[Snippets] Fixed handling of Parameters with 1D shapes in SplitDimensionM pass (#29573)

### Details:
- *Fixed handling of `Parameters` with 1D shapes in `SplitDimensionM`
pass. No need to insert `Reshape` op on input with 1D shape since `M`
dimension has index `1` from the end.*

### Tickets:
 - *149846*

Author: a-sidorova

src/common/snippets/include/snippets/pass/split_dimension_m.hpp

@@ -82,9 +82,14 @@ class SplitDimensionM: public CommonOptimizations::SubgraphPass {
 
     void reshape_subgraph(const std::shared_ptr<op::Subgraph>& subgraph, const ov::Shape& shape, size_t batch_m_dim, size_t new_m_dim);
 
+    static size_t get_dim_M(const ov::Shape& shape) {
+        return *(shape.rbegin() + dim_M_index);
+    }
+
     size_t m_concurrency;
 
     static const size_t min_kernel_m;
+    static const size_t dim_M_index;
 };
 } // namespace pass
 } // namespace snippets

src/common/snippets/src/pass/split_dimension_m.cpp

@@ -8,9 +8,6 @@
 #include "snippets/utils/utils.hpp"
 
 namespace {
-size_t get_dim_M(const ov::Shape& shape) {
-    return *(shape.rbegin() + 1);
-}
 bool is_prime_number(size_t value) {
     if (ov::snippets::utils::one_of(value, 2lu, 3lu)) return true;
     if (value == 1 || value % 2 == 0 || value % 3 == 0) return false;
@@ -28,6 +25,7 @@ namespace snippets {
 namespace pass {
 
 const size_t SplitDimensionM::min_kernel_m = 32;
+const size_t SplitDimensionM::dim_M_index = 1;
 
 bool SplitDimensionM::is_supported_matmul(const std::shared_ptr<const ov::Node>& node) {
     const auto matmul = ov::as_type_ptr<const ov::op::v0::MatMul>(node);
@@ -113,13 +111,15 @@ std::vector<size_t> SplitDimensionM::get_updated_order(const std::vector<size_t>
 }
 
 ov::snippets::VectorDims SplitDimensionM::reshape_m_dim(ov::snippets::VectorDims shape, size_t m_index, size_t batch_m_dim, size_t new_m_dim) {
+    OPENVINO_ASSERT(m_index < shape.size(), "Incorrect M index: it should be less than target shape rank");
     if (shape[m_index] == 1)
         return unsqueeze_m_dim(std::move(shape), m_index);
     shape[m_index] = new_m_dim;
     shape.insert(shape.begin() + m_index, batch_m_dim);
     return shape;
 }
 ov::snippets::VectorDims SplitDimensionM::unsqueeze_m_dim(ov::snippets::VectorDims shape, size_t m_index) {
+    OPENVINO_ASSERT(m_index < shape.size(), "Incorrect M index: it should be less than target shape rank");
     shape.insert(shape.begin() + m_index, 1);
     return shape;
 }
@@ -194,6 +194,7 @@ void SplitDimensionM::reshape_subgraph(const std::shared_ptr<op::Subgraph>& subg
     };
 
     auto get_updated_shape = [&](const ov::snippets::VectorDims& shape, size_t m_index, bool split_m_dim) {
+        OPENVINO_ASSERT(m_index < shape.size(), "Dimension index must be less than shape rank");
         const auto current_m_dim = shape[m_index];
         OPENVINO_ASSERT(!split_m_dim || current_m_dim == 1 || current_m_dim == m_dim, "Incorrect shape for splitting!");
         const auto new_shape = split_m_dim ? reshape_m_dim(shape, m_index, batch_m_dim, new_m_dim) : unsqueeze_m_dim(shape, m_index);
@@ -205,7 +206,8 @@ void SplitDimensionM::reshape_subgraph(const std::shared_ptr<op::Subgraph>& subg
         const auto order_constant = ov::as_type_ptr<ov::op::v0::Constant>(transpose->get_input_node_shared_ptr(1));
         OPENVINO_ASSERT(order_constant != nullptr, "Transpose must have Constant order");
         const auto order = order_constant->cast_vector<size_t>();
-        const auto m_index = is_input ? order[order.size() - 2] : order.size() - 2;  // Index of M dimension in the previous order
+        const auto forward_index = order.size() - 1 - dim_M_index;
+        const auto m_index = is_input ? order[forward_index] : forward_index;  // Index of M dimension in the previous order
         const auto new_order = get_updated_order(order, m_index);
         transpose->set_argument(1, std::make_shared<ov::op::v0::Constant>(order_constant->get_element_type(), ov::Shape{new_order.size()}, new_order));
         return m_index;
@@ -217,9 +219,13 @@ void SplitDimensionM::reshape_subgraph(const std::shared_ptr<op::Subgraph>& subg
             return;
 
         const auto shape = param->get_partial_shape().get_shape();
+        // if the index of dimension M is equal or greater than Shape rank, no need to reshape it.
+        if (shape.size() <= dim_M_index)
+            return;
+
         const auto consumers = param->get_output_target_inputs(0);
         const auto shared_consumer = consumers.begin()->get_node()->shared_from_this();
-        auto m_index = shape.size() - 2;
+        auto m_index = shape.size() - 1 - dim_M_index;
         if (ov::is_type<ov::op::v1::Transpose>(shared_consumer)) {
             m_index = reshape_transpose(shared_consumer, true);
         }

src/common/snippets/tests/src/pass/mha_tokenization.cpp

@@ -240,6 +240,16 @@ TEST_F(TokenizeMHASnippetsTests, smoke_Snippets_MHASelect_SplitM) {
     run();
 }
 
+TEST_F(TokenizeMHASnippetsTests, smoke_Snippets_MHASelect_SplitM_ScalarParams) {
+    const auto& f = MHASelectSplitMFunction(std::vector<PartialShape>{{8, 512, 18}, {8, 18, 64}, {1}, {64}, {8, 64, 512}},
+                                            std::vector<Shape>{{8, 2, 256, 18}, {8, 1, 18, 64}, {}, {},
+                                                               {8, 1, 64, 512}, {8, 512, 512}});
+    model = f.getOriginal();
+    model_ref = f.getReference();
+    config.set_concurrency(16);
+    run();
+}
+
 TEST_F(TokenizeMHASnippetsTests, smoke_Snippets_MHA_Reshape_extraction) {
     const auto& f = MHAWithExtractedReshapeFunction(std::vector<PartialShape>{{400, 196, 80},
                                                                               {400, 80, 196},

src/tests/ov_helpers/ov_snippets_models/src/subgraph_mha.cpp

@@ -471,7 +471,10 @@ std::shared_ptr<ov::Model> MHASelectSplitMFunction::initReference() const {
     auto param2 = std::make_shared<ov::opset1::Parameter>(precision, input_shapes[4]);
     ov::ParameterVector ngraphParam = {param0, param1, addParam, selectParam, param2};
 
-    auto make_reshape = [](const std::shared_ptr<ov::Node>& node, const ov::Shape& new_shape) {
+    auto make_reshape = [](const std::shared_ptr<ov::Node>& node, const ov::Shape& new_shape) -> std::shared_ptr<ov::Node> {
+        if (new_shape.empty()) {
+            return node;
+        }
         auto shape_const = ov::op::v0::Constant::create(ov::element::i32, {new_shape.size()}, new_shape);
         return std::make_shared<ov::op::v1::Reshape>(node, shape_const, true);
     };