Implement UnalignedLoad and UnalignedStore in WASM using LoadByte/Shift/Or and StoreByte/Shift/And.

src/wasm/ast-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/signature.h"
 
 #include "src/bit-vector.h"
 #include "src/flags.h"
 #include "src/handles.h"
 #include "src/zone-containers.h"
@@ skipping 1086 matching lines @@
 
   void PushIf(SsaEnv* end_env, SsaEnv* false_env) {
     int stack_depth = static_cast<int>(stack_.size());
     control_.push_back(
         {pc_, stack_depth, end_env, false_env, nullptr, kAstStmt, false});
   }
 
   int DecodeLoadMem(LocalType type, MachineType mem_type) {
     MemoryAccessOperand operand(this, pc_);
     Value index = Pop(0, kAstI32);
-    TFNode* node =
-        BUILD(LoadMem, type, mem_type, index.node, operand.offset, position());
+    TFNode* node = BUILD(LoadMem, type, mem_type, index.node, operand.offset,
+                         operand.alignment, position());
     Push(type, node);
     return 1 + operand.length;
   }
 
   int DecodeStoreMem(LocalType type, MachineType mem_type) {
     MemoryAccessOperand operand(this, pc_);
     Value val = Pop(1, type);
     Value index = Pop(0, kAstI32);
-    BUILD(StoreMem, mem_type, index.node, operand.offset, val.node, position());
+    BUILD(StoreMem, mem_type, index.node, operand.offset, operand.alignment,
+          val.node, position());
     Push(type, val.node);
     return 1 + operand.length;
   }
 
   void DoReturn() {
     int count = static_cast<int>(sig_->return_count());
     TFNode** buffer = nullptr;
     if (build()) buffer = builder_->Buffer(count);
 
     // Pop return values off the stack in reverse order.
@@ skipping 518 matching lines @@
 BitVector* AnalyzeLoopAssignmentForTesting(Zone* zone, size_t num_locals,
                                            const byte* start, const byte* end) {
   FunctionBody body = {nullptr, nullptr, nullptr, start, end};
   SR_WasmDecoder decoder(zone, nullptr, body);
   return decoder.AnalyzeLoopAssignmentForTesting(start, num_locals);
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8