Title: bpo-36618: Add -fmax-type-align=8 flag for clang by vstinner · Pull Request #12809 · python/cpython · GitHub
Open Graph Title: bpo-36618: Add -fmax-type-align=8 flag for clang by vstinner · Pull Request #12809 · python/cpython
X Title: bpo-36618: Add -fmax-type-align=8 flag for clang by vstinner · Pull Request #12809 · python/cpython
Description: 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 expected to CFLAGS and not just CFLAGS_NODIST, since third party C extensions can have the same issue. https://bugs.python.org/issue36618
Open Graph Description: 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 MOVAP...
X Description: 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 MOVAP...
Opengraph URL: https://github.com/python/cpython/pull/12809
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