Force proper code aligment in wasm serializer.

Change-Id: Iace7040f7327cbc76e75a0cd7229221c93a9456e
Reviewed-on: https://chromium-review.googlesource.com/975547Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Cr-Commit-Position: refs/heads/master@{#52174}

src/wasm/wasm-code-manager.h

@@ -100,7 +100,7 @@ class V8_EXPORT_PRIVATE WasmCode final {
   // kOther is used if we have WasmCode that is neither
   // liftoff- nor turbofan-compiled, i.e. if Kind is
   // not a kFunction.
-  enum Tier : int8_t { kLiftoff, kTurbofan, kOther };
+  enum Tier : int32_t { kLiftoff, kTurbofan, kOther };
 
   Vector<byte> instructions() const { return instructions_; }
   Vector<const byte> reloc_info() const {

src/wasm/wasm-serialization.cc

@@ -377,6 +377,7 @@ void NativeModuleSerializer::BufferCodeInAllocatedScratch(
   writer.Write(code->tier());
   // next is the code, which we have to reloc.
   Address serialized_code_start = writer.current_buffer().start();
+  DCHECK(IsAddressAligned(serialized_code_start, 4));
   // write the code and everything else
   writer.WriteVector(code->instructions());
   writer.WriteVector(code->reloc_info());