Move some utility classes to header files

[zturner]

Summary

There were a bunch of useful utility classes and compiler test macros stashed away inside of ItaniumDemangle.cpp. A long time ago, in D34667, there was an attempt to add a Microsoft demangler. It got stalled but I'm intending to pick this up and finish it off. It had done a lot of the same stuff as was already being done in the helper classes in ItaniumDemangle.cpp such as testing for various compiler features, copying StringView from LLVM, etc. So all of the stuff that would be useful to a different demangler, I'm moving out into header files which can be included by the Microsoft demangler. In a followup patch, I'll rebase Rui's work on top of the new changes, finish it up, and then upload a new version of the MS demangler.

[dblaikie]

Might be worth some unit tests now that these are reusable components.

[zturner]

In D49399#1164231, @dblaikie wrote:

Might be worth some unit tests now that these are reusable components.

They're not suuuper re-usable. They're still considered private implementation details (i.e. they're in the source directory, not the include directory). a unittest wouldn't be able to #include the header file. If you think it's worth doing so, I can make them public, but I don't think we want anyone outside of LLVMDemangle including these, so it's iffy. I'll submit this for now, if you think I should move the files to the include directory and add unit tests, we can do that in a followup.

[dblaikie]

Ah, yeah, fair point that they're still implementation details/can't be
included from tests - fine fine (:

llvm/lib/Demangle/CMakeLists.txt

 add_llvm_library(LLVMDemangle
   ItaniumDemangle.cpp
+  
+  ADDITIONAL_HEADER_DIRS
+  "${LLVM_MAIN_INCLUDE_DIR}/llvm/Demangle"
 )

llvm/lib/Demangle/Compiler.h

+//===--- Compiler.h ---------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//
+// This file contains a variety of feature test macros copied from
+// include/llvm/Support/Compiler.h so that LLVMDemangle does not need to take
+// a dependency on LLVMSupport.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEMANGLE_COMPILER_H
+#define LLVM_DEMANGLE_COMPILER_H
+
+#ifdef _MSC_VER
+// snprintf is implemented in VS 2015
+#if _MSC_VER < 1900
+#define snprintf _snprintf_s
+#endif
+#endif
+
+#ifndef __has_feature
+#define __has_feature(x) 0
+#endif
+
+#ifndef __has_cpp_attribute
+#define __has_cpp_attribute(x) 0
+#endif
+
+#ifndef __has_attribute
+#define __has_attribute(x) 0
+#endif
+
+#ifndef __has_builtin
+#define __has_builtin(x) 0
+#endif
+
+#ifndef LLVM_GNUC_PREREQ
+#if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
+#define LLVM_GNUC_PREREQ(maj, min, patch)                                      \
+  ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >=          \
+   ((maj) << 20) + ((min) << 10) + (patch))
+#elif defined(__GNUC__) && defined(__GNUC_MINOR__)
+#define LLVM_GNUC_PREREQ(maj, min, patch)                                      \
+  ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10))
+#else
+#define LLVM_GNUC_PREREQ(maj, min, patch) 0
+#endif
+#endif
+
+#if __has_attribute(used) || LLVM_GNUC_PREREQ(3, 1, 0)
+#define LLVM_ATTRIBUTE_USED __attribute__((__used__))
+#else
+#define LLVM_ATTRIBUTE_USED
+#endif
+
+#if __has_builtin(__builtin_unreachable) || LLVM_GNUC_PREREQ(4, 5, 0)
+#define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
+#elif defined(_MSC_VER)
+#define LLVM_BUILTIN_UNREACHABLE __assume(false)
+#endif
+
+#if __has_attribute(noinline) || LLVM_GNUC_PREREQ(3, 4, 0)
+#define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
+#elif defined(_MSC_VER)
+#define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
+#else
+#define LLVM_ATTRIBUTE_NOINLINE
+#endif
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED
+#else
+#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE
+#endif
+
+#if __cplusplus > 201402L && __has_cpp_attribute(fallthrough)
+#define LLVM_FALLTHROUGH [[fallthrough]]
+#elif __has_cpp_attribute(gnu::fallthrough)
+#define LLVM_FALLTHROUGH [[gnu::fallthrough]]
+#elif !__cplusplus
+// Workaround for llvm.org/PR23435, since clang 3.6 and below emit a spurious
+// error when __has_cpp_attribute is given a scoped attribute in C mode.
+#define LLVM_FALLTHROUGH
+#elif __has_cpp_attribute(clang::fallthrough)
+#define LLVM_FALLTHROUGH [[clang::fallthrough]]
+#else
+#define LLVM_FALLTHROUGH
+#endif
+
+#endif

llvm/lib/Demangle/ItaniumDemangle.cpp

 //===------------------------- ItaniumDemangle.cpp ------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 // FIXME: (possibly) incomplete list of features that clang mangles that this
 // file does not yet support:
 //   - C++ modules TS
 
 #include "llvm/Demangle/Demangle.h"
+#include "Compiler.h"
+#include "StringView.h"
+#include "Utility.h"
 
-#include <algorithm>
 #include <cassert>
 #include <cctype>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <numeric>
 #include <vector>
 
-#ifdef _MSC_VER
-// snprintf is implemented in VS 2015
-#if _MSC_VER < 1900
-#define snprintf _snprintf_s
-#endif
-#endif
-
-// A variety of feature test macros copied from include/llvm/Support/Compiler.h
-#ifndef __has_feature
-#define __has_feature(x) 0
-#endif
-
-#ifndef __has_cpp_attribute
-#define __has_cpp_attribute(x) 0
-#endif
-
-#ifndef __has_attribute
-#define __has_attribute(x) 0
-#endif
-
-#ifndef __has_builtin
-#define __has_builtin(x) 0
-#endif
-
-#ifndef LLVM_GNUC_PREREQ
-#if defined(__GNUC__) && defined(__GNUC_MINOR__) && defined(__GNUC_PATCHLEVEL__)
-#define LLVM_GNUC_PREREQ(maj, min, patch)                                      \
-  ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) + __GNUC_PATCHLEVEL__ >=          \
-   ((maj) << 20) + ((min) << 10) + (patch))
-#elif defined(__GNUC__) && defined(__GNUC_MINOR__)
-#define LLVM_GNUC_PREREQ(maj, min, patch)                                      \
-  ((__GNUC__ << 20) + (__GNUC_MINOR__ << 10) >= ((maj) << 20) + ((min) << 10))
-#else
-#define LLVM_GNUC_PREREQ(maj, min, patch) 0
-#endif
-#endif
-
-#if __has_attribute(used) || LLVM_GNUC_PREREQ(3, 1, 0)
-#define LLVM_ATTRIBUTE_USED __attribute__((__used__))
-#else
-#define LLVM_ATTRIBUTE_USED
-#endif
-
-#if __has_builtin(__builtin_unreachable) || LLVM_GNUC_PREREQ(4, 5, 0)
-#define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
-#elif defined(_MSC_VER)
-#define LLVM_BUILTIN_UNREACHABLE __assume(false)
-#endif
-
-#if __has_attribute(noinline) || LLVM_GNUC_PREREQ(3, 4, 0)
-#define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
-#elif defined(_MSC_VER)
-#define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
-#else
-#define LLVM_ATTRIBUTE_NOINLINE
-#endif
-
-#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED
-#else
-#define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE
-#endif
-
-#if __cplusplus > 201402L && __has_cpp_attribute(fallthrough)
-#define LLVM_FALLTHROUGH [[fallthrough]]
-#elif __has_cpp_attribute(gnu::fallthrough)
-#define LLVM_FALLTHROUGH [[gnu::fallthrough]]
-#elif !__cplusplus
-// Workaround for llvm.org/PR23435, since clang 3.6 and below emit a spurious
-// error when __has_cpp_attribute is given a scoped attribute in C mode.
-#define LLVM_FALLTHROUGH
-#elif __has_cpp_attribute(clang::fallthrough)
-#define LLVM_FALLTHROUGH [[clang::fallthrough]]
-#else
-#define LLVM_FALLTHROUGH
-#endif
 
 namespace {
 
-class StringView {
-  const char *First;
-  const char *Last;
-
-public:
-  template <size_t N>
-  StringView(const char (&Str)[N]) : First(Str), Last(Str + N - 1) {}
-  StringView(const char *First_, const char *Last_) : First(First_), Last(Last_) {}
-  StringView() : First(nullptr), Last(nullptr) {}
-
-  StringView substr(size_t From, size_t To) {
-    if (To >= size())
-      To = size() - 1;
-    if (From >= size())
-      From = size() - 1;
-    return StringView(First + From, First + To);
-  }
-
-  StringView dropFront(size_t N) const {
-    if (N >= size())
-      N = size() - 1;
-    return StringView(First + N, Last);
-  }
-
-  bool startsWith(StringView Str) const {
-    if (Str.size() > size())
-      return false;
-    return std::equal(Str.begin(), Str.end(), begin());
-  }
-
-  const char &operator[](size_t Idx) const { return *(begin() + Idx); }
-
-  const char *begin() const { return First; }
-  const char *end() const { return Last; }
-  size_t size() const { return static_cast<size_t>(Last - First); }
-  bool empty() const { return First == Last; }
-};
-
-bool operator==(const StringView &LHS, const StringView &RHS) {
-  return LHS.size() == RHS.size() &&
-         std::equal(LHS.begin(), LHS.end(), RHS.begin());
-}
-
-// Stream that AST nodes write their string representation into after the AST
-// has been parsed.
-class OutputStream {
-  char *Buffer;
-  size_t CurrentPosition;
-  size_t BufferCapacity;
-
-  // Ensure there is at least n more positions in buffer.
-  void grow(size_t N) {
-    if (N + CurrentPosition >= BufferCapacity) {
-      BufferCapacity *= 2;
-      if (BufferCapacity < N + CurrentPosition)
-        BufferCapacity = N + CurrentPosition;
-      Buffer = static_cast<char *>(std::realloc(Buffer, BufferCapacity));
-    }
-  }
-
-public:
-  OutputStream(char *StartBuf, size_t Size)
-      : Buffer(StartBuf), CurrentPosition(0), BufferCapacity(Size) {}
-  OutputStream() = default;
-  void reset(char *Buffer_, size_t BufferCapacity_) {
-    CurrentPosition = 0;
-    Buffer = Buffer_;
-    BufferCapacity = BufferCapacity_;
-  }
-
-  /// 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();
-  unsigned CurrentPackMax = std::numeric_limits<unsigned>::max();
-
-  OutputStream &operator+=(StringView R) {
-    size_t Size = R.size();
-    if (Size == 0)
-      return *this;
-    grow(Size);
-    memmove(Buffer + CurrentPosition, R.begin(), Size);
-    CurrentPosition += Size;
-    return *this;
-  }
-
-  OutputStream &operator+=(char C) {
-    grow(1);
-    Buffer[CurrentPosition++] = C;
-    return *this;
-  }
-
-  size_t getCurrentPosition() const { return CurrentPosition; }
-  void setCurrentPosition(size_t NewPos) { CurrentPosition = NewPos; }
-
-  char back() const {
-    return CurrentPosition ? Buffer[CurrentPosition - 1] : '\0';
-  }
-
-  bool empty() const { return CurrentPosition == 0; }
-
-  char *getBuffer() { return Buffer; }
-  char *getBufferEnd() { return Buffer + CurrentPosition - 1; }
-  size_t getBufferCapacity() { return BufferCapacity; }
-};
-
-template <class T>
-class SwapAndRestore {
-  T &Restore;
-  T OriginalValue;
-public:
-  SwapAndRestore(T& Restore_, T NewVal)
-      : Restore(Restore_), OriginalValue(Restore) {
-    Restore = std::move(NewVal);
-  }
-  ~SwapAndRestore() { Restore = std::move(OriginalValue); }
-
-  SwapAndRestore(const SwapAndRestore &) = delete;
-  SwapAndRestore &operator=(const SwapAndRestore &) = delete;
-};
 
 // Base class of all AST nodes. The AST is built by the parser, then is
 // traversed by the printLeft/Right functions to produce a demangled string.
 class Node {
 public:
   enum Kind : unsigned char {
     KNodeArrayNode,
     KDotSuffix,

llvm/lib/Demangle/StringView.h

+//===--- StringView.h -------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//
+// This file contains a limited version of LLVM's StringView class.  It is
+// copied here so that LLVMDemangle need not take a dependency on LLVMSupport.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEMANGLE_STRINGVIEW_H
+#define LLVM_DEMANGLE_STRINGVIEW_H
+
+#include <algorithm>
+
+class StringView {
+  const char *First;
+  const char *Last;
+
+public:
+  template <size_t N>
+  StringView(const char(&Str)[N]) : First(Str), Last(Str + N - 1) {}
+  StringView(const char *First_, const char *Last_) : First(First_), Last(Last_) {}
+  StringView() : First(nullptr), Last(nullptr) {}
+
+  StringView substr(size_t From, size_t To) {
+    if (To >= size())
+      To = size() - 1;
+    if (From >= size())
+      From = size() - 1;
+    return StringView(First + From, First + To);
+  }
+
+  StringView dropFront(size_t N) const {
+    if (N >= size())
+      N = size() - 1;
+    return StringView(First + N, Last);
+  }
+
+  bool startsWith(StringView Str) const {
+    if (Str.size() > size())
+      return false;
+    return std::equal(Str.begin(), Str.end(), begin());
+  }
+
+  const char &operator[](size_t Idx) const { return *(begin() + Idx); }
+
+  const char *begin() const { return First; }
+  const char *end() const { return Last; }
+  size_t size() const { return static_cast<size_t>(Last - First); }
+  bool empty() const { return First == Last; }
+};
+
+bool operator==(const StringView &LHS, const StringView &RHS) {
+  return LHS.size() == RHS.size() &&
+    std::equal(LHS.begin(), LHS.end(), RHS.begin());
+}
+
+
+#endif

llvm/lib/Demangle/Utility.h

+//===--- Utility.h ----------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//
+// This file contains several utility classes used by the demangle library.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEMANGLE_UTILITY_H
+#define LLVM_DEMANGLE_UTILITY_H
+
+#include <cstring>
+
+// Stream that AST nodes write their string representation into after the AST
+// has been parsed.
+class OutputStream {
+  char *Buffer;
+  size_t CurrentPosition;
+  size_t BufferCapacity;
+
+  // Ensure there is at least n more positions in buffer.
+  void grow(size_t N) {
+    if (N + CurrentPosition >= BufferCapacity) {
+      BufferCapacity *= 2;
+      if (BufferCapacity < N + CurrentPosition)
+        BufferCapacity = N + CurrentPosition;
+      Buffer = static_cast<char *>(std::realloc(Buffer, BufferCapacity));
+    }
+  }
+
+public:
+  OutputStream(char *StartBuf, size_t Size)
+    : Buffer(StartBuf), CurrentPosition(0), BufferCapacity(Size) {}
+  OutputStream() = default;
+  void reset(char *Buffer_, size_t BufferCapacity_) {
+    CurrentPosition = 0;
+    Buffer = Buffer_;
+    BufferCapacity = BufferCapacity_;
+  }
+
+  /// 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();
+  unsigned CurrentPackMax = std::numeric_limits<unsigned>::max();
+
+  OutputStream &operator+=(StringView R) {
+    size_t Size = R.size();
+    if (Size == 0)
+      return *this;
+    grow(Size);
+    std::memmove(Buffer + CurrentPosition, R.begin(), Size);
+    CurrentPosition += Size;
+    return *this;
+  }
+
+  OutputStream &operator+=(char C) {
+    grow(1);
+    Buffer[CurrentPosition++] = C;
+    return *this;
+  }
+
+  size_t getCurrentPosition() const { return CurrentPosition; }
+  void setCurrentPosition(size_t NewPos) { CurrentPosition = NewPos; }
+
+  char back() const {
+    return CurrentPosition ? Buffer[CurrentPosition - 1] : '\0';
+  }
+
+  bool empty() const { return CurrentPosition == 0; }
+
+  char *getBuffer() { return Buffer; }
+  char *getBufferEnd() { return Buffer + CurrentPosition - 1; }
+  size_t getBufferCapacity() { return BufferCapacity; }
+};
+
+template <class T>
+class SwapAndRestore {
+  T &Restore;
+  T OriginalValue;
+public:
+  SwapAndRestore(T& Restore_, T NewVal)
+    : Restore(Restore_), OriginalValue(Restore) {
+    Restore = std::move(NewVal);
+  }
+  ~SwapAndRestore() { Restore = std::move(OriginalValue); }
+
+  SwapAndRestore(const SwapAndRestore &) = delete;
+  SwapAndRestore &operator=(const SwapAndRestore &) = delete;
+};
+
+#endif