JitRegCache: Add revertable binds

Source/Core/Core/PowerPC/Jit64/RegCache/CachedReg.h

@@ -41,6 +41,8 @@ public:
   {
     if (!away)
     {
+      ASSERT(!revertable);
+
       if (location.IsImm())
         return LocationType::SpeculativeImmediate;
 
@@ -63,6 +65,7 @@ public:
 
   void SetFlushed()
   {
+    ASSERT(!revertable);
     away = false;
     location = default_location;
   }
@@ -73,6 +76,24 @@ public:
     location = Gen::Imm32(imm32);
   }
 
+  bool IsRevertable() const { return revertable; }
+  void SetRevertable()
+  {
+    ASSERT(IsBound());
+    revertable = true;
+  }
+  void SetRevert()
+  {
+    ASSERT(revertable);
+    revertable = false;
+    SetFlushed();
+  }
+  void SetCommit()
+  {
+    ASSERT(revertable);
+    revertable = false;
+  }
+
   bool IsLocked() const { return locked > 0; }
   void Lock() { locked++; }
   void Unlock()
@@ -86,6 +107,7 @@ private:
   Gen::OpArg default_location{};
   Gen::OpArg location{};
   bool away = false;  // value not in source register
+  bool revertable = false;
   size_t locked = 0;
 };
 
@@ -139,6 +161,7 @@ public:
   bool ShouldLoad() const { return read; }
   bool ShouldDirty() const { return write; }
   bool ShouldKillImmediate() const { return kill_imm; }
+  bool ShouldBeRevertable() const { return revertable; }
 
   void Realized() { realized = true; }
   void RealizedBound()
@@ -147,16 +170,17 @@ public:
     bind = true;
   }
 
-  void AddUse(RCMode mode) { AddConstraint(false, mode, false); }
-  void AddUseNoImm(RCMode mode) { AddConstraint(false, mode, true); }
-  void AddBind(RCMode mode) { AddConstraint(true, mode, false); }
+  void AddUse(RCMode mode) { AddConstraint(false, mode, false, false); }
+  void AddUseNoImm(RCMode mode) { AddConstraint(false, mode, true, false); }
+  void AddBind(RCMode mode) { AddConstraint(true, mode, false, false); }
+  void AddRevertableBind(RCMode mode) { AddConstraint(true, mode, false, true); }
 
 private:
-  void AddConstraint(bool should_bind, RCMode mode, bool should_kill_imm)
+  void AddConstraint(bool should_bind, RCMode mode, bool should_kill_imm, bool should_revertable)
   {
     if (realized)
     {
-      ASSERT(IsCompatible(should_bind, mode, should_kill_imm));
+      ASSERT(IsCompatible(should_bind, mode, should_kill_imm, should_revertable));
       return;
     }
 
@@ -166,6 +190,9 @@ private:
     if (should_kill_imm)
       kill_imm = true;
 
+    if (should_revertable)
+      revertable = true;
+
     switch (mode)
     {
     case RCMode::Read:
@@ -181,12 +208,14 @@ private:
     }
   }
 
-  bool IsCompatible(bool should_bind, RCMode mode, bool should_kill_imm)
+  bool IsCompatible(bool should_bind, RCMode mode, bool should_kill_imm, bool should_revertable)
   {
     if (should_bind && !bind)
       return false;
     if (should_kill_imm && !kill_imm)
       return false;
+    if (should_revertable && !revertable)
+      return false;
 
     switch (mode)
     {
@@ -204,4 +233,5 @@ private:
   bool write = false;
   bool read = false;
   bool kill_imm = false;
+  bool revertable = false;
 };

Source/Core/Core/PowerPC/Jit64/RegCache/JitRegCache.cpp

@@ -328,6 +328,7 @@ void RegCache::Flush(FlushMode mode, BitSet32 regsToFlush)
   {
     ASSERT_MSG(DYNA_REC, !m_regs[i].IsLocked(), "Someone forgot to unlock PPC reg %u (X64 reg %i).",
                i, RX(i));
+    ASSERT_MSG(DYNA_REC, !m_regs[i].IsRevertable(), "Register transaction is in progress!");
 
     switch (m_regs[i].GetLocationType())
     {
@@ -373,7 +374,7 @@ bool RegCache::SanityCheck() const
       break;
     case PPCCachedReg::LocationType::Bound:
     {
-      if (m_regs[i].IsLocked())
+      if (m_regs[i].IsLocked() || m_regs[i].IsRevertable())
         return false;
 
       Gen::X64Reg xr = m_regs[i].Location().GetSimpleReg();
@@ -413,6 +414,7 @@ void RegCache::BindToRegister(preg_t i, bool doLoad, bool makeDirty)
 
     ASSERT_MSG(DYNA_REC, !m_xregs[xr].IsDirty(), "Xreg %i already dirty", xr);
     ASSERT_MSG(DYNA_REC, !m_xregs[xr].IsLocked(), "GetFreeXReg returned locked register");
+    ASSERT_MSG(DYNA_REC, !m_regs[i].IsRevertable(), "Invalid transaction state");
 
     m_xregs[xr].SetBoundTo(i, makeDirty || m_regs[i].IsAway());
 
@@ -441,6 +443,9 @@ void RegCache::BindToRegister(preg_t i, bool doLoad, bool makeDirty)
 
 void RegCache::StoreFromRegister(preg_t i, FlushMode mode)
 {
+  // When a transaction is in progress, allowing the store would overwrite the old value.
+  ASSERT_MSG(DYNA_REC, !m_regs[i].IsRevertable(), "Register transaction is in progress!");
+
   bool doStore = false;
 
   switch (m_regs[i].GetLocationType())
@@ -611,6 +616,18 @@ RCX64Reg RegCache::Bind(preg_t preg, RCMode mode)
   return RCX64Reg{this, preg};
 }
 
+RCX64Reg RegCache::BindOrImm(preg_t preg, RCMode mode)
+{
+  m_constraints[preg].AddBindOrImm(mode);
+  return RCX64Reg{this, preg};
+}
+
+RCX64Reg RegCache::RevertableBind(preg_t preg, RCMode mode)
+{
+  m_constraints[preg].AddRevertableBind(mode);
+  return RCX64Reg{this, preg};
+}
+
 RCX64Reg RegCache::Scratch(X64Reg xr)
 {
   FlushX(xr);
@@ -622,6 +639,26 @@ RCForkGuard RegCache::Fork()
   return RCForkGuard{*this};
 }
 
+void RegCache::Revert()
+{
+  ASSERT(IsAllUnlocked());
+  for (auto& reg : m_regs)
+  {
+    if (reg.IsRevertable())
+      reg.SetRevert();
+  }
+}
+
+void RegCache::Commit()
+{
+  ASSERT(IsAllUnlocked());
+  for (auto& reg : m_regs)
+  {
+    if (reg.IsRevertable())
+      reg.SetCommit();
+  }
+}
+
 bool RegCache::IsAllUnlocked() const
 {
   return std::none_of(m_regs.begin(), m_regs.end(), [](const auto& r){ return r.IsLocked(); }) &&
@@ -673,6 +710,14 @@ void RegCache::Realize(preg_t preg)
     m_constraints[preg].RealizedBound();
   };
 
+  if (m_constraints[preg].ShouldBeRevertable())
+  {
+    StoreFromRegister(preg, FlushMode::MaintainState);
+    do_bind();
+    m_regs[preg].SetRevertable();
+    return;
+  }
+
   if (m_constraints[preg].ShouldBind())
   {
     do_bind();

Source/Core/Core/PowerPC/Jit64/RegCache/JitRegCache.h

@@ -235,9 +235,12 @@ public:
   RCOpArg Use(preg_t preg, RCMode mode);
   RCOpArg UseNoImm(preg_t preg, RCMode mode);
   RCX64Reg Bind(preg_t preg, RCMode mode);
+  RCX64Reg RevertableBind(preg_t preg, RCMode mode);
   RCX64Reg Scratch(Gen::X64Reg xr);
 
   RCForkGuard Fork();
+  void Revert();
+  void Commit();
 
   bool IsAllUnlocked() const;