WASM: Reserve an ignored section for source code meta information.

src/wasm/module-decoder.cc

 // 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.
 
 #include "src/macro-assembler.h"
 #include "src/objects.h"
 #include "src/v8.h"
 
 #include "src/wasm/decoder.h"
 #include "src/wasm/module-decoder.h"
@@ skipping 163 matching lines @@
                   static_cast<int>(pc_ - start_));
             uint16_t index = u16();
             if (index >= module->functions->size()) {
               error(pc_ - 2, "invalid function index");
               break;
             }
             module->function_table->push_back(index);
           }
           break;
         }
+        case kDeclWLL: {
+          // Reserved for experimentation by the Web Low-level Language project
+          // which is augmenting the binary encoding with source code meta
+          // information. This section does not affect the semantics of the code
+          // and can be ignored by the runtime. https://github.com/JSStats/wll
+          int length;
+          uint32_t section_size = u32v(&length, "section size");
+          if (pc_ + section_size > limit_ || pc_ + section_size < pc_) {
+            error(pc_ - length, "invalid section size");
+            break;
+          }
+          pc_ += section_size;
+          break;
+        }
         default:
           error(pc_ - 1, nullptr, "unrecognized section 0x%02x", section);
           break;
       }
     }
 
     return toResult(module);
   }
 
   uint32_t SafeReserve(uint32_t count) {
@@ skipping 330 matching lines @@
   if (function_start > function_end) return FunctionError("start > end");
   if (size > kMaxFunctionSize)
     return FunctionError("size > maximum function size");
   WasmFunction* function = new WasmFunction();
   ModuleDecoder decoder(zone, function_start, function_end, false);
   return decoder.DecodeSingleFunction(module_env, function);
 }
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8