Open
Description
This was originally reported against perl as Perl/perl5#22132 but appears to be a clang issue.
Reduced test case (as opposed to the perl source):
22132.txt (.txt since github didn't like .c)
This was originally reported against clang 17.0.6 as supplied with FreeBSD 13.3, but was reproducible on Debian Linux bookworm with the clang/llvm builds from apt.llvm.org since clang 15.
$ clang-14 -O2 -march=amdfam10 22132.c && ./a.out required_even_ix $ clang-15 -O2 -march=amdfam10 22132.c && ./a.out requiredEven_ix $ clang-16 -O2 -march=amdfam10 22132.c && ./a.out requiredEven_ix $ clang-17 -O2 -march=amdfam10 22132.c && ./a.out requiredEven_ix $ clang-18 -O2 -march=amdfam10 22132.c && ./a.out requiredEven_ix $ clang-18 -O2 -march=amdfam10 22132.c && ./a.out | hd 00000000 72 65 71 75 69 72 65 64 7f 45 76 65 6e 5f 69 78 |required.Even_ix| 00000010 0a |.| 00000011 $ clang-18 -O2 22132.c && ./a.out required_even_ix $ clang-18 -O2 -march=x86-64-v2 22132.c && ./a.out required_even_ix $ clang-18 --version Debian clang version 18.1.4 (++20240410110204+b6ebea7972cd-1~exp1~20240410230232.97) Target: x86_64-pc-linux-gnu Thread model: posix InstalledDir: /usr/bin $ clang-17 --version Debian clang version 17.0.6 (++20231208085813+6009708b4367-1~exp1~20231208085906.81) Target: x86_64-pc-linux-gnu Thread model: posix InstalledDir: /usr/bin $ cat /etc/os-release PRETTY_NAME="Debian GNU/Linux 12 (bookworm)" NAME="Debian GNU/Linux" VERSION_ID="12" VERSION="12 (bookworm)" VERSION_CODENAME=bookworm ID=debian HOME_URL="https://www.debian.org/" SUPPORT_URL="https://www.debian.org/support" BUG_REPORT_URL="https://bugs.debian.org/" $ clang-18 -O2 -fsanitize=address 22132.c && ./a.out required_even_ix $ clang-18 -O2 -fsanitize=undefined 22132.c && ./a.out required_even_ix 