* Moritz Strübe: > Hey. > > Am 11.05.2020 um 15:59 schrieb Thomas Neumann via Gcc: >> In a way I am disagreeing with the paper, of course, in that I propose >> to make the existing exception mechanism faster instead of inventing a >> new exception mechanism. But what I agree on with P0709 is that it is >> unfortunate that many projects disable exceptions due to performance >> concerns. And I think the performance problems can be solved. > > I just wanted to point out that Herbceptions do not only fix > performance issues, but also code-size problems. While anything below > 4GB of RAM is considered under-powered for a PC, typical deep embedded > environments have something around 32k of program memory and 2K of > ram. And even those running Linux often have around 32MB program > memory and 8MB of RAM. Also most of these systems are very cost > sensitive, so each byte matters. Therefore RTTI and exceptions are one > of the main reasons why parts of the embedded community consider C++ > unusable: They do some experiments using C++ and the code size > explodes. And even if you know what you are doing and turn interrupts > and RTTI off, adding a std::nothrow to every "new" to do decent error > handling is pretty annoying. Not mentioning the parts of the C++ > library that don't provide exception-free error-handling.
The flag-return proposal has costs as well, especially if applied verbatim without any additional language changes. There won't be large tables, but code size will increase across all non-leaf, noexcept(false) functions. My worry is that the overhead will be enough to deter embedded users, and then we are stuck with a third error handling approach for C++. Thanks, Florian
