[ Reported to the Debian BTS as report #85468, #169004 Please CC 85468@bugs.debian.org on replies. Log of report can be found at http://bugs.debian.org/85468 for alpha http://bugs.debian.org/169004 for ia64 ] [ reported for 2.95.2, rechecked with gcc-3_2-branch 20021212, Debian source code found at http://packages.debian.org/unstable/net/fping.html ] Herbert Xu writes: I attempted to make a minimal test case but failed as the stripped down version actually produced the correct code. The problem arose in fping. The relevant code is in fping.c:wait_for_reply(), memcpy(&sent_time, icp->icmp_data + offsetof(PING_DATA, ping_ts), sizeof(sent_time)); memcpy(&this_count, icp->icmp_data, sizeof(this_count)); Since icp->icmp_data is 4-byte aligned, one would expect the memcpys to do five 4-byte loads. However, the actual assembly produced with gcc -S -g -O2 is $LM490: .stabn 68,0,1157,$LM490 lds $f11,8($10) $LM491: .stabn 68,0,1155,$LM491 ldt $f10,16($10) ldt $f12,24($10) $LM492: .stabn 68,0,1157,$LM492 sts $f11,80($30) $LM493: .stabn 68,0,1155,$LM493 stt $f10,88($30) stt $f12,96($30) Which causes two unaligned traps. The followup for gcc-3.2: It still happens with 3.2 branch 20021212 on alpha. This is the assembly: 26bc: 08 00 2a a0 ldl t0,8(s1) 26c0: 10 00 4a a4 ldq t1,16(s1) 26c4: 18 00 6a a4 ldq t2,24(s1) 26c8: 40 00 3e b0 stl t0,64(sp) 26cc: 48 00 5e b4 stq t1,72(sp) 26d0: 50 00 7e b4 stq t2,80(sp) Release: 3.2.1 (Debian) (Debian unstable) Environment: System: Debian GNU/Linux (unstable) Architecture: alpha-linux, ia64-linux host: alpha-linux Configured with: ../src/configure -v --enable-languages=c,c++,java,f77,proto,pascal,objc,ada --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-gxx-include-dir=/usr/include/c++/3.2 --enable-shared --with-system-zlib --enable-nls --without-included-gettext --enable-__cxa_atexit --enable-clocale=gnu --enable-java-gc=boehm --enable-objc-gc i386-linux Thread model: posix gcc version 3.2.2 20021212 (Debian prerelease)
*** This bug has been marked as a duplicate of 9080 ***
From: Herbert Xu <herbert@gondor.apana.org.au> To: rth@gcc.gnu.org, 169004@bugs.debian.org, 85468@bugs.debian.org, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org, nobody@gcc.gnu.org, gcc-gnats@gcc.gnu.org Cc: Subject: Re: target/9082: [alpha,ia64] memcpy makes unaligned access Date: Sun, 26 Jan 2003 21:45:30 +1100 On Sun, Jan 26, 2003 at 10:22:31AM -0000, rth@gcc.gnu.org wrote: > Synopsis: [alpha,ia64] memcpy makes unaligned access > > State-Changed-From-To: open->closed > State-Changed-By: rth > State-Changed-When: Sun Jan 26 10:22:31 2003 > State-Changed-Why: > When submitting bugs to gcc, one must include the test case, > not reference it in some package elsewhere. This reduces the > possibility that the bug requires specific system headers to > be reproduced. I'm sorry about that, I'll get the preprocessed program sent to you. > That said, it's obvious this is a duplicate of PR 9080, > which is closed due to the input program being invalid. I'm afraid I don't see the connection between the two reports. In my case, memcpy is correct programmatically but it's triggering an alignment error as it's performing 8-byte loads when the source argument is 4-byte aligned (the destination is 8-byte aligned though). -- Debian GNU/Linux 3.0 is out! ( http://www.debian.org/ ) Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt