On Tue, May 19, 2026 at 11:03 AM Avi Kivity <[email protected]> wrote:
> > > On Tue, May 19, 2026 at 2:22 AM <[email protected]> wrote: > >> Dear contributor, >> >> Our automatic CI has detected problems related to your patch(es). Please >> find some details below. >> >> In aarch64 native, after: >> | commit gcc-17-570-g79e29562907b >> | Author: Avi Kivity <[email protected]> >> | Date: Thu Feb 26 19:59:41 2026 +0200 >> | >> | libstdc++: optimize std::uninitialized_move{,_n}() to memcpy when >> possible [PR121789] >> | >> | std::uninitialized_move{,_n} delegates to the corresponding >> | std::uninitialized_copy() variant after wrapping with a move >> | iterator, but the std::uninitialized_copy() doesn't unwrap the >> | ... 17 lines of the commit log omitted. >> >> Produces 1 regression: >> | >> | regressions.sum: >> | Running g++:g++.dg/torture/dg-torture.exp ... >> | FAIL: g++.dg/torture/pr118521.C -O1 (test for excess errors) >> > > I'll take a look. > In file included from /mnt/gcc.bin/include/c++/17.0.0/vector:67, from ./gcc/testsuite/g++.dg/torture/pr118521.C:5: In function ‘_ForwardIterator std::uninitialized_fill_n(_ForwardIterator, _Size, const _Tp&) [with _ForwardIterator = char*; _Size = long unsigned int; _Tp = char]’, inlined from ‘constexpr _ForwardIterator std::__uninitialized_fill_n_a(_ForwardIterator, _Size, const _Tp&, allocator<_Tp>&) [with _ForwardIterator = char*; _Size = long unsigned int; _Tp = char; _Tp2 = char]’ at /mnt/gcc.bin/include/c++/17.0.0/bits/stl_uninitialized.h:778:39, inlined from ‘constexpr void std::vector<_Tp, _Alloc>::_M_fill_append(size_type, const value_type&) [with _Tp = char; _Alloc = std::allocator<char>]’ at /mnt/gcc.bin/include/c++/17.0.0/bits/vector.tcc:776:36, inlined from ‘constexpr void std::vector<_Tp, _Alloc>::_M_fill_insert(iterator, size_type, const value_type&) [with _Tp = char; _Alloc = std::allocator<char>]’ at /mnt/gcc.bin/include/c++/17.0.0/bits/vector.tcc:668:20, inlined from ‘constexpr std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, size_type, const value_type&) [with _Tp = char; _Alloc = std::allocator<char>]’ at /mnt/gcc.bin/include/c++/17.0.0/bits/stl_vector.h:1565:16, inlined from ‘void foo()’ at ./gcc/testsuite/g++.dg/torture/pr118521.C:12:11: /mnt/gcc.bin/include/c++/17.0.0/bits/stl_uninitialized.h:577:39: warning: ‘void* __builtin_memset(void*, int, long unsigned int)’ writing 2 bytes into a region of size 0 overflows the destination [-Wstringop-overflow=] 577 | __builtin_memset(__dest, (unsigned char)__x, __n); | ~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I think it's a victim of an existing (and very annoying) misdetection of memory overwrites (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=125187). It's not directly related to my patch (which optimizes moving a range, not filling it), but my patch changes the detection logic causing gcc to think the region is of size 0 (where it should be 4). I enhanced the test code to be a full program and verified it works with asan. I'm not sure how to proceed. I don't want to patch pr118521.C to disable -Wstringop-overflow, since that's what it's testing. Copying Richard, the original author of the test (a2755339c6c9832467c573d956e91565943ecdc1). > > >> >> Used configuration : >> *CI config* tcwg_gcc_check aarch64-linux-gnu >> *configure and test flags:* none, autodetected on >> aarch64-unknown-linux-gnu--disable-multilib --enable-fix-cortex-a53-835769 >> --enable-fix-cortex-a53-843419 --with-arch=armv8-a >> >> We track this bug report under >> https://linaro.atlassian.net/browse/GNU-1906. Please let us know if you >> have a fix. >> >> If you have any questions regarding this report, please ask on >> [email protected] mailing list. >> >> >> -----------------8<--------------------------8<--------------------------8<-------------------------- >> >> The information below contains the details of the failures, and the ways >> to reproduce a debug environment: >> >> You can find the failure logs in *.log.1.xz files in >> * >> http://54.172.246.49:9090/jobs/tcwg_gcc_check--master-aarch64-build/builds/10197/archive/artifacts/00-sumfiles/ >> The full lists of regressions and improvements as well as configure and >> make commands are in >> * >> http://54.172.246.49:9090/jobs/tcwg_gcc_check--master-aarch64-build/builds/10197/archive/artifacts/notify/ >> The list of [ignored] baseline and flaky failures are in >> * >> http://54.172.246.49:9090/jobs/tcwg_gcc_check--master-aarch64-build/builds/10197/archive/artifacts/sumfiles/xfails.xfail >> >> Current build : >> http://54.172.246.49:9090/jobs/tcwg_gcc_check--master-aarch64-build/builds/10197/archive/artifacts/ >> Reference build : >> http://54.172.246.49:9090/jobs/tcwg_gcc_check--master-aarch64-build/builds/10196/archive/artifacts/ >> >> Instruction to reproduce the build : >> https://gitlab.com/LinaroLtd/tcwg/ci/interesting-commits/-/raw/master/gcc/sha1/79e29562907b454cdb867195b34cf63156d2d0cc/tcwg_gcc_check/master-aarch64/reproduction_instructions.txt >> >> Full commit : See in git+ssh://[email protected]/git/gcc.git > >
