From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4CFF46E0.6090705@domain.hid> Date: Wed, 08 Dec 2010 09:50:40 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <4CFE1E35.3020603@domain.hid> <4CFE1FA4.2030501@domain.hid> <4CFE217A.1010609@domain.hid> <4CFE23DE.8050906@domain.hid> <4CFE413C.30908@domain.hid> <4CFE9731.1000004@domain.hid> <4CFF34DE.3030603@domain.hid> In-Reply-To: <4CFF34DE.3030603@domain.hid> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Xenomai-core] Problem with gcc-4.5.1 List-Id: Xenomai life and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anders Blomdell Cc: "xenomai@xenomai.org" Anders Blomdell wrote: > On 2010-12-07 21.21, Gilles Chanteperdrix wrote: >> Anders Blomdell wrote: >>> On 12/07/2010 01:09 PM, Gilles Chanteperdrix wrote: >>> > Anders Blomdell wrote: >>> >> On 12/07/2010 12:51 PM, Gilles Chanteperdrix wrote: >>> >>> Anders Blomdell wrote: >>> >>>> When compiling Xenomai on Fedora-14 with gcc-4.5.1 [version 4.5.1 >>> >>>> 20100924 (Red Hat 4.5.1-4)], the loading of xeno_nucleus fails >>> with the >>> >>>> attached kernel OOPS, a notable difference between the 4.5.1 compiled >>> >>>> version and a working one built with gcc-4.4.4 on the same system with >>> >>>> the same configuration, sis tthat __rthal_x86_nodiv_ullimd is not >>> >>>> inlined, is this anybody has seen before? >>> >>> No, that is new, we need to see the disassembly of >>> __rthal_x86_nodiv_ullimd >>> >> >>> >> objdump -S: >>> >> >>> >> static inline __attribute__((const)) unsigned long long >>> >> __rthal_x86_nodiv_ullimd(const unsigned long long op, >>> >> const unsigned long long frac, >>> >> unsigned integ) >>> >> { >>> >> e7a8: 55 push %ebp >>> >> e7a9: 89 e5 mov %esp,%ebp >>> >> e7ab: 57 push %edi >>> >> e7ac: 56 push %esi >>> >> e7ad: 53 push %ebx >>> >> e7ae: 83 ec 10 sub $0x10,%esp >>> >> e7b1: 8d 7d 08 lea 0x8(%ebp),%edi >>> >> e7b4: e8 fc ff ff ff call >>> e7b5<__rthal_x86_nodiv_ullimd+0xd> >>> >> e7b9: 8b 1f mov (%edi),%ebx >>> >> e7bb: 8b 4f 04 mov 0x4(%edi),%ecx >>> >> register unsigned rm __asm__("esi"); >>> >> register unsigned rh __asm__("edi"); >>> >> unsigned fracl, frach, opl, oph; >>> >> register unsigned long long t; >>> >> >>> >> __rthal_u64tou32(op, oph, opl); >>> >> e7be: 89 45 e8 mov %eax,-0x18(%ebp) >>> >> __rthal_u64tou32(frac, frach, fracl); >>> >> e7c1: 89 5d f0 mov %ebx,-0x10(%ebp) >>> >> register unsigned rm __asm__("esi"); >>> >> register unsigned rh __asm__("edi"); >>> >> unsigned fracl, frach, opl, oph; >>> >> register unsigned long long t; >>> >> >>> >> __rthal_u64tou32(op, oph, opl); >>> >> e7c4: 89 55 e4 mov %edx,-0x1c(%ebp) >>> >> __rthal_u64tou32(frac, frach, fracl); >>> >> e7c7: 89 4d ec mov %ecx,-0x14(%ebp) >>> >> >>> >> __asm__ ("mov %[oph], %%eax\n\t" >>> >> e7ca: 8b 45 e4 mov -0x1c(%ebp),%eax >>> >> e7cd: f7 65 ec mull -0x14(%ebp) >>> >> e7d0: 89 c6 mov %eax,%esi >>> >> e7d2: 89 d7 mov %edx,%edi >>> >> e7d4: 8b 45 e8 mov -0x18(%ebp),%eax >>> >> e7d7: f7 65 f0 mull -0x10(%ebp) >>> >> e7da: 89 d1 mov %edx,%ecx >>> >> e7dc: d1 e0 shl %eax >>> >> e7de: 83 d1 00 adc $0x0,%ecx >>> >> e7e1: 83 d6 00 adc $0x0,%esi >>> >> e7e4: 83 d7 00 adc $0x0,%edi >>> >> e7e7: 8b 45 e4 mov -0x1c(%ebp),%eax >>> >> e7ea: f7 65 f0 mull -0x10(%ebp) >>> >> e7ed: 01 c1 add %eax,%ecx >>> >> e7ef: 11 d6 adc %edx,%esi >>> >> e7f1: 83 d7 00 adc $0x0,%edi >>> >> e7f4: 8b 45 e8 mov -0x18(%ebp),%eax >>> >> e7f7: f7 65 ec mull -0x14(%ebp) >>> >> e7fa: 01 c1 add %eax,%ecx >>> >> e7fc: 11 d6 adc %edx,%esi >>> >> e7fe: 83 d7 00 adc $0x0,%edi >>> >> e801: 8b 45 e8 mov -0x18(%ebp),%eax >>> >> e804: f7 67 08 mull 0x8(%edi) >>> > >>> > Problem is here: edi is used by gcc as if it contained an address >>> > whereas it is used by the assembly for the computation. Should be marked >>> > "early clobber". So, >>> > >>> > in include/asm-x86/arith_32.h, replace: >>> > >>> > : [rl]"=c"(rl), [rm]"=S"(rm), [rh]"=D"(rh), "=A"(t) >>> > >>> > with: >>> > >>> > : [rl]"=&c"(rl), [rm]"=&S"(rm), [rh]"=&D"(rh), "=&A"(t) >>> > >>> > >>> >>> No cigar (:-() >> Ok. Maybe we can try something less radical, such as: >> >> : [rl]"=c"(rl), [rm]"=S"(rm), [rh]"=&D"(rh), "=A"(t) >> >> This is incorrect, but we can hope for the best... > As previously said, changing the optimization from -Os to anything else for > xeno_nucleus (see patch in mail dated 'Tue, 07 Dec 2010 17:20:37 +0100'), solved > that issue (incorrect code + hope for the best -> spurious disasters). Rather > compile time errors than runtime errors. We are not going to decide instead of the user what optimization level to use, if he wants to use -Os, we have to make it work for -Os. If this one does not work, we have other things to try. -- Gilles.