llvm/lib/Support/ItaniumManglingCanonicalizer.cpp

   1 //===----------------- ItaniumManglingCanonicalizer.cpp -------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Support/ItaniumManglingCanonicalizer.h"
  10 #include "llvm/ADT/DenseMap.h"
  11 #include "llvm/ADT/FoldingSet.h"
  12 #include "llvm/ADT/StringRef.h"
  13 #include "llvm/Demangle/ItaniumDemangle.h"
  14 #include "llvm/Support/Allocator.h"
  15
  16 using namespace llvm;
  17 using llvm::itanium_demangle::ForwardTemplateReference;
  18 using llvm::itanium_demangle::Node;
  19 using llvm::itanium_demangle::NodeKind;
  20 using llvm::itanium_demangle::StringView;
  21
  22 namespace {
  23 struct FoldingSetNodeIDBuilder {
  24   llvm::FoldingSetNodeID &ID;
  25   void operator()(const Node *P) { ID.AddPointer(P); }
  26   void operator()(StringView Str) {
  27     ID.AddString(llvm::StringRef(Str.begin(), Str.size()));
  28   }
  29   template <typename T>
  30   std::enable_if_t<std::is_integral<T>::value || std::is_enum<T>::value>
  31   operator()(T V) {
  32     ID.AddInteger((unsigned long long)V);
  33   }
  34   void operator()(itanium_demangle::NodeArray A) {
  35     ID.AddInteger(A.size());
  36     for (const Node *N : A)
  37       (*this)(N);
  38   }
  39 };
  40
  41 template<typename ...T>
  42 void profileCtor(llvm::FoldingSetNodeID &ID, Node::Kind K, T ...V) {
  43   FoldingSetNodeIDBuilder Builder = {ID};
  44   Builder(K);
  45   int VisitInOrder[] = {
  46     (Builder(V), 0) ...,
  47     0 // Avoid empty array if there are no arguments.
  48   };
  49   (void)VisitInOrder;
  50 }
  51
  52 // FIXME: Convert this to a generic lambda when possible.
  53 template<typename NodeT> struct ProfileSpecificNode {
  54   FoldingSetNodeID &ID;
  55   template<typename ...T> void operator()(T ...V) {
  56     profileCtor(ID, NodeKind<NodeT>::Kind, V...);
  57   }
  58 };
  59
  60 struct ProfileNode {
  61   FoldingSetNodeID &ID;
  62   template<typename NodeT> void operator()(const NodeT *N) {
  63     N->match(ProfileSpecificNode<NodeT>{ID});
  64   }
  65 };
  66
  67 template<> void ProfileNode::operator()(const ForwardTemplateReference *N) {
  68   llvm_unreachable("should never canonicalize a ForwardTemplateReference");
  69 }
  70
  71 void profileNode(llvm::FoldingSetNodeID &ID, const Node *N) {
  72   N->visit(ProfileNode{ID});
  73 }
  74
  75 class FoldingNodeAllocator {
  76   class alignas(alignof(Node *)) NodeHeader : public llvm::FoldingSetNode {
  77   public:
  78     // 'Node' in this context names the injected-class-name of the base class.
  79     itanium_demangle::Node *getNode() {
  80       return reinterpret_cast<itanium_demangle::Node *>(this + 1);
  81     }
  82     void Profile(llvm::FoldingSetNodeID &ID) { profileNode(ID, getNode()); }
  83   };
  84
  85   BumpPtrAllocator RawAlloc;
  86   llvm::FoldingSet<NodeHeader> Nodes;
  87
  88 public:
  89   void reset() {}
  90
  91   template <typename T, typename... Args>
  92   std::pair<Node *, bool> getOrCreateNode(bool CreateNewNodes, Args &&... As) {
  93     // FIXME: Don't canonicalize forward template references for now, because
  94     // they contain state (the resolved template node) that's not known at their
  95     // point of creation.
  96     if (std::is_same<T, ForwardTemplateReference>::value) {
  97       // Note that we don't use if-constexpr here and so we must still write
  98       // this code in a generic form.
  99       return {new (RawAlloc.Allocate(sizeof(T), alignof(T)))
 100                   T(std::forward<Args>(As)...),
 101               true};
 102     }
 103
 104     llvm::FoldingSetNodeID ID;
 105     profileCtor(ID, NodeKind<T>::Kind, As...);
 106
 107     void *InsertPos;
 108     if (NodeHeader *Existing = Nodes.FindNodeOrInsertPos(ID, InsertPos))
 109       return {static_cast<T*>(Existing->getNode()), false};
 110
 111     if (!CreateNewNodes)
 112       return {nullptr, true};
 113
 114     static_assert(alignof(T) <= alignof(NodeHeader),
 115                   "underaligned node header for specific node kind");
 116     void *Storage =
 117         RawAlloc.Allocate(sizeof(NodeHeader) + sizeof(T), alignof(NodeHeader));
 118     NodeHeader *New = new (Storage) NodeHeader;
 119     T *Result = new (New->getNode()) T(std::forward<Args>(As)...);
 120     Nodes.InsertNode(New, InsertPos);
 121     return {Result, true};
 122   }
 123
 124   template<typename T, typename... Args>
 125   Node *makeNode(Args &&...As) {
 126     return getOrCreateNode<T>(true, std::forward<Args>(As)...).first;
 127   }
 128
 129   void *allocateNodeArray(size_t sz) {
 130     return RawAlloc.Allocate(sizeof(Node *) * sz, alignof(Node *));
 131   }
 132 };
 133
 134 class CanonicalizerAllocator : public FoldingNodeAllocator {
 135   Node *MostRecentlyCreated = nullptr;
 136   Node *TrackedNode = nullptr;
 137   bool TrackedNodeIsUsed = false;
 138   bool CreateNewNodes = true;
 139   llvm::SmallDenseMap<Node*, Node*, 32> Remappings;
 140
 141   template<typename T, typename ...Args> Node *makeNodeSimple(Args &&...As) {
 142     std::pair<Node *, bool> Result =
 143         getOrCreateNode<T>(CreateNewNodes, std::forward<Args>(As)...);
 144     if (Result.second) {
 145       // Node is new. Make a note of that.
 146       MostRecentlyCreated = Result.first;
 147     } else if (Result.first) {
 148       // Node is pre-existing; check if it's in our remapping table.
 149       if (auto *N = Remappings.lookup(Result.first)) {
 150         Result.first = N;
 151         assert(Remappings.find(Result.first) == Remappings.end() &&
 152                "should never need multiple remap steps");
 153       }
 154       if (Result.first == TrackedNode)
 155         TrackedNodeIsUsed = true;
 156     }
 157     return Result.first;
 158   }
 159
 160   /// Helper to allow makeNode to be partially-specialized on T.
 161   template<typename T> struct MakeNodeImpl {
 162     CanonicalizerAllocator &Self;
 163     template<typename ...Args> Node *make(Args &&...As) {
 164       return Self.makeNodeSimple<T>(std::forward<Args>(As)...);
 165     }
 166   };
 167
 168 public:
 169   template<typename T, typename ...Args> Node *makeNode(Args &&...As) {
 170     return MakeNodeImpl<T>{*this}.make(std::forward<Args>(As)...);
 171   }
 172
 173   void reset() { MostRecentlyCreated = nullptr; }
 174
 175   void setCreateNewNodes(bool CNN) { CreateNewNodes = CNN; }
 176
 177   void addRemapping(Node *A, Node *B) {
 178     // Note, we don't need to check whether B is also remapped, because if it
 179     // was we would have already remapped it when building it.
 180     Remappings.insert(std::make_pair(A, B));
 181   }
 182
 183   bool isMostRecentlyCreated(Node *N) const { return MostRecentlyCreated == N; }
 184
 185   void trackUsesOf(Node *N) {
 186     TrackedNode = N;
 187     TrackedNodeIsUsed = false;
 188   }
 189   bool trackedNodeIsUsed() const { return TrackedNodeIsUsed; }
 190 };
 191
 192 /// Convert St3foo to NSt3fooE so that equivalences naming one also affect the
 193 /// other.
 194 template<>
 195 struct CanonicalizerAllocator::MakeNodeImpl<
 196            itanium_demangle::StdQualifiedName> {
 197   CanonicalizerAllocator &Self;
 198   Node *make(Node *Child) {
 199     Node *StdNamespace = Self.makeNode<itanium_demangle::NameType>("std");
 200     if (!StdNamespace)
 201       return nullptr;
 202     return Self.makeNode<itanium_demangle::NestedName>(StdNamespace, Child);
 203   }
 204 };
 205
 206 // FIXME: Also expand built-in substitutions?
 207
 208 using CanonicalizingDemangler =
 209     itanium_demangle::ManglingParser<CanonicalizerAllocator>;
 210 } // namespace
 211
 212 struct ItaniumManglingCanonicalizer::Impl {
 213   CanonicalizingDemangler Demangler = {nullptr, nullptr};
 214 };
 215
 216 ItaniumManglingCanonicalizer::ItaniumManglingCanonicalizer() : P(new Impl) {}
 217 ItaniumManglingCanonicalizer::~ItaniumManglingCanonicalizer() { delete P; }
 218
 219 ItaniumManglingCanonicalizer::EquivalenceError
 220 ItaniumManglingCanonicalizer::addEquivalence(FragmentKind Kind, StringRef First,
 221                                              StringRef Second) {
 222   auto &Alloc = P->Demangler.ASTAllocator;
 223   Alloc.setCreateNewNodes(true);
 224
 225   auto Parse = [&](StringRef Str) {
 226     P->Demangler.reset(Str.begin(), Str.end());
 227     Node *N = nullptr;
 228     switch (Kind) {
 229       // A <name>, with minor extensions to allow arbitrary namespace and
 230       // template names that can't easily be written as <name>s.
 231     case FragmentKind::Name:
 232       // Very special case: allow "St" as a shorthand for "3std". It's not
 233       // valid as a <name> mangling, but is nonetheless the most natural
 234       // way to name the 'std' namespace.
 235       if (Str.size() == 2 && P->Demangler.consumeIf("St"))
 236         N = P->Demangler.make<itanium_demangle::NameType>("std");
 237       // We permit substitutions to name templates without their template
 238       // arguments. This mostly just falls out, as almost all template names
 239       // are valid as <name>s, but we also want to parse <substitution>s as
 240       // <name>s, even though they're not.
 241       else if (Str.startswith("S"))
 242         // Parse the substitution and optional following template arguments.
 243         N = P->Demangler.parseType();
 244       else
 245         N = P->Demangler.parseName();
 246       break;
 247
 248       // A <type>.
 249     case FragmentKind::Type:
 250       N = P->Demangler.parseType();
 251       break;
 252
 253       // An <encoding>.
 254     case FragmentKind::Encoding:
 255       N = P->Demangler.parseEncoding();
 256       break;
 257     }
 258
 259     // If we have trailing junk, the mangling is invalid.
 260     if (P->Demangler.numLeft() != 0)
 261       N = nullptr;
 262
 263     // If any node was created after N, then we cannot safely remap it because
 264     // it might already be in use by another node.
 265     return std::make_pair(N, Alloc.isMostRecentlyCreated(N));
 266   };
 267
 268   Node *FirstNode, *SecondNode;
 269   bool FirstIsNew, SecondIsNew;
 270
 271   std::tie(FirstNode, FirstIsNew) = Parse(First);
 272   if (!FirstNode)
 273     return EquivalenceError::InvalidFirstMangling;
 274
 275   Alloc.trackUsesOf(FirstNode);
 276   std::tie(SecondNode, SecondIsNew) = Parse(Second);
 277   if (!SecondNode)
 278     return EquivalenceError::InvalidSecondMangling;
 279
 280   // If they're already equivalent, there's nothing to do.
 281   if (FirstNode == SecondNode)
 282     return EquivalenceError::Success;
 283
 284   if (FirstIsNew && !Alloc.trackedNodeIsUsed())
 285     Alloc.addRemapping(FirstNode, SecondNode);
 286   else if (SecondIsNew)
 287     Alloc.addRemapping(SecondNode, FirstNode);
 288   else
 289     return EquivalenceError::ManglingAlreadyUsed;
 290
 291   return EquivalenceError::Success;
 292 }
 293
 294 static ItaniumManglingCanonicalizer::Key
 295 parseMaybeMangledName(CanonicalizingDemangler &Demangler, StringRef Mangling,
 296                       bool CreateNewNodes) {
 297   Demangler.ASTAllocator.setCreateNewNodes(CreateNewNodes);
 298   Demangler.reset(Mangling.begin(), Mangling.end());
 299   // Attempt demangling only for names that look like C++ mangled names.
 300   // Otherwise, treat them as extern "C" names. We permit the latter to
 301   // be remapped by (eg)
 302   //   encoding 6memcpy 7memmove
 303   // consistent with how they are encoded as local-names inside a C++ mangling.
 304   Node *N;
 305   if (Mangling.startswith("_Z") || Mangling.startswith("__Z") ||
 306       Mangling.startswith("___Z") || Mangling.startswith("____Z"))
 307     N = Demangler.parse();
 308   else
 309     N = Demangler.make<itanium_demangle::NameType>(
 310         StringView(Mangling.data(), Mangling.size()));
 311   return reinterpret_cast<ItaniumManglingCanonicalizer::Key>(N);
 312 }
 313
 314 ItaniumManglingCanonicalizer::Key
 315 ItaniumManglingCanonicalizer::canonicalize(StringRef Mangling) {
 316   return parseMaybeMangledName(P->Demangler, Mangling, true);
 317 }
 318
 319 ItaniumManglingCanonicalizer::Key
 320 ItaniumManglingCanonicalizer::lookup(StringRef Mangling) {
 321   return parseMaybeMangledName(P->Demangler, Mangling, false);
 322 }