Debugger: Add string comparison to conditional breakpoints.

Source/Core/Core/PowerPC/Expression.cpp

@@ -135,7 +135,44 @@ static double CallstackFunc(expr_func* f, vec_expr_t* args, void* c)
   return 0;
 }
 
-static std::array<expr_func, 22> g_expr_funcs{{
+static std::optional<std::string> ReadStringArg(const Core::CPUThreadGuard& guard, expr* e)
+{
+  double num = expr_eval(e);
+  if (!std::isnan(num))
+  {
+    u32 address = static_cast<u32>(num);
+    return PowerPC::HostGetString(guard, address);
+  }
+
+  const char* cstr = expr_get_str(e);
+  if (cstr != nullptr)
+  {
+    return std::string(cstr);
+  }
+
+  return std::nullopt;
+}
+
+static double StreqFunc(expr_func* f, vec_expr_t* args, void* c)
+{
+  if (vec_len(args) != 2)
+    return 0;
+
+  const auto* guard = reinterpret_cast<const Core::CPUThreadGuard*>(c);
+  std::array<std::string, 2> strs;
+  for (int i = 0; i < 2; i++)
+  {
+    std::optional<std::string> arg = ReadStringArg(*guard, &vec_nth(args, i));
+    if (arg == std::nullopt)
+      return 0;
+
+    strs[i] = std::move(*arg);
+  }
+
+  return strs[0] == strs[1];
+}
+
+static std::array<expr_func, 23> g_expr_funcs{{
     // For internal storage and comparisons, everything is auto-converted to Double.
     // If u64 ints are added, this could produce incorrect results.
     {"read_u8", HostReadFunc<u8>},
@@ -158,6 +195,7 @@ static std::array<expr_func, 22> g_expr_funcs{{
     {"u32", CastFunc<u32>},
     {"s32", CastFunc<s32, u32>},
     {"callstack", CallstackFunc},
+    {"streq", StreqFunc},
     {},
 }};
 

Source/Core/DolphinQt/Debugger/BreakpointDialog.cpp

@@ -337,6 +337,7 @@ void BreakpointDialog::ShowConditionHelp()
       "Set a register: r1 = 8\n"
       "Casts: s8(0xff). Available: s8, u8, s16, u16, s32, u32\n"
       "Callstack: callstack(0x80123456), callstack(\"anim\")\n"
+      "Compare Strings: streq(r3, \"abc\"). Both parameters can be addresses or string constants.\n"
       "Read Memory: read_u32(0x80000000). Available: u8, s8, u16, s16, u32, s32, f32, f64\n"
       "Write Memory: write_u32(r3, 0x80000000). Available: u8, u16, u32, f32, f64\n"
       "*currently writing will always be triggered\n"
@@ -355,8 +356,8 @@ void BreakpointDialog::ShowConditionHelp()
       "Write and break: r4 = 8, 1\n"
       "Write and continue: f3 = f1 + f2, 0\n"
       "The condition must always be last\n\n"
-      "Strings should only be used in callstack() and \"quoted\". Do not assign strings to a "
-      "variable.\n"
+      "Strings should only be used in callstack() or streq() and \"quoted\". Do not assign strings "
+      "to a variable.\n"
       "All variables will be printed in the Memory Interface log, if there's a hit or a NaN "
       "result. To check for issues, assign a variable to your equation, so it can be printed.\n\n"
       "Note: All values are internally converted to Doubles for calculations. It's possible for "