El 11/05/2011 13:01, Steven Maenhout escribió:
I'm using Boost 1.46 on Linux x86_64 in combination with gcc version 4.5.1. I'm trying to implement a a sparse matrix in a shared memory segment as a vector of maps. When trying to update previously inserted elements of the matrix, at a certain point, the program either crashes or stalls indefinitely. This only occurs if the gcc optimization is set higher than O0. If compiler optimizations are completely turned off (so using the -O0 switch) the program works as expected.
Please try latest trunk code or continue reading. offset_ptr works somewhat outside the standard, since it can point from stack to shared memory and the compiler is allowed to do optimizations that legally break offset_ptr assumptions. The only fix is to disallow some optimizations for offset_ptr set_offset/get_offset code, just like in MSVC. I've inserted some __attribute__((noinline)) in those functions for Boost 1.47. It would be glad if you could me know finding the correct way to make offset_ptr work again in GCC. Maybe we need to insert some asm("") statement to disallow some interprocedual optimizations. Some other relative point implementations, like those used in ACE are not header-only and I think they avoid this kind of problems, although in theory whole-program optimizations can also hurt. Best, Ion