bpo-36618: Don't add -fmax-type-align=8 flag for clang by vstinner · Pull Request #13320 · python/cpython
if test -n "${cc_is_clang}" then # bpo-36618: Add -fmax-type-align=8 to CFLAGS when clang compiler is # detected. The pymalloc memory allocator aligns memory on 8 bytes. On # x86-64, clang expects alignment on 16 bytes by default and so uses MOVAPS # instruction which can lead to segmentation fault. Instruct clang that # Python is limited to alignemnt on 8 bytes to use MOVUPS instruction # instead: slower but don't trigger a SIGSEGV if the memory is not aligned # on 16 bytes. # # Sadly, the flag must be added to CFLAGS and not just CFLAGS_NODIST, # since third party C extensions can have the same issue. # # Check if -fmax-type-align flag is supported (it's not supported by old # clang versions): if "$CC" -v --help 2>/dev/null |grep -- -fmax-type-align > /dev/null; then CFLAGS="$CFLAGS -fmax-type-align=8" fi fi