Unify string debug printing

This unifies functionality between release-mode ShortPrint and
debug-mode Print:

- Prefixes and suffixes are now consistent. 'u' for two-byte, '#' for
  internalized, 'c' for cons, '>' for thin.
- Logic was simplified and is now based on 3 functions:
  PrefixForDebugPrint, PrintUC16, SuffixForDebugPrint.
- %DebugPrint no longer interprets strings as 'code markers'.
- The ancient and unused use_verbose_printer flag was removed.

Bug: v8:10581
Change-Id: Iebc6a746a2683f9f5a8ef60579836e7f66a188fa
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2224868
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68103}

src/diagnostics/objects-printer.cc

@@ -1046,34 +1046,9 @@ void JSMessageObject::JSMessageObjectPrint(std::ostream& os) {  // NOLINT
 }
 
 void String::StringPrint(std::ostream& os) {  // NOLINT
-  if (!IsOneByteRepresentation()) {
-    os << "u";
-  }
-  if (StringShape(*this).IsInternalized()) {
-    os << "#";
-  } else if (StringShape(*this).IsCons()) {
-    os << "c\"";
-  } else if (StringShape(*this).IsThin()) {
-    os << ">\"";
-  } else {
-    os << "\"";
-  }
-
-  const char truncated_epilogue[] = "...<truncated>";
-  int len = length();
-  if (!FLAG_use_verbose_printer) {
-    if (len > 100) {
-      len = 100 - sizeof(truncated_epilogue);
-    }
-  }
-  for (int i = 0; i < len; i++) {
-    os << AsUC16(Get(i));
-  }
-  if (len != length()) {
-    os << truncated_epilogue;
-  }
-
-  if (!StringShape(*this).IsInternalized()) os << "\"";
+  os << PrefixForDebugPrint();
+  PrintUC16(os, 0, length());
+  os << SuffixForDebugPrint();
 }
 
 void Name::NamePrint(std::ostream& os) {  // NOLINT
@@ -1475,9 +1450,7 @@ void Code::CodePrint(std::ostream& os) {  // NOLINT
   PrintHeader(os, "Code");
   os << "\n";
 #ifdef ENABLE_DISASSEMBLER
-  if (FLAG_use_verbose_printer) {
   Disassemble(nullptr, os, GetIsolate());
-  }
 #endif
 }
 

src/flags/flag-definitions.h

@@ -1251,7 +1251,6 @@ DEFINE_BOOL(native_code_counters, DEBUG_BOOL,
 DEFINE_BOOL(thin_strings, true, "Enable ThinString support")
 DEFINE_BOOL(trace_prototype_users, false,
             "Trace updates to prototype user tracking")
-DEFINE_BOOL(use_verbose_printer, true, "allows verbose printing")
 DEFINE_BOOL(trace_for_in_enumerate, false, "Trace for-in enumerate slow-paths")
 DEFINE_BOOL(trace_maps, false, "trace map creation")
 DEFINE_BOOL(trace_maps_details, true, "also log map details")

src/objects/objects.cc

@@ -5840,10 +5840,8 @@ void Symbol::SymbolShortPrint(std::ostream& os) {
   os << "<Symbol:";
   if (!description().IsUndefined()) {
     os << " ";
-    HeapStringAllocator allocator;
-    StringStream accumulator(&allocator);
-    String::cast(description()).StringShortPrint(&accumulator, false);
-    os << accumulator.ToCString().get();
+    String description_as_string = String::cast(description());
+    description_as_string.PrintUC16(os, 0, description_as_string.length());
   } else {
     os << " (" << PrivateSymbolToName() << ")";
   }

src/objects/string.cc

@@ -298,69 +298,60 @@ bool String::SupportsExternalization() {
   return !isolate->heap()->IsInGCPostProcessing();
 }
 
-void String::StringShortPrint(StringStream* accumulator, bool show_details) {
-  const char* internalized_marker = this->IsInternalizedString() ? "#" : "";
-
-  int len = length();
-  if (len > kMaxShortPrintLength) {
-    accumulator->Add("<Very long string[%s%u]>", internalized_marker, len);
-    return;
+const char* String::PrefixForDebugPrint() const {
+  StringShape shape(*this);
+  if (IsTwoByteRepresentation()) {
+    StringShape shape(*this);
+    if (shape.IsInternalized()) {
+      return "u#";
+    } else if (shape.IsCons()) {
+      return "uc\"";
+    } else if (shape.IsThin()) {
+      return "u>\"";
+    } else {
+      return "u\"";
     }
+  } else {
+    StringShape shape(*this);
+    if (shape.IsInternalized()) {
+      return "#";
+    } else if (shape.IsCons()) {
+      return "c\"";
+    } else if (shape.IsThin()) {
+      return ">\"";
+    } else {
+      return "\"";
+    }
+  }
+  UNREACHABLE();
+}
 
+const char* String::SuffixForDebugPrint() const {
+  StringShape shape(*this);
+  if (shape.IsInternalized()) return "";
+  return "\"";
+}
+
+void String::StringShortPrint(StringStream* accumulator) {
   if (!LooksValid()) {
     accumulator->Add("<Invalid String>");
     return;
   }
 
-  StringCharacterStream stream(*this);
+  const int len = length();
+  accumulator->Add("<String[%u]: ", len);
+  accumulator->Add(PrefixForDebugPrint());
 
-  bool truncated = false;
   if (len > kMaxShortPrintLength) {
-    len = kMaxShortPrintLength;
-    truncated = true;
+    accumulator->Add("...<truncated>>");
+    accumulator->Add(SuffixForDebugPrint());
+    accumulator->Put('>');
+    return;
   }
-  bool one_byte = true;
-  for (int i = 0; i < len; i++) {
-    uint16_t c = stream.GetNext();
 
-    if (c < 32 || c >= 127) {
-      one_byte = false;
-    }
-  }
-  stream.Reset(*this);
-  if (one_byte) {
-    if (show_details)
-      accumulator->Add("<String[%s%u]: ", internalized_marker, length());
-    for (int i = 0; i < len; i++) {
-      accumulator->Put(static_cast<char>(stream.GetNext()));
-    }
-    if (show_details) accumulator->Put('>');
-  } else {
-    // Backslash indicates that the string contains control
-    // characters and that backslashes are therefore escaped.
-    if (show_details)
-      accumulator->Add("<String[%s%u]\\: ", internalized_marker, length());
-    for (int i = 0; i < len; i++) {
-      uint16_t c = stream.GetNext();
-      if (c == '\n') {
-        accumulator->Add("\\n");
-      } else if (c == '\r') {
-        accumulator->Add("\\r");
-      } else if (c == '\\') {
-        accumulator->Add("\\\\");
-      } else if (c < 32 || c > 126) {
-        accumulator->Add("\\x%02x", c);
-      } else {
-        accumulator->Put(static_cast<char>(c));
-      }
-    }
-    if (truncated) {
-      accumulator->Put('.');
-      accumulator->Put('.');
-      accumulator->Put('.');
-    }
-    if (show_details) accumulator->Put('>');
-  }
+  PrintUC16(accumulator, 0, len);
+  accumulator->Add(SuffixForDebugPrint());
+  accumulator->Put('>');
 }
 
 void String::PrintUC16(std::ostream& os, int start, int end) {  // NOLINT
@@ -371,6 +362,25 @@ void String::PrintUC16(std::ostream& os, int start, int end) {  // NOLINT
   }
 }
 
+void String::PrintUC16(StringStream* accumulator, int start, int end) {
+  if (end < 0) end = length();
+  StringCharacterStream stream(*this, start);
+  for (int i = start; i < end && stream.HasMore(); i++) {
+    uint16_t c = stream.GetNext();
+    if (c == '\n') {
+      accumulator->Add("\\n");
+    } else if (c == '\r') {
+      accumulator->Add("\\r");
+    } else if (c == '\\') {
+      accumulator->Add("\\\\");
+    } else if (!std::isprint(c)) {
+      accumulator->Add("\\x%02x", c);
+    } else {
+      accumulator->Put(static_cast<char>(c));
+    }
+  }
+}
+
 // static
 Handle<String> String::Trim(Isolate* isolate, Handle<String> string,
                             TrimMode mode) {

src/objects/string.h

@@ -353,8 +353,11 @@ class String : public TorqueGeneratedString<String, Name> {
   bool LooksValid();
 
   // Dispatched behavior.
-  void StringShortPrint(StringStream* accumulator, bool show_details = true);
+  const char* PrefixForDebugPrint() const;
+  const char* SuffixForDebugPrint() const;
+  void StringShortPrint(StringStream* accumulator);
   void PrintUC16(std::ostream& os, int start = 0, int end = -1);  // NOLINT
+  void PrintUC16(StringStream* accumulator, int start, int end);
 #if defined(DEBUG) || defined(OBJECT_PRINT)
   char* ToAsciiArray();
 #endif

src/runtime/runtime-test.cc

@@ -752,38 +752,21 @@ RUNTIME_FUNCTION(Runtime_DebugPrint) {
     bool weak = maybe_object.IsWeak();
 
 #ifdef OBJECT_PRINT
-    if (object.IsString() && !isolate->context().is_null()) {
-      DCHECK(!weak);
-      // If we have a string, assume it's a code "marker"
-      // and print some interesting cpu debugging info.
-      object.Print(os);
-      JavaScriptFrameIterator it(isolate);
-      JavaScriptFrame* frame = it.frame();
-      os << "fp = " << reinterpret_cast<void*>(frame->fp())
-         << ", sp = " << reinterpret_cast<void*>(frame->sp())
-         << ", caller_sp = " << reinterpret_cast<void*>(frame->caller_sp())
-         << ": ";
-    } else {
     os << "DebugPrint: ";
-      if (weak) {
-        os << "[weak] ";
-      }
+    if (weak) os << "[weak] ";
     object.Print(os);
-    }
     if (object.IsHeapObject()) {
       HeapObject::cast(object).map().Print(os);
     }
 #else
-    if (weak) {
-      os << "[weak] ";
-    }
+    if (weak) os << "[weak] ";
     // ShortPrint is available in release mode. Print is not.
     os << Brief(object);
 #endif
   }
   os << std::endl;
 
-  return args[0];  // return TOS
+  return args[0];
 }
 
 RUNTIME_FUNCTION(Runtime_PrintWithNameForAssert) {