From ce494a5e4fe28d13fc2325b4051d3b040aa92ac0 Mon Sep 17 00:00:00 2001
From: Fiora <fioraaeterna@gmail.com>
Date: Mon, 8 Sep 2014 04:16:50 -0700
Subject: [PATCH] JIT: fix a corner case in crXXX

It didn't behave correctly with an input of zero, resulting in some games
breaking (at the least, Fight Night 2). This should be fixed now.

Also clean it up, add a few comments, and fix some variants of the instruction
that are so rare that they probably never got tested.
---
 .../PowerPC/Jit64/Jit_SystemRegisters.cpp     | 38 +++++++++++--------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/Source/Core/Core/PowerPC/Jit64/Jit_SystemRegisters.cpp b/Source/Core/Core/PowerPC/Jit64/Jit_SystemRegisters.cpp
index f7278e9a55..d1b0f72c92 100644
--- a/Source/Core/Core/PowerPC/Jit64/Jit_SystemRegisters.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/Jit_SystemRegisters.cpp
@@ -45,6 +45,17 @@ void Jit64::SetCRFieldBit(int field, int bit, Gen::X64Reg in)
 	MOV(64, R(RSCRATCH2), PPCSTATE(cr_val[field]));
 	MOVZX(32, 8, in, R(in));
 
+	// Gross but necessary; if the input is totally zero and we set SO or LT,
+	// or even just add the (1<<32), GT will suddenly end up set without us
+	// intending to. This can break actual games, so fix it up.
+	if (bit != CR_GT_BIT)
+	{
+		TEST(64, R(RSCRATCH2), R(RSCRATCH2));
+		FixupBranch dont_clear_gt = J_CC(CC_NZ);
+		BTS(64, R(RSCRATCH2), Imm8(63));
+		SetJumpTarget(dont_clear_gt);
+	}
+
 	switch (bit)
 	{
 	case CR_SO_BIT:  // set bit 61 to input
@@ -434,38 +445,35 @@ void Jit64::crXXX(UGeckoInstruction inst)
 	// instance, if the two CR bits being loaded are the same, two loads are
 	// not required.
 
-	// USES_CR
-	// crandc or crorc or creqv or crnand or crnor
-	bool negateA = inst.SUBOP10 == 129 || inst.SUBOP10 == 417 || inst.SUBOP10 == 289 || inst.SUBOP10 == 225 || inst.SUBOP10 == 33;
-	// crnand or crnor
-	bool negateB = inst.SUBOP10 == 225 || inst.SUBOP10 == 33;
+	// creqv or crnand or crnor
+	bool negateA = inst.SUBOP10 == 289 || inst.SUBOP10 == 225 || inst.SUBOP10 == 33;
+	// crandc or crorc or crnand or crnor
+	bool negateB = inst.SUBOP10 == 129 || inst.SUBOP10 == 417 || inst.SUBOP10 == 225 || inst.SUBOP10 == 33;
 
-	GetCRFieldBit(inst.CRBA >> 2, 3 - (inst.CRBA & 3), RSCRATCH2, negateA);
-	GetCRFieldBit(inst.CRBB >> 2, 3 - (inst.CRBB & 3), RSCRATCH, negateB);
+	GetCRFieldBit(inst.CRBA >> 2, 3 - (inst.CRBA & 3), RSCRATCH, negateA);
+	GetCRFieldBit(inst.CRBB >> 2, 3 - (inst.CRBB & 3), RSCRATCH2, negateB);
 
 	// Compute combined bit
 	switch (inst.SUBOP10)
 	{
 	case 33:  // crnor: ~(A || B) == (~A && ~B)
-	case 129: // crandc
-	case 257: // crand
+	case 129: // crandc: A && ~B
+	case 257: // crand:  A && B
 		AND(8, R(RSCRATCH), R(RSCRATCH2));
 		break;
 
-	case 193: // crxor
-	case 289: // creqv
+	case 193: // crxor: A ^ B
+	case 289: // creqv: ~(A ^ B) = ~A ^ B
 		XOR(8, R(RSCRATCH), R(RSCRATCH2));
 		break;
 
 	case 225: // crnand: ~(A && B) == (~A || ~B)
-	case 417: // crorc
-	case 449: // cror
+	case 417: // crorc: A || ~B
+	case 449: // cror:  A || B
 		OR(8, R(RSCRATCH), R(RSCRATCH2));
 		break;
 	}
 
 	// Store result bit in CRBD
 	SetCRFieldBit(inst.CRBD >> 2, 3 - (inst.CRBD & 3), RSCRATCH);
-
-	gpr.UnlockAllX();
 }