Dimitry Andric via llvm-dev
2021-Sep-25 09:51 UTC
[llvm-dev] Problem with clang optimizer?
It is only occurring (as far as I can see now) on x86_64, with -mavx enabled. Or with a target CPU that supports AVX. And it is not Apple clang specific. -Dimitry> On 24 Sep 2021, at 15:30, Blumenthal, Uri - 0553 - MITLL via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > I tried to reproduce it on goldbolt with clang 12.0.0 and 12.0.1 but things seem fine when I run it there: https://godbolt.org/z/vrq8j6Kj7 <https://godbolt.org/z/vrq8j6Kj7>. > Can you share your exact clang invocation? Does it only reproduce in some specific environment? > > Save the source I posted before into “sha3-reproducer.cxx” file. Let me know if you want it re-posted here. > > $ clang++-mp-12 -v > clang version 12.0.1 > Target: x86_64-apple-darwin20.6.0 > Thread model: posix > InstalledDir: /opt/local/libexec/llvm-12/bin > $ clang++-mp-12 -o s -O3 sha3-reproducer.cxx > $ ./s > Assertion failed: (T[0] == 16394434931424703552u), function main, file sha3-reproducer.cxx, line 103. > Abort trap: 6 > $ clang++-mp-12 -o s -O2 sha3-reproducer.cxx > $ ./s > Assertion failed: (T[0] == 16394434931424703552u), function main, file sha3-reproducer.cxx, line 103. > Abort trap: 6 > $ clang++-mp-12 -o s -O1 sha3-reproducer.cxx > $ ./s > $ > > Clang-12 is installed via Macports, which is why we invoke the executable as clang++-mp-12. > > The same problem manifests in exactly the same way in the Xcode-13 version of Clang (presumably based on LLVM Clang-12). > > I’ll be happy to provide more of specific details, if you let me know what you need. > > > Also, it generally helps to reduce code bug reports as much as possible; creduce can help with that: https://embed.cs.utah.edu/creduce/using/ <https://embed.cs.utah.edu/creduce/using/>. > > Understood. Unfortunately, the above reproducer is the best we could come up with. An alternative is trying to build the Botan package itself https://github.com/randombit/botan.git <https://github.com/randombit/botan.git>. > > > > > On Thu, Sep 23, 2021 at 10:14 PM Blumenthal, Uri - 0553 - MITLL via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: >> I’m not sure if this is the correct list, so please direct me to the right one if this bug report shouldn’t go here. >> >> The problem is: invoking clang (v12) with -O2 or better optimization flags generates wrong object code for the following C++. Compiling it with -O1 generates working binary. >> >> >> ================>> >> #include <cstdint> >> #include <cassert> >> >> template<size_t ROT, typename T> >> inline constexpr T rotl(T input) >> { >> static_assert(ROT > 0 && ROT < 8*sizeof(T), "Invalid rotation constant"); >> return static_cast<T>((input << ROT) | (input >> (8*sizeof(T) - ROT))); >> } >> >> inline void SHA3_round(uint64_t T[25], const uint64_t A[25], uint64_t RC) >> { >> const uint64_t C0 = A[0] ^ A[5] ^ A[10] ^ A[15] ^ A[20]; >> const uint64_t C1 = A[1] ^ A[6] ^ A[11] ^ A[16] ^ A[21]; >> >> // the calculation of C2 fails for -O3 or -O2 with clang 12 >> // FWIW: it would produce a value that doesn't fit into a _signed_ 64-bit int >> const uint64_t C2 = A[2] ^ A[7] ^ A[12] ^ A[17] ^ A[22]; >> >> const uint64_t C3 = A[3] ^ A[8] ^ A[13] ^ A[18] ^ A[23]; >> const uint64_t C4 = A[4] ^ A[9] ^ A[14] ^ A[19] ^ A[24]; >> >> const uint64_t D0 = rotl<1>(C0) ^ C3; >> const uint64_t D1 = rotl<1>(C1) ^ C4; >> const uint64_t D2 = rotl<1>(C2) ^ C0; >> const uint64_t D3 = rotl<1>(C3) ^ C1; >> const uint64_t D4 = rotl<1>(C4) ^ C2; >> >> const uint64_t B00 = A[ 0] ^ D1; >> const uint64_t B01 = rotl<44>(A[ 6] ^ D2); >> const uint64_t B02 = rotl<43>(A[12] ^ D3); >> const uint64_t B03 = rotl<21>(A[18] ^ D4); >> const uint64_t B04 = rotl<14>(A[24] ^ D0); >> T[ 0] = B00 ^ (~B01 & B02) ^ RC; >> T[ 1] = B01 ^ (~B02 & B03); >> T[ 2] = B02 ^ (~B03 & B04); >> T[ 3] = B03 ^ (~B04 & B00); >> T[ 4] = B04 ^ (~B00 & B01); >> >> const uint64_t B05 = rotl<28>(A[ 3] ^ D4); >> const uint64_t B06 = rotl<20>(A[ 9] ^ D0); >> const uint64_t B07 = rotl< 3>(A[10] ^ D1); >> const uint64_t B08 = rotl<45>(A[16] ^ D2); >> const uint64_t B09 = rotl<61>(A[22] ^ D3); >> T[ 5] = B05 ^ (~B06 & B07); >> T[ 6] = B06 ^ (~B07 & B08); >> T[ 7] = B07 ^ (~B08 & B09); >> T[ 8] = B08 ^ (~B09 & B05); >> T[ 9] = B09 ^ (~B05 & B06); >> >> // --- instructions starting from here can be removed >> // and the -O3 dicrepancy is still triggered >> >> const uint64_t B10 = rotl< 1>(A[ 1] ^ D2); >> const uint64_t B11 = rotl< 6>(A[ 7] ^ D3); >> const uint64_t B12 = rotl<25>(A[13] ^ D4); >> const uint64_t B13 = rotl< 8>(A[19] ^ D0); >> const uint64_t B14 = rotl<18>(A[20] ^ D1); >> T[10] = B10 ^ (~B11 & B12); >> T[11] = B11 ^ (~B12 & B13); >> T[12] = B12 ^ (~B13 & B14); >> T[13] = B13 ^ (~B14 & B10); >> T[14] = B14 ^ (~B10 & B11); >> >> const uint64_t B15 = rotl<27>(A[ 4] ^ D0); >> const uint64_t B16 = rotl<36>(A[ 5] ^ D1); >> const uint64_t B17 = rotl<10>(A[11] ^ D2); >> const uint64_t B18 = rotl<15>(A[17] ^ D3); >> const uint64_t B19 = rotl<56>(A[23] ^ D4); >> T[15] = B15 ^ (~B16 & B17); >> T[16] = B16 ^ (~B17 & B18); >> T[17] = B17 ^ (~B18 & B19); >> T[18] = B18 ^ (~B19 & B15); >> T[19] = B19 ^ (~B15 & B16); >> >> const uint64_t B20 = rotl<62>(A[ 2] ^ D3); >> const uint64_t B21 = rotl<55>(A[ 8] ^ D4); >> const uint64_t B22 = rotl<39>(A[14] ^ D0); >> const uint64_t B23 = rotl<41>(A[15] ^ D1); >> const uint64_t B24 = rotl< 2>(A[21] ^ D2); >> T[20] = B20 ^ (~B21 & B22); >> T[21] = B21 ^ (~B22 & B23); >> T[22] = B22 ^ (~B23 & B24); >> T[23] = B23 ^ (~B24 & B20); >> T[24] = B24 ^ (~B20 & B21); >> } >> >> int main() >> { >> uint64_t T[25]; >> >> uint64_t A[25] = { >> 15515230172486u, 9751542238472685244u, 220181482233372672u, >> 2303197730119u, 9537012007446913720u, 0u, 14782389640143539577u, >> 2305843009213693952u, 1056340403235818873u, 16396894922196123648u, >> 13438274300558u, 3440198220943040u, 0u, 3435902021559310u, 64u, >> 14313837075027532897u, 32768u, 6880396441885696u, 14320469711924527201u, >> 0u, 9814829303127743595u, 18014398509481984u, 14444556046857390455u, >> 4611686018427387904u, 18041275058083100u }; >> >> SHA3_round(T, A, 0x0000000000008082); >> >> assert(T[0] == 16394434931424703552u); >> assert(T[1] == 10202638136074191489u); >> assert(T[2] == 6432602484395933614u); >> assert(T[3] == 10616058301262943899u); >> assert(T[4] == 14391824303596635982u); >> assert(T[5] == 5673590995284149638u); >> assert(T[6] == 15681872423764765508u); >> assert(T[7] == 11470206704342013341u); >> assert(T[8] == 8508807405493883168u); >> assert(T[9] == 9461805213344568570u); >> assert(T[10] == 8792313850970105187u); >> assert(T[11] == 13508586629627657374u); >> assert(T[12] == 5157283382205130943u); >> assert(T[13] == 375019647457809685u); >> assert(T[14] == 9294608398083155963u); >> assert(T[15] == 16923121173371064314u); >> assert(T[16] == 4737739424553008030u); >> assert(T[17] == 5823987023293412593u); >> assert(T[18] == 13908063749137376267u); >> assert(T[19] == 13781177305593198238u); >> assert(T[20] == 9673833001659673401u); >> assert(T[21] == 17282395057630454440u); >> assert(T[22] == 12906624984756985556u); >> assert(T[23] == 3081478361927354234u); >> assert(T[24] == 93297594635310132u); >> >> return 0; >> } >> ================>> >> Your help debugging and fixing this problem is appreciated! >> -- >> Regards, >> Uri Blumenthal Voice: (781) 981-1638 >> Secure Resilient Systems and Technologies Cell: (339) 223-5363 >> MIT Lincoln Laboratory >> 244 Wood Street, Lexington, MA <https://www.google.com/maps/search/Wood+Street,+Lexington,+MA+02420-9108?entry=gmail&source=g> 02420-9108 <https://www.google.com/maps/search/Wood+Street,+Lexington,+MA+02420-9108?entry=gmail&source=g> >> >> Web: https://www.ll.mit.edu/biographies/uri-blumenthal <https://www.ll.mit.edu/biographies/uri-blumenthal> >> Root CA: https://www.ll.mit.edu/llrca2.pem <https://www.ll.mit.edu/llrca2.pem> >> >> There are two ways to design a system. One is to make is so simple there are obviously no deficiencies. >> The other is to make it so complex there are no obvious deficiencies. >> - C. A. R. Hoare >> >> _______________________________________________ >> LLVM Developers mailing list >> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org> >> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev <https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev> > > > -- > Jakub Kuderski > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org> > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev <https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20210925/df4c8ddc/attachment-0001.html> -------------- next part -------------- A non-text attachment was scrubbed... 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It reproduced for me with -march=nehalem which does not have AVX. On Sat, Sep 25, 2021 at 2:51 AM Dimitry Andric via llvm-dev < llvm-dev at lists.llvm.org> wrote:> It is only occurring (as far as I can see now) on x86_64, with -mavx > enabled. Or with a target CPU that supports AVX. And it is not Apple clang > specific. > > -Dimitry > > On 24 Sep 2021, at 15:30, Blumenthal, Uri - 0553 - MITLL via llvm-dev < > llvm-dev at lists.llvm.org> wrote: > > I tried to reproduce it on goldbolt with clang 12.0.0 and 12.0.1 but > things seem fine when I run it there: https://godbolt.org/z/vrq8j6Kj7. > Can you share your exact clang invocation? Does it only reproduce in some > specific environment? > > Save the source I posted before into “sha3-reproducer.cxx” file. Let me > know if you want it re-posted here. > > $ clang++-mp-12 -v > clang version 12.0.1 > Target: x86_64-apple-darwin20.6.0 > Thread model: posix > InstalledDir: /opt/local/libexec/llvm-12/bin > $ clang++-mp-12 -o s -O3 sha3-reproducer.cxx > $ ./s > Assertion failed: (T[0] == 16394434931424703552u), function main, file > sha3-reproducer.cxx, line 103. > Abort trap: 6 > $ clang++-mp-12 -o s -O2 sha3-reproducer.cxx > $ ./s > Assertion failed: (T[0] == 16394434931424703552u), function main, file > sha3-reproducer.cxx, line 103. > Abort trap: 6 > $ clang++-mp-12 -o s -O1 sha3-reproducer.cxx > $ ./s > $ > > Clang-12 is installed via Macports, which is why we invoke the executable > as clang++-mp-12. > > The same problem manifests in exactly the same way in the Xcode-13 version > of Clang (presumably based on LLVM Clang-12). > > I’ll be happy to provide more of specific details, if you let me know what > you need. > > > Also, it generally helps to reduce code bug reports as much as possible; > creduce can help with that: https://embed.cs.utah.edu/creduce/using/. > > Understood. Unfortunately, the above reproducer is the best we could come > up with. An alternative is trying to build the Botan package itself > https://github.com/randombit/botan.git. > > > > > On Thu, Sep 23, 2021 at 10:14 PM Blumenthal, Uri - 0553 - MITLL via > llvm-dev <llvm-dev at lists.llvm.org> wrote: > > I’m not sure if this is the correct list, so please direct me to the right > one if this bug report shouldn’t go here. > > The problem is: invoking clang (v12) with -O2 or better optimization flags > generates wrong object code for the following C++. Compiling it with -O1 > generates working binary. > > > ================> > #include <cstdint> > #include <cassert> > > template<size_t ROT, typename T> > inline constexpr T rotl(T input) > { > static_assert(ROT > 0 && ROT < 8*sizeof(T), "Invalid rotation > constant"); > return static_cast<T>((input << ROT) | (input >> (8*sizeof(T) - ROT))); > } > > inline void SHA3_round(uint64_t T[25], const uint64_t A[25], uint64_t RC) > { > const uint64_t C0 = A[0] ^ A[5] ^ A[10] ^ A[15] ^ A[20]; > const uint64_t C1 = A[1] ^ A[6] ^ A[11] ^ A[16] ^ A[21]; > > // the calculation of C2 fails for -O3 or -O2 with clang 12 > // FWIW: it would produce a value that doesn't fit into a _signed_ > 64-bit int > const uint64_t C2 = A[2] ^ A[7] ^ A[12] ^ A[17] ^ A[22]; > > const uint64_t C3 = A[3] ^ A[8] ^ A[13] ^ A[18] ^ A[23]; > const uint64_t C4 = A[4] ^ A[9] ^ A[14] ^ A[19] ^ A[24]; > > const uint64_t D0 = rotl<1>(C0) ^ C3; > const uint64_t D1 = rotl<1>(C1) ^ C4; > const uint64_t D2 = rotl<1>(C2) ^ C0; > const uint64_t D3 = rotl<1>(C3) ^ C1; > const uint64_t D4 = rotl<1>(C4) ^ C2; > > const uint64_t B00 = A[ 0] ^ D1; > const uint64_t B01 = rotl<44>(A[ 6] ^ D2); > const uint64_t B02 = rotl<43>(A[12] ^ D3); > const uint64_t B03 = rotl<21>(A[18] ^ D4); > const uint64_t B04 = rotl<14>(A[24] ^ D0); > T[ 0] = B00 ^ (~B01 & B02) ^ RC; > T[ 1] = B01 ^ (~B02 & B03); > T[ 2] = B02 ^ (~B03 & B04); > T[ 3] = B03 ^ (~B04 & B00); > T[ 4] = B04 ^ (~B00 & B01); > > const uint64_t B05 = rotl<28>(A[ 3] ^ D4); > const uint64_t B06 = rotl<20>(A[ 9] ^ D0); > const uint64_t B07 = rotl< 3>(A[10] ^ D1); > const uint64_t B08 = rotl<45>(A[16] ^ D2); > const uint64_t B09 = rotl<61>(A[22] ^ D3); > T[ 5] = B05 ^ (~B06 & B07); > T[ 6] = B06 ^ (~B07 & B08); > T[ 7] = B07 ^ (~B08 & B09); > T[ 8] = B08 ^ (~B09 & B05); > T[ 9] = B09 ^ (~B05 & B06); > > // --- instructions starting from here can be removed > // and the -O3 dicrepancy is still triggered > > const uint64_t B10 = rotl< 1>(A[ 1] ^ D2); > const uint64_t B11 = rotl< 6>(A[ 7] ^ D3); > const uint64_t B12 = rotl<25>(A[13] ^ D4); > const uint64_t B13 = rotl< 8>(A[19] ^ D0); > const uint64_t B14 = rotl<18>(A[20] ^ D1); > T[10] = B10 ^ (~B11 & B12); > T[11] = B11 ^ (~B12 & B13); > T[12] = B12 ^ (~B13 & B14); > T[13] = B13 ^ (~B14 & B10); > T[14] = B14 ^ (~B10 & B11); > > const uint64_t B15 = rotl<27>(A[ 4] ^ D0); > const uint64_t B16 = rotl<36>(A[ 5] ^ D1); > const uint64_t B17 = rotl<10>(A[11] ^ D2); > const uint64_t B18 = rotl<15>(A[17] ^ D3); > const uint64_t B19 = rotl<56>(A[23] ^ D4); > T[15] = B15 ^ (~B16 & B17); > T[16] = B16 ^ (~B17 & B18); > T[17] = B17 ^ (~B18 & B19); > T[18] = B18 ^ (~B19 & B15); > T[19] = B19 ^ (~B15 & B16); > > const uint64_t B20 = rotl<62>(A[ 2] ^ D3); > const uint64_t B21 = rotl<55>(A[ 8] ^ D4); > const uint64_t B22 = rotl<39>(A[14] ^ D0); > const uint64_t B23 = rotl<41>(A[15] ^ D1); > const uint64_t B24 = rotl< 2>(A[21] ^ D2); > T[20] = B20 ^ (~B21 & B22); > T[21] = B21 ^ (~B22 & B23); > T[22] = B22 ^ (~B23 & B24); > T[23] = B23 ^ (~B24 & B20); > T[24] = B24 ^ (~B20 & B21); > } > > int main() > { > uint64_t T[25]; > > uint64_t A[25] = { > 15515230172486u, 9751542238472685244u, 220181482233372672u, > 2303197730119u, 9537012007446913720u, 0u, 14782389640143539577u, > 2305843009213693952u, 1056340403235818873u, 16396894922196123648u, > 13438274300558u, 3440198220943040u, 0u, 3435902021559310u, 64u, > 14313837075027532897u, 32768u, 6880396441885696u, > 14320469711924527201u, > 0u, 9814829303127743595u, 18014398509481984u, > 14444556046857390455u, > 4611686018427387904u, 18041275058083100u }; > > SHA3_round(T, A, 0x0000000000008082); > > assert(T[0] == 16394434931424703552u); > assert(T[1] == 10202638136074191489u); > assert(T[2] == 6432602484395933614u); > assert(T[3] == 10616058301262943899u); > assert(T[4] == 14391824303596635982u); > assert(T[5] == 5673590995284149638u); > assert(T[6] == 15681872423764765508u); > assert(T[7] == 11470206704342013341u); > assert(T[8] == 8508807405493883168u); > assert(T[9] == 9461805213344568570u); > assert(T[10] == 8792313850970105187u); > assert(T[11] == 13508586629627657374u); > assert(T[12] == 5157283382205130943u); > assert(T[13] == 375019647457809685u); > assert(T[14] == 9294608398083155963u); > assert(T[15] == 16923121173371064314u); > assert(T[16] == 4737739424553008030u); > assert(T[17] == 5823987023293412593u); > assert(T[18] == 13908063749137376267u); > assert(T[19] == 13781177305593198238u); > assert(T[20] == 9673833001659673401u); > assert(T[21] == 17282395057630454440u); > assert(T[22] == 12906624984756985556u); > assert(T[23] == 3081478361927354234u); > assert(T[24] == 93297594635310132u); > > return 0; > } > ================> > Your help debugging and fixing this problem is appreciated! > -- > Regards, > Uri Blumenthal Voice: (781) 981-1638 > Secure Resilient Systems and Technologies Cell: (339) 223-5363 > MIT Lincoln Laboratory > 244 Wood Street, Lexington, MA > <https://www.google.com/maps/search/Wood+Street,+Lexington,+MA+02420-9108?entry=gmail&source=g> > 02420-9108 > <https://www.google.com/maps/search/Wood+Street,+Lexington,+MA+02420-9108?entry=gmail&source=g> > > > Web: https://www.ll.mit.edu/biographies/uri-blumenthal > Root CA: https://www.ll.mit.edu/llrca2.pem > > *There are two ways to design a system. One is to make is so simple there > are obviously no deficiencies.* > *The other is to make it so complex there are no obvious deficiencies.* > * > - > C. A. R. Hoare* > > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > > > -- > Jakub Kuderski > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev > > > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-- ~Craig -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20210925/8af2b6da/attachment.html>