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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>
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| .. | ||
| arch-aarch64.h | ||
| arch-arm.h | ||
| arch-i386.h | ||
| arch-mips.h | ||
| arch-riscv.h | ||
| arch-x86_64.h | ||
| arch.h | ||
| ctype.h | ||
| errno.h | ||
| Makefile | ||
| nolibc.h | ||
| signal.h | ||
| std.h | ||
| stdio.h | ||
| stdlib.h | ||
| string.h | ||
| sys.h | ||
| time.h | ||
| types.h | ||
| unistd.h | ||