Move the closure of the subset of flang/runtime/*.h header files that
are referenced by source files outside flang/runtime (apart from unit tests)
into a new directory (flang/include/flang/Runtime) so that relative
include paths into ../runtime need not be used.
flang/runtime/pgmath.h.inc is moved to flang/include/flang/Evaluate;
it's not used by the runtime.
Differential Revision: https://reviews.llvm.org/D109107
Define an API for the transformational intrinsic function MATMUL,
implement it, and add some basic unit tests. The large number of
possible argument type combinations are covered by a set of
generalized templates that are instantiated for each valid
pair of possible argument types.
Places where BLAS-2/3 routines could be called for acceleration
are marked with TODOs. Handling for other special cases (e.g.,
known-shape 3x3 matrices and vectors) are deferred.
Some minor tweaks were made to the recent related implementation
of DOT_PRODUCT to reflect lessons learned.
Differential Revision: https://reviews.llvm.org/D102652