[libcxxabi] [lldb] [llvm] [WIP] [ItaniumDemangle] Add infrastructure to track location information of parts of a demangled function name (PR #133249)

Michael Buch via llvm-commits llvm-commits at lists.llvm.org
Tue Apr 8 06:36:52 PDT 2025


https://github.com/Michael137 updated https://github.com/llvm/llvm-project/pull/133249

>From 5183ff468fc31c754f1e26c792384f9c5fd9c19c Mon Sep 17 00:00:00 2001
From: Michael Buch <michaelbuch12 at gmail.com>
Date: Tue, 11 Mar 2025 08:57:13 +0000
Subject: [PATCH] [llvm][ItaniumDemangle] Add function name location tracking

---
 libcxxabi/src/demangle/ItaniumDemangle.h     |  64 +++---
 libcxxabi/src/demangle/Utility.h             |   7 +
 lldb/include/lldb/Core/Demangle.h            |  90 ++++++++
 lldb/source/Core/CMakeLists.txt              |   1 +
 lldb/source/Core/Demangle.cpp                | 221 +++++++++++++++++++
 lldb/unittests/Core/MangledTest.cpp          | 143 ++++++++++++
 llvm/include/llvm/Demangle/ItaniumDemangle.h |  64 +++---
 llvm/include/llvm/Demangle/Utility.h         |   7 +
 8 files changed, 541 insertions(+), 56 deletions(-)
 create mode 100644 lldb/include/lldb/Core/Demangle.h
 create mode 100644 lldb/source/Core/Demangle.cpp

diff --git a/libcxxabi/src/demangle/ItaniumDemangle.h b/libcxxabi/src/demangle/ItaniumDemangle.h
index 3df41b5f4d7d0..89a24def830f2 100644
--- a/libcxxabi/src/demangle/ItaniumDemangle.h
+++ b/libcxxabi/src/demangle/ItaniumDemangle.h
@@ -281,9 +281,9 @@ class Node {
   }
 
   void print(OutputBuffer &OB) const {
-    printLeft(OB);
+    OB.printLeft(*this);
     if (RHSComponentCache != Cache::No)
-      printRight(OB);
+      OB.printRight(*this);
   }
 
   // Print the "left" side of this Node into OutputBuffer.
@@ -458,11 +458,11 @@ class QualType final : public Node {
   }
 
   void printLeft(OutputBuffer &OB) const override {
-    Child->printLeft(OB);
+    OB.printLeft(*Child);
     printQuals(OB);
   }
 
-  void printRight(OutputBuffer &OB) const override { Child->printRight(OB); }
+  void printRight(OutputBuffer &OB) const override { OB.printRight(*Child); }
 };
 
 class ConversionOperatorType final : public Node {
@@ -491,7 +491,7 @@ class PostfixQualifiedType final : public Node {
   template<typename Fn> void match(Fn F) const { F(Ty, Postfix); }
 
   void printLeft(OutputBuffer &OB) const override {
-    Ty->printLeft(OB);
+    OB.printLeft(*Ty);
     OB += Postfix;
   }
 };
@@ -577,7 +577,7 @@ struct AbiTagAttr : Node {
   std::string_view getBaseName() const override { return Base->getBaseName(); }
 
   void printLeft(OutputBuffer &OB) const override {
-    Base->printLeft(OB);
+    OB.printLeft(*Base);
     OB += "[abi:";
     OB += Tag;
     OB += "]";
@@ -644,7 +644,7 @@ class PointerType final : public Node {
     // We rewrite objc_object<SomeProtocol>* into id<SomeProtocol>.
     if (Pointee->getKind() != KObjCProtoName ||
         !static_cast<const ObjCProtoName *>(Pointee)->isObjCObject()) {
-      Pointee->printLeft(OB);
+      OB.printLeft(*Pointee);
       if (Pointee->hasArray(OB))
         OB += " ";
       if (Pointee->hasArray(OB) || Pointee->hasFunction(OB))
@@ -663,7 +663,7 @@ class PointerType final : public Node {
         !static_cast<const ObjCProtoName *>(Pointee)->isObjCObject()) {
       if (Pointee->hasArray(OB) || Pointee->hasFunction(OB))
         OB += ")";
-      Pointee->printRight(OB);
+      OB.printRight(*Pointee);
     }
   }
 };
@@ -729,7 +729,7 @@ class ReferenceType : public Node {
     std::pair<ReferenceKind, const Node *> Collapsed = collapse(OB);
     if (!Collapsed.second)
       return;
-    Collapsed.second->printLeft(OB);
+    OB.printLeft(*Collapsed.second);
     if (Collapsed.second->hasArray(OB))
       OB += " ";
     if (Collapsed.second->hasArray(OB) || Collapsed.second->hasFunction(OB))
@@ -746,7 +746,7 @@ class ReferenceType : public Node {
       return;
     if (Collapsed.second->hasArray(OB) || Collapsed.second->hasFunction(OB))
       OB += ")";
-    Collapsed.second->printRight(OB);
+    OB.printRight(*Collapsed.second);
   }
 };
 
@@ -766,7 +766,7 @@ class PointerToMemberType final : public Node {
   }
 
   void printLeft(OutputBuffer &OB) const override {
-    MemberType->printLeft(OB);
+    OB.printLeft(*MemberType);
     if (MemberType->hasArray(OB) || MemberType->hasFunction(OB))
       OB += "(";
     else
@@ -778,7 +778,7 @@ class PointerToMemberType final : public Node {
   void printRight(OutputBuffer &OB) const override {
     if (MemberType->hasArray(OB) || MemberType->hasFunction(OB))
       OB += ")";
-    MemberType->printRight(OB);
+    OB.printRight(*MemberType);
   }
 };
 
@@ -798,7 +798,7 @@ class ArrayType final : public Node {
   bool hasRHSComponentSlow(OutputBuffer &) const override { return true; }
   bool hasArraySlow(OutputBuffer &) const override { return true; }
 
-  void printLeft(OutputBuffer &OB) const override { Base->printLeft(OB); }
+  void printLeft(OutputBuffer &OB) const override { OB.printLeft(*Base); }
 
   void printRight(OutputBuffer &OB) const override {
     if (OB.back() != ']')
@@ -807,7 +807,7 @@ class ArrayType final : public Node {
     if (Dimension)
       Dimension->print(OB);
     OB += "]";
-    Base->printRight(OB);
+    OB.printRight(*Base);
   }
 
   bool printInitListAsType(OutputBuffer &OB,
@@ -851,7 +851,7 @@ class FunctionType final : public Node {
   // by printing out the return types's left, then print our parameters, then
   // finally print right of the return type.
   void printLeft(OutputBuffer &OB) const override {
-    Ret->printLeft(OB);
+    OB.printLeft(*Ret);
     OB += " ";
   }
 
@@ -859,7 +859,7 @@ class FunctionType final : public Node {
     OB.printOpen();
     Params.printWithComma(OB);
     OB.printClose();
-    Ret->printRight(OB);
+    OB.printRight(*Ret);
 
     if (CVQuals & QualConst)
       OB += " const";
@@ -964,6 +964,8 @@ class FunctionEncoding final : public Node {
   FunctionRefQual getRefQual() const { return RefQual; }
   NodeArray getParams() const { return Params; }
   const Node *getReturnType() const { return Ret; }
+  const Node *getAttrs() const { return Attrs; }
+  const Node *getRequires() const { return Requires; }
 
   bool hasRHSComponentSlow(OutputBuffer &) const override { return true; }
   bool hasFunctionSlow(OutputBuffer &) const override { return true; }
@@ -972,10 +974,11 @@ class FunctionEncoding final : public Node {
 
   void printLeft(OutputBuffer &OB) const override {
     if (Ret) {
-      Ret->printLeft(OB);
+      OB.printLeft(*Ret);
       if (!Ret->hasRHSComponent(OB))
         OB += " ";
     }
+
     Name->print(OB);
   }
 
@@ -983,8 +986,9 @@ class FunctionEncoding final : public Node {
     OB.printOpen();
     Params.printWithComma(OB);
     OB.printClose();
+
     if (Ret)
-      Ret->printRight(OB);
+      OB.printRight(*Ret);
 
     if (CVQuals & QualConst)
       OB += " const";
@@ -1324,14 +1328,14 @@ class NonTypeTemplateParamDecl final : public Node {
   template<typename Fn> void match(Fn F) const { F(Name, Type); }
 
   void printLeft(OutputBuffer &OB) const override {
-    Type->printLeft(OB);
+    OB.printLeft(*Type);
     if (!Type->hasRHSComponent(OB))
       OB += " ";
   }
 
   void printRight(OutputBuffer &OB) const override {
     Name->print(OB);
-    Type->printRight(OB);
+    OB.printRight(*Type);
   }
 };
 
@@ -1376,11 +1380,11 @@ class TemplateParamPackDecl final : public Node {
   template<typename Fn> void match(Fn F) const { F(Param); }
 
   void printLeft(OutputBuffer &OB) const override {
-    Param->printLeft(OB);
+    OB.printLeft(*Param);
     OB += "...";
   }
 
-  void printRight(OutputBuffer &OB) const override { Param->printRight(OB); }
+  void printRight(OutputBuffer &OB) const override { OB.printRight(*Param); }
 };
 
 /// An unexpanded parameter pack (either in the expression or type context). If
@@ -1445,13 +1449,13 @@ class ParameterPack final : public Node {
     initializePackExpansion(OB);
     size_t Idx = OB.CurrentPackIndex;
     if (Idx < Data.size())
-      Data[Idx]->printLeft(OB);
+      OB.printLeft(*Data[Idx]);
   }
   void printRight(OutputBuffer &OB) const override {
     initializePackExpansion(OB);
     size_t Idx = OB.CurrentPackIndex;
     if (Idx < Data.size())
-      Data[Idx]->printRight(OB);
+      OB.printRight(*Data[Idx]);
   }
 };
 
@@ -1609,13 +1613,13 @@ struct ForwardTemplateReference : Node {
     if (Printing)
       return;
     ScopedOverride<bool> SavePrinting(Printing, true);
-    Ref->printLeft(OB);
+    OB.printLeft(*Ref);
   }
   void printRight(OutputBuffer &OB) const override {
     if (Printing)
       return;
     ScopedOverride<bool> SavePrinting(Printing, true);
-    Ref->printRight(OB);
+    OB.printRight(*Ref);
   }
 };
 
@@ -1767,7 +1771,7 @@ class DtorName : public Node {
 
   void printLeft(OutputBuffer &OB) const override {
     OB += "~";
-    Base->printLeft(OB);
+    OB.printLeft(*Base);
   }
 };
 
@@ -2047,7 +2051,7 @@ class CastExpr : public Node {
     {
       ScopedOverride<unsigned> LT(OB.GtIsGt, 0);
       OB += "<";
-      To->printLeft(OB);
+      OB.printLeft(*To);
       OB += ">";
     }
     OB.printOpen();
@@ -6176,6 +6180,10 @@ struct ManglingParser : AbstractManglingParser<ManglingParser<Alloc>, Alloc> {
                                Alloc>::AbstractManglingParser;
 };
 
+inline void OutputBuffer::printLeft(const Node &N) { N.printLeft(*this); }
+
+inline void OutputBuffer::printRight(const Node &N) { N.printRight(*this); }
+
 DEMANGLE_NAMESPACE_END
 
 #if defined(__clang__)
diff --git a/libcxxabi/src/demangle/Utility.h b/libcxxabi/src/demangle/Utility.h
index f1fad35d60d98..a38bef762dd57 100644
--- a/libcxxabi/src/demangle/Utility.h
+++ b/libcxxabi/src/demangle/Utility.h
@@ -27,6 +27,8 @@
 
 DEMANGLE_NAMESPACE_BEGIN
 
+class Node;
+
 // Stream that AST nodes write their string representation into after the AST
 // has been parsed.
 class OutputBuffer {
@@ -79,10 +81,15 @@ class OutputBuffer {
   OutputBuffer(const OutputBuffer &) = delete;
   OutputBuffer &operator=(const OutputBuffer &) = delete;
 
+  virtual ~OutputBuffer() {}
+
   operator std::string_view() const {
     return std::string_view(Buffer, CurrentPosition);
   }
 
+  virtual void printLeft(const Node &N);
+  virtual void printRight(const Node &N);
+
   /// If a ParameterPackExpansion (or similar type) is encountered, the offset
   /// into the pack that we're currently printing.
   unsigned CurrentPackIndex = std::numeric_limits<unsigned>::max();
diff --git a/lldb/include/lldb/Core/Demangle.h b/lldb/include/lldb/Core/Demangle.h
new file mode 100644
index 0000000000000..27f0cacbdd48f
--- /dev/null
+++ b/lldb/include/lldb/Core/Demangle.h
@@ -0,0 +1,90 @@
+//===-- Demangle.h ----------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_CORE_DEMANGLE_H
+#define LLDB_CORE_DEMANGLE_H
+
+#include "llvm/Demangle/ItaniumDemangle.h"
+#include "llvm/Demangle/Utility.h"
+
+#include <cstddef>
+#include <utility>
+
+namespace lldb_private {
+
+struct TrackingOutputBuffer;
+
+// Stores information about parts of a demangled function name.
+struct FunctionNameInfo {
+  /// A [start, end) pair for the function basename.
+  /// The basename is the name without scope qualifiers
+  /// and without template parameters. E.g.,
+  /// \code{.cpp}
+  ///    void foo::bar<int>::someFunc<float>(int) const &&
+  ///                        ^       ^
+  ///                      start    end
+  /// \endcode
+  std::pair<size_t, size_t> BasenameLocs;
+
+  /// A [start, end) pair for the function scope qualifiers.
+  /// E.g., for
+  /// \code{.cpp}
+  ///    void foo::bar<int>::qux<float>(int) const &&
+  ///         ^              ^
+  ///       start           end
+  /// \endcode
+  std::pair<size_t, size_t> ScopeLocs;
+
+  /// Indicates the [start, end) of the function argument lits.
+  /// E.g.,
+  /// \code{.cpp}
+  ///    int (*getFunc<float>(float, double))(int, int)
+  ///                        ^              ^
+  ///                      start           end
+  /// \endcode
+  std::pair<size_t, size_t> ArgumentLocs;
+
+  bool startedPrintingArguments() const;
+  bool shouldTrack(TrackingOutputBuffer &OB) const;
+  bool canFinalize(TrackingOutputBuffer &OB) const;
+  void updateBasenameEnd(TrackingOutputBuffer &OB);
+  void updateScopeStart(TrackingOutputBuffer &OB);
+  void updateScopeEnd(TrackingOutputBuffer &OB);
+  void finalizeArgumentEnd(TrackingOutputBuffer &OB);
+  void finalizeStart(TrackingOutputBuffer &OB);
+  void finalizeEnd(TrackingOutputBuffer &OB);
+  bool hasBasename() const;
+};
+
+struct TrackingOutputBuffer : public llvm::itanium_demangle::OutputBuffer {
+  using OutputBuffer::OutputBuffer;
+
+  FunctionNameInfo FunctionInfo;
+  unsigned FunctionPrintingDepth = 0;
+
+  [[nodiscard]] llvm::itanium_demangle::ScopedOverride<unsigned>
+  enterFunctionTypePrinting();
+
+  bool isPrintingTopLevelFunctionType() const;
+
+  void printLeft(const llvm::itanium_demangle::Node &N) override;
+  void printRight(const llvm::itanium_demangle::Node &N) override;
+
+private:
+  void printLeftImpl(const llvm::itanium_demangle::FunctionType &N);
+  void printRightImpl(const llvm::itanium_demangle::FunctionType &N);
+
+  void printLeftImpl(const llvm::itanium_demangle::FunctionEncoding &N);
+  void printRightImpl(const llvm::itanium_demangle::FunctionEncoding &N);
+
+  void printLeftImpl(const llvm::itanium_demangle::NestedName &N);
+  void printLeftImpl(const llvm::itanium_demangle::NameWithTemplateArgs &N);
+};
+} // namespace lldb_private
+
+#endif // LLDB_CORE_DEMANGLE_H
diff --git a/lldb/source/Core/CMakeLists.txt b/lldb/source/Core/CMakeLists.txt
index 0a08da0fec230..1882a3886174b 100644
--- a/lldb/source/Core/CMakeLists.txt
+++ b/lldb/source/Core/CMakeLists.txt
@@ -28,6 +28,7 @@ add_lldb_library(lldbCore
   Debugger.cpp
   DebuggerEvents.cpp
   Declaration.cpp
+  Demangle.cpp
   Disassembler.cpp
   DumpDataExtractor.cpp
   DumpRegisterValue.cpp
diff --git a/lldb/source/Core/Demangle.cpp b/lldb/source/Core/Demangle.cpp
new file mode 100644
index 0000000000000..122e006409816
--- /dev/null
+++ b/lldb/source/Core/Demangle.cpp
@@ -0,0 +1,221 @@
+//===-- Demangle.cpp ------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "lldb/Core/Demangle.h"
+
+using namespace llvm::itanium_demangle;
+
+namespace lldb_private {
+
+bool FunctionNameInfo::startedPrintingArguments() const {
+  return ArgumentLocs.first > 0;
+}
+
+bool FunctionNameInfo::shouldTrack(TrackingOutputBuffer &OB) const {
+  if (!OB.isPrintingTopLevelFunctionType())
+    return false;
+
+  if (OB.isGtInsideTemplateArgs())
+    return false;
+
+  if (startedPrintingArguments())
+    return false;
+
+  return true;
+}
+
+bool FunctionNameInfo::canFinalize(TrackingOutputBuffer &OB) const {
+  if (!OB.isPrintingTopLevelFunctionType())
+    return false;
+
+  if (OB.isGtInsideTemplateArgs())
+    return false;
+
+  if (!startedPrintingArguments())
+    return false;
+
+  return true;
+}
+
+void FunctionNameInfo::updateBasenameEnd(TrackingOutputBuffer &OB) {
+  if (!shouldTrack(OB))
+    return;
+
+  BasenameLocs.second = OB.getCurrentPosition();
+}
+
+void FunctionNameInfo::updateScopeStart(TrackingOutputBuffer &OB) {
+  if (!shouldTrack(OB))
+    return;
+
+  ScopeLocs.first = OB.getCurrentPosition();
+}
+
+void FunctionNameInfo::updateScopeEnd(TrackingOutputBuffer &OB) {
+  if (!shouldTrack(OB))
+    return;
+
+  ScopeLocs.second = OB.getCurrentPosition();
+}
+
+void FunctionNameInfo::finalizeArgumentEnd(TrackingOutputBuffer &OB) {
+  if (!canFinalize(OB))
+    return;
+
+  OB.FunctionInfo.ArgumentLocs.second = OB.getCurrentPosition();
+}
+
+void FunctionNameInfo::finalizeStart(TrackingOutputBuffer &OB) {
+  if (!shouldTrack(OB))
+    return;
+
+  OB.FunctionInfo.ArgumentLocs.first = OB.getCurrentPosition();
+
+  // If nothing has set the end of the basename yet (for example when
+  // printing templates), then the beginning of the arguments is the end of
+  // the basename.
+  if (BasenameLocs.second == 0)
+    OB.FunctionInfo.BasenameLocs.second = OB.getCurrentPosition();
+
+  DEMANGLE_ASSERT(!shouldTrack(OB), "");
+  DEMANGLE_ASSERT(canFinalize(OB), "");
+}
+
+void FunctionNameInfo::finalizeEnd(TrackingOutputBuffer &OB) {
+  if (!canFinalize(OB))
+    return;
+
+  if (ScopeLocs.first > OB.FunctionInfo.ScopeLocs.second)
+    ScopeLocs.second = OB.FunctionInfo.ScopeLocs.first;
+  BasenameLocs.first = OB.FunctionInfo.ScopeLocs.second;
+}
+
+bool FunctionNameInfo::hasBasename() const {
+  return BasenameLocs.first != BasenameLocs.second && BasenameLocs.second > 0;
+}
+
+ScopedOverride<unsigned> TrackingOutputBuffer::enterFunctionTypePrinting() {
+  return {FunctionPrintingDepth, FunctionPrintingDepth + 1};
+}
+
+bool TrackingOutputBuffer::isPrintingTopLevelFunctionType() const {
+  return FunctionPrintingDepth == 1;
+}
+
+void TrackingOutputBuffer::printLeft(const Node &N) {
+  switch (N.getKind()) {
+  case Node::KFunctionType:
+    printLeftImpl(static_cast<const FunctionType &>(N));
+    break;
+  case Node::KFunctionEncoding:
+    printLeftImpl(static_cast<const FunctionEncoding &>(N));
+    break;
+  case Node::KNestedName:
+    printLeftImpl(static_cast<const NestedName &>(N));
+    break;
+  case Node::KNameWithTemplateArgs:
+    printLeftImpl(static_cast<const NameWithTemplateArgs &>(N));
+    break;
+  default:
+    N.printLeft(*this);
+  }
+}
+
+void TrackingOutputBuffer::printRight(const Node &N) {
+  switch (N.getKind()) {
+  case Node::KFunctionType:
+    printRightImpl(static_cast<const FunctionType &>(N));
+    break;
+  case Node::KFunctionEncoding:
+    printRightImpl(static_cast<const FunctionEncoding &>(N));
+    break;
+  default:
+    N.printRight(*this);
+  }
+}
+
+void TrackingOutputBuffer::printLeftImpl(const FunctionType &N) {
+  auto Scoped = enterFunctionTypePrinting();
+  N.printLeft(*this);
+}
+
+void TrackingOutputBuffer::printRightImpl(const FunctionType &N) {
+  auto Scoped = enterFunctionTypePrinting();
+  N.printRight(*this);
+}
+
+void TrackingOutputBuffer::printLeftImpl(const FunctionEncoding &N) {
+  auto Scoped = enterFunctionTypePrinting();
+
+  const Node *Ret = N.getReturnType();
+  if (Ret) {
+    printLeft(*Ret);
+    if (!Ret->hasRHSComponent(*this))
+      *this += " ";
+  }
+
+  FunctionInfo.updateScopeStart(*this);
+
+  N.getName()->print(*this);
+}
+
+void TrackingOutputBuffer::printRightImpl(const FunctionEncoding &N) {
+  auto Scoped = enterFunctionTypePrinting();
+  FunctionInfo.finalizeStart(*this);
+
+  printOpen();
+  N.getParams().printWithComma(*this);
+  printClose();
+
+  FunctionInfo.finalizeArgumentEnd(*this);
+
+  const Node *Ret = N.getReturnType();
+
+  if (Ret)
+    printRight(*Ret);
+
+  auto CVQuals = N.getCVQuals();
+  auto RefQual = N.getRefQual();
+  auto *Attrs = N.getAttrs();
+  auto *Requires = N.getRequires();
+
+  if (CVQuals & QualConst)
+    *this += " const";
+  if (CVQuals & QualVolatile)
+    *this += " volatile";
+  if (CVQuals & QualRestrict)
+    *this += " restrict";
+  if (RefQual == FrefQualLValue)
+    *this += " &";
+  else if (RefQual == FrefQualRValue)
+    *this += " &&";
+  if (Attrs != nullptr)
+    Attrs->print(*this);
+  if (Requires != nullptr) {
+    *this += " requires ";
+    Requires->print(*this);
+  }
+
+  FunctionInfo.finalizeEnd(*this);
+}
+
+void TrackingOutputBuffer::printLeftImpl(const NestedName &N) {
+  N.Qual->print(*this);
+  *this += "::";
+  FunctionInfo.updateScopeEnd(*this);
+  N.Name->print(*this);
+  FunctionInfo.updateBasenameEnd(*this);
+}
+
+void TrackingOutputBuffer::printLeftImpl(const NameWithTemplateArgs &N) {
+  N.Name->print(*this);
+  FunctionInfo.updateBasenameEnd(*this);
+  N.TemplateArgs->print(*this);
+}
+
+} // namespace lldb_private
diff --git a/lldb/unittests/Core/MangledTest.cpp b/lldb/unittests/Core/MangledTest.cpp
index a3760ba43b3c9..2f4e1755a4074 100644
--- a/lldb/unittests/Core/MangledTest.cpp
+++ b/lldb/unittests/Core/MangledTest.cpp
@@ -11,6 +11,7 @@
 #include "TestingSupport/SubsystemRAII.h"
 #include "TestingSupport/TestUtilities.h"
 
+#include "lldb/Core/Demangle.h"
 #include "lldb/Core/Mangled.h"
 #include "lldb/Core/Module.h"
 #include "lldb/Core/ModuleSpec.h"
@@ -319,3 +320,145 @@ TEST(MangledTest, NameIndexes_FindFunctionSymbols) {
   EXPECT_EQ(0, Count("undemangable", eFunctionNameTypeBase));
   EXPECT_EQ(0, Count("undemangable", eFunctionNameTypeMethod));
 }
+
+struct DemanglingPartsTestCase {
+  const char *mangled;
+  FunctionNameInfo expected_info;
+  std::string_view basename;
+  std::string_view scope;
+  bool valid_basename = true;
+};
+
+DemanglingPartsTestCase g_demangling_parts_test_cases[] = {
+    // clang-format off
+   { "_ZNVKO3BarIN2ns3QuxIiEEE1CIPFi3FooIS_IiES6_EEE6methodIS6_EENS5_IT_SC_E5InnerIiEESD_SD_",
+     { .BasenameLocs = {92, 98}, .ScopeLocs = {36, 92}, .ArgumentLocs = { 108, 158 } },
+     .basename = "method",
+     .scope = "Bar<ns::Qux<int>>::C<int (*)(Foo<Bar<int>, Bar<int>>)>::"
+   },
+   { "_Z7getFuncIfEPFiiiET_",
+     { .BasenameLocs = {6, 13}, .ScopeLocs = {6, 6}, .ArgumentLocs = { 20, 27 } },
+     .basename = "getFunc",
+     .scope = ""
+   },
+   { "_ZN1f1b1c1gEv",
+     { .BasenameLocs = {9, 10}, .ScopeLocs = {0, 9}, .ArgumentLocs = { 10, 12 } },
+     .basename = "g",
+     .scope = "f::b::c::"
+   },
+   { "_ZN5test73fD1IiEEDTcmtlNS_1DEL_ZNS_1bEEEcvT__EES2_",
+     { .BasenameLocs = {45, 48}, .ScopeLocs = {38, 45}, .ArgumentLocs = { 53, 58 } },
+     .basename = "fD1",
+     .scope = "test7::"
+   },
+   { "_ZN5test73fD1IiEEDTcmtlNS_1DEL_ZNS_1bINDT1cE1dEEEEEcvT__EES2_",
+     { .BasenameLocs = {61, 64}, .ScopeLocs = {54, 61}, .ArgumentLocs = { 69, 79 } },
+     .basename = "fD1",
+     .scope = "test7::"
+   },
+   { "_ZN5test7INDT1cE1dINDT1cE1dEEEE3fD1INDT1cE1dINDT1cE1dEEEEEDTcmtlNS_1DEL_ZNS_1bINDT1cE1dEEEEEcvT__EES2_",
+     { .BasenameLocs = {120, 123}, .ScopeLocs = {81, 120}, .ArgumentLocs = { 155, 168 } },
+     .basename = "fD1",
+     .scope = "test7<decltype(c)::d<decltype(c)::d>>::"
+   },
+   { "_ZN8nlohmann16json_abi_v3_11_310basic_jsonINSt3__13mapENS2_6vectorENS2_12basic_stringIcNS2_11char_traitsIcEENS2_9allocatorIcEEEEbxydS8_NS0_14adl_serializerENS4_IhNS8_IhEEEEvE5parseIRA29_KcEESE_OT_NS2_8functionIFbiNS0_6detail13parse_event_tERSE_EEEbb",
+     { .BasenameLocs = {687, 692}, .ScopeLocs = {343, 687}, .ArgumentLocs = { 713, 1174 } },
+     .basename = "parse",
+     .scope = "nlohmann::json_abi_v3_11_3::basic_json<std::__1::map, std::__1::vector, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, bool, long long, unsigned long long, double, std::__1::allocator, nlohmann::json_abi_v3_11_3::adl_serializer, std::__1::vector<unsigned char, std::__1::allocator<unsigned char>>, void>::"
+   },
+   { "_ZN8nlohmann16json_abi_v3_11_310basic_jsonINSt3__13mapENS2_6vectorENS2_12basic_stringIcNS2_11char_traitsIcEENS2_9allocatorIcEEEEbxydS8_NS0_14adl_serializerENS4_IhNS8_IhEEEEvEC1EDn",
+     { .BasenameLocs = {344, 354}, .ScopeLocs = {0, 344}, .ArgumentLocs = { 354, 370 } },
+     .basename = "basic_json",
+     .scope = "nlohmann::json_abi_v3_11_3::basic_json<std::__1::map, std::__1::vector, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, bool, long long, unsigned long long, double, std::__1::allocator, nlohmann::json_abi_v3_11_3::adl_serializer, std::__1::vector<unsigned char, std::__1::allocator<unsigned char>>, void>::"
+   },
+   { "_Z3fppIiEPFPFvvEiEf",
+     { .BasenameLocs = {10, 13}, .ScopeLocs = {10, 10}, .ArgumentLocs = { 18, 25 } },
+     .basename = "fpp",
+     .scope = ""
+   },
+   { "_Z3fppIiEPFPFvvEN2ns3FooIiEEEf",
+     { .BasenameLocs = {10, 13}, .ScopeLocs = {10, 10}, .ArgumentLocs = { 18, 25 } },
+     .basename = "fpp",
+     .scope = ""
+   },
+   { "_Z3fppIiEPFPFvPFN2ns3FooIiEENS2_3BarIfE3QuxEEEPFS2_S2_EEf",
+     { .BasenameLocs = {10, 13}, .ScopeLocs = {10, 10}, .ArgumentLocs = { 18, 25 } },
+     .basename = "fpp",
+     .scope = ""
+   },
+   { "_ZN2ns8HasFuncsINS_3FooINS1_IiE3BarIfE3QuxEEEE3fppIiEEPFPFvvEiEf",
+     { .BasenameLocs = {64, 67}, .ScopeLocs = {10, 64}, .ArgumentLocs = { 72, 79 } },
+     .basename = "fpp",
+     .scope = "ns::HasFuncs<ns::Foo<ns::Foo<int>::Bar<float>::Qux>>::"
+   },
+   { "_ZN2ns8HasFuncsINS_3FooINS1_IiE3BarIfE3QuxEEEE3fppIiEEPFPFvvES2_Ef",
+     { .BasenameLocs = {64, 67}, .ScopeLocs = {10, 64}, .ArgumentLocs = { 72, 79 } },
+     .basename = "fpp",
+     .scope = "ns::HasFuncs<ns::Foo<ns::Foo<int>::Bar<float>::Qux>>::"
+   },
+   { "_ZN2ns8HasFuncsINS_3FooINS1_IiE3BarIfE3QuxEEEE3fppIiEEPFPFvPFS2_S5_EEPFS2_S2_EEf",
+     { .BasenameLocs = {64, 67}, .ScopeLocs = {10, 64}, .ArgumentLocs = { 72, 79 } },
+     .basename = "fpp",
+     .scope = "ns::HasFuncs<ns::Foo<ns::Foo<int>::Bar<float>::Qux>>::"
+   },
+   { "_ZTV11ImageLoader",
+     { .BasenameLocs = {0, 0}, .ScopeLocs = {0, 0}, .ArgumentLocs = { 0, 0 } },
+     .basename = "",
+     .scope = "",
+     .valid_basename = false
+   }
+    // clang-format on
+};
+
+struct DemanglingPartsTestFixture
+    : public ::testing::TestWithParam<DemanglingPartsTestCase> {};
+
+namespace {
+class TestAllocator {
+  llvm::BumpPtrAllocator Alloc;
+
+public:
+  void reset() { Alloc.Reset(); }
+
+  template <typename T, typename... Args> T *makeNode(Args &&...args) {
+    return new (Alloc.Allocate(sizeof(T), alignof(T)))
+        T(std::forward<Args>(args)...);
+  }
+
+  void *allocateNodeArray(size_t sz) {
+    return Alloc.Allocate(sizeof(llvm::itanium_demangle::Node *) * sz,
+                          alignof(llvm::itanium_demangle::Node *));
+  }
+};
+} // namespace
+
+TEST_P(DemanglingPartsTestFixture, DemanglingParts) {
+  const auto &[mangled, info, basename, scope, valid_basename] = GetParam();
+
+  llvm::itanium_demangle::ManglingParser<TestAllocator> Parser(
+      mangled, mangled + ::strlen(mangled));
+
+  const auto *Root = Parser.parse();
+
+  ASSERT_NE(nullptr, Root);
+
+  TrackingOutputBuffer OB;
+  Root->print(OB);
+  auto demangled = std::string_view(OB);
+
+  ASSERT_EQ(OB.FunctionInfo.hasBasename(), valid_basename);
+
+  EXPECT_EQ(OB.FunctionInfo.BasenameLocs, info.BasenameLocs);
+  EXPECT_EQ(OB.FunctionInfo.ScopeLocs, info.ScopeLocs);
+  EXPECT_EQ(OB.FunctionInfo.ArgumentLocs, info.ArgumentLocs);
+
+  auto get_part = [&](const std::pair<size_t, size_t> &loc) {
+    return demangled.substr(loc.first, loc.second - loc.first);
+  };
+
+  EXPECT_EQ(get_part(OB.FunctionInfo.BasenameLocs), basename);
+  EXPECT_EQ(get_part(OB.FunctionInfo.ScopeLocs), scope);
+}
+
+INSTANTIATE_TEST_SUITE_P(DemanglingPartsTests, DemanglingPartsTestFixture,
+                         ::testing::ValuesIn(g_demangling_parts_test_cases));
diff --git a/llvm/include/llvm/Demangle/ItaniumDemangle.h b/llvm/include/llvm/Demangle/ItaniumDemangle.h
index b0363c1a7a786..aab45f351e070 100644
--- a/llvm/include/llvm/Demangle/ItaniumDemangle.h
+++ b/llvm/include/llvm/Demangle/ItaniumDemangle.h
@@ -281,9 +281,9 @@ class Node {
   }
 
   void print(OutputBuffer &OB) const {
-    printLeft(OB);
+    OB.printLeft(*this);
     if (RHSComponentCache != Cache::No)
-      printRight(OB);
+      OB.printRight(*this);
   }
 
   // Print the "left" side of this Node into OutputBuffer.
@@ -458,11 +458,11 @@ class QualType final : public Node {
   }
 
   void printLeft(OutputBuffer &OB) const override {
-    Child->printLeft(OB);
+    OB.printLeft(*Child);
     printQuals(OB);
   }
 
-  void printRight(OutputBuffer &OB) const override { Child->printRight(OB); }
+  void printRight(OutputBuffer &OB) const override { OB.printRight(*Child); }
 };
 
 class ConversionOperatorType final : public Node {
@@ -491,7 +491,7 @@ class PostfixQualifiedType final : public Node {
   template<typename Fn> void match(Fn F) const { F(Ty, Postfix); }
 
   void printLeft(OutputBuffer &OB) const override {
-    Ty->printLeft(OB);
+    OB.printLeft(*Ty);
     OB += Postfix;
   }
 };
@@ -577,7 +577,7 @@ struct AbiTagAttr : Node {
   std::string_view getBaseName() const override { return Base->getBaseName(); }
 
   void printLeft(OutputBuffer &OB) const override {
-    Base->printLeft(OB);
+    OB.printLeft(*Base);
     OB += "[abi:";
     OB += Tag;
     OB += "]";
@@ -644,7 +644,7 @@ class PointerType final : public Node {
     // We rewrite objc_object<SomeProtocol>* into id<SomeProtocol>.
     if (Pointee->getKind() != KObjCProtoName ||
         !static_cast<const ObjCProtoName *>(Pointee)->isObjCObject()) {
-      Pointee->printLeft(OB);
+      OB.printLeft(*Pointee);
       if (Pointee->hasArray(OB))
         OB += " ";
       if (Pointee->hasArray(OB) || Pointee->hasFunction(OB))
@@ -663,7 +663,7 @@ class PointerType final : public Node {
         !static_cast<const ObjCProtoName *>(Pointee)->isObjCObject()) {
       if (Pointee->hasArray(OB) || Pointee->hasFunction(OB))
         OB += ")";
-      Pointee->printRight(OB);
+      OB.printRight(*Pointee);
     }
   }
 };
@@ -729,7 +729,7 @@ class ReferenceType : public Node {
     std::pair<ReferenceKind, const Node *> Collapsed = collapse(OB);
     if (!Collapsed.second)
       return;
-    Collapsed.second->printLeft(OB);
+    OB.printLeft(*Collapsed.second);
     if (Collapsed.second->hasArray(OB))
       OB += " ";
     if (Collapsed.second->hasArray(OB) || Collapsed.second->hasFunction(OB))
@@ -746,7 +746,7 @@ class ReferenceType : public Node {
       return;
     if (Collapsed.second->hasArray(OB) || Collapsed.second->hasFunction(OB))
       OB += ")";
-    Collapsed.second->printRight(OB);
+    OB.printRight(*Collapsed.second);
   }
 };
 
@@ -766,7 +766,7 @@ class PointerToMemberType final : public Node {
   }
 
   void printLeft(OutputBuffer &OB) const override {
-    MemberType->printLeft(OB);
+    OB.printLeft(*MemberType);
     if (MemberType->hasArray(OB) || MemberType->hasFunction(OB))
       OB += "(";
     else
@@ -778,7 +778,7 @@ class PointerToMemberType final : public Node {
   void printRight(OutputBuffer &OB) const override {
     if (MemberType->hasArray(OB) || MemberType->hasFunction(OB))
       OB += ")";
-    MemberType->printRight(OB);
+    OB.printRight(*MemberType);
   }
 };
 
@@ -798,7 +798,7 @@ class ArrayType final : public Node {
   bool hasRHSComponentSlow(OutputBuffer &) const override { return true; }
   bool hasArraySlow(OutputBuffer &) const override { return true; }
 
-  void printLeft(OutputBuffer &OB) const override { Base->printLeft(OB); }
+  void printLeft(OutputBuffer &OB) const override { OB.printLeft(*Base); }
 
   void printRight(OutputBuffer &OB) const override {
     if (OB.back() != ']')
@@ -807,7 +807,7 @@ class ArrayType final : public Node {
     if (Dimension)
       Dimension->print(OB);
     OB += "]";
-    Base->printRight(OB);
+    OB.printRight(*Base);
   }
 
   bool printInitListAsType(OutputBuffer &OB,
@@ -851,7 +851,7 @@ class FunctionType final : public Node {
   // by printing out the return types's left, then print our parameters, then
   // finally print right of the return type.
   void printLeft(OutputBuffer &OB) const override {
-    Ret->printLeft(OB);
+    OB.printLeft(*Ret);
     OB += " ";
   }
 
@@ -859,7 +859,7 @@ class FunctionType final : public Node {
     OB.printOpen();
     Params.printWithComma(OB);
     OB.printClose();
-    Ret->printRight(OB);
+    OB.printRight(*Ret);
 
     if (CVQuals & QualConst)
       OB += " const";
@@ -964,6 +964,8 @@ class FunctionEncoding final : public Node {
   FunctionRefQual getRefQual() const { return RefQual; }
   NodeArray getParams() const { return Params; }
   const Node *getReturnType() const { return Ret; }
+  const Node *getAttrs() const { return Attrs; }
+  const Node *getRequires() const { return Requires; }
 
   bool hasRHSComponentSlow(OutputBuffer &) const override { return true; }
   bool hasFunctionSlow(OutputBuffer &) const override { return true; }
@@ -972,10 +974,11 @@ class FunctionEncoding final : public Node {
 
   void printLeft(OutputBuffer &OB) const override {
     if (Ret) {
-      Ret->printLeft(OB);
+      OB.printLeft(*Ret);
       if (!Ret->hasRHSComponent(OB))
         OB += " ";
     }
+
     Name->print(OB);
   }
 
@@ -983,8 +986,9 @@ class FunctionEncoding final : public Node {
     OB.printOpen();
     Params.printWithComma(OB);
     OB.printClose();
+
     if (Ret)
-      Ret->printRight(OB);
+      OB.printRight(*Ret);
 
     if (CVQuals & QualConst)
       OB += " const";
@@ -1324,14 +1328,14 @@ class NonTypeTemplateParamDecl final : public Node {
   template<typename Fn> void match(Fn F) const { F(Name, Type); }
 
   void printLeft(OutputBuffer &OB) const override {
-    Type->printLeft(OB);
+    OB.printLeft(*Type);
     if (!Type->hasRHSComponent(OB))
       OB += " ";
   }
 
   void printRight(OutputBuffer &OB) const override {
     Name->print(OB);
-    Type->printRight(OB);
+    OB.printRight(*Type);
   }
 };
 
@@ -1376,11 +1380,11 @@ class TemplateParamPackDecl final : public Node {
   template<typename Fn> void match(Fn F) const { F(Param); }
 
   void printLeft(OutputBuffer &OB) const override {
-    Param->printLeft(OB);
+    OB.printLeft(*Param);
     OB += "...";
   }
 
-  void printRight(OutputBuffer &OB) const override { Param->printRight(OB); }
+  void printRight(OutputBuffer &OB) const override { OB.printRight(*Param); }
 };
 
 /// An unexpanded parameter pack (either in the expression or type context). If
@@ -1445,13 +1449,13 @@ class ParameterPack final : public Node {
     initializePackExpansion(OB);
     size_t Idx = OB.CurrentPackIndex;
     if (Idx < Data.size())
-      Data[Idx]->printLeft(OB);
+      OB.printLeft(*Data[Idx]);
   }
   void printRight(OutputBuffer &OB) const override {
     initializePackExpansion(OB);
     size_t Idx = OB.CurrentPackIndex;
     if (Idx < Data.size())
-      Data[Idx]->printRight(OB);
+      OB.printRight(*Data[Idx]);
   }
 };
 
@@ -1609,13 +1613,13 @@ struct ForwardTemplateReference : Node {
     if (Printing)
       return;
     ScopedOverride<bool> SavePrinting(Printing, true);
-    Ref->printLeft(OB);
+    OB.printLeft(*Ref);
   }
   void printRight(OutputBuffer &OB) const override {
     if (Printing)
       return;
     ScopedOverride<bool> SavePrinting(Printing, true);
-    Ref->printRight(OB);
+    OB.printRight(*Ref);
   }
 };
 
@@ -1767,7 +1771,7 @@ class DtorName : public Node {
 
   void printLeft(OutputBuffer &OB) const override {
     OB += "~";
-    Base->printLeft(OB);
+    OB.printLeft(*Base);
   }
 };
 
@@ -2047,7 +2051,7 @@ class CastExpr : public Node {
     {
       ScopedOverride<unsigned> LT(OB.GtIsGt, 0);
       OB += "<";
-      To->printLeft(OB);
+      OB.printLeft(*To);
       OB += ">";
     }
     OB.printOpen();
@@ -6176,6 +6180,10 @@ struct ManglingParser : AbstractManglingParser<ManglingParser<Alloc>, Alloc> {
                                Alloc>::AbstractManglingParser;
 };
 
+inline void OutputBuffer::printLeft(const Node &N) { N.printLeft(*this); }
+
+inline void OutputBuffer::printRight(const Node &N) { N.printRight(*this); }
+
 DEMANGLE_NAMESPACE_END
 
 #if defined(__clang__)
diff --git a/llvm/include/llvm/Demangle/Utility.h b/llvm/include/llvm/Demangle/Utility.h
index e893cceea2cdc..6a1bf6d0e6b63 100644
--- a/llvm/include/llvm/Demangle/Utility.h
+++ b/llvm/include/llvm/Demangle/Utility.h
@@ -27,6 +27,8 @@
 
 DEMANGLE_NAMESPACE_BEGIN
 
+class Node;
+
 // Stream that AST nodes write their string representation into after the AST
 // has been parsed.
 class OutputBuffer {
@@ -79,10 +81,15 @@ class OutputBuffer {
   OutputBuffer(const OutputBuffer &) = delete;
   OutputBuffer &operator=(const OutputBuffer &) = delete;
 
+  virtual ~OutputBuffer() {}
+
   operator std::string_view() const {
     return std::string_view(Buffer, CurrentPosition);
   }
 
+  virtual void printLeft(const Node &N);
+  virtual void printRight(const Node &N);
+
   /// If a ParameterPackExpansion (or similar type) is encountered, the offset
   /// into the pack that we're currently printing.
   unsigned CurrentPackIndex = std::numeric_limits<unsigned>::max();



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