From a6d5a7ea9e82141a1383df8d5896321fb0fbc9ff Mon Sep 17 00:00:00 2001
From: magumagu9 <magumagu9@gmail.com>
Date: Sat, 22 Nov 2008 20:49:58 +0000
Subject: [PATCH] Fix the dirty bit and make the register cache use it to be a
 bit more clever: it skips storing a register back to memory if its value
 hasn't changed. This happens with stuff like compares and fast memory loads.

This is the first in a series of enhancements I have in my tree for the
jit that I plan to commit over the next few hours.  I'm likely to
cause some breakage, so if you see regrassions, please report them; if
you can track them down to a specific revision, that would be very
helpful.  I'm trying to make the changes small to allow pinpointing
regressions more easily.



git-svn-id: https://dolphin-emu.googlecode.com/svn/trunk@1252 8ced0084-cf51-0410-be5f-012b33b47a6e
---
 Source/Core/Core/Src/PowerPC/Jit64/JitRegCache.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Source/Core/Core/Src/PowerPC/Jit64/JitRegCache.cpp b/Source/Core/Core/Src/PowerPC/Jit64/JitRegCache.cpp
index 645475d92e..2392f22dd3 100644
--- a/Source/Core/Core/Src/PowerPC/Jit64/JitRegCache.cpp
+++ b/Source/Core/Core/Src/PowerPC/Jit64/JitRegCache.cpp
@@ -198,6 +198,7 @@ namespace Jit64
 		if (regs[preg].away && regs[preg].location.IsSimpleReg())
 		{
 			xregs[regs[preg].location.GetSimpleReg()].free = true;
+			xregs[regs[preg].location.GetSimpleReg()].dirty = false;
 			regs[preg].away = false;
 		}
 	}
@@ -291,7 +292,7 @@ namespace Jit64
 			if (xlocks[xr]) PanicAlert("GetFreeXReg returned locked register");
 			xregs[xr].free = false;
 			xregs[xr].ppcReg = i;
-			xregs[xr].dirty = makeDirty;
+			xregs[xr].dirty = makeDirty || regs[i].location.IsImm();
 			OpArg newloc = ::Gen::R(xr);
 			if (doLoad || regs[i].location.IsImm())
 				MOV(32, newloc, regs[i].location);
@@ -321,11 +322,13 @@ namespace Jit64
 	{
 		if (regs[i].away)
 		{
+			bool doStore = true;
 			if (regs[i].location.IsSimpleReg())
 			{
 				X64Reg xr = RX(i);
 				xregs[xr].free = true;
 				xregs[xr].ppcReg = -1;
+				doStore = xregs[xr].dirty;
 				xregs[xr].dirty = false;
 			}
 			else
@@ -333,7 +336,8 @@ namespace Jit64
 				//must be immediate - do nothing
 			}
 			OpArg newLoc = GetDefaultLocation(i);
-			MOV(32, newLoc, regs[i].location);
+			if (doStore)
+				MOV(32, newLoc, regs[i].location);
 			regs[i].location = newLoc;
 			regs[i].away = false;
 		}