The GCC model for extended instructions like these is that you compile
with -msse3 etc. These affect code generation for whole compilation units,
so the idea is that you have a separate .c file for each instruction set
class and then indirect to the desired one at runtime.
Without e.g. -msse4.1, the GCC built-ins used by <foointrin.h> are not
available. However, in our specific case of compiling with -msse2 and
wanting to use SSE3.1 code, enough built-ins are available that we only
need to provide a little hack for pshufb.
Upgrading this to also use SSE4.1 instructions doesn't appear feasible
without a lot of undesirable duplication of GCC built-in functions and
headers, so we'd probably have to move to the GCC model of separate
source files for that.
git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@6014 8ced0084-cf51-0410-be5f-012b33b47a6e
824b509d2e