Hello, We are using GCC 3.3.1 and have a requirement imposed upon us by our customer to "...establish that the C++ compiler implements dynamic binding by utilizing static lookup tables..." This implies the need for documentation on GCC's implementation of dynamic dispatch, which is typically achieved in "most compilers" through static vtables. At the GCC site (http://gcc.gnu.org/onlinedocs/gcc-3.3.1/gcc/Vague-Linkage.html#Vague-Li nkage), the manual for our compiler states: =========== Vtables C++ virtual functions are implemented in most compilers using a lookup table, known as a vtable. The vtable contains pointers to the virtual functions provided by a class, and each object of the class contains a pointer to its vtable (or vtables, in some multiple-inheritance situations). If the class declares any non-inline, non-pure virtual functions, the first one is chosen as the "key method" for the class, and the vtable is only emitted in the translation unit where the key method is defined. Note: If the chosen key method is later defined as inline, the vtable will still be emitted in every translation unit which defines it. Make sure that any inline virtuals are declared inline in the class body, even if they are not defined there. =========== The best we have here is an inference that the 3.3.1 compiler uses lookup tables (note the term "most compilers"), and no indication at all re whether they are static in size and content. The C++ FAQ site (http://www.parashift.com/c++-faq-lite/virtual-functions.html#faq-20.4) implies that "most C++ compilers" use a scheme similar to the one presented on that page, i.e., that the v-tables are created at compile time, and are static in size and content. The only run-time (dynamic) aspect is the initialization of the v-pointer in the class constructor. Is there any information available which documents, or can it be otherwise officially confirmed, that GCC uses static v-tables? Regards, Greg Lacefield Principal Software Engineer Honeywell CommNav Engineering Aerospace -- Redmond 15001 NE 36th Street, M/S B13E Redmond, Washington 98052 (425) 376-2353 office (425) 647-5281 mobile (425) 885-8319 fax mailto:greg.lacefield@xxxxxxxxxxxxx
