For associative atomic ops (add, and, or, xor), we can take advantage of
their associativity to do just a single hardware atomic instruction,
rather than one for each of the running program instances (as the previous
implementation did.)
The basic approach is to locally compute a reduction across the active
program instances with the given op and to then issue a single HW atomic
with that reduced value as the operand. We then take the old value that
was stored in the location that is returned from the HW atomic op and
use that to compute the values to return to each of the program instances
(conceptually representing the cumulative effect of each of the preceding
program instances having performed their atomic operation.)
Issue #56.
Emit calls to masked_store, not masked_store_blend, when handling
masked stores emitted by the frontend.
Fix bug in binary8to16 macro in builtins.m4
Fix bug in 16-wide version of __reduce_add_float
Remove blend function implementations for masked_store_blend for
AVX; just forward those on to the corresponding real masked store
functions.
Compute a "local" min/max across the active program instances and
then do a single atomic memory op.
Added a few tests to exercise global min/max atomics (which were
previously untested!)
Just pulling out the elements and doing a set of scalar equality tests
is the best approach for those (nearly 2x better than the rotate and
vector equality check that we use for 32-bit stuff).
- Renamed stdlib-sse.ll to builtins-sse.ll (etc.) in an attempt to better indicate
the fact that the stuff in those files has a role beyond implementing stuff for
the standard library.
- Moved declarations of the various __pseudo_* functions from being done with LLVM
API calls in builtins.cpp to just straight up declarations in LLVM assembly
language in builtins.m4. (Much less code to do it this way, and more clear what's
going on.)
