feat(wasm-c-api): allow not copying the wasm binary into the module

core/iwasm/aot/aot_loader.c

@@ -4065,8 +4065,8 @@ create_sections(AOTModule *module, const uint8 *buf, uint32 size,
 }
 
 static bool
-load(const uint8 *buf, uint32 size, AOTModule *module, char *error_buf,
-     uint32 error_buf_size)
+load(const uint8 *buf, uint32 size, AOTModule *module,
+     bool wasm_binary_freeable, char *error_buf, uint32 error_buf_size)
 {
     const uint8 *buf_end = buf + size;
     const uint8 *p = buf, *p_end = buf_end;
@@ -4090,8 +4090,8 @@ load(const uint8 *buf, uint32 size, AOTModule *module, char *error_buf,
                          error_buf_size))
         return false;
 
-    ret = load_from_sections(module, section_list, true, error_buf,
-                             error_buf_size);
+    ret = load_from_sections(module, section_list, !wasm_binary_freeable,
+                             error_buf, error_buf_size);
     if (!ret) {
         /* If load_from_sections() fails, then aot text is destroyed
            in destroy_sections() */
@@ -4135,7 +4135,8 @@ aot_load_from_aot_file(const uint8 *buf, uint32 size, const LoadArgs *args,
         return NULL;
 
     os_thread_jit_write_protect_np(false); /* Make memory writable */
-    if (!load(buf, size, module, error_buf, error_buf_size)) {
+    if (!load(buf, size, module, args->wasm_binary_freeable, error_buf,
+              error_buf_size)) {
         aot_unload(module);
         return NULL;
     }

core/iwasm/common/wasm_c_api.c

@@ -42,6 +42,8 @@
 typedef struct wasm_module_ex_t {
     struct WASMModuleCommon *module_comm_rt;
     wasm_byte_vec_t *binary;
+    /* If true, binary in wasm_module_ex_t contains a copy of the WASM binary */
+    bool is_binary_cloned;
     korp_mutex lock;
     uint32 ref_count;
 #if WASM_ENABLE_WASM_CACHE != 0
@@ -2234,7 +2236,7 @@ try_reuse_loaded_module(wasm_store_t *store, char *binary_hash)
 #endif /* WASM_ENABLE_WASM_CACHE != 0 */
 
 wasm_module_t *
-wasm_module_new_ex(wasm_store_t *store, const wasm_byte_vec_t *binary,
+wasm_module_new_ex(wasm_store_t *store, wasm_byte_vec_t *binary,
                    const LoadArgs *args)
 {
     char error_buf[128] = { 0 };
@@ -2283,13 +2285,19 @@ wasm_module_new_ex(wasm_store_t *store, const wasm_byte_vec_t *binary,
     if (!module_ex)
         goto quit;
 
-    module_ex->binary = malloc_internal(sizeof(wasm_byte_vec_t));
-    if (!module_ex->binary)
-        goto free_module;
+    module_ex->is_binary_cloned = args->clone_wasm_binary;
+    if (args->clone_wasm_binary) {
+        module_ex->binary = malloc_internal(sizeof(wasm_byte_vec_t));
+        if (!module_ex->binary)
+            goto free_module;
 
-    wasm_byte_vec_copy(module_ex->binary, binary);
-    if (!module_ex->binary->data)
-        goto free_binary;
+        wasm_byte_vec_copy(module_ex->binary, binary);
+        if (!module_ex->binary->data)
+            goto free_binary;
+    }
+    else {
+        module_ex->binary = binary;
+    }
 
     module_ex->module_comm_rt = wasm_runtime_load_ex(
         (uint8 *)module_ex->binary->data, (uint32)module_ex->binary->size, args,
@@ -2328,9 +2336,11 @@ wasm_module_new_ex(wasm_store_t *store, const wasm_byte_vec_t *binary,
 unload:
     wasm_runtime_unload(module_ex->module_comm_rt);
 free_vec:
-    wasm_byte_vec_delete(module_ex->binary);
+    if (args->clone_wasm_binary)
+        wasm_byte_vec_delete(module_ex->binary);
 free_binary:
-    wasm_runtime_free(module_ex->binary);
+    if (args->clone_wasm_binary)
+        wasm_runtime_free(module_ex->binary);
 free_module:
     wasm_runtime_free(module_ex);
 quit:
@@ -2343,7 +2353,9 @@ wasm_module_new(wasm_store_t *store, const wasm_byte_vec_t *binary)
 {
     LoadArgs args = { 0 };
     args.name = "";
-    return wasm_module_new_ex(store, binary, &args);
+    args.clone_wasm_binary = true;
+    args.wasm_binary_freeable = false;
+    return wasm_module_new_ex(store, (wasm_byte_vec_t *)binary, &args);
 }
 
 bool
@@ -2402,7 +2414,8 @@ wasm_module_delete_internal(wasm_module_t *module)
         return;
     }
 
-    DEINIT_VEC(module_ex->binary, wasm_byte_vec_delete);
+    if (module_ex->is_binary_cloned)
+        DEINIT_VEC(module_ex->binary, wasm_byte_vec_delete);
 
     if (module_ex->module_comm_rt) {
         wasm_runtime_unload(module_ex->module_comm_rt);

core/iwasm/include/wasm_c_api.h

@@ -527,16 +527,23 @@ typedef struct WASMModuleCommon *wasm_module_t;
 #define LOAD_ARGS_OPTION_DEFINED
 typedef struct LoadArgs {
     char *name;
+    /* True by default, used by wasm-c-api only.
+    If false, the wasm input buffer (wasm_byte_vec_t) is referenced by the
+    module instead of being cloned. Hence, it can be freed after module loading. */
+    bool clone_wasm_binary;
+    /* False by default, used by wasm-c-api only.
+    If true, the AOT/wasm loader creates a copy of some module fields (e.g. const
+    strings), making it possible to free the wasm binary buffer after loading. */
+    bool wasm_binary_freeable;
     /* TODO: more fields? */
 } LoadArgs;
 #endif /* LOAD_ARGS_OPTION_DEFINED */
 
-WASM_API_EXTERN own wasm_module_t* wasm_module_new(
-  wasm_store_t*, const wasm_byte_vec_t* binary);
+WASM_API_EXTERN own wasm_module_t* wasm_module_new(wasm_store_t*, const wasm_byte_vec_t* binary);
 
 // please refer to wasm_runtime_load_ex(...) in core/iwasm/include/wasm_export.h
 WASM_API_EXTERN own wasm_module_t* wasm_module_new_ex(
-  wasm_store_t*, const wasm_byte_vec_t* binary, const LoadArgs *args);
+  wasm_store_t*, wasm_byte_vec_t* binary, const LoadArgs *args);
 
 WASM_API_EXTERN void wasm_module_delete(own wasm_module_t*);
 

core/iwasm/include/wasm_export.h

@@ -222,6 +222,10 @@ typedef struct RuntimeInitArgs {
 #define LOAD_ARGS_OPTION_DEFINED
 typedef struct LoadArgs {
     char *name;
+    /* This option is only used by the Wasm C API (see wasm_c_api.h) */
+    bool clone_wasm_binary;
+    /* This option is only used by the Wasm C API (see wasm_c_api.h) */
+    bool wasm_binary_freeable;
     /* TODO: more fields? */
 } LoadArgs;
 #endif /* LOAD_ARGS_OPTION_DEFINED */

core/iwasm/interpreter/wasm_loader.c

@@ -6376,8 +6376,8 @@ static union {
 #define is_little_endian() (__ue.b == 1)
 
 static bool
-load(const uint8 *buf, uint32 size, WASMModule *module, char *error_buf,
-     uint32 error_buf_size)
+load(const uint8 *buf, uint32 size, WASMModule *module,
+     bool wasm_binary_freeable, char *error_buf, uint32 error_buf_size)
 {
     const uint8 *buf_end = buf + size;
     const uint8 *p = buf, *p_end = buf_end;
@@ -6405,8 +6405,8 @@ load(const uint8 *buf, uint32 size, WASMModule *module, char *error_buf,
     }
 
     if (!create_sections(buf, size, &section_list, error_buf, error_buf_size)
-        || !load_from_sections(module, section_list, true, error_buf,
-                               error_buf_size)) {
+        || !load_from_sections(module, section_list, !wasm_binary_freeable,
+                               error_buf, error_buf_size)) {
         destroy_sections(section_list);
         return false;
     }
@@ -6582,7 +6582,8 @@ wasm_loader_load(uint8 *buf, uint32 size,
     module->load_size = size;
 #endif
 
-    if (!load(buf, size, module, error_buf, error_buf_size)) {
+    if (!load(buf, size, module, args->wasm_binary_freeable, error_buf,
+              error_buf_size)) {
         goto fail;
     }
 

doc/memory_tune.md

@@ -30,3 +30,4 @@ Normally there are some methods to tune the memory usage:
 - set the app heap size with `wasm_runtime_instantiate`
 - use `nostdlib` mode, add `-Wl,--strip-all`: refer to [How to reduce the footprint](./build_wasm_app.md#2-how-to-reduce-the-footprint) of building wasm app for more details
 - use XIP mode, refer to [WAMR XIP (Execution In Place) feature introduction](./xip.md) for more details
+- when using the Wasm C API, set `clone_wasm_binary=false` and `wasm_binary_freeable=true` in `LoadArgs` and free the wasm binary buffer (with `wasm_byte_vec_delete`) after module loading