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

src/compiler/mips64/instruction-selector-mips64.cc

Index: src/compiler/mips64/instruction-selector-mips64.cc
diff --git a/src/compiler/mips64/instruction-selector-mips64.cc b/src/compiler/mips64/instruction-selector-mips64.cc
index 3516e76501fba1c6793e710bdd3675d1fdb379e6..7ea4b62b5922e1b131a5d44097c26f43e269240b 100644
--- a/src/compiler/mips64/instruction-selector-mips64.cc
+++ b/src/compiler/mips64/instruction-selector-mips64.cc
@@ -2057,6 +2057,19 @@ InstructionSelector::SupportedMachineOperatorFlags() {
          MachineOperatorBuilder::kFloat32RoundTiesEven;
 }
 
+// static
+MachineOperatorBuilder::AlignmentRequirements
+InstructionSelector::AlignmentRequirements() {
+  if (kArchVariant == kMips64r6) {
+    return MachineOperatorBuilder::AlignmentRequirements::
+        FullUnalignedAccessSupport();
+  } else {
+    DCHECK(kArchVariant == kMips64r2);
+    return MachineOperatorBuilder::AlignmentRequirements::
+        NoUnalignedAccessSupport();
+  }
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8