From 163ed9b185ce2eed9a9e5a54da840fd8788608b4 Mon Sep 17 00:00:00 2001
From: Merry <git@mary.rs>
Date: Fri, 22 Jul 2022 23:58:30 +0100
Subject: [PATCH] backend/arm64: Implement LeastSignificantWord

---
 .../backend/arm64/emit_arm64_data_processing.cpp      | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/dynarmic/backend/arm64/emit_arm64_data_processing.cpp b/src/dynarmic/backend/arm64/emit_arm64_data_processing.cpp
index fb7ca191..2b221d46 100644
--- a/src/dynarmic/backend/arm64/emit_arm64_data_processing.cpp
+++ b/src/dynarmic/backend/arm64/emit_arm64_data_processing.cpp
@@ -73,10 +73,13 @@ void EmitIR<IR::Opcode::Pack2x64To1x128>(oaknut::CodeGenerator& code, EmitContex
 
 template<>
 void EmitIR<IR::Opcode::LeastSignificantWord>(oaknut::CodeGenerator& code, EmitContext& ctx, IR::Inst* inst) {
-    (void)code;
-    (void)ctx;
-    (void)inst;
-    ASSERT_FALSE("Unimplemented");
+    auto args = ctx.reg_alloc.GetArgumentInfo(inst);
+
+    auto Wresult = ctx.reg_alloc.WriteW(inst);
+    auto Xoperand = ctx.reg_alloc.ReadX(args[0]);
+    RegAlloc::Realize(Wresult, Xoperand);
+
+    code.MOV(Wresult, Xoperand->toW());  // TODO: Zext elimination
 }
 
 template<>