From 9264e2e04c32f3daee5417276e133026f6f0cbc7 Mon Sep 17 00:00:00 2001
From: Tillmann Karras <tilkax@gmail.com>
Date: Sat, 6 Aug 2016 21:04:13 +0100
Subject: [PATCH] Use XOR when loading a zero immediate

---
 src/backend_x64/reg_alloc.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/backend_x64/reg_alloc.cpp b/src/backend_x64/reg_alloc.cpp
index f9469480..78ce97a4 100644
--- a/src/backend_x64/reg_alloc.cpp
+++ b/src/backend_x64/reg_alloc.cpp
@@ -485,7 +485,11 @@ std::tuple<HostLoc, bool> RegAlloc::UseHostLoc(IR::Inst* use_inst, HostLocList d
 
 Gen::X64Reg RegAlloc::LoadImmediateIntoRegister(IR::Value imm, Gen::X64Reg reg) {
     ASSERT_MSG(imm.IsImmediate(), "imm is not an immediate");
-    code->MOV(32, Gen::R(reg), ImmediateToOpArg(imm));
+    Gen::OpArg op_arg = ImmediateToOpArg(imm);
+    if (op_arg.GetImmValue() == 0)
+        code->XOR(32, Gen::R(reg), Gen::R(reg));
+    else
+        code->MOV(32, Gen::R(reg), op_arg);
     return reg;
 }