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Re: define MMX/SSE intrinsics without requiring cmdline isa flags
On Thu, 19 Aug 2010, Michael Meissner wrote:
> One of the concerns when I did the original work 2 years ago to add target
> support was if the compiler adds all of the builtins, it makes the compiler
> slower at startup because it has to create all of those extra functions (both
> time to create and more importantly, memory requirements for those functions).
As long as built-in functions have names starting __builtin_ or __sync_ as
checked by is_builtin_name (there's also a hardcoded __builtin_ check in
c-typeck.c:build_function_call_vec, and one in
c-common.c:disable_builtin_function; the various checks should probably be
centralized) it ought to be possible to create them lazily (if such an
identifier is encountered and hasn't been declared, allow the back end to
work out what to declare with that name). And addition of new target
built-ins whose names do not match that pattern should be strongly
deprecated.
--
Joseph S. Myers
joseph@codesourcery.com