From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4CFE23DE.8050906@domain.hid> Date: Tue, 07 Dec 2010 13:09:02 +0100 From: Gilles Chanteperdrix MIME-Version: 1.0 References: <4CFE1E35.3020603@domain.hid> <4CFE1FA4.2030501@domain.hid> <4CFE217A.1010609@domain.hid> In-Reply-To: <4CFE217A.1010609@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 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) > But us I said, in the working version, the code seems to be inlined > everywhere. Should I send the two object modules as well (probably as a > private message?). The code should work the same whatever gcc decides regarding inlining. Whether we like gcc decision is a different issue. Note that there is an option to get gcc to go back to the old behaviour (inlining as the source command). -- Gilles.