Repository: ggml-org/llama.cpp
Pull request: llama-quant: add support for mmproj

This PR allows `llama-quantize` to work with mmproj. It should allow quantizing mmproj to Qx_K and Qx_0 variants (no imatrix), reducing memory usage on mobile deployments.

Tested with https://huggingface.co/Qwen/Qwen2-VL-7B-Instruct

To quantize the mmproj:

```
llama-quantize mmproj-model-f16.gguf mmproj-model-Q4_K_M.gguf Q4_K_M
```

Then, use it as usual:

```
llama-mtmd-cli -m language_model.gguf --mmproj mmproj-model-Q4_K_M.gguf
```

Ref discussion: https://github.com/ggml-org/llama.cpp/discussions/15453

Changed files:
filename: src/llama-arch.cpp
patch: @@ -5,6 +5,7 @@
 #include <map>
 
 static const std::map<llm_arch, const char *> LLM_ARCH_NAMES = {
+    { LLM_ARCH_CLIP,             "clip"             }, // dummy, only used by llama-quantize
     { LLM_ARCH_LLAMA,            "llama"            },
     { LLM_ARCH_LLAMA4,           "llama4"           },
     { LLM_ARCH_DECI,             "deci"             },
@@ -275,6 +276,10 @@ static const std::map<llm_kv, const char *> LLM_KV_NAMES = {
 };
 
 static const std::map<llm_arch, std::map<llm_tensor, const char *>> LLM_TENSOR_NAMES = {
+    {
+        LLM_ARCH_CLIP,
+        {},
+    },
     {
         LLM_ARCH_LLAMA,
         {

filename: src/llama-arch.h
patch: @@ -9,6 +9,7 @@
 //
 
 enum llm_arch {
+    LLM_ARCH_CLIP,
     LLM_ARCH_LLAMA,
     LLM_ARCH_LLAMA4,
     LLM_ARCH_DECI,

filename: src/llama-model.cpp
patch: @@ -478,7 +478,8 @@ void llama_model::load_hparams(llama_model_loader & ml) {
     ml.get_key(LLM_KV_GENERAL_NAME, name, false);
 
     // everything past this point is not vocab-related
-    if (hparams.vocab_only) {
+    // for CLIP models, we only need to load tensors, no hparams
+    if (hparams.vocab_only || ml.get_arch() == LLM_ARCH_CLIP) {
         return;
     }
 
@@ -20013,6 +20014,7 @@ int32_t llama_n_head(const llama_model * model) {
 llama_rope_type llama_model_rope_type(const llama_model * model) {
     switch (model->arch) {
         // these models do not use RoPE
+        case LLM_ARCH_CLIP:
         case LLM_ARCH_GPT2:
         case LLM_ARCH_GPTJ:
         case LLM_ARCH_MPT:

filename: src/llama-quant.cpp
patch: @@ -701,6 +701,7 @@ static void llama_model_quantize_impl(const std::string & fname_inp, const std::
         });
     }
 
+    bool is_clip_model = false;
     for (const auto * it : tensors) {
         const struct ggml_tensor * tensor = it->tensor;
 
@@ -714,12 +715,14 @@ static void llama_model_quantize_impl(const std::string & fname_inp, const std::
         } else if (name == LLM_TN(model.arch)(LLM_TENSOR_OUTPUT, "weight")) {
             qs.has_output = true;
         }
+
+        is_clip_model |= name.rfind("mm.", 0) == 0; // check the "mm." prefix
     }
 
     qs.n_ffn_down = qs.n_ffn_gate = qs.n_ffn_up = (int)model.hparams.n_layer;
 
     // sanity checks for models that have attention layers
-    if (qs.n_attention_wv != 0)
+    if (qs.n_attention_wv != 0 && !is_clip_model)
     {
         const auto & n_head_kv_iter = model.hparams.n_head_kv_arr.begin();
         // attention layers have a non-zero number of kv heads
@@ -881,6 +884,9 @@ static void llama_model_quantize_impl(const std::string & fname_inp, const std::
         // do not quantize relative position bias (T5)
         quantize &= name.find("attn_rel_b.weight") == std::string::npos;
 
+        // do not quantize specific multimodal tensors
+        quantize &= name.find(".position_embd.") == std::string::npos;
+
         ggml_type new_type;
         void * new_data;
         size_t new_size;

filename: src/llama.cpp
patch: @@ -124,6 +124,9 @@ static int llama_model_load(const std::string & fname, std::vector<std::string>
         } catch(const std::exception & e) {
             throw std::runtime_error("error loading model hyperparameters: " + std::string(e.what()));
         }
+        if (model.arch == LLM_ARCH_CLIP) {
+            throw std::runtime_error("CLIP cannot be used as main model, use it with --mmproj instead");
+        }
         try {
             model.load_vocab(ml);
         } catch(const std::exception & e) {