Hi All, I am trying to understand certain EXPR nodes, when they are generated and how code generated from them behaves in the resulting program.
The nodes that have me a little confused are: TRY_CATCH_EXPR TRY_FINALLY_EXPR MUST_NOT_THROW_EXPR EH_FILTER_EXPR Note: I have read the GCC Internals documentation and the documentation in the appropriate .def files for these tree codes. It does not mention the information I am after. TRY_CATCH_EXPR/TRY_FINALLY_EXPR When code generated from these nodes encounter an exception while processing code from operand 0 is there an implicit rethrow of that exception at the end of the block of code given by operand 1 or does it "sink" the exception and only rethrow it if the user specifically requests it (In C++ anyway)? In what situations are these nodes generated? MUST_NOT_THROW_EXPR What sort of code produces one of these nodes? They do not seem to be used for the throw() specifiers for a function (At least in C++) as i would have expected. EH_FILTER_EXPR In what situations are these nodes generated? I assume that the code that these filters applies to is external to the node and if an exception occurs in this external code that does not match any of the types in the EH_FILTER_TYPES list (Do they have to be exact matches/how is type matching done here) then it calls the EH_FILTER_FAILURE which could be for example a call to terminate()? How does the EH_FILTER_MUST_NOT_THROW() macro work? If it returns true then the filter allows NO exceptions and if false then allows only exceptions of type that are in this list? Is it possible for the EH_FILTER_TYPES list to be empty and EH_FILTER_MUST_NOT_THROW() to return false? Thanks for any information on these questions. It will help me a great deal. Brendon.
