8 ms·

This sounds interesting - thank you! We need to interoperate with C++ - so we couldn't use this, could we? We could add this pointer to our own frames but C++

This sounds interesting - thank you! We need to interoperate with C++ - so we couldn't use this, could we? We could add this pointer to our own frames but C++ frames won't have this info - so I'm not sure how they would interoperate. We need to be able to throw an exception and invoke both Clasp frame cleanups and C++ frame cleanups up the stack. We have a crazy mix of C++ and CL frames on the stack at any time.

gumby 7y ago
Sure you could. You presumably already have a mechanism for doing frame unwinding either via compatibility with the C++ runtime's throw() implementation or by supplying your own. So for your own stack frames you can do what you like. Exceptions raised by c++ code called from lisp would also work the same way as they do now. And when you are unwinding a lisp->C++ boundary (that is, lisp code called by a C++ function) you are free to do what you like until you get to the first Lisp frame; if it doesn't have an unwind-protect then its "ignore me" pointer just points up to its caller, which is examined by the C++ runtime anyway. The nice part of that second paragraph is that if that first lisp callee was called by a non-c++ function (say a fortran function) you might even have an opportunity to set the "parent frame for inspection pointer" to skip over all the fortran frames and point directly to the lowest C++ function below you...which you could manage via a small change to gold or llvm-ld.