DSP/LabelMap: Use std::optional with GetLabelValue()

Rather than use a bool and out parameter, we can collapse them into one
by using a std::optional.

Source/Core/Core/DSP/DSPAssembler.cpp

@@ -200,9 +200,9 @@ s32 DSPAssembler::ParseValue(const char* str)
     else  // Everything else is a label.
     {
       // Lookup label
-      u16 value;
-      if (m_labels.GetLabelValue(ptr, &value))
-        return value;
+      if (const std::optional<u16> value = m_labels.GetLabelValue(ptr))
+        return *value;
+
       if (m_cur_pass == 2)
         ShowError(AssemblerError::UnknownLabel, str);
     }

Source/Core/Core/DSP/LabelMap.cpp

@@ -33,11 +33,11 @@ void LabelMap::RegisterDefaults()
 
 void LabelMap::RegisterLabel(const std::string& label, u16 lval, LabelType type)
 {
-  u16 old_value;
-  if (GetLabelValue(label, &old_value) && old_value != lval)
+  const std::optional<u16> old_value = GetLabelValue(label);
+  if (old_value && old_value != lval)
   {
     printf("WARNING: Redefined label %s to %04x - old value %04x\n", label.c_str(), lval,
-           old_value);
+           *old_value);
     DeleteLabel(label);
   }
   labels.emplace_back(label, lval, type);
@@ -54,16 +54,15 @@ void LabelMap::DeleteLabel(const std::string& label)
   labels.erase(iter);
 }
 
-bool LabelMap::GetLabelValue(const std::string& name, u16* value, LabelType type) const
+std::optional<u16> LabelMap::GetLabelValue(const std::string& name, LabelType type) const
 {
-  for (auto& label : labels)
+  for (const auto& label : labels)
   {
-    if (!name.compare(label.name))
+    if (name == label.name)
     {
-      if (type & label.type)
+      if ((type & label.type) != 0)
       {
-        *value = label.addr;
-        return true;
+        return label.addr;
       }
       else
       {
@@ -71,7 +70,8 @@ bool LabelMap::GetLabelValue(const std::string& name, u16* value, LabelType type
       }
     }
   }
-  return false;
+
+  return std::nullopt;
 }
 
 void LabelMap::Clear()

Source/Core/Core/DSP/LabelMap.h

@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <optional>
 #include <string>
 #include <vector>
 
@@ -28,7 +29,7 @@ public:
   void RegisterDefaults();
   void RegisterLabel(const std::string& label, u16 lval, LabelType type = LABEL_VALUE);
   void DeleteLabel(const std::string& label);
-  bool GetLabelValue(const std::string& label, u16* value, LabelType type = LABEL_ANY) const;
+  std::optional<u16> GetLabelValue(const std::string& label, LabelType type = LABEL_ANY) const;
   void Clear();
 
 private: