[LLDB] Format lldb-server's target XML

[DavidSpickett]

Summary

So that the XML isn't one giant line. Which wasn't
a problem for lldb but was for me trying to troubleshoot
it using the logs.

It now looks like:

<?xml version="1.0"?>
<target version="1.0">
  <architecture>aarch64</architecture>
  <feature>
    <...>
    <reg name="fpcr" .../>
  </feature>
</target>

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp

return llvm::createStringError(llvm::inconvertibleErrorCode(),
                                    "No thread available");
 
   Log *log = GetLog(LLDBLog::Process | LLDBLog::Thread);
   // Get the register context for the first thread.
   NativeRegisterContext &reg_context = thread->GetRegisterContext();
 
   StreamString response;
 
-  response.Printf("<?xml version=\"1.0\"?>");
-  response.Printf("<target version=\"1.0\">");
+  response.Printf("<?xml version=\"1.0\"?>\n");
+  response.Printf("<target version=\"1.0\">\n");
+  response.IndentMore();
 
-  response.Printf("<architecture>%s</architecture>",
+  response.Indent();
+  response.Printf("<architecture>%s</architecture>\n",
                   m_current_process->GetArchitecture()
                       .GetTriple()
                       .getArchName()
                       .str()
                       .c_str());
 
-  response.Printf("<feature>");
+  response.Indent("<feature>\n");
 
   const int registers_count = reg_context.GetUserRegisterCount();
+  if (registers_count)
+    response.IndentMore();
+
   for (int reg_index = 0; reg_index < registers_count; reg_index++) {
     const RegisterInfo *reg_info =
         reg_context.GetRegisterInfoAtIndex(reg_index);
 
     if (!reg_info) {
       LLDB_LOGF(log,
                 "%s failed to get register info for register index %" PRIu32,
                 "target.xml", reg_index);
       continue;
     }
 
-    response.Printf("<reg name=\"%s\" bitsize=\"%" PRIu32 "\" regnum=\"%d\" ",
+    response.Indent();
+    response.Printf("<reg name=\"%s\" bitsize=\"%" PRIu32
+                    "\" regnum=\"%d\" ",
                     reg_info->name, reg_info->byte_size * 8, reg_index);
 
     if (!reg_context.RegisterOffsetIsDynamic())
       response.Printf("offset=\"%" PRIu32 "\" ", reg_info->byte_offset);
 
     if (reg_info->alt_name && reg_info->alt_name[0])
       response.Printf("altname=\"%s\" ", reg_info->alt_name);
 
for (int reg_index = 0; reg_index < registers_count; reg_index++) {
     }
 
     if (reg_info->invalidate_regs && reg_info->invalidate_regs[0]) {
       response.PutCString("invalidate_regnums=\"");
       CollectRegNums(reg_info->invalidate_regs, response, false);
       response.Printf("\" ");
     }
 
-    response.Printf("/>");
+    response.Printf("/>\n");
   }
 
-  response.Printf("</feature>");
-  response.Printf("</target>");
+  if (registers_count)
+    response.IndentLess();
+
+  response.Indent("</feature>\n");
+  response.IndentLess();
+  response.Indent("</target>\n");
   return MemoryBuffer::getMemBufferCopy(response.GetString(), "target.xml");
 }
 
 llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
 GDBRemoteCommunicationServerLLGS::ReadXferObject(llvm::StringRef object,
                                                  llvm::StringRef annex) {
   // Make sure we have a valid process.
   if (!m_current_process ||

lldb/test/API/tools/lldb-server/TestPtyServer.py

def test_pty_server(self):
         self.prep_debug_monitor_and_inferior()
 
         # target.xml transfer should trigger a large enough packet to check
         # for partial write regression
         self.test_sequence.add_log_lines([
             "read packet: $qXfer:features:read:target.xml:0,200000#00",
             {
                 "direction": "send",
-                "regex": re.compile("^\$l(.+)#[0-9a-fA-F]{2}$"),
+                "regex": re.compile("^\$l(.+)#[0-9a-fA-F]{2}$", flags=re.DOTALL),
                 "capture": {1: "target_xml"},
             }],
             True)
         context = self.expect_gdbremote_sequence()
         # verify that we have received a complete, non-malformed XML
         self.assertIsNotNone(ET.fromstring(context.get("target_xml")))

lldb/test/API/tools/lldb-server/registers-target-xml-reading/TestGdbRemoteTargetXmlPacket.py

def test_g_target_xml_returns_correct_data(self):
         OFFSET = 0
         LENGTH = 0x1ffff0
         self.test_sequence.add_log_lines([
             "read packet: $qXfer:features:read:target.xml:{:x},{:x}#00".format(
                     OFFSET,
                     LENGTH),
             {   
                 "direction": "send", 
-                "regex": re.compile("^\$l(.+)#[0-9a-fA-F]{2}$"), 
+                "regex": re.compile("^\$l(.+)#[0-9a-fA-F]{2}$", flags=re.DOTALL),
                 "capture": {1: "target_xml"}
             }],
             True)
         context = self.expect_gdbremote_sequence()
 
         target_xml = context.get("target_xml")
         
         root = ET.fromstring(target_xml)