Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 20 Mar 2002 12:43:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 20 Mar 2002 12:42:56 -0500 Received: from ep09.kernel.pl ([212.87.11.162]:42128 "EHLO ep09.kernel.pl") by vger.kernel.org with ESMTP id ; Wed, 20 Mar 2002 12:42:42 -0500 Date: Wed, 20 Mar 2002 18:42:38 +0100 From: Michal Moskal To: linux-kernel@vger.kernel.org Subject: [PATCH] gcc-3.1 ffs problem, kernel 2.4.18 Message-ID: <20020320174238.GA13533@ep09.kernel.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.3.27i X-AntiVirus: scanned for viruses by AMaViS 0.2.1 (http://amavis.org/) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Following patch is needed to compile linux-2.4.18 with xfs patch with recent gcc 3.1 snapshot. It is clearly bug in linux includes (they use asm code unconditionally, even on constants, and they can get constants if exposed to tree-inliner). Other asm includes might need fixing too, I saw asm-cris is fixed already. Beside this linux-2.4.18 compiled with gcc-3.1 20020311 works fine for me. diff -ur linux-/include/asm-i386/bitops.h linux/include/asm-i386/bitops.h --- linux-/include/asm-i386/bitops.h Thu Nov 22 20:46:18 2001 +++ linux/include/asm-i386/bitops.h Tue Mar 5 21:08:15 2002 @@ -316,6 +316,8 @@ return (offset + set + res); } +#include + /** * ffz - find first zero in word. * @word: The word to search @@ -324,10 +326,16 @@ */ static __inline__ unsigned long ffz(unsigned long word) { - __asm__("bsfl %1,%0" - :"=r" (word) - :"r" (~word)); - return word; + /* The generic_ffs function is used to avoid the asm when the + argument is a constant. */ + if (__builtin_constant_p (word)) { + return (~word ? (unsigned long) generic_ffs ((int) ~word) - 1 : 32); + } else { + __asm__("bsfl %1,%0" + :"=r" (word) + :"r" (~word)); + return word; + } } #ifdef __KERNEL__ @@ -342,13 +350,19 @@ */ static __inline__ int ffs(int x) { - int r; - - __asm__("bsfl %1,%0\n\t" - "jnz 1f\n\t" - "movl $-1,%0\n" - "1:" : "=r" (r) : "g" (x)); - return r+1; + /* The generic_ffs function is used to avoid the asm when the + argument is a constant. */ + if (__builtin_constant_p (x)) { + return generic_ffs (x); + } else { + int r; + + __asm__("bsfl %1,%0\n\t" + "jnz 1f\n\t" + "movl $-1,%0\n" + "1:" : "=r" (r) : "g" (x)); + return r+1; + } } /** -- : Michal Moskal :::::::: malekith/at/pld.org.pl : GCS {C,UL}++++$ a? !tv : PLD Linux ::::::: Wroclaw University, CS Dept : {E-,w}-- {b++,e}>+++ h - 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/