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bpo-36618: Don't add -fmax-type-align=8 flag for clang (GH-13320) · python/cpython@d97adfb

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Original file line numberDiff line numberDiff line change

@@ -6905,26 +6905,6 @@ then

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esac

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fi

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if test -n "${cc_is_clang}"

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then

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# bpo-36618: Add -fmax-type-align=8 to CFLAGS when clang compiler is

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# detected. The pymalloc memory allocator aligns memory on 8 bytes. On

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# x86-64, clang expects alignment on 16 bytes by default and so uses MOVAPS

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# instruction which can lead to segmentation fault. Instruct clang that

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# Python is limited to alignemnt on 8 bytes to use MOVUPS instruction

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# instead: slower but don't trigger a SIGSEGV if the memory is not aligned

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# on 16 bytes.

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#

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# Sadly, the flag must be added to CFLAGS and not just CFLAGS_NODIST,

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# since third party C extensions can have the same issue.

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#

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# Check if -fmax-type-align flag is supported (it's not supported by old

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# clang versions):

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if "$CC" -v --help 2>/dev/null |grep -- -fmax-type-align > /dev/null; then

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CFLAGS="$CFLAGS -fmax-type-align=8"

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fi

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fi

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Original file line numberDiff line numberDiff line change

@@ -1543,26 +1543,6 @@ then

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esac

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fi

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if test -n "${cc_is_clang}"

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then

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# bpo-36618: Add -fmax-type-align=8 to CFLAGS when clang compiler is

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# detected. The pymalloc memory allocator aligns memory on 8 bytes. On

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# x86-64, clang expects alignment on 16 bytes by default and so uses MOVAPS

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# instruction which can lead to segmentation fault. Instruct clang that

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# Python is limited to alignemnt on 8 bytes to use MOVUPS instruction

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# instead: slower but don't trigger a SIGSEGV if the memory is not aligned

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# on 16 bytes.

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#

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# Sadly, the flag must be added to CFLAGS and not just CFLAGS_NODIST,

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# since third party C extensions can have the same issue.

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#

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# Check if -fmax-type-align flag is supported (it's not supported by old

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# clang versions):

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if "$CC" -v --help 2>/dev/null |grep -- -fmax-type-align > /dev/null; then

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CFLAGS="$CFLAGS -fmax-type-align=8"

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fi

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fi

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AC_SUBST(BASECFLAGS)

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AC_SUBST(CFLAGS_NODIST)

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AC_SUBST(LDFLAGS_NODIST)