Codec detection doesn’t work in test_base64 on musl libc

[jirutka]

When I build v0.5.1 using cmake on Alpine Linux x86_64 (running in a VM), the tests (not just benchmark) fail on illegal instruction. However, the base64 utility works fine, so it seems that the detection is broken only in the tests? When I disable all AVX (-DBASE64_WITH_AVX512=OFF, -DBASE64_WITH_AVX2=OFF, -DBASE64_WITH_AVX=OFF), the tests pass.

I read related issues (#77, #95), but these are just about the benchmarks, not the tests.

./build/bin/test_base64
Codec AVX2:
The process was killed by SIGILL: Illegal instruction

strace ./build/bin/test_base64
execve("./build/bin/test_base64", ["./build/bin/test_base64"], 0x7fff8f113da0 /* 19 vars */) = 0
arch_prctl(ARCH_SET_FS, 0x7f07fcfafb08) = 0
set_tid_address(0x7f07fcfaff70)         = 16075
brk(NULL)                               = 0x55e997446000
brk(0x55e997448000)                     = 0x55e997448000
mmap(0x55e997446000, 4096, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x55e997446000
open("build/bin/libbase64.so.0", O_RDONLY|O_LARGEFILE|O_CLOEXEC) = 3
fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
fstat(3, {st_mode=S_IFREG|0755, st_size=84016, ...}) = 0
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0\0\0\0\0\0\0\0"..., 960) = 960
mmap(NULL, 86016, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f07fcef9000
mmap(0x7f07fcefa000, 57344, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED, 3, 0x1000) = 0x7f07fcefa000
mmap(0x7f07fcf08000, 16384, PROT_READ, MAP_PRIVATE|MAP_FIXED, 3, 0xf000) = 0x7f07fcf08000
mmap(0x7f07fcf0c000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x12000) = 0x7f07fcf0c000
close(3)                                = 0
mprotect(0x7f07fcf0c000, 4096, PROT_READ) = 0
mprotect(0x7f07fcfac000, 4096, PROT_READ) = 0
mprotect(0x55e996638000, 4096, PROT_READ) = 0
ioctl(1, TIOCGWINSZ, {ws_row=77, ws_col=189, ws_xpixel=1701, ws_ypixel=1386}) = 0
writev(1, [{iov_base="Codec AVX2", iov_len=10}, {iov_base=":\n", iov_len=2}], 2Codec AVX2:
) = 12
--- SIGILL {si_signo=SIGILL, si_code=ILL_ILLOPN, si_addr=0x7f07fcf06c48} ---
+++ killed by SIGILL +++
The process was killed by SIGILL: Illegal instruction

[aklomp]

Does the VM support AVX2 instructions?

Runtime detection is done through CPU flags. Maybe the VM sets the CPU flags incorrectly for some reason?

[aklomp]

CI passes for the latest release for Alpine AMD64.

[mayeut]

There's no automatic feature detection in tests. Tests try to run what was built, even if unsupported (the base64 utility uses the dynamic/runtime dispatch & is thus unaffected).
Maybe #145 could help (allows to disable some tests using environment variables).