[Lldb-commits] [lldb] Initial step in targets DAP support (PR #86623)

[via lldb-commits]

================
@@ -3180,14 +3180,153 @@ void request_stepIn(const llvm::json::Object &request) {
   llvm::json::Object response;
   FillResponse(request, response);
   auto arguments = request.getObject("arguments");
+
+  std::string step_in_target;
+  uint64_t target_id = GetUnsigned(arguments, "targetId", 0);
+  auto it = g_dap.step_in_targets.find(target_id);
+  if (it != g_dap.step_in_targets.end())
+    step_in_target = it->second;
+
+  const bool single_thread = GetBoolean(arguments, "singleThread", false);
+  lldb::RunMode run_mode =
+      single_thread ? lldb::eOnlyThisThread : lldb::eOnlyDuringStepping;
   lldb::SBThread thread = g_dap.GetLLDBThread(*arguments);
   if (thread.IsValid()) {
     // Remember the thread ID that caused the resume so we can set the
     // "threadCausedFocus" boolean value in the "stopped" events.
     g_dap.focus_tid = thread.GetThreadID();
-    thread.StepInto();
+    thread.StepInto(step_in_target.c_str(), run_mode);
+  } else {
+    response["success"] = llvm::json::Value(false);
+  }
+  g_dap.SendJSON(llvm::json::Value(std::move(response)));
+}
+
+// "StepInTargetsRequest": {
+//   "allOf": [ { "$ref": "#/definitions/Request" }, {
+//     "type": "object",
+//     "description": "This request retrieves the possible step-in targets for
+//     the specified stack frame.\nThese targets can be used in the `stepIn`
+//     request.\nClients should only call this request if the corresponding
+//     capability `supportsStepInTargetsRequest` is true.", "properties": {
+//       "command": {
+//         "type": "string",
+//         "enum": [ "stepInTargets" ]
+//       },
+//       "arguments": {
+//         "$ref": "#/definitions/StepInTargetsArguments"
+//       }
+//     },
+//     "required": [ "command", "arguments"  ]
+//   }]
+// },
+// "StepInTargetsArguments": {
+//   "type": "object",
+//   "description": "Arguments for `stepInTargets` request.",
+//   "properties": {
+//     "frameId": {
+//       "type": "integer",
+//       "description": "The stack frame for which to retrieve the possible
+//       step-in targets."
+//     }
+//   },
+//   "required": [ "frameId" ]
+// },
+// "StepInTargetsResponse": {
+//   "allOf": [ { "$ref": "#/definitions/Response" }, {
+//     "type": "object",
+//     "description": "Response to `stepInTargets` request.",
+//     "properties": {
+//       "body": {
+//         "type": "object",
+//         "properties": {
+//           "targets": {
+//             "type": "array",
+//             "items": {
+//               "$ref": "#/definitions/StepInTarget"
+//             },
+//             "description": "The possible step-in targets of the specified
+//             source location."
+//           }
+//         },
+//         "required": [ "targets" ]
+//       }
+//     },
+//     "required": [ "body" ]
+//   }]
+// }
+void request_stepInTargets(const llvm::json::Object &request) {
+  llvm::json::Object response;
+  FillResponse(request, response);
+  auto arguments = request.getObject("arguments");
+
+  g_dap.step_in_targets.clear();
+  lldb::SBFrame frame = g_dap.GetLLDBFrame(*arguments);
+  if (frame.IsValid()) {
+    lldb::SBAddress pc_addr = frame.GetPCAddress();
+    lldb::SBAddress line_end_addr =
+        pc_addr.GetLineEntry().GetSameLineContiguousAddressRangeEnd(true);
+    lldb::SBInstructionList insts = g_dap.target.ReadInstructions(
+        pc_addr, line_end_addr, /*flavor_string=*/nullptr);
+
+    if (!insts.IsValid()) {
+      response["success"] = false;
+      response["message"] = "Failed to get instructions for frame.";
+      g_dap.SendJSON(llvm::json::Value(std::move(response)));
+      return;
+    }
+
+    llvm::json::Array step_in_targets;
+    const auto num_insts = insts.GetSize();
+    for (size_t i = 0; i < num_insts; ++i) {
+      lldb::SBInstruction inst = insts.GetInstructionAtIndex(i);
+      if (!inst.IsValid())
+        break;
+
+      lldb::addr_t inst_addr = inst.GetAddress().GetLoadAddress(g_dap.target);
+
+      // Note: currently only x86/x64 supports flow kind.
+      lldb::InstructionControlFlowKind flow_kind =
+          inst.GetControlFlowKind(g_dap.target);
+      if (flow_kind == lldb::eInstructionControlFlowKindCall) {
+        // Use call site instruction address as id which is easy to debug.
+        llvm::json::Object step_in_target;
+        step_in_target["id"] = inst_addr;
+
+        llvm::StringRef call_operand_name = inst.GetOperands(g_dap.target);
+        lldb::addr_t call_target_addr;
+        if (call_operand_name.getAsInteger(0, call_target_addr))
+          continue;
----------------
jeffreytan81 wrote:

I have looked into using the comment. But it is not very portable:
```
    0x55555555a426 <+934>:  callq  0x555555558990 ; bar at main.cpp:64
    0x55555555a42b <+939>:  movl   %eax, -0xb0(%rbp)
    0x55555555a431 <+945>:  callq  0x5555555589a0 ; bar2 at main.cpp:68
    0x55555555a436 <+950>:  movl   -0xb0(%rbp), %edi
    0x55555555a43c <+956>:  movl   %eax, %esi
    0x55555555a43e <+958>:  callq  0x555555558970 ; foo at main.cpp:60
```

1. We will have to manually parse the comment to get the target function name.
2. The function name does not include the function overloaded parameters like "foo" vs "for(int, int)". 

https://github.com/llvm/llvm-project/pull/86623