> On Jan 24, 2018, at 4:14 PM, Zachary Turner <ztur...@google.com> wrote: > > That's true, but shouldn't it be possible to demangle up until the last point > you got something meaningful? (I don't know the details of itanium mangling, > just assuming this is possible)
anywhere you cut the string many things can go wrong. I think this would fall under the "start to demangle the string and if the output buffer goes over a certain length, abort the demangling which is solution #4 from my original email. > > On Wed, Jan 24, 2018 at 3:54 PM Greg Clayton <clayb...@gmail.com > <mailto:clayb...@gmail.com>> wrote: > If you just cut off the string, then it might not demangle without an error > if you truncate the mangled string at a specific point... > >> On Jan 24, 2018, at 3:52 PM, Zachary Turner <ztur...@google.com >> <mailto:ztur...@google.com>> wrote: >> >> What about doing a partial demangle? Take at most 1024 (for example) >> characters from the mangled name, demangle that, and then display ... at the >> end. >> >> On Wed, Jan 24, 2018 at 3:48 PM Greg Clayton via lldb-dev >> <lldb-dev@lists.llvm.org <mailto:lldb-dev@lists.llvm.org>> wrote: >> I have an issue where I am debugging a C++ binary that is around 250MB in >> size. It contains some mangled names that are crazy: >> >> _ZNK3shk6detail17CallbackPublisherIZNS_5ThrowERKNSt15__exception_ptr13exception_ptrEEUlOT_E_E9SubscribeINS0_9ConcatMapINS0_18CallbackSubscriberIZNS_6GetAllIiNS1_IZZNS_9ConcatMapIZNS_6ConcatIJNS1_IZZNS_3MapIZZNS_7IfEmptyIS9_EEDaS7_ENKUlS6_E_clINS1_IZZNS_4TakeIiEESI_S7_ENKUlS6_E_clINS1_IZZNS_6FilterIZNS_9ElementAtEmEUlS7_E_EESI_S7_ENKUlS6_E_clINS1_IZZNSL_ImEESI_S7_ENKUlS6_E_clINS1_IZNS_4FromINS0_22InfiniteRangeContainerIiEEEESI_S7_EUlS7_E_EEEESI_S6_EUlS7_E_EEEESI_S6_EUlS7_E_EEEESI_S6_EUlS7_E_EEEESI_S6_EUlS7_E_EESI_S7_ENKUlS6_E_clIS14_EESI_S6_EUlS7_E_EERNS1_IZZNSH_IS9_EESI_S7_ENKSK_IS14_EESI_S6_EUlS7_E0_EEEEESI_DpOT_EUlS7_E_EESI_S7_ENKUlS6_E_clINS1_IZNS_5StartIJZNS_4JustIJS19_S1C_EEESI_S1F_EUlvE_ZNS1K_IJS19_S1C_EEESI_S1F_EUlvE0_EEESI_S1F_EUlS7_E_EEEESI_S6_EUlS7_E_EEEESt6vectorIS6_SaIS6_EERKT0_NS_12ElementCountEbEUlS7_E_ZNSD_IiS1Q_EES1T_S1W_S1X_bEUlOS3_E_ZNSD_IiS1Q_EES1T_S1W_S1X_bEUlvE_EES1G_S1O_E25ConcatMapValuesSubscriberEEEDaS7_ >> >> This de-mangles to something that is 72MB in size and takes 280 seconds (try >> running "time c++filt -n" on the above string). >> >> There are probably many symbols likes this in this binary. Currently lldb >> will de-mangle all names in the symbol table so that we can chop up the >> names so we know function base names and we might be able to classify a base >> name as a method or function for breakpoint categorization. >> >> My questions is: how do we work around such issues in LLDB? A few solutions >> I can think of: >> 1 - time each name demangle and if it takes too long somehow stop >> de-mangling similar symbols or symbols over a certain length? >> 2 - allow a setting that says "don't de-mangle names that start with..." and >> the setting has a list of prefixes. >> 3 - have a setting that turns off de-mangling symbols over a certain length >> all of the time with a default of something like 256 or 512 >> 4 - modify our FastDemangler to abort if the de-mangled string goes over a >> certain limit to avoid bad cases like this... >> >> #1 would still mean we get a huge delay (like 280 seconds) when starting to >> debug this binary, but might prevent multiple symbols from adding to that >> delay... >> >> #2 would require debugging debugging once and then knowing which symbols >> took a while to de-mangle. If we time each de-mangle, we can warn that there >> are large mangled names and print the mangled name so the user might know? >> >> #3 would disable de-mangling of long names at the risk of not de-mangling >> names that are close to the limit >> >> #4 requires that our FastDemangle code can decode the string mangled string. >> The fast de-mangler currently aborts on tricky de-mangling and we fall back >> onto cxa_demangle from the C++ library which doesn't not have a cutoff on >> length... >> >> Can anyone else think of any other solutions? >> >> Greg Clayton >> >> >> >> >> >> >> _______________________________________________ >> lldb-dev mailing list >> lldb-dev@lists.llvm.org <mailto:lldb-dev@lists.llvm.org> >> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev >> <http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev> >
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