CPU/Recompiler: Add GetValueInHostOrScratchRegister helper

src/core/cpu_recompiler_code_generator.h

@@ -179,6 +179,7 @@ private:
   void ConvertValueSizeInPlace(Value* value, RegSize size, bool sign_extend);
 
   Value GetValueInHostRegister(const Value& value, bool allow_zero_register = true);
+  Value GetValueInHostOrScratchRegister(const Value& value, bool allow_zero_register = true);
 
   void SwitchToFarCode();
   void SwitchToNearCode();

src/core/cpu_recompiler_code_generator_aarch64.cpp

@@ -182,6 +182,19 @@ Value CodeGenerator::GetValueInHostRegister(const Value& value, bool allow_zero_
   return new_value;
 }
 
+Value CodeGenerator::GetValueInHostOrScratchRegister(const Value& value, bool allow_zero_register /* = true */)
+{
+  if (value.IsInHostRegister())
+    return Value::FromHostReg(&m_register_cache, value.host_reg, value.size);
+
+  if (value.HasConstantValue(0) && allow_zero_register)
+    return Value::FromHostReg(&m_register_cache, static_cast<HostReg>(31), value.size);
+
+  Value new_value = Value::FromHostReg(&m_register_cache, RSCRATCH, value.size);
+  EmitCopyValue(new_value.host_reg, value);
+  return new_value;
+}
+
 void CodeGenerator::EmitBeginBlock()
 {
   m_emit->Sub(a64::sp, a64::sp, FUNCTION_STACK_SIZE);

src/core/cpu_recompiler_code_generator_x64.cpp

@@ -196,6 +196,16 @@ Value CodeGenerator::GetValueInHostRegister(const Value& value, bool allow_zero_
   return new_value;
 }
 
+Value CodeGenerator::GetValueInHostOrScratchRegister(const Value& value, bool allow_zero_register /* = true */)
+{
+  if (value.IsInHostRegister())
+    return Value(value.regcache, value.host_reg, value.size, ValueFlags::Valid | ValueFlags::InHostRegister);
+
+  Value new_value = m_register_cache.AllocateScratch(value.size);
+  EmitCopyValue(new_value.host_reg, value);
+  return new_value;
+}
+
 void CodeGenerator::EmitBeginBlock()
 {
   m_register_cache.AssumeCalleeSavedRegistersAreSaved();