external reference > > > > > > > > It is not since we #define inline to be __attribute__((always_inline)). > > > > > > as i said, that was not what we intended ... and actually, > > > always_inline does not mean always inline ... it is still possible to > > > get gcc to not inline things when building debug versions. > > > > Do you have any example for your claim "to get gcc to not inline things > > when building debug versions"? > > $ cat test.c > __attribute__((always_inline)) int foo(void) { return 0; } > int main(void){ return foo(); } > $ gcc -g test.c -o test > $ readelf -s test | grep FUNC | grep -v _ > 61: 00000000004004b8 11 FUNC GLOBAL DEFAULT 13 foo > 68: 00000000004004c3 11 FUNC GLOBAL DEFAULT 13 main > > looks pretty straightforward to me That a function gets emitted for a non-static inline function is expected (and unrelated to the static inline cases). But if you replace "__attribute__((always_inline))" with "inline __attribute__((always_inline))" as we do in the kernel, foo() is no longer called from main(). And if you make it "static inline __attribute__((always_inline))" (which is what "static inline" in the kernel expands to), there's no longer a function "foo" in the binary. > -mike cu Adrian -- "Is there not promise of rain?" Ling Tan asked suddenly out of the darkness. There had been need of rain for many days. "Only a promise," Lao Er said. Pearl S. Buck - Dragon Seed