TP: enable tensor split for LFM2/LFM2MOE (#26993)

Assisted-by: deepseek-v4-flash

src/llama-arch.cpp

@@ -1062,8 +1062,6 @@ bool llm_arch_supports_sm_tensor(const llm_arch & arch) {
         case LLM_ARCH_NEMOTRON_H:
         case LLM_ARCH_NEMOTRON_H_MOE:
         case LLM_ARCH_GRANITE_HYBRID:
-        case LLM_ARCH_LFM2:
-        case LLM_ARCH_LFM2MOE:
         case LLM_ARCH_MINIMAX_01:
         case LLM_ARCH_MINIMAX_M2:
         case LLM_ARCH_MINIMAX_M3:

src/llama-model.cpp

@@ -487,6 +487,10 @@ struct ggml_backend_meta_split_state llama_meta_device_get_split_state(const str
             return get_tensor_config_impl(GGML_BACKEND_SPLIT_AXIS_1, "ssm_out.weight");
         }
         if (std::regex_match(tensor_name, pattern_r_cache) || std::regex_match(tensor_name, pattern_s_cache)) {
+            if (ud->model->arch == LLM_ARCH_LFM2 || ud->model->arch == LLM_ARCH_LFM2MOE) {
+                // the LFM2 shortconv block runs fully mirrored, so its conv state must be mirrored too
+                return get_tensor_config_impl(GGML_BACKEND_SPLIT_AXIS_MIRRORED, "");
+            }
             return get_tensor_config_impl(GGML_BACKEND_SPLIT_AXIS_0, "ssm_out.weight");
         }
         if (std::regex_match(tensor_name, pattern_ssm_conv1d)) {