From fc9f2d9cea4fc0e92e16edbe075780d68c591cc7 Mon Sep 17 00:00:00 2001
From: Sintendo <3380580+Sintendo@users.noreply.github.com>
Date: Wed, 6 Aug 2025 00:30:31 +0200
Subject: [PATCH] JitArm64_Integer: subfcx - Optimize b == 0

Equivalent to a negation, no need to materialize the zero.

Before:
0x52800015   mov    w21, #0x0                 ; =0
0x6b1802b6   subs   w22, w21, w24

After:
0x6b1803f6   negs   w22, w24
---
 Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp b/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
index 31b8f96f71..25a4ada478 100644
--- a/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
+++ b/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
@@ -1443,6 +1443,14 @@ void JitArm64::subfcx(UGeckoInstruction inst)
     if (inst.Rc)
       ComputeRC0(gpr.R(d));
   }
+  else if (gpr.IsImm(b, 0))
+  {
+    gpr.BindToRegister(d, d == a);
+    CARRY_IF_NEEDED(NEG, NEGS, gpr.R(d), gpr.R(a));
+    ComputeCarry();
+    if (inst.Rc)
+      ComputeRC0(gpr.R(d));
+  }
   else
   {
     gpr.BindToRegister(d, d == a || d == b);