Yes, exactly. Jim
> On Feb 24, 2016, at 4:11 AM, Tamas Berghammer <tbergham...@google.com> wrote: > > tberghammer added a comment. > > In http://reviews.llvm.org/D17535#360519, @bhushan wrote: > >> In MIPS, we can not put a breakpoint in middle of an atomic sequence. >> If we do so (and that breakpoint is hit) then continuing from breakpoint >> address will cause "SC" to fail due to a breakpoint exception. >> SC fails when there’s been any exception serviced since the LL. This will >> then become a "never ending" sequence. > > > I agree that we shouldn't put a breakpoint in the middle of an atomic > sequence (same is true on arm/aarch64) but your patch isn't preventing LLDB > from doing it. I think what Jim and I are asking for is a solution where the > atomic sequences are handled on host side so we either ensure that we don't > set a breakpoint inside them or gracefully handle the continuing from them > (with removing the breakpoint and only putting it back after the "SC" > succeeded in the next iteration). > >> Similarly when doing assembly level debugging of an atomic sequence if we >> step only 1 instruction (as we are debugging assembly code) > >> we will end up putting breakpoint on next instruction (within atomic >> sequence) and will cause "SC" to fail because of reason mentioned above. > > > I expect that if somebody debug some atomic instruction sequences at assemply > level then they will know about the behavior of LL and SC and they will work > around the limitation with putting a breakpoint after SC to exit the loop > around the atomic sequence. For me as a user it would be worrying if an > instruction single step steps more then 1 actual instruction. Additionally we > can add a new step command what steps out from an atomic sequence if there is > user need for it. > >> That means an atomic sequence, starting with LL and ending with SC needs to >> be treated as a "single instruction block". > > > Agree, but I think we should do it on the host side. > > > Repository: > rL LLVM > > http://reviews.llvm.org/D17535 > > > _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
