Yes - once the undefined behavior has happened, the compiler can dispense with everything else, so if it can prove that your after-the-fact checks can only happen in case of signed overflow, it can simply omit them. Great fun.
Dr Hipp landed https://www.sqlite.org/src/info/db3ebd7c52cfc5fc , which is basically what you suggested. I also see that some systems include __builtin_mul_overflow() intrinsics, which can use the CPU's overflow flag, if available, which seems plausible. -scott On Tue, Sep 20, 2016 at 4:51 PM, Bernardo Sulzbach <mafagafogiga...@gmail.com> wrote: > In time, ignore my previous reply to this thread as SQLite portability > requirements make it invalid (at least I think they would). According to the > C language standard, signed overflow is undefined behavior and, therefore, > should not be relied upon. > > There is also a simpler way to check it using a division of the maximum > possible value by the multiplier (which will never overflow). > > > -- > Bernardo Sulzbach > http://www.mafagafogigante.org/ > mafagafogiga...@mafagafogigante.org > _______________________________________________ > sqlite-users mailing list > sqlite-users@mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
