On 11/8/23 00:59, Thomas Huth wrote:
When compiling QEMU with Clang 17 on a s390x, the compilation fails:In file included from ../accel/tcg/cputlb.c:32: In file included from /root/qemu/include/exec/helper-proto-common.h:10: In file included from /root/qemu/include/qemu/atomic128.h:62: /root/qemu/host/include/generic/host/atomic128-ldst.h:68:15: error: __sync builtin operation MUST have natural alignment (consider using __ atomic). [-Werror,-Wsync-alignment] 68 | } while (!__sync_bool_compare_and_swap_16(ptr_align, old, new.i)); | ^ In file included from ../accel/tcg/cputlb.c:32: In file included from /root/qemu/include/exec/helper-proto-common.h:10: In file included from /root/qemu/include/qemu/atomic128.h:61: /root/qemu/host/include/generic/host/atomic128-cas.h:36:11: error: __sync builtin operation MUST have natural alignment (consider using __a tomic). [-Werror,-Wsync-alignment] 36 | r.i = __sync_val_compare_and_swap_16(ptr_align, c.i, n.i); | ^ 2 errors generated. It's arguably a bug in Clang since we already use __builtin_assume_aligned() to tell the compiler that the pointer is properly aligned. But according to https://github.com/llvm/llvm-project/issues/69146 it seems like the Clang folks don't see an easy fix on their side and recommend to use a type declared with __attribute__((aligned(16))) to work around this problem. Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1934 Signed-off-by: Thomas Huth <[email protected]> --- host/include/generic/host/atomic128-cas.h | 2 +- host/include/generic/host/atomic128-ldst.h | 2 +- include/qemu/int128.h | 1 + 3 files changed, 3 insertions(+), 2 deletions(-)
Reviewed-by: Richard Henderson <[email protected]> r~
