From b59c0d0b45db3d98f4627891666bb53867014919 Mon Sep 17 00:00:00 2001
From: "Unknown W. Brackets" <checkins@unknownbrackets.org>
Date: Fri, 29 Dec 2017 12:46:09 -0800
Subject: [PATCH] arm64jit: Use CMN for CMPI2R if possible.

It's not hit all that often, but it is hit.
---
 Common/Arm64Emitter.cpp | 8 ++++++++
 Common/Arm64Emitter.h   | 1 +
 2 files changed, 9 insertions(+)

diff --git a/Common/Arm64Emitter.cpp b/Common/Arm64Emitter.cpp
index ad834e1872..43dcbe4ba6 100644
--- a/Common/Arm64Emitter.cpp
+++ b/Common/Arm64Emitter.cpp
@@ -1547,6 +1547,10 @@ void ARM64XEmitter::CMP(ARM64Reg Rn, u32 imm, bool shift)
 {
 	EncodeAddSubImmInst(1, true, shift, imm, Rn, Is64Bit(Rn) ? SP : WSP);
 }
+void ARM64XEmitter::CMN(ARM64Reg Rn, u32 imm, bool shift)
+{
+	EncodeAddSubImmInst(0, true, shift, imm, Rn, Is64Bit(Rn) ? SP : WSP);
+}
 
 // Data Processing (Immediate)
 void ARM64XEmitter::MOVZ(ARM64Reg Rd, u32 imm, ShiftAmount pos)
@@ -3754,11 +3758,15 @@ bool ARM64XEmitter::TrySUBI2R(ARM64Reg Rd, ARM64Reg Rn, u64 imm) {
 }
 
 bool ARM64XEmitter::TryCMPI2R(ARM64Reg Rn, u64 imm) {
+	s64 negated = Is64Bit(Rn) ? -(s64)imm : -(s32)(u32)imm;
 	u32 val;
 	bool shift;
 	if (IsImmArithmetic(imm, &val, &shift)) {
 		CMP(Rn, val, shift);
 		return true;
+	} else if (IsImmArithmetic((u64)negated, &val, &shift)) {
+		CMN(Rn, val, shift);
+		return true;
 	} else {
 		return false;
 	}
diff --git a/Common/Arm64Emitter.h b/Common/Arm64Emitter.h
index 097d82a85a..a6ce09b3fa 100644
--- a/Common/Arm64Emitter.h
+++ b/Common/Arm64Emitter.h
@@ -591,6 +591,7 @@ public:
 	void SUB(ARM64Reg Rd, ARM64Reg Rn, u32 imm, bool shift = false);
 	void SUBS(ARM64Reg Rd, ARM64Reg Rn, u32 imm, bool shift = false);
 	void CMP(ARM64Reg Rn, u32 imm, bool shift = false);
+	void CMN(ARM64Reg Rn, u32 imm, bool shift = false);
 
 	// Data Processing (Immediate)
 	void MOVZ(ARM64Reg Rd, u32 imm, ShiftAmount pos = SHIFT_0);