[tools][wasm] wami: Support hexdump for invalid modules

When trying to understand why a given module fails to validate, it
can be helpful to disassemble it as far as possible until reaching
the erroneous byte(s).

Change-Id: I0056ba1a81b85a486c0446d15bbf54ccb2e8332e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3827866Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82433}

src/wasm/function-body-decoder-impl.h

@@ -246,7 +246,6 @@ HeapType read_heap_type(Decoder* decoder, const byte* pc,
               decoder, pc,
               "invalid heap type '%s', enable with --experimental-wasm-gc",
               HeapType::from_code(code).name().c_str());
-          return HeapType(HeapType::kBottom);
         }
         V8_FALLTHROUGH;
       case kExternRefCode:
@@ -261,7 +260,6 @@ HeapType read_heap_type(Decoder* decoder, const byte* pc,
                                 "invalid heap type '%s', enable with "
                                 "--experimental-wasm-stringref",
                                 HeapType::from_code(code).name().c_str());
-          return HeapType(HeapType::kBottom);
         }
         return HeapType::from_code(code);
       default:
@@ -274,7 +272,6 @@ HeapType read_heap_type(Decoder* decoder, const byte* pc,
       DecodeError<validate>(decoder, pc,
                             "Invalid indexed heap type, enable with "
                             "--experimental-wasm-typed-funcref");
-      return HeapType(HeapType::kBottom);
     }
     uint32_t type_index = static_cast<uint32_t>(heap_index);
     if (!VALIDATE(type_index < kV8MaxWasmTypes)) {
@@ -289,7 +286,6 @@ HeapType read_heap_type(Decoder* decoder, const byte* pc,
     if (!VALIDATE(module == nullptr || type_index < module->types.capacity())) {
       DecodeError<validate>(decoder, pc, "Type index %u is out of bounds",
                             type_index);
-      return HeapType(HeapType::kBottom);
     }
     return HeapType(type_index);
   }

src/wasm/module-decoder-impl.h

@@ -33,6 +33,7 @@ class NoTracer {
   // Hooks for extracting byte offsets of things.
   void TypeOffset(uint32_t offset) {}
   void ImportOffset(uint32_t offset) {}
+  void ImportsDone() {}
   void TableOffset(uint32_t offset) {}
   void MemoryOffset(uint32_t offset) {}
   void TagOffset(uint32_t offset) {}
@@ -866,6 +867,7 @@ class ModuleDecoderTemplate : public Decoder {
           break;
       }
     }
+    tracer_.ImportsDone();
   }
 
   void DecodeFunctionSection() {
@@ -1676,7 +1678,7 @@ class ModuleDecoderTemplate : public Decoder {
       }
       // Shift the offset by the remaining section payload
       offset += section_iter.payload_length();
-      if (!section_iter.more()) break;
+      if (!section_iter.more() || !ok()) break;
       section_iter.advance(true);
     }
 
@@ -2203,6 +2205,7 @@ class ModuleDecoderTemplate : public Decoder {
       tracer_.NextLineIfFull();
     }
     tracer_.NextLineIfNonEmpty();
+    if (failed()) return nullptr;
 
     // Parse return types.
     std::vector<ValueType> returns;

src/wasm/wasm-disassembler.cc

@@ -608,6 +608,7 @@ class OffsetsProvider {
   void DataOffset(uint32_t offset) { data_offsets_.push_back(offset); }
 
   // Unused by this tracer:
+  void ImportsDone() {}
   void Bytes(const byte* start, uint32_t count) {}
   void Description(const char* desc) {}
   void Description(const char* desc, size_t length) {}