Adjust some id bit shifts to fit inside 32 bit integers

Summary:
The DAP on vscode uses a JavaScript `number` for identifiers while the
Visual Studio version uses a C# `Int` for identifiers. lldb-vscode is
bit shifting identifiers 32 bits and then bitwise ORing another 32 bit
identifier into a 64 bit id to form a unique ID. Change this to
a a partitioning of the 32 bits that makes sense for the data types.

Reviewers: clayborg

Differential Revision: https://reviews.llvm.org/D53599

4 files changed, 107 insertions, 6 deletions

diff --git a/lldb/tools/lldb-vscode/JSONUtils.cpp b/lldb/tools/lldb-vscode/JSONUtils.cpp
index 2c6a5d6d67a..019a9db624d 100644
--- a/lldb/tools/lldb-vscode/JSONUtils.cpp
+++ b/lldb/tools/lldb-vscode/JSONUtils.cpp
@@ -288,8 +288,7 @@ llvm::json::Value CreateBreakpoint(lldb::SBBreakpointLocation &bp_loc) {
     return llvm::json::Value(std::move(object));
 
   object.try_emplace("verified", true);
-  const auto bp_id = bp_loc.GetBreakpoint().GetID();
-  const auto vs_id = (int64_t)(((int64_t)bp_id << 32) | bp_loc.GetID());
+  const auto vs_id = MakeVSCodeBreakpointID(bp_loc);
   object.try_emplace("id", vs_id);
   auto bp_addr = bp_loc.GetAddress();
   if (bp_addr.IsValid()) {
diff --git a/lldb/tools/lldb-vscode/LLDBUtils.cpp b/lldb/tools/lldb-vscode/LLDBUtils.cpp
index 797eda09ccd..9653522a2d3 100644
--- a/lldb/tools/lldb-vscode/LLDBUtils.cpp
+++ b/lldb/tools/lldb-vscode/LLDBUtils.cpp
@@ -65,9 +65,34 @@ bool ThreadHasStopReason(lldb::SBThread &thread) {
   return false;
 }
 
+static uint32_t constexpr THREAD_INDEX_SHIFT = 19;
+
+uint32_t GetLLDBThreadIndexID(uint64_t dap_frame_id) {
+  return dap_frame_id >> THREAD_INDEX_SHIFT;
+}
+
+uint32_t GetLLDBFrameID(uint64_t dap_frame_id) {
+  return dap_frame_id & ((1u << THREAD_INDEX_SHIFT) - 1);
+}
+
 int64_t MakeVSCodeFrameID(lldb::SBFrame &frame) {
-  return (int64_t)frame.GetThread().GetIndexID() << 32 |
-         (int64_t)frame.GetFrameID();
+  return (int64_t)(frame.GetThread().GetIndexID() << THREAD_INDEX_SHIFT |
+                   frame.GetFrameID());
+}
+
+static uint32_t constexpr BREAKPOINT_ID_SHIFT = 22;
+
+uint32_t GetLLDBBreakpointID(uint64_t dap_breakpoint_id) {
+  return dap_breakpoint_id >> BREAKPOINT_ID_SHIFT;
+}
+
+uint32_t GetLLDBBreakpointLocationID(uint64_t dap_breakpoint_id) {
+  return dap_breakpoint_id & ((1u << BREAKPOINT_ID_SHIFT) - 1);
+}
+
+int64_t MakeVSCodeBreakpointID(lldb::SBBreakpointLocation &bp_loc) {
+  return (int64_t)(bp_loc.GetBreakpoint().GetID() << BREAKPOINT_ID_SHIFT |
+                   bp_loc.GetID());
 }
 
 } // namespace lldb_vscode
diff --git a/lldb/tools/lldb-vscode/LLDBUtils.h b/lldb/tools/lldb-vscode/LLDBUtils.h
index f5ff2c97561..96ebb85f14b 100644
--- a/lldb/tools/lldb-vscode/LLDBUtils.h
+++ b/lldb/tools/lldb-vscode/LLDBUtils.h
@@ -89,6 +89,82 @@ bool ThreadHasStopReason(lldb::SBThread &thread);
 //----------------------------------------------------------------------
 int64_t MakeVSCodeFrameID(lldb::SBFrame &frame);
 
+///----------------------------------------------------------------------
+/// Given a VSCode frame ID, convert to a LLDB thread index id.
+///
+/// VSCode requires a Stackframe "id" to be unique, so we use the frame
+/// index in the lower THREAD_INDEX_SHIFT bits and the thread index ID in
+/// the upper 32 - THREAD_INDEX_SHIFT bits.
+///
+/// @param[in] dap_frame_id
+///     The VSCode frame ID to convert to a thread index ID.
+///
+/// @return
+///     The LLDB thread index ID.
+//----------------------------------------------------------------------
+uint32_t GetLLDBThreadIndexID(uint64_t dap_frame_id);
+
+///----------------------------------------------------------------------
+/// Given a VSCode frame ID, convert to a LLDB frame ID.
+///
+/// VSCode requires a Stackframe "id" to be unique, so we use the frame
+/// index in the lower THREAD_INDEX_SHIFT bits and the thread index ID in
+/// the upper 32 - THREAD_INDEX_SHIFT bits.
+///
+/// @param[in] dap_frame_id
+///     The VSCode frame ID to convert to a frame ID.
+///
+/// @return
+///     The LLDB frame index ID.
+//----------------------------------------------------------------------
+uint32_t GetLLDBFrameID(uint64_t dap_frame_id);
+
+///----------------------------------------------------------------------
+/// Given a LLDB breakpoint, make a breakpoint ID that is unique to a
+/// specific breakpoint and breakpoint location.
+///
+/// VSCode requires a Breakpoint "id" to be unique, so we use the
+/// breakpoint ID in the lower BREAKPOINT_ID_SHIFT bits and the
+/// breakpoint location ID in the upper BREAKPOINT_ID_SHIFT bits.
+///
+/// @param[in] frame
+///     The LLDB stack frame object generate the ID for
+///
+/// @return
+///     A unique integer that allows us to easily find the right
+///     stack frame within a thread on subsequent VS code requests.
+//----------------------------------------------------------------------
+int64_t MakeVSCodeBreakpointID(lldb::SBBreakpointLocation &bp_loc);
+
+///----------------------------------------------------------------------
+/// Given a VSCode breakpoint ID, convert to a LLDB breakpoint ID.
+///
+/// VSCode requires a Breakpoint "id" to be unique, so we use the
+/// breakpoint ID in the lower BREAKPOINT_ID_SHIFT bits and the
+/// breakpoint location ID in the upper BREAKPOINT_ID_SHIFT bits.
+///
+/// @param[in] dap_breakpoint_id
+///     The VSCode breakpoint ID to convert to an LLDB breakpoint ID.
+///
+/// @return
+///     The LLDB breakpoint ID.
+//----------------------------------------------------------------------
+uint32_t GetLLDBBreakpointID(uint64_t dap_breakpoint_id);
+
+///----------------------------------------------------------------------
+/// Given a VSCode breakpoint ID, convert to a LLDB breakpoint location ID.
+///
+/// VSCode requires a Breakpoint "id" to be unique, so we use the
+/// breakpoint ID in the lower BREAKPOINT_ID_SHIFT bits and the
+/// breakpoint location ID in the upper BREAKPOINT_ID_SHIFT bits.
+///
+/// @param[in] dap_breakpoint_id
+///     The VSCode frame ID to convert to a breakpoint location ID.
+///
+/// @return
+///     The LLDB breakpoint location ID.
+//----------------------------------------------------------------------
+uint32_t GetLLDBBreakpointLocationID(uint64_t dap_breakpoint_id);
 } // namespace lldb_vscode
 
 #endif
diff --git a/lldb/tools/lldb-vscode/VSCode.cpp b/lldb/tools/lldb-vscode/VSCode.cpp
index a8667769ab4..d268c45aca6 100644
--- a/lldb/tools/lldb-vscode/VSCode.cpp
+++ b/lldb/tools/lldb-vscode/VSCode.cpp
@@ -308,9 +308,10 @@ lldb::SBFrame VSCode::GetLLDBFrame(const llvm::json::Object &arguments) {
   const uint64_t frame_id = GetUnsigned(arguments, "frameId", UINT64_MAX);
   lldb::SBProcess process = target.GetProcess();
   // Upper 32 bits is the thread index ID
-  lldb::SBThread thread = process.GetThreadByIndexID(frame_id >> 32);
+  lldb::SBThread thread =
+      process.GetThreadByIndexID(GetLLDBThreadIndexID(frame_id));
   // Lower 32 bits is the frame index
-  return thread.GetFrameAtIndex(frame_id & 0xffffffffu);
+  return thread.GetFrameAtIndex(GetLLDBFrameID(frame_id));
 }
 
 llvm::json::Value VSCode::CreateTopLevelScopes() {