New update.

* Removed other checkings of empty blas.ldflags in blas.py and test_blas.py. * Correction in alt_gemm_template.c to prevent some test failures in test_blas.py (occuring after above modification): in some tests, a zero-content matrix is passed as C (with M*N == 0). Now if we encounter this case, we just skip it (gemm not calculated, C not modified). * Correction in blas_headers.py to prevent some old string- formating errors when strings are C code containing "%" symbols. Now test_blas.py runs perfectly. I have to re-run all other tests tonight.

New update.
70896325 · notoraptor · 24f96fa8 · 70896325 · 70896325 · 70896325
--- a/theano/tensor/alt_gemm_template.c
+++ b/theano/tensor/alt_gemm_template.c
@@ -73,7 +73,12 @@ void %(name)s(
    const %(float_type)s* ALPHA, %(float_type)s* A, const int* LDA, 
    %(float_type)s* B, const int* LDB, const %(float_type)s* BETA, 
    %(float_type)s* C, const int* LDC) {
-    if(*M < 0 || *N < 0 || *K < 0 || *LDA < 0 || *LDB < 0 || *LDC < 0)
+    /* NB: it seems that matrix+matrix and scalar*matrix functions
+     * defined above do not allocate iterator for a matrix with 0
+     * content, that is a matrix whose nrow*ncol == 0. As these
+     * functions actually work with M*N matrices (op(A)*op(B) and/or C),
+     * I think that we could just return if M or N is null. */
+    if(*M < 1 || *N < 1 || *K < 0 || *LDA < 0 || *LDB < 0 || *LDC < 0)
        return;
    int nrowa, ncola, nrowb, ncolb;
    int is_A_transposable = alt_trans_to_bool(TRANSA);

--- a/theano/tensor/blas.py
+++ b/theano/tensor/blas.py
@@ -1037,10 +1037,7 @@ class Gemm(GemmRelated):
        if node.inputs[0].type.dtype.startswith('complex'):
            raise utils.MethodNotDefined('%s.c_code'
                                         % self.__class__.__name__)
-        if not config.blas.ldflags:
-            return super(Gemm, self).c_code(node, name,
-                                            (_z, _a, _x, _y, _b), (_zout, ),
-                                            sub)
+        # if not config.blas.ldflags: # return super(Gemm, self).c_code(node, name, (_z, _a, _x, _y, _b), (_zout, ), sub)
        full_code = self.build_gemm_call() % dict(locals(), **sub)
        return full_code

@@ -2154,9 +2151,7 @@ class BatchedDot(Op):
        _z, = out
        fail = sub["fail"]

-        if not config.blas.ldflags:
-            return super(BatchedDot, self).c_code(node, name,
-                                                  inp, out, sub)
+        # if not config.blas.ldflags: # return super(BatchedDot, self).c_code(node, name, inp, out, sub)

        # generate contiguity condition
        def contiguous(var, ndim):

--- a/theano/tensor/blas_headers.py
+++ b/theano/tensor/blas_headers.py
@@ -985,8 +985,7 @@ def blas_header_text():
                    }
                    """)

-    header += gemm_code
-    return header % {'const': const}
+    return (header % {'const': const}) + gemm_code


 def mkl_threads_text():

--- a/theano/tensor/tests/test_blas.py
+++ b/theano/tensor/tests/test_blas.py
@@ -95,7 +95,8 @@ class t_gemm(TestCase):

            cmp_linker(copy(z), a, x, y, b, 'c|py')
            cmp_linker(copy(z), a, x, y, b, 'py')
-            if (config.blas.ldflags and not dtype.startswith("complex")
+            # if (config.blas.ldflags and not dtype.startswith("complex")
+            if (not dtype.startswith("complex")
                and theano.config.cxx):
                # If blas.ldflags is equal to '', the C code will not
                # be generated