tools/nolibc: prevent gcc from making memset() loop over itself
When building on ARM in thumb mode with gcc-11.3 at -O2 or -O3, nolibc-test segfaults during the select() tests. It turns out that at this level, gcc recognizes an opportunity for using memset() to zero the fd_set, but it miscompiles it because it also recognizes a memset pattern as well, and decides to call memset() from the memset() code: 000122bc <memset>: 122bc: b510 push {r4, lr} 122be: 0004 movs r4, r0 122c0: 2a00 cmp r2, #0 122c2: d003 beq.n 122cc <memset+0x10> 122c4: 23ff movs r3, #255 ; 0xff 122c6: 4019 ands r1, r3 122c8: f7ff fff8 bl 122bc <memset> 122cc: 0020 movs r0, r4 122ce: bd10 pop {r4, pc} Simply placing an empty asm() statement inside the loop suffices to avoid this. Signed-off-by:Willy Tarreau <w@1wt.eu> Signed-off-by:
Paul E. McKenney <paulmck@kernel.org>
parent
55abdd1f
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