[lldb] Add QSupported key to report watchpoint types supported (#80376)

debugserver on arm64 devices can manage both Byte Address Select
watchpoints (1-8 bytes) and MASK watchpoints (8 bytes-2 gigabytes). This
adds a SupportedWatchpointTypes key to the QSupported response from
debugserver with a list of these, so lldb can take full advantage of
them when creating larger regions with a single hardware watchpoint.

Also add documentation for this, and two other lldb extensions, to the
lldb-gdb-remote.txt documentation.

Re-enable TestLargeWatchpoint.py on Darwin systems when testing with the
in-tree built debugserver. I can remove the "in-tree built debugserver"
in the future when this new key is handled by an Xcode debugserver.

1 files changed, 17 insertions, 0 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
index 7bb44984..6f8aa26 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
@@ -403,6 +403,18 @@ void GDBRemoteCommunicationClient::GetRemoteQSupported() {
         x.split(compressions, ',');
         if (!compressions.empty())
           MaybeEnableCompression(compressions);
+      } else if (x.consume_front("SupportedWatchpointTypes=")) {
+        llvm::SmallVector<llvm::StringRef, 4> watchpoint_types;
+        x.split(watchpoint_types, ',');
+        m_watchpoint_types = eWatchpointHardwareFeatureUnknown;
+        for (auto wp_type : watchpoint_types) {
+          if (wp_type == "x86_64")
+            m_watchpoint_types |= eWatchpointHardwareX86;
+          if (wp_type == "aarch64-mask")
+            m_watchpoint_types |= eWatchpointHardwareArmMASK;
+          if (wp_type == "aarch64-bas")
+            m_watchpoint_types |= eWatchpointHardwareArmBAS;
+        }
       } else if (x.consume_front("PacketSize=")) {
         StringExtractorGDBRemote packet_response(x);
         m_max_packet_size =
@@ -1828,6 +1840,11 @@ std::optional<uint32_t> GDBRemoteCommunicationClient::GetWatchpointSlotCount() {
   return num;
 }
 
+WatchpointHardwareFeature
+GDBRemoteCommunicationClient::GetSupportedWatchpointTypes() {
+  return m_watchpoint_types;
+}
+
 std::optional<bool> GDBRemoteCommunicationClient::GetWatchpointReportedAfter() {
   if (m_qHostInfo_is_valid == eLazyBoolCalculate)
     GetHostInfo();