From fdcea8566ded2b0575e30da7e43c81859095bc44 Mon Sep 17 00:00:00 2001
From: JosJuice <josjuice@gmail.com>
Date: Sat, 29 May 2021 11:44:04 +0200
Subject: [PATCH] JitArm64: Improve Arm64FPRCache::GetCallerSavedUsed

If we're only using the lower 64 bits of a callee-saved
register, GetCallerSavedUsed can return false for it.
---
 .../Core/PowerPC/JitArm64/JitArm64_RegCache.cpp     | 13 ++++++++++++-
 .../Core/Core/PowerPC/JitArm64/JitArm64_RegCache.h  |  1 +
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Source/Core/Core/PowerPC/JitArm64/JitArm64_RegCache.cpp b/Source/Core/Core/PowerPC/JitArm64/JitArm64_RegCache.cpp
index fdd4790807..6f86c69aab 100644
--- a/Source/Core/Core/PowerPC/JitArm64/JitArm64_RegCache.cpp
+++ b/Source/Core/Core/PowerPC/JitArm64/JitArm64_RegCache.cpp
@@ -742,6 +742,17 @@ bool Arm64FPRCache::IsCalleeSaved(ARM64Reg reg) const
   return std::find(callee_regs.begin(), callee_regs.end(), reg) != callee_regs.end();
 }
 
+bool Arm64FPRCache::IsTopHalfUsed(ARM64Reg reg) const
+{
+  for (const OpArg& r : m_guest_registers)
+  {
+    if (r.GetReg() != ARM64Reg::INVALID_REG && DecodeReg(r.GetReg()) == DecodeReg(reg))
+      return r.GetType() == RegType::Register;
+  }
+
+  return false;
+}
+
 void Arm64FPRCache::FlushRegister(size_t preg, bool maintain_state, ARM64Reg tmp_reg)
 {
   OpArg& reg = m_guest_registers[preg];
@@ -846,7 +857,7 @@ BitSet32 Arm64FPRCache::GetCallerSavedUsed() const
   BitSet32 registers(0);
   for (const auto& it : m_host_registers)
   {
-    if (it.IsLocked())
+    if (it.IsLocked() && (!IsCalleeSaved(it.GetReg()) || IsTopHalfUsed(it.GetReg())))
       registers[DecodeReg(it.GetReg())] = true;
   }
   return registers;
diff --git a/Source/Core/Core/PowerPC/JitArm64/JitArm64_RegCache.h b/Source/Core/Core/PowerPC/JitArm64/JitArm64_RegCache.h
index a8a110b1e1..9be43a3a6e 100644
--- a/Source/Core/Core/PowerPC/JitArm64/JitArm64_RegCache.h
+++ b/Source/Core/Core/PowerPC/JitArm64/JitArm64_RegCache.h
@@ -351,6 +351,7 @@ protected:
 
 private:
   bool IsCalleeSaved(Arm64Gen::ARM64Reg reg) const;
+  bool IsTopHalfUsed(Arm64Gen::ARM64Reg reg) const;
 
   void FlushRegisters(BitSet32 regs, bool maintain_state, Arm64Gen::ARM64Reg tmp_reg);
 };