expand dtype support

mlx/safetensor.cpp

@@ -16,6 +16,8 @@ Token Tokenizer::getToken() {
   if (!this->hasMoreTokens()) {
     return Token{TOKEN::NULL_TYPE};
   }
+  // loc is not that important here, but need to increment location
+  // so might as well do it all in one line
   switch (nextChar) {
     case '{':
       return Token{TOKEN::CURLY_OPEN, ++this->_loc};
@@ -34,7 +36,7 @@ Token Tokenizer::getToken() {
       while (_data[++this->_loc] != '"' && this->hasMoreTokens())
         ;
       if (!this->hasMoreTokens()) {
-        throw new std::runtime_error("no more chars to parse");
+        throw std::runtime_error("no more chars to parse");
       }
       return Token{TOKEN::STRING, start, ++this->_loc};
     }
@@ -46,7 +48,7 @@ Token Tokenizer::getToken() {
         nextChar = this->_data[++this->_loc];
       }
       if (!this->hasMoreTokens()) {
-        throw new std::runtime_error("no more chars to parse");
+        throw std::runtime_error("no more chars to parse");
       }
       return Token{TOKEN::NUMBER, start, this->_loc};
     }
@@ -95,7 +97,6 @@ JSONNode parseJson(const char* data, size_t len) {
             return *obj;
           }
           if (ctx.top()->is_type(JSONNode::Type::STRING)) {
-            // key is above
             auto key = ctx.top();
             ctx.pop();
             if (ctx.top()->is_type(JSONNode::Type::OBJECT)) {
@@ -159,11 +160,42 @@ JSONNode parseJson(const char* data, size_t len) {
         break;
     }
   }
-  throw std::runtime_error("[unreachable] invalid json");
+  throw std::runtime_error(
+      "[parseJson] json was invalid and could not be parsed");
 }
 
 } // namespace io
 
+Dtype dtype_from_safe_tensor_str(std::string str) {
+  if (str == ST_F32) {
+    return float32;
+  } else if (str == ST_F16) {
+    return float16;
+  } else if (str == ST_BF16) {
+    return bfloat16;
+  } else if (str == ST_I64) {
+    return int64;
+  } else if (str == ST_I32) {
+    return int32;
+  } else if (str == ST_I16) {
+    return int16;
+  } else if (str == ST_I8) {
+    return int8;
+  } else if (str == ST_U64) {
+    return uint64;
+  } else if (str == ST_U32) {
+    return uint32;
+  } else if (str == ST_U16) {
+    return uint16;
+  } else if (str == ST_U8) {
+    return uint8;
+  } else if (str == ST_BOOL) {
+    return bool_;
+  } else {
+    throw std::runtime_error("[safetensor] unsupported dtype " + str);
+  }
+}
+
 /** Load array from reader in safetensor format */
 std::unordered_map<std::string, array> load_safetensor(
     std::shared_ptr<io::Reader> in_stream,
@@ -185,12 +217,13 @@ std::unordered_map<std::string, array> load_safetensor(
   char json[jsonHeaderLength];
   in_stream->read(json, jsonHeaderLength);
   auto metadata = io::parseJson(json, jsonHeaderLength);
+  // Should always be an object on the top-level
   if (!metadata.is_type(io::JSONNode::Type::OBJECT)) {
     throw std::runtime_error(
         "[load_safetensor] Invalid json metadata " + in_stream->label());
   }
   size_t offset = jsonHeaderLength + 8;
-  // Parse the json raw data
+  // Load the arrays using metadata
   std::unordered_map<std::string, array> res;
   for (auto& [key, obj] : *metadata.getObject()) {
     std::string dtype = obj->getObject()->at("dtype")->getString();
@@ -204,7 +237,7 @@ std::unordered_map<std::string, array> load_safetensor(
     for (const auto& offset : *data_offsets) {
       data_offsets_vec.push_back(offset->getNumber());
     }
-    if (dtype == "F32") {
+    Dtype type = dtype_from_safe_tensor_str(dtype);
     auto loaded_array = array(
         shape_vec,
         float32,
@@ -217,10 +250,6 @@ std::unordered_map<std::string, array> load_safetensor(
         std::vector<array>{});
     res.insert({key, loaded_array});
   }
-  }
-  // for (auto& [key, arr] : res) {
-  //   arr.eval();
-  // }
   return res;
 }
 

mlx/safetensor.h

@@ -9,7 +9,26 @@
 
 namespace mlx::core {
 
+#define ST_F16 "F16"
+#define ST_BF16 "BF16"
+#define ST_F32 "F32"
+
+#define ST_BOOL "BOOL"
+#define ST_I8 "I8"
+#define ST_I16 "I16"
+#define ST_I32 "I32"
+#define ST_I64 "I64"
+#define ST_U8 "U8"
+#define ST_U16 "U16"
+#define ST_U32 "U32"
+#define ST_U64 "U64"
+
 namespace io {
+// NOTE: This json parser is a bare minimum implementation for safetensors,
+// it does not support all of json features, and does not have alot of edge case
+// catches. This is okay as safe tensor json is very simple and we can assume it
+// is always valid and well formed, but this should not be used for general json
+// parsing
 class JSONNode;
 using JSONObject = std::unordered_map<std::string, JSONNode*>;
 using JSONList = std::vector<JSONNode*>;