[wasm] Refactor function name table and lookup

src/wasm/wasm-function-name-table.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/wasm/wasm-function-name-table.h"
 
 #include "src/wasm/wasm-module.h"
 
 namespace v8 {
 namespace internal {
 namespace wasm {
 
 // Build an array with all function names. If there are N functions in the
 // module, then the first (kIntSize * (N+1)) bytes are integer entries.
 // The first integer entry encodes the number of functions in the module.
 // The entries 1 to N contain offsets into the second part of this array.
 // If a function is unnamed (not to be confused with an empty name), then the
 // integer entry is the negative offset of the next function name.
 // After these N+1 integer entries, the second part begins, which holds a
 // concatenation of all function names.
-//
-// Returns undefined if the array length would not fit in an integer value.
-Handle<Object> BuildFunctionNamesTable(Isolate* isolate,
-                                       const WasmModule* module) {
+Handle<ByteArray> BuildFunctionNamesTable(Isolate* isolate,
+                                          const WasmModule* module) {
   uint64_t func_names_length = 0;
   for (auto& func : module->functions) func_names_length += func.name_length;
   int num_funcs_int = static_cast<int>(module->functions.size());
   int current_offset = (num_funcs_int + 1) * kIntSize;
   uint64_t total_array_length = current_offset + func_names_length;
   int total_array_length_int = static_cast<int>(total_array_length);
-  // Check for overflow. Just skip function names if it happens.
-  if (total_array_length_int != total_array_length || num_funcs_int < 0 ||
-      num_funcs_int != module->functions.size())
-    return isolate->factory()->undefined_value();
+  // Check for overflow.
+  CHECK(total_array_length_int == total_array_length && num_funcs_int >= 0 &&
+        num_funcs_int == module->functions.size());
   Handle<ByteArray> func_names_array =
       isolate->factory()->NewByteArray(total_array_length_int, TENURED);
-  if (func_names_array.is_null()) return isolate->factory()->undefined_value();
   func_names_array->set_int(0, num_funcs_int);
   int func_index = 0;
   for (const WasmFunction& fun : module->functions) {
     WasmName name = module->GetNameOrNull(&fun);
     if (name.start() == nullptr) {
       func_names_array->set_int(func_index + 1, -current_offset);
     } else {
       func_names_array->copy_in(current_offset,
                                 reinterpret_cast<const byte*>(name.start()),
                                 name.length());
@@ skipping 18 matching lines @@
                         : abs(func_names_array->get_int(func_index + 2));
   ScopedVector<byte> buffer(next_offset - offset);
   func_names_array->copy_out(offset, buffer.start(), next_offset - offset);
   if (!unibrow::Utf8::Validate(buffer.start(), buffer.length())) return {};
   return factory->NewStringFromUtf8(Vector<const char>::cast(buffer));
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8