[x64] use movl for move instruction with word32 operand.

Before:
  488bd6 REX.W movq rdx, rsi

After:
  8bd6 movl rdx, rsi

This CL can save a 1-byte encoding length for move instruction.

Change-Id: Ief482b4093f22ab810dbc693e8d9ed55a8c14c84
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3875397
Commit-Queue: Jialu Zhang <jialu.zhang@intel.com>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83070}

src/compiler/backend/x64/code-generator-x64.cc

@@ -5211,7 +5211,17 @@ void CodeGenerator::AssembleMove(InstructionOperand* source,
   switch (MoveType::InferMove(source, destination)) {
     case MoveType::kRegisterToRegister:
       if (source->IsRegister()) {
-        __ movq(g.ToRegister(destination), g.ToRegister(source));
+        MachineRepresentation src_rep =
+            LocationOperand::cast(source)->representation();
+        MachineRepresentation dest_rep =
+            LocationOperand::cast(destination)->representation();
+        if (dest_rep == MachineRepresentation::kWord32 &&
+            src_rep == MachineRepresentation::kWord32) {
+          DCHECK(destination->IsRegister());
+          __ movl(g.ToRegister(destination), g.ToRegister(source));
+        } else {
+          __ movq(g.ToRegister(destination), g.ToRegister(source));
+        }
       } else {
         DCHECK(source->IsFPRegister());
         __ Movapd(g.ToDoubleRegister(destination), g.ToDoubleRegister(source));