A new algorithm for identification of a SCoP statement that implement a matrix

multiplication

The current identification of a SCoP statement that implement a matrix
multiplication does not help to identify different permutations of loops that
contain it and check for dependencies, which can prevent it from being
optimized. It also requires external determination of the operands of
the matrix multiplication. This patch contains the implementation of a new
algorithm that helps to avoid these issues. It also modifies the test cases
that generate matrix multiplications with linearized accesses, because
the new algorithm does not support them.

Reviewed-by: Michael Kruse <llvm@meinersbur.de&gt;,>
             Tobias Grosser <tobias@grosser.es>

Differential Revision: https://reviews.llvm.org/D28357

llvm-svn: 293890