From: Andrii Nakryiko andriin@fb.com

[ Upstream commit 4670d68b9254710fdeaf794cad54d8b2c9929e0a ]

Some recent changes in latest Clang started causing the following warning when unrolling strobemeta test case main loop:

progs/strobemeta.h:416:2: warning: loop not unrolled: the optimizer was unable to perform the requested transformation; the transformation might be disabled or specified as part of an unsupported transformation ordering [-Wpass-failed=transform-warning]

This patch simplifies loop's exit condition to depend only on constant max iteration number (STROBE_MAX_MAP_ENTRIES), while moving early termination logic inside the loop body. The changes are equivalent from program logic standpoint, but fixes the warning. It also appears to improve generated BPF code, as it fixes previously failing non-unrolled strobemeta test cases.

Cc: Alexei Starovoitov ast@fb.com Signed-off-by: Andrii Nakryiko andriin@fb.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/bpf/progs/strobemeta.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/progs/strobemeta.h b/tools/testing/selftests/bpf/progs/strobemeta.h index 8a399bdfd9203..067eb625d01c5 100644 --- a/tools/testing/selftests/bpf/progs/strobemeta.h +++ b/tools/testing/selftests/bpf/progs/strobemeta.h @@ -413,7 +413,10 @@ static __always_inline void *read_map_var(struct strobemeta_cfg *cfg, #else #pragma unroll #endif - for (int i = 0; i < STROBE_MAX_MAP_ENTRIES && i < map.cnt; ++i) { + for (int i = 0; i < STROBE_MAX_MAP_ENTRIES; ++i) { + if (i >= map.cnt) + break; + descr->key_lens[i] = 0; len = bpf_probe_read_str(payload, STROBE_MAX_STR_LEN, map.entries[i].key);