[GDBStub] Prevent adding BP if other BP shares same host addr

Fixes assert error with BPs set very close to each other
(in IDA the failed BP will also show different color)

src/xenia/debug/gdb/gdbstub.cc

@@ -692,7 +692,7 @@ std::string GDBStub::GetThreadStateReply(uint32_t thread_id, uint8_t signal) {
   return "S05";
 }
 
-void GDBStub::CreateCodeBreakpoint(uint64_t address) {
+bool GDBStub::CreateCodeBreakpoint(uint64_t address) {
 #ifdef DEBUG
   debugging::DebugPrint("GDBStub: Adding breakpoint: {:X}\n", address);
 #endif
@@ -705,16 +705,30 @@ void GDBStub::CreateCodeBreakpoint(uint64_t address) {
         OnBreakpointHit(breakpoint, thread_info);
       });
 
+  // Fetch list of host addrs used by the new BP
+  std::vector<uintptr_t> host_addresses;
+  breakpoint->ForEachHostAddress([&host_addresses](uintptr_t host_address) {
+    host_addresses.push_back(host_address);
+  });
+
   auto& map = state.code_breakpoints_by_guest_address;
-  auto it = map.find(breakpoint->guest_address());
-  if (it != map.end()) {
-    // Already exists!
-    return;
+  for (auto& kvp : map) {
+    if (kvp.first == breakpoint->guest_address()) {
+      return false;  // Already exists!
+    }
+    for (auto& host_address : host_addresses) {
+      if (kvp.second->ContainsHostAddress(host_address)) {
+        return false;  // Host addr is in use by another BP already
+      }
+    }
   }
+
   map.emplace(breakpoint->guest_address(), breakpoint.get());
 
   processor_->AddBreakpoint(breakpoint.get());
   state.all_breakpoints.emplace_back(std::move(breakpoint));
+
+  return true;
 }
 
 void GDBStub::DeleteCodeBreakpoint(uint64_t address) {
@@ -881,8 +895,8 @@ std::string GDBStub::HandleGDBCommand(const GDBCommand& command) {
              auto& hex_addr = cmd.data.substr(2);
              uint64_t addr = std::stoull(hex_addr.substr(0, hex_addr.find(',')),
                                          nullptr, 16);
-             CreateCodeBreakpoint(addr);
-             return kGdbReplyOK;
+
+             return CreateCodeBreakpoint(addr) ? kGdbReplyOK : kGdbReplyError;
            }},
           // Delete breakpoint
           {"z",

src/xenia/debug/gdb/gdbstub.h

@@ -73,7 +73,7 @@ class GDBStub : public cpu::DebugListener {
 
   std::string GetThreadStateReply(uint32_t thread_id, uint8_t signal);
 
-  void CreateCodeBreakpoint(uint64_t address);
+  bool CreateCodeBreakpoint(uint64_t address);
   void DeleteCodeBreakpoint(uint64_t address);
   void DeleteCodeBreakpoint(cpu::Breakpoint* breakpoint);
   cpu::Breakpoint* LookupBreakpointAtAddress(uint64_t address);