From a6853ea2ae7d828e535874e6f2244786921df594 Mon Sep 17 00:00:00 2001
From: Ed Addario <eaddario@hotmail.com>
Date: Thu, 16 Oct 2025 11:20:24 +0100
Subject: [PATCH] Add tensor type and depth heuristics

---
 src/llama-quant.cpp | 94 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 83 insertions(+), 11 deletions(-)

diff --git a/src/llama-quant.cpp b/src/llama-quant.cpp
index 0f256eface..38d20e3d0f 100644
--- a/src/llama-quant.cpp
+++ b/src/llama-quant.cpp
@@ -16,6 +16,7 @@
 #include <thread>
 #include <unordered_map>
 #include <optional>
+#include <unordered_set>
 
 // Quantization types. Changes to this struct must be replicated in quantize.cpp
 struct tensor_quantization {
@@ -685,13 +686,6 @@ static std::unordered_map<std::string, ggml_type> target_bpw_type(
         GGML_TYPE_F16
     };
 
-    const char * important_tensors[] = {
-        ".output.weight",
-        ".attn_output.weight",
-        ".ffn_down.weight",
-        ".ffn_down_shexp.weight"
-    };
-
     constexpr double epsilon = 1e-12;
     constexpr double infinity = std::numeric_limits<double>::infinity();
     constexpr uint32_t file_magic = 0x42505731;  // BPW1
@@ -1544,11 +1538,89 @@ static std::unordered_map<std::string, ggml_type> target_bpw_type(
         return emit_overrides();
     }
 
-    auto is_important = [&](const std::string & tensor_name) -> bool {
-        return std::any_of(std::begin(important_tensors), std::end(important_tensors), [&](const char* imp) {
-                return tensor_name.find(imp) != std::string::npos;
+    auto tensor_importance = [&](const std::vector<tensor_info> & all_vec) -> std::unordered_map<std::string, float> {
+        std::unordered_map<std::string, float> scores;
+        for (const auto & ti : all_vec) {
+            const std::string name = ggml_get_name(ti.w->tensor);
+            float total_score = 0.0f;
+            float depth_score = 0.0f;
+            float type_score = 0.0f;
+
+            // Depth component: output, embeddings & early/late layers are important
+            if (name.find("output.weight") != std::string::npos ||
+                name.find("token_embd.weight") != std::string::npos) {
+                depth_score = 1.0f;
             }
-        );
+            else if (name.find(".attn_output.weight") != std::string::npos) {
+                depth_score = 0.9f;
+            } else {
+                static const std::regex layer_pattern(R"(blk\.(\d+)\.)");
+                std::smatch match;
+                if (std::regex_search(name, match, layer_pattern)) {
+                    const int layer = std::stoi(match[1]);
+                    const float normalized_layer = (float)layer / (float)std::max(1, (int)model.hparams.n_layer - 1);
+                    const float center_dist = std::abs(normalized_layer - 0.5f) * 2.0f;
+                    depth_score = 0.2f + 0.6f * center_dist;
+                }
+            }
+
+            // Type component: certain tensor types are more important
+            if (name.find("output.weight") != std::string::npos) {
+                type_score = 1.0f;
+            } else if (name.find(".attn_output.weight") != std::string::npos) {
+                type_score = 0.9f;
+            } else if (name.find(".ffn_down.weight") != std::string::npos ||
+                       name.find(".ffn_down_shexp.weight") != std::string::npos ||
+                       name.find(".ffn_down_exps.weight") != std::string::npos) {
+                type_score = 0.8f;
+            } else if (name.find(".attn_q.weight") != std::string::npos ||
+                       name.find(".attn_k.weight") != std::string::npos ||
+                       name.find(".attn_v.weight") != std::string::npos ||
+                       name.find(".attn_qkv.weight") != std::string::npos) {
+                type_score = 0.7f;
+            } else if (name.find(".ffn_up.weight") != std::string::npos ||
+                       name.find(".ffn_gate.weight") != std::string::npos ||
+                       name.find(".ffn_up_shexp.weight") != std::string::npos ||
+                       name.find(".ffn_gate_shexp.weight") != std::string::npos ||
+                       name.find(".ffn_up_exps.weight") != std::string::npos ||
+                       name.find(".ffn_gate_exps.weight") != std::string::npos) {
+                type_score = 0.6f;
+            } else if (name.find("token_embd.weight") != std::string::npos) {
+                type_score = 0.5f;
+            }
+
+            // Weighted combination
+            total_score = 0.80f * type_score + 0.20f * depth_score; // 80% type + 20% depth
+            scores[name] = total_score;
+        }
+
+        return scores;
+    };
+
+    auto select_tensors = [&](const std::vector<tensor_info> & all_vec) -> std::unordered_set<std::string> {
+        const auto scores = tensor_importance(all_vec);
+
+        // Sort by score
+        std::vector<std::pair<std::string, float>> sorted_scores(scores.begin(), scores.end());
+        std::sort(sorted_scores.begin(), sorted_scores.end(), [](const auto & a, const auto & b) { return a.second > b.second; });
+
+        // Select top percentile
+        const size_t n_important = std::max<size_t>(1, std::llround((double)sorted_scores.size() * 0.25f)); // top 25%
+
+        std::unordered_set<std::string> important;
+        for (size_t i = 0; i < std::min(n_important, sorted_scores.size()); ++i) {
+            important.insert(sorted_scores[i].first);
+            //LLAMA_LOG_DEBUG("\t%s: important tensor %s (score %.4f)\n", func, sorted_scores[i].first.c_str(), sorted_scores[i].second);
+        }
+
+        LLAMA_LOG_INFO("%s: prioritizing %zu out off %zu tensors\n", func, important.size(), sorted_scores.size());
+        return important;
+    };
+
+    const auto important_set = select_tensors(all);
+
+    auto is_important = [&](const std::string & tensor_name) -> bool {
+        return important_set.count(tensor_name) > 0;
     };
 
     // Lagrangian relaxation to minimise error subject to a bpw target constraint