Recall: code is tested with:

$ theano-cache purge && THEANO_FLAGS=blas.ldflags= nosetests theano/tensor/nnet/tests/test_abstract_conv.py:TestCorrConv2d

NB:
1) dgemm_ is never called in these tests. Only sgemm_ is called.
2) All LDA,LDB,LDC are always in the set {M;N;K} during these tests.