[fuzzer] Slightly improve generated test cases

Mostly cosmetic changes. The biggest change is to encode block result
types using symbolic names instead of hex numbers.

R=ahaas@chromium.org

Change-Id: Ic0e6eccf687338e68508094168ddd70734cef301
Reviewed-on: https://chromium-review.googlesource.com/973527
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52138}

src/wasm/function-body-decoder.cc

@@ -959,9 +959,32 @@ bool PrintRawWasmCode(AccountingAllocator* allocator, const FunctionBody& body,
 
     os << RawOpcodeName(opcode) << ",";
 
+    if (opcode == kExprLoop || opcode == kExprIf || opcode == kExprBlock ||
+        opcode == kExprTry) {
+      DCHECK_EQ(2, length);
+
+      switch (i.pc()[1]) {
+#define CASE_LOCAL_TYPE(local_name, type_name) \
+  case kLocal##local_name:                     \
+    os << " kWasm" #type_name ",";             \
+    break;
+
+        CASE_LOCAL_TYPE(I32, I32)
+        CASE_LOCAL_TYPE(I64, I64)
+        CASE_LOCAL_TYPE(F32, F32)
+        CASE_LOCAL_TYPE(F64, F64)
+        CASE_LOCAL_TYPE(S128, S128)
+        CASE_LOCAL_TYPE(Void, Stmt)
+        default:
+          os << " 0x" << AsHex(i.pc()[1], 2) << ",";
+          break;
+      }
+#undef CASE_LOCAL_TYPE
+    } else {
       for (unsigned j = 1; j < length; ++j) {
         os << " 0x" << AsHex(i.pc()[j], 2) << ",";
       }
+    }
 
     switch (opcode) {
       case kExprElse:

test/fuzzer/wasm-fuzzer-common.cc

@@ -165,7 +165,7 @@ void GenerateTestCase(Isolate* isolate, ModuleWireBytes wire_bytes,
         "load('test/mjsunit/wasm/wasm-module-builder.js');\n"
         "\n"
         "(function() {\n"
-        "  var builder = new WasmModuleBuilder();\n";
+        "  const builder = new WasmModuleBuilder();\n";
 
   if (module->has_memory) {
     os << "  builder.addMemory(" << module->initial_pages;
@@ -185,14 +185,15 @@ void GenerateTestCase(Isolate* isolate, ModuleWireBytes wire_bytes,
 
   for (const WasmFunction& func : module->functions) {
     Vector<const uint8_t> func_code = wire_bytes.GetFunctionBytes(&func);
-    os << "  // Generate function " << func.func_index << " (out of "
+    os << "  // Generate function " << (func.func_index + 1) << " (out of "
        << module->functions.size() << ").\n";
     // Generate signature.
-    os << "  sig" << func.func_index << " = makeSig("
+    os << "  sig" << (func.func_index + 1) << " = makeSig("
        << PrintParameters(func.sig) << ", " << PrintReturns(func.sig) << ");\n";
 
     // Add function.
-    os << "  builder.addFunction(undefined, sig" << func.func_index << ")\n";
+    os << "  builder.addFunction(undefined, sig" << (func.func_index + 1)
+       << ")\n";
 
     // Add locals.
     BodyLocalDecls decls(&tmp_zone);
@@ -226,8 +227,8 @@ void GenerateTestCase(Isolate* isolate, ModuleWireBytes wire_bytes,
   }
 
   if (compiles) {
-    os << "  var module = builder.instantiate();\n"
-          "  module.exports.main(1, 2, 3);\n";
+    os << "  const instance = builder.instantiate();\n"
+          "  print(instance.exports.main(1, 2, 3));\n";
   } else {
     os << "  assertThrows(function() { builder.instantiate(); }, "
           "WebAssembly.CompileError);\n";