Improve VSCode DAP logpoint value summary (#71723)

Currently VSCode logpoint uses `SBValue::GetValue` to get the value for
printing. This is not providing an intuitive result for std::string or
char * -- it shows the pointer value instead of the string content.

This patch improves by prefers `SBValue::GetSummary()` before using
`SBValue::GetValue()`.

---------

Co-authored-by: jeffreytan81 <[email protected]>

Author: jeffreytan81

lldb/test/API/tools/lldb-dap/breakpoint/TestDAP_logpoints.py

@@ -48,7 +48,7 @@ def test_logmessage_basic(self):
         # 1. First at the loop line with logMessage
         # 2. Second guard breakpoint at a line after loop
         logMessage_prefix = "This is log message for { -- "
-        logMessage = logMessage_prefix + "{i + 3}"
+        logMessage = logMessage_prefix + "{i + 3}, {message}"
         [loop_breakpoint_id, post_loop_breakpoint_id] = self.set_source_breakpoints(
             self.main_path,
             [loop_line, after_loop_line],
@@ -72,10 +72,13 @@ def test_logmessage_basic(self):
         loop_count = 10
         self.assertEqual(len(logMessage_output), loop_count)
 
+        message_addr_pattern = r"\b0x[0-9A-Fa-f]+\b"
+        message_content = '"Hello from main!"'
         # Verify log message match
         for idx, logMessage_line in enumerate(logMessage_output):
             result = idx + 3
-            self.assertEqual(logMessage_line, logMessage_prefix + str(result))
+            reg_str = f"{logMessage_prefix}{result}, {message_addr_pattern} {message_content}"
+            self.assertRegex(logMessage_line, reg_str)
 
     @skipIfWindows
     @skipIfRemote

lldb/test/API/tools/lldb-dap/breakpoint/main.cpp

@@ -28,6 +28,7 @@ int main(int argc, char const *argv[]) {
     exit(1);
   }
 
+  const char *message = "Hello from main!";
   int (*foo)(int) = (int (*)(int))dlsym(handle, "foo");
   if (foo == nullptr) {
     fprintf(stderr, "%s\n", dlerror());
@@ -38,6 +39,7 @@ int main(int argc, char const *argv[]) {
   for (int i = 0; i < 10; ++i) {
     int x = twelve(i) + thirteen(i) + a::fourteen(i); // break loop
   }
+  printf("%s\n", message);
   try {
     throw std::invalid_argument("throwing exception for testing");
   } catch (...) {

lldb/tools/lldb-dap/BreakpointBase.cpp

@@ -8,6 +8,7 @@
 
 #include "BreakpointBase.h"
 #include "DAP.h"
+#include "JSONUtils.h"
 #include "llvm/ADT/StringExtras.h"
 
 using namespace lldb_dap;
@@ -295,9 +296,7 @@ bool BreakpointBase::BreakpointHitCallback(
           frame.GetValueForVariablePath(expr, lldb::eDynamicDontRunTarget);
       if (value.GetError().Fail())
         value = frame.EvaluateExpression(expr);
-      const char *expr_val = value.GetValue();
-      if (expr_val)
-        output += expr_val;
+      output += ValueToString(value);
     } else {
       output += messagePart.text;
     }

lldb/tools/lldb-dap/JSONUtils.cpp

@@ -210,8 +210,7 @@ static std::optional<std::string> TryCreateAutoSummary(lldb::SBValue value) {
   return TryCreateAutoSummaryForContainer(value);
 }
 
-void SetValueForKey(lldb::SBValue &v, llvm::json::Object &object,
-                    llvm::StringRef key) {
+std::string ValueToString(lldb::SBValue v) {
   std::string result;
   llvm::raw_string_ostream strm(result);
 
@@ -242,6 +241,12 @@ void SetValueForKey(lldb::SBValue &v, llvm::json::Object &object,
       }
     }
   }
+  return result;
+}
+
+void SetValueForKey(lldb::SBValue &v, llvm::json::Object &object,
+                    llvm::StringRef key) {
+  std::string result = ValueToString(v);
   EmplaceSafeString(object, key, result);
 }
 

lldb/tools/lldb-dap/JSONUtils.h

@@ -167,6 +167,9 @@ std::vector<std::string> GetStrings(const llvm::json::Object *obj,
 void FillResponse(const llvm::json::Object &request,
                   llvm::json::Object &response);
 
+/// Utility function to convert SBValue \v into a string.
+std::string ValueToString(lldb::SBValue v);
+
 /// Emplace the string value from an SBValue into the supplied object
 /// using \a key as the key that will contain the value.
 ///