Benchmark special vector case in GEMV

tests/tensor/test_blas_c.py

@@ -413,6 +413,32 @@ class TestBlasStridesC(TestBlasStrides):
     mode = mode_blas_opt
 
 
+def test_gemv_vector_dot_perf(benchmark):
+    n = 400_000
+    a = pt.vector("A", shape=(n,))
+    b = pt.vector("x", shape=(n,))
+
+    out = CGemv(inplace=True)(
+        pt.empty((1,)),
+        1.0,
+        a[None],
+        b,
+        0.0,
+    )
+    fn = pytensor.function([a, b], out, accept_inplace=True, trust_input=True)
+
+    rng = np.random.default_rng(430)
+    test_a = rng.normal(size=n)
+    test_b = rng.normal(size=n)
+
+    np.testing.assert_allclose(
+        fn(test_a, test_b),
+        np.dot(test_a, test_b),
+    )
+
+    benchmark(fn, test_a, test_b)
+
+
 @pytest.mark.parametrize(
     "neg_stride1", (True, False), ids=["neg_stride1", "pos_stride1"]
 )