From 76a13604ef49b522281af75675f044d59a74e871 Mon Sep 17 00:00:00 2001
From: Pierre Bourdon <delroth@gmail.com>
Date: Tue, 19 Jun 2012 06:35:30 +0200
Subject: [PATCH] Optimize mtmsr by going to an exception exit only if EE are
 enabled and some exceptions are pending.

---
 .../Src/PowerPC/Jit64/Jit_SystemRegisters.cpp | 20 ++++++++++++++++---
 .../Core/Core/Src/PowerPC/Jit64IL/IR_X86.cpp  | 17 +++++++++++++++-
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/Source/Core/Core/Src/PowerPC/Jit64/Jit_SystemRegisters.cpp b/Source/Core/Core/Src/PowerPC/Jit64/Jit_SystemRegisters.cpp
index 5cb7f0e13b..b977e82b28 100644
--- a/Source/Core/Core/Src/PowerPC/Jit64/Jit_SystemRegisters.cpp
+++ b/Source/Core/Core/Src/PowerPC/Jit64/Jit_SystemRegisters.cpp
@@ -123,10 +123,24 @@ void Jit64::mtmsr(UGeckoInstruction inst)
 	gpr.Flush(FLUSH_ALL);
 	fpr.Flush(FLUSH_ALL);
 
-	// Force an external exception when going out of mtmsr in order to check
-	// immediately for interrupts that were delayed because of MSR.EE=0.
+	// If some exceptions are pending and EE are now enabled, force checking
+	// external exceptions when going out of mtmsr in order to execute delayed
+	// interrupts as soon as possible.
+	MOV(32, R(EAX), M(&MSR));
+	TEST(32, R(EAX), Imm32(0x8000));
+	FixupBranch eeDisabled = J_CC(CC_Z);
+
+	MOV(32, R(EAX), M((void*)&PowerPC::ppcState.Exceptions));
+	TEST(32, R(EAX), R(EAX));
+	FixupBranch noExceptionsPending = J_CC(CC_Z);
+
 	MOV(32, M(&PC), Imm32(js.compilerPC + 4));
-	WriteExceptionExit();
+	WriteExternalExceptionExit();
+
+	SetJumpTarget(eeDisabled);
+	SetJumpTarget(noExceptionsPending);
+	WriteExit(js.compilerPC + 4, 0);
+
 	js.firstFPInstructionFound = false;
 }
 
diff --git a/Source/Core/Core/Src/PowerPC/Jit64IL/IR_X86.cpp b/Source/Core/Core/Src/PowerPC/Jit64IL/IR_X86.cpp
index 448f51d1c6..d9aa46f6b5 100644
--- a/Source/Core/Core/Src/PowerPC/Jit64IL/IR_X86.cpp
+++ b/Source/Core/Core/Src/PowerPC/Jit64IL/IR_X86.cpp
@@ -997,8 +997,23 @@ static void DoWriteCode(IRBuilder* ibuild, JitIL* Jit, bool UseProfile, bool Mak
 			unsigned InstLoc = ibuild->GetImmValue(getOp2(I));
 			regStoreInstToConstLoc(RI, 32, getOp1(I), &MSR);
 			regNormalRegClear(RI, I);
+
+			// If some exceptions are pending and EE are now enabled, force checking
+			// external exceptions when going out of mtmsr in order to execute delayed
+			// interrupts as soon as possible.
+			Jit->MOV(32, R(EAX), M(&MSR));
+			Jit->TEST(32, R(EAX), Imm32(0x8000));
+			FixupBranch eeDisabled = Jit->J_CC(CC_Z);
+
+			Jit->MOV(32, R(EAX), M((void*)&PowerPC::ppcState.Exceptions));
+			Jit->TEST(32, R(EAX), R(EAX));
+			FixupBranch noExceptionsPending = Jit->J_CC(CC_Z);
+
 			Jit->MOV(32, M(&PC), Imm32(InstLoc + 4));
-			Jit->WriteExceptionExit();
+			Jit->WriteExceptionExit(); // TODO: Implement WriteExternalExceptionExit for JitIL
+
+			Jit->SetJumpTarget(eeDisabled);
+			Jit->SetJumpTarget(noExceptionsPending);
 			break;
 		}
 		case StoreGQR: {