[lldb][lldb-server] Enable sending RegisterFlags as XML

lldb/include/lldb/Target/RegisterFlags.h

@@ -10,6 +10,7 @@
 #define LLDB_TARGET_REGISTERFLAGS_H
 
 #include "lldb/Utility/Log.h"
+#include "lldb/Utility/StreamString.h"
 
 namespace lldb_private {
 
@@ -51,6 +52,10 @@ class RegisterFlags {
     /// covered by either field.
     unsigned PaddingDistance(const Field &other) const;
 
+    /// Output XML that describes this field, to be inserted into a target XML
+    /// file.
+    void ToXML(StreamString &strm) const;
+
     bool operator<(const Field &rhs) const {
       return GetStart() < rhs.GetStart();
     }
@@ -106,6 +111,9 @@ class RegisterFlags {
   /// be split into many tables as needed.
   std::string AsTable(uint32_t max_width) const;
 
+  // Output XML that describes this set of flags.
+  void ToXML(StreamString &strm) const;
+
 private:
   const std::string m_id;
   /// Size in bytes

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

@@ -3094,6 +3094,12 @@ GDBRemoteCommunicationServerLLGS::BuildTargetXml() {
       continue;
     }
 
+    if (reg_info->flags_type) {
+      response.IndentMore();
+      reg_info->flags_type->ToXML(response);
+      response.IndentLess();
+    }
+
     response.Indent();
     response.Printf("<reg name=\"%s\" bitsize=\"%" PRIu32
                     "\" regnum=\"%d\" ",
@@ -3113,6 +3119,10 @@ GDBRemoteCommunicationServerLLGS::BuildTargetXml() {
     if (!format.empty())
       response << "format=\"" << format << "\" ";
 
+    if (reg_info->flags_type) {
+      response << "type=\"" << reg_info->flags_type->GetID() << "\" ";
+    }
+
     const char *const register_set_name =
         reg_context.GetRegisterSetNameForRegisterAtIndex(reg_index);
     if (register_set_name)

lldb/source/Target/RegisterFlags.cpp

@@ -175,3 +175,35 @@ std::string RegisterFlags::AsTable(uint32_t max_width) const {
 
   return table;
 }
+
+void RegisterFlags::ToXML(StreamString &strm) const {
+  // Example XML:
+  // <flags id="cpsr_flags" size="4">
+  //   <field name="incorrect" start="0" end="0"/>
+  // </flags>
+  strm.Indent();
+  strm << "<flags id=\"" << GetID() << "\" ";
+  strm.Printf("size=\"%d\"", GetSize());
+  strm << ">";
+  for (const Field &field : m_fields) {
+    // Skip padding fields.
+    if (field.GetName().empty())
+      continue;
+
+    strm << "\n";
+    strm.IndentMore();
+    field.ToXML(strm);
+    strm.IndentLess();
+  }
+  strm.PutChar('\n');
+  strm.Indent("</flags>\n");
+}
+
+void RegisterFlags::Field::ToXML(StreamString &strm) const {
+  // Example XML:
+  // <field name="correct" start="0" end="0"/>
+  strm.Indent();
+  strm << "<field name=\"" << GetName() << "\" ";
+  strm.Printf("start=\"%d\" end=\"%d\"", GetStart(), GetEnd());
+  strm << "/>";
+}

lldb/unittests/Target/RegisterFlagsTest.cpp

@@ -258,3 +258,35 @@ TEST(RegisterFlagsTest, AsTable) {
             "| really long name |",
             max_many_columns.AsTable(23));
 }
+
+TEST(RegisterFieldsTest, ToXML) {
+  StreamString strm;
+
+  // RegisterFlags requires that some fields be given, so no testing of empty
+  // input.
+
+  // Unnamed fields are padding that are ignored. This applies to fields passed
+  // in, and those generated to fill the other bits (31-1 here).
+  RegisterFlags("Foo", 4, {RegisterFlags::Field("", 0, 0)}).ToXML(strm);
+  ASSERT_EQ(strm.GetString(), "<flags id=\"Foo\" size=\"4\">\n"
+                              "</flags>\n");
+
+  strm.Clear();
+  RegisterFlags("Foo", 4, {RegisterFlags::Field("abc", 0, 0)}).ToXML(strm);
+  ASSERT_EQ(strm.GetString(), "<flags id=\"Foo\" size=\"4\">\n"
+                              "  <field name=\"abc\" start=\"0\" end=\"0\"/>\n"
+                              "</flags>\n");
+
+  strm.Clear();
+  // Should use the current indentation level as a starting point.
+  strm.IndentMore();
+  RegisterFlags(
+      "Bar", 5,
+      {RegisterFlags::Field("f1", 25, 32), RegisterFlags::Field("f2", 10, 24)})
+      .ToXML(strm);
+  ASSERT_EQ(strm.GetString(),
+            "  <flags id=\"Bar\" size=\"5\">\n"
+            "    <field name=\"f1\" start=\"25\" end=\"32\"/>\n"
+            "    <field name=\"f2\" start=\"10\" end=\"24\"/>\n"
+            "  </flags>\n");
+}