> Right, I didn't look at the details of the uses of > DONT_USE_BUILTIN_SETJMP and JMP_BUF_SIZE but it looks like the ones in > picochip and stormy16 are redundant too: > > For picochip, this port defines DONT_USE_BUILTIN_SETJMP but in the .c > file (and after all #includes), so it is never exported and not > otherwise referenced in picochip.c, hence dead: > config/picochip/picochip.c:#undef DONT_USE_BUILTIN_SETJMP > config/picochip/picochip.c:#define DONT_USE_BUILTIN_SETJMP 1 > > stormy16 only undefines DONT_USE_BUILTIN_SETJMP (which is the default > anyway) so these two lines are redundant: > config/stormy16/stormy16.h:#undef DONT_USE_BUILTIN_SETJMP > config/stormy16/stormy16.h:#define JMP_BUF_SIZE 8
That's my understanding as well. > That leaves only rl78 and ia64: > $ egrep "DONT_USE_BUILTIN_SETJMP|JMP_BUF_SIZE" config/* config/*/* > config/ia64/freebsd.h:#define JMP_BUF_SIZE 76 > config/ia64/hpux.h:#define JMP_BUF_SIZE (8 * 76) > config/ia64/ia64.h:#define DONT_USE_BUILTIN_SETJMP > config/ia64/linux.h:#define JMP_BUF_SIZE 76 > config/ia64/vms.h:#define JMP_BUF_SIZE (8 * 76) > config/rl78/rl78.h:/*#define DONT_USE_BUILTIN_SETJMP 1*/ > config/rl78/rl78.h:#undef DONT_USE_BUILTIN_SETJMP > config/rl78/rl78.h:#define JMP_BUF_SIZE (8*3+8) > > The ia64 ones have no useful comments. The 76 is a magic number and it > seems strange to me that the size of JMP_BUF_SIZE depends on the OS > (linux and freebsd have 76, hpux has 8*76, and vms copied the hpux > example with the comment: "Maybe same as HPUX? Needs to be > checked."). And anyway, these macros are only relevant for SJLJ > exceptions - who uses that on ia64?? It looks like DONT_USE_BUILTIN_SETJMP was invented for the IA-64, probably because of the Register Stack Engine. But SPARC also has register windows, albeit less sophisticated, and can do without it. Morever, the Ada compiler uses __builtin_setjmp/__builtin_longjmp internally on the host (EH is used for error recovery) and is known to work fine on IA-64/Linux, HP-UX and VMS. In the end, it would appear that DONT_USE_BUILTIN_SETJMP was a quick trick to solve specific issues that could very likely have been solved otherwise. We should probably keep it for the sake of IA-64 and get rid of it for all other architectures, documenting that it isn't to be used in normal circumstances. -- Eric Botcazou
