Explicitly documented that fact that ICC needs the -mmic flag to compile for KNC.
Updated ISPC User Guide with details on ICC compiler options that impact FP performance in generated code.
In particular, this gives us desired behavior for NaNs (all compares
involving a NaN evaluate to true). This in turn allows writing the
canonical isnan() function as "v != v".
Added isnan() to the standard library as well.
Previously, we were trying to take a uniform seed and then shuffle that
around to initialize the state for each of the program instances. This
was becoming increasingly untenable and brittle.
Now a varying seed is expected and used.
This was unnecessary overhead to impose on all callers; the user
should handle these as needed on their own.
Also added some explanatory text to the documentation that highlights
that memory_barrier() is only needed across HW threads/cores, not
across program instances in a gang.
Now, the pointed-to type is always uniform by default (if an explicit
rate qualifier isn't provided). This rule is easier to remember and
seems to work well in more cases than the previous rule from 6d7ff7eba2.
Now, if a struct member has an explicit 'uniform' or 'varying'
qualifier, then that member has that variability, regardless of
the variability of the struct's variability. Members without
'uniform' or 'varying' have unbound variability, and in turn
inherit the variability of the struct.
As a result of this, now structs can properly be 'varying' by default,
just like all the other types, while still having sensible semantics.
Now, if rate qualifiers aren't used to specify otherwise, varying
pointers point to uniform types by default. As before, uniform
pointers point to varying types by default.
float *foo; // varying pointer to uniform float
float * uniform foo; // uniform pointer to varying float
These defaults seem to require the least amount of explicit
uniform/varying qualifiers for most common cases, though TBD if it
would be easier to have a single rule that e.g. the pointed-to type
is always uniform by default.
