feat: Instantiate hybrid cache for hybrid models (currently none)

This includes a slight architectural change where create_memory now only
uses model architectures in the switch statement if their required cache
type is not handled by llm_arch_is_[recurrent|hybrid].

Branch: HybridCache

Signed-off-by: Gabe Goodhart <ghart@us.ibm.com>

Author: gabe-l-hart

src/llama-model.cpp

@@ -13195,59 +13195,112 @@ llama_memory_i * llama_model::create_memory(const llama_memory_params & params,
     llama_memory_i * res;
 
     switch (arch) {
+        // Models that need specific instantiation should be handled in the
+        // switch statement
         case LLM_ARCH_BERT:
         case LLM_ARCH_JINA_BERT_V2:
         case LLM_ARCH_NOMIC_BERT:
         case LLM_ARCH_NOMIC_BERT_MOE:
             {
                 res = nullptr;
             } break;
-        case LLM_ARCH_MAMBA:
-        case LLM_ARCH_RWKV6:
-        case LLM_ARCH_RWKV6QWEN2:
-        case LLM_ARCH_RWKV7:
-        case LLM_ARCH_ARWKV7:
-            {
-                res = new llama_kv_cache_recurrent(
-                        *this,
-                        nullptr,
-                        GGML_TYPE_F32,
-                        GGML_TYPE_F32,
-                        cparams.offload_kqv,
-                        std::max((uint32_t) 1, cparams.n_seq_max));
-            } break;
+        // Models that need standard caching should rely on recurrent/hybrid
+        // checks
         default:
             {
-                const auto padding = llama_kv_cache_unified::get_padding(cparams);
-
-                cparams.n_ctx = GGML_PAD(cparams.n_ctx, padding);
+                if (llm_arch_is_hybrid(arch)) {
+                    // make vectors of recurrent and non-recurrent layer indices
+                    std::vector<size_t> recurrent_layers;
+                    std::vector<size_t> unified_layers;
+                    for (auto il = 0u; il < hparams.n_layer; ++il) {
+                        if (hparams.recurrent_layer(il)) {
+                            recurrent_layers.push_back(il);
+                        } else {
+                            unified_layers.push_back(il);
+                        }
+                    }
 
-                LLAMA_LOG_DEBUG("%s: n_ctx = %u (padded)\n", __func__, cparams.n_ctx);
+                    const auto padding = llama_kv_cache_unified::get_padding(cparams);
+                    cparams.n_ctx = GGML_PAD(cparams.n_ctx, padding);
+                    LLAMA_LOG_DEBUG("%s: n_ctx = %u (padded)\n", __func__, cparams.n_ctx);
+
+                    // initialize the children
+                    std::vector<llama_kv_cache_hybrid::child_cache> children;
+                    children.emplace_back(
+                        std::unique_ptr<llama_kv_cache>(
+                            new llama_kv_cache_recurrent(
+                                *this,
+                                [&](int32_t il) {
+                                    return hparams.recurrent_layer(il);
+                                },
+                                GGML_TYPE_F32,
+                                GGML_TYPE_F32,
+                                cparams.offload_kqv,
+                                std::max((uint32_t) 1, cparams.n_seq_max))
+                        ),
+                        std::move(recurrent_layers)
+                    );
+                    children.emplace_back(
+                        std::unique_ptr<llama_kv_cache>(
+                            new llama_kv_cache_unified(
+                                *this,
+                                [&](int32_t il) {
+                                    return ! hparams.recurrent_layer(il);
+                                },
+                                params.type_k,
+                                params.type_v,
+                                !cparams.flash_attn,
+                                cparams.offload_kqv,
+                                cparams.n_ctx,
+                                padding,
+                                hparams.n_swa,
+                                hparams.swa_type)
+                        ),
+                        std::move(unified_layers)
+                    );
 
-                if (hparams.n_swa > 0) {
-                    res = new llama_kv_cache_unified_iswa(
-                            *this,
-                            params.type_k,
-                            params.type_v,
-                            !cparams.flash_attn,
-                            cparams.offload_kqv,
-                            cparams.n_ctx,
-                            params.swa_full,
-                            cparams.n_seq_max,
-                            cparams.n_batch,
-                            padding);
-                } else {
-                    res = new llama_kv_cache_unified(
+                    // initialize the hybrid cache with both children
+                    res = new llama_kv_cache_hybrid(hparams, std::move(children));
+                } else if (llm_arch_is_recurrent(arch)) {
+                    res = new llama_kv_cache_recurrent(
                             *this,
                             nullptr,
-                            params.type_k,
-                            params.type_v,
-                            !cparams.flash_attn,
+                            GGML_TYPE_F32,
+                            GGML_TYPE_F32,
                             cparams.offload_kqv,
-                            cparams.n_ctx,
-                            padding,
-                            hparams.n_swa,
-                            hparams.swa_type);
+                            std::max((uint32_t) 1, cparams.n_seq_max));
+                } else {
+                    const auto padding = llama_kv_cache_unified::get_padding(cparams);
+
+                    cparams.n_ctx = GGML_PAD(cparams.n_ctx, padding);
+
+                    LLAMA_LOG_DEBUG("%s: n_ctx = %u (padded)\n", __func__, cparams.n_ctx);
+
+                    if (hparams.n_swa > 0) {
+                        res = new llama_kv_cache_unified_iswa(
+                                *this,
+                                params.type_k,
+                                params.type_v,
+                                !cparams.flash_attn,
+                                cparams.offload_kqv,
+                                cparams.n_ctx,
+                                params.swa_full,
+                                cparams.n_seq_max,
+                                cparams.n_batch,
+                                padding);
+                    } else {
+                        res = new llama_kv_cache_unified(
+                                *this,
+                                nullptr,
+                                params.type_k,
+                                params.type_v,
+                                !cparams.flash_attn,
+                                cparams.offload_kqv,
+                                cparams.n_ctx,
+                                padding,
+                                hparams.n_swa,
+                                hparams.swa_type);
+                    }
                 }
             }
     }