backend: factor out common elements in model code (#1089)

* backend: factor out common structs in model code

prepping to hack on these by hopefully making there be fewer places to fix the same bug

rename

* use common buffer wrapper instead of manual malloc

* fix replit compile warnings

gpt4all-backend/gptj.cpp

@@ -2,6 +2,7 @@
 #include "gptj_impl.h"
 
 #include "utils.h"
+#include "llmodel_shared.h"
 
 #include <cassert>
 #include <cmath>
@@ -63,39 +64,6 @@ struct gptj_layer {
     struct ggml_tensor * c_mlp_proj_b;
 };
 
-struct gptj_buffer {
-    uint8_t * addr = NULL;
-    size_t size = 0;
-
-    void resize(size_t size) {
-        delete[] addr;
-        addr = new uint8_t[size];
-        this->size = size;
-    }
-
-    ~gptj_buffer() {
-        fflush(stdout);
-        delete[] addr;
-    }
-};
-
-struct gptj_kv_cache {
-    struct ggml_tensor * k;
-    struct ggml_tensor * v;
-
-    struct ggml_context * ctx = NULL;
-
-    gptj_buffer buf;
-
-    int n; // number of tokens currently in the cache
-
-    ~gptj_kv_cache() {
-        if (ctx) {
-            ggml_free(ctx);
-        }
-    }
-};
-
 struct gptj_model {
     gptj_hparams hparams;
 
@@ -111,13 +79,13 @@ struct gptj_model {
     std::vector<gptj_layer> layers;
 
     // key + value memory
-    struct gptj_kv_cache kv_self;
+    struct llm_kv_cache kv_self;
 
     //
     struct ggml_context * ctx;
     std::map<std::string, struct ggml_tensor *> tensors;
 
-    gptj_buffer buf;
+    llm_buffer buf;
 
     ~gptj_model() {
         if (ctx) {
@@ -128,7 +96,7 @@ struct gptj_model {
 
 static bool kv_cache_init(
         const struct gptj_hparams & hparams,
-             struct gptj_kv_cache & cache,
+              struct llm_kv_cache & cache,
                          ggml_type   wtype,
                                int   n_ctx) {
     const int n_embd  = hparams.n_embd;