On Wed, Sep 25, 2019 at 1:33 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > On Wed, Sep 25, 2019 at 11:52:05AM -0700, Andrii Nakryiko wrote: > > 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@xxxxxx> > > Signed-off-by: Andrii Nakryiko <andriin@xxxxxx> > > Sounds like a clang regression? Was that from an official release? It does, but I didn't dig deep enough to figure out what exactly caused this. The version I used was latest Clang 10 built from sources. Might be worth-while to investigate this further to prevent some other unexpected breakages for user programs. > > Applied. Thanks!
