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 0021f1228681fa1f9a94c48a4418f7382cb88827..d624c79b6b745498aed767f09f8a2975882196de 100644
--- a/src/compiler/mips64/instruction-selector-mips64.cc
+++ b/src/compiler/mips64/instruction-selector-mips64.cc
@@ -2051,6 +2051,19 @@ InstructionSelector::SupportedMachineOperatorFlags() {
          MachineOperatorBuilder::kFloat32RoundTiesEven;
 }
 
+// static
+MachineOperatorBuilder::AlignmentRequirements
+InstructionSelector::AlignmentConfiguration() {
+  if (kArchVariant == kMips64r6) {
+    return MachineOperatorBuilder::AlignmentRequirements::
+        FullUnalignedAccessSupport();
+  } else {
+    DCHECK(kArchVariant == kMips64r2);
+    return MachineOperatorBuilder::AlignmentRequirements::
+        NoUnalignedAccessSupport();
+  }
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8