From c130a496f28010d6bc59bb9c45013f69fbdd3dc3 Mon Sep 17 00:00:00 2001
From: Fiora <fioraaeterna@gmail.com>
Date: Fri, 19 Sep 2014 01:40:02 -0700
Subject: [PATCH] JIT: fix fsel/ps_sel implementations for NaN input

fselx was the main problem, but ps_sel was wrong too (even if there were no
known reported bugs with it).

This fixes Beyond Good and Evil (at the least).
---
 Source/Core/Core/PowerPC/Jit64/Jit_FloatingPoint.cpp | 12 +++++++-----
 Source/Core/Core/PowerPC/Jit64/Jit_Paired.cpp        | 12 ++++++------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/Source/Core/Core/PowerPC/Jit64/Jit_FloatingPoint.cpp b/Source/Core/Core/PowerPC/Jit64/Jit_FloatingPoint.cpp
index a20dd17e89..f79818fa77 100644
--- a/Source/Core/Core/PowerPC/Jit64/Jit_FloatingPoint.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/Jit_FloatingPoint.cpp
@@ -212,10 +212,12 @@ void Jit64::fselx(UGeckoInstruction inst)
 	int c = inst.FC;
 
 	fpr.Lock(a, b, c, d);
-	MOVSD(XMM0, fpr.R(a));
-	PXOR(XMM1, R(XMM1));
-	// XMM0 = XMM0 < 0 ? all 1s : all 0s
-	CMPSD(XMM0, R(XMM1), LT);
+	MOVSD(XMM1, fpr.R(a));
+	PXOR(XMM0, R(XMM0));
+	// This condition is very tricky; there's only one right way to handle both the case of
+	// negative/positive zero and NaN properly.
+	// (a >= -0.0 ? c : b) transforms into (0 > a ? b : c), hence the NLE.
+	CMPSD(XMM0, R(XMM1), NLE);
 	if (cpu_info.bSSE4_1)
 	{
 		MOVSD(XMM1, fpr.R(c));
@@ -228,7 +230,7 @@ void Jit64::fselx(UGeckoInstruction inst)
 		PANDN(XMM1, fpr.R(c));
 		POR(XMM1, R(XMM0));
 	}
-	fpr.BindToRegister(d, false);
+	fpr.BindToRegister(d, true);
 	MOVSD(fpr.RX(d), R(XMM1));
 	fpr.UnlockAll();
 }
diff --git a/Source/Core/Core/PowerPC/Jit64/Jit_Paired.cpp b/Source/Core/Core/PowerPC/Jit64/Jit_Paired.cpp
index f08fb6b863..83fe2ca4cf 100644
--- a/Source/Core/Core/PowerPC/Jit64/Jit_Paired.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/Jit_Paired.cpp
@@ -43,17 +43,17 @@ void Jit64::ps_sel(UGeckoInstruction inst)
 
 	if (cpu_info.bSSE4_1)
 	{
-		MOVAPD(XMM0, fpr.R(a));
-		PXOR(XMM1, R(XMM1));
-		CMPPD(XMM0, R(XMM1), LT); // XMM0 = XMM0 < 0 ? all 1s : all 0s
+		MOVAPD(XMM1, fpr.R(a));
+		PXOR(XMM0, R(XMM0));
+		CMPPD(XMM0, R(XMM1), NLE);
 		MOVAPD(XMM1, fpr.R(c));
 		BLENDVPD(XMM1, fpr.R(b));
 	}
 	else
 	{
-		MOVAPD(XMM1, fpr.R(a));
-		PXOR(XMM0, R(XMM0));
-		CMPPD(XMM1, R(XMM0), LT); // XMM0 = XMM0 < 0 ? all 1s : all 0s
+		MOVAPD(XMM0, fpr.R(a));
+		PXOR(XMM1, R(XMM1));
+		CMPPD(XMM1, R(XMM0), NLE);
 		MOVAPD(XMM0, R(XMM1));
 		PAND(XMM1, fpr.R(b));
 		PANDN(XMM0, fpr.R(c));