[wasm] factor lower level utilties out of WasmFullDecoder

src/wasm/function-body-decoder.h

 // Copyright 2015 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.
 
 #ifndef V8_WASM_FUNCTION_BODY_DECODER_H_
 #define V8_WASM_FUNCTION_BODY_DECODER_H_
 
 #include <iterator>
 
 #include "src/base/compiler-specific.h"
@@ skipping 341 matching lines @@
 
 inline DecodeResult BuildTFGraph(AccountingAllocator* allocator,
                                  TFBuilder* builder, FunctionSig* sig,
                                  const byte* start, const byte* end) {
   FunctionBody body = {sig, nullptr, start, end};
   return BuildTFGraph(allocator, builder, body);
 }
 
 struct BodyLocalDecls {
   // The size of the encoded declarations.
-  uint32_t decls_encoded_size;  // size of encoded declarations
+  uint32_t encoded_size;  // size of encoded declarations
 
-  // Total number of locals.
-  uint32_t total_local_count;
-
-  // List of {local type, count} pairs.
-  ZoneVector<std::pair<ValueType, uint32_t>> local_types;
+  ZoneVector<ValueType> type_list;
 
   // Constructor initializes the vector.
-  explicit BodyLocalDecls(Zone* zone)
-      : decls_encoded_size(0), total_local_count(0), local_types(zone) {}
+  explicit BodyLocalDecls(Zone* zone) : encoded_size(0), type_list(zone) {}
 };
 
-V8_EXPORT_PRIVATE bool DecodeLocalDecls(BodyLocalDecls& decls,
+V8_EXPORT_PRIVATE bool DecodeLocalDecls(BodyLocalDecls* decls,
                                         const byte* start, const byte* end);
 V8_EXPORT_PRIVATE BitVector* AnalyzeLoopAssignmentForTesting(Zone* zone,
                                                              size_t num_locals,
                                                              const byte* start,
                                                              const byte* end);
 
 // Computes the length of the opcode at the given address.
 V8_EXPORT_PRIVATE unsigned OpcodeLength(const byte* pc, const byte* end);
 
 // A simple forward iterator for bytecodes.
@@ skipping 83 matching lines @@
   }
 
   bool has_next() { return pc_ < end_; }
 };
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_FUNCTION_BODY_DECODER_H_