From b2d87c49b6c5f722308a71926b5150e37bc38153 Mon Sep 17 00:00:00 2001
From: JosJuice <josjuice@gmail.com>
Date: Mon, 12 Jul 2021 16:26:03 +0200
Subject: [PATCH] JitArm64: Implement mtfsb0x

Part 3 of implementing the FPSCR system register instructions.
---
 Source/Core/Core/PowerPC/JitArm64/Jit.h       |  4 ++-
 .../JitArm64/JitArm64_SystemRegisters.cpp     | 33 +++++++++++++++++++
 .../Core/PowerPC/JitArm64/JitArm64_Tables.cpp |  2 +-
 3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/Source/Core/Core/PowerPC/JitArm64/Jit.h b/Source/Core/Core/PowerPC/JitArm64/Jit.h
index ddab950334..f4ca4c0485 100644
--- a/Source/Core/Core/PowerPC/JitArm64/Jit.h
+++ b/Source/Core/Core/PowerPC/JitArm64/Jit.h
@@ -119,6 +119,7 @@ public:
   void mtcrf(UGeckoInstruction inst);
   void mcrfs(UGeckoInstruction inst);
   void mffsx(UGeckoInstruction inst);
+  void mtfsb0x(UGeckoInstruction inst);
 
   // LoadStore
   void lXX(UGeckoInstruction inst);
@@ -261,8 +262,9 @@ protected:
   void FakeLKExit(u32 exit_address_after_return);
   void WriteBLRExit(Arm64Gen::ARM64Reg dest);
 
-  void FixGTBeforeSettingCRFieldBit(Arm64Gen::ARM64Reg reg);
   Arm64Gen::FixupBranch JumpIfCRFieldBit(int field, int bit, bool jump_if_set);
+  void FixGTBeforeSettingCRFieldBit(Arm64Gen::ARM64Reg reg);
+  void UpdateRoundingMode();
 
   void ComputeRC0(Arm64Gen::ARM64Reg reg);
   void ComputeRC0(u64 imm);
diff --git a/Source/Core/Core/PowerPC/JitArm64/JitArm64_SystemRegisters.cpp b/Source/Core/Core/PowerPC/JitArm64/JitArm64_SystemRegisters.cpp
index 3b3dff85d1..02c9e7a2e0 100644
--- a/Source/Core/Core/PowerPC/JitArm64/JitArm64_SystemRegisters.cpp
+++ b/Source/Core/Core/PowerPC/JitArm64/JitArm64_SystemRegisters.cpp
@@ -48,6 +48,19 @@ void JitArm64::FixGTBeforeSettingCRFieldBit(Arm64Gen::ARM64Reg reg)
   gpr.Unlock(WA);
 }
 
+void JitArm64::UpdateRoundingMode()
+{
+  const BitSet32 gprs_to_save = gpr.GetCallerSavedUsed();
+  const BitSet32 fprs_to_save = fpr.GetCallerSavedUsed();
+
+  ABI_PushRegisters(gprs_to_save);
+  m_float_emit.ABI_PushRegisters(fprs_to_save, ARM64Reg::X8);
+  MOVP2R(ARM64Reg::X8, &PowerPC::RoundingModeUpdated);
+  BLR(ARM64Reg::X8);
+  m_float_emit.ABI_PopRegisters(fprs_to_save, ARM64Reg::X8);
+  ABI_PopRegisters(gprs_to_save);
+}
+
 void JitArm64::mtmsr(UGeckoInstruction inst)
 {
   INSTRUCTION_START
@@ -754,3 +767,23 @@ void JitArm64::mffsx(UGeckoInstruction inst)
   gpr.Unlock(WA);
   gpr.Unlock(WB);
 }
+
+void JitArm64::mtfsb0x(UGeckoInstruction inst)
+{
+  INSTRUCTION_START
+  JITDISABLE(bJITSystemRegistersOff);
+  FALLBACK_IF(inst.Rc);
+
+  u32 mask = ~(0x80000000 >> inst.CRBD);
+
+  ARM64Reg WA = gpr.GetReg();
+
+  LDR(IndexType::Unsigned, WA, PPC_REG, PPCSTATE_OFF(fpscr));
+  AND(WA, WA, LogicalImm(mask, 32));
+  STR(IndexType::Unsigned, WA, PPC_REG, PPCSTATE_OFF(fpscr));
+
+  gpr.Unlock(WA);
+
+  if (inst.CRBD >= 29)
+    UpdateRoundingMode();
+}
diff --git a/Source/Core/Core/PowerPC/JitArm64/JitArm64_Tables.cpp b/Source/Core/Core/PowerPC/JitArm64/JitArm64_Tables.cpp
index 5f9af44d9b..00a563ad5c 100644
--- a/Source/Core/Core/PowerPC/JitArm64/JitArm64_Tables.cpp
+++ b/Source/Core/Core/PowerPC/JitArm64/JitArm64_Tables.cpp
@@ -316,7 +316,7 @@ constexpr std::array<GekkoOPTemplate, 15> table63{{
 
     {64, &JitArm64::mcrfs},                   // mcrfs
     {583, &JitArm64::mffsx},                  // mffsx
-    {70, &JitArm64::FallBackToInterpreter},   // mtfsb0x
+    {70, &JitArm64::mtfsb0x},                 // mtfsb0x
     {38, &JitArm64::FallBackToInterpreter},   // mtfsb1x
     {134, &JitArm64::FallBackToInterpreter},  // mtfsfix
     {711, &JitArm64::FallBackToInterpreter},  // mtfsfx