[SYCL] Unique stable name rebase (#3835)

This reverts our existing implementation, updates the library uses of this, and adds the community patch back:

8347ee4

Author: Erich Keane

clang/docs/LanguageExtensions.rst

@@ -1794,7 +1794,7 @@ correctly in any circumstances. It can be used if:
   metaprogramming algorithms to be able to specify/detect types generically.
 
 - the generated kernel binary does not contain indirect calls because they
-  are eliminated using compiler optimizations e.g. devirtualization. 
+  are eliminated using compiler optimizations e.g. devirtualization.
 
 - the selected target supports the function pointer like functionality e.g.
   most CPU targets.
@@ -2404,29 +2404,39 @@ argument.
   int *pb =__builtin_preserve_access_index(&v->c[3].b);
   __builtin_preserve_access_index(v->j);
 
-``__builtin_unique_stable_name``
---------------------------------
+``__builtin_sycl_unique_stable_name``
+-------------------------------------
 
-``__builtin_unique_stable_name()`` is a builtin that takes a type or expression and
-produces a string literal containing a unique name for the type (or type of the
-expression) that is stable across split compilations.
+``__builtin_sycl_unique_stable_name()`` is a builtin that takes a type and
+produces a string literal containing a unique name for the type that is stable
+across split compilations, mainly to support SYCL/Data Parallel C++ language.
 
 In cases where the split compilation needs to share a unique token for a type
 across the boundary (such as in an offloading situation), this name can be used
-for lookup purposes.
+for lookup purposes, such as in the SYCL Integration Header.
+
+The value of this builtin is computed entirely at compile time, so it can be
+used in constant expressions. This value encodes lambda functions based on a
+stable numbering order in which they appear in their local declaration contexts.
+Once this builtin is evaluated in a constexpr context, it is erroneous to use
+it in an instantiation which changes its value.
+
+In order to produce the unique name, the current implementation of the bultin
+uses Itanium mangling even if the host compilation uses a different name
+mangling scheme at runtime. The mangler marks all the lambdas required to name
+the SYCL kernel and emits a stable local ordering of the respective lambdas,
+starting from ``10000``. The initial value of ``10000`` serves as an obvious
+differentiator from ordinary lambda mangling numbers but does not serve any
+other purpose and may change in the future. The resulting pattern is
+demanglable. When non-lambda types are passed to the builtin, the mangler emits
+their usual pattern without any special treatment.
+
+**Syntax**:
 
-This builtin is superior to RTTI for this purpose for two reasons.  First, this
-value is computed entirely at compile time, so it can be used in constant
-expressions. Second, this value encodes lambda functions based on line-number
-rather than the order in which it appears in a function. This is valuable
-because it is stable in cases where an unrelated lambda is introduced
-conditionally in the same function.
+.. code-block:: c
 
-The current implementation of this builtin uses a slightly modified Itanium
-Mangler to produce the unique name. The lambda ordinal is replaced with one or
-more line/column pairs in the format ``LINE->COL``, separated with a ``~``
-character. Typically, only one pair will be included, however in the case of
-macro expansions the entire macro expansion stack is expressed.
+  // Computes a unique stable name for the given type.
+  constexpr const char * __builtin_sycl_unique_stable_name( type-id );
 
 Multiprecision Arithmetic Builtins
 ----------------------------------
@@ -2622,7 +2632,7 @@ Guaranteed inlined copy
 ``__builtin_memcpy_inline`` has been designed as a building block for efficient
 ``memcpy`` implementations. It is identical to ``__builtin_memcpy`` but also
 guarantees not to call any external functions. See LLVM IR `llvm.memcpy.inline
-<https://llvm.org/docs/LangRef.html#llvm-memcpy-inline-intrinsic>`_ intrinsic 
+<https://llvm.org/docs/LangRef.html#llvm-memcpy-inline-intrinsic>`_ intrinsic
 for more information.
 
 This is useful to implement a custom version of ``memcpy``, implement a

clang/include/clang/AST/ASTContext.h

@@ -103,6 +103,7 @@ class DynTypedNode;
 class DynTypedNodeList;
 class Expr;
 class GlobalDecl;
+class ItaniumMangleContext;
 class MangleContext;
 class MangleNumberingContext;
 class MaterializeTemporaryExpr;
@@ -2360,6 +2361,12 @@ class ASTContext : public RefCountedBase<ASTContext> {
   /// If \p T is null pointer, assume the target in ASTContext.
   MangleContext *createMangleContext(const TargetInfo *T = nullptr);
 
+  /// Creates a device mangle context to correctly mangle lambdas in a mixed
+  /// architecture compile by setting the lambda mangling number source to the
+  /// DeviceLambdaManglingNumber. Currently this asserts that the TargetInfo
+  /// (from the AuxTargetInfo) is a an itanium target.
+  MangleContext *createDeviceMangleContext(const TargetInfo &T);
+
   void DeepCollectObjCIvars(const ObjCInterfaceDecl *OI, bool leafClass,
                             SmallVectorImpl<const ObjCIvarDecl*> &Ivars) const;
 
@@ -3163,10 +3170,31 @@ OPT_LIST(V)
 
   StringRef getCUIDHash() const;
 
+  void AddSYCLKernelNamingDecl(const CXXRecordDecl *RD);
+  bool IsSYCLKernelNamingDecl(const NamedDecl *RD) const;
+  unsigned GetSYCLKernelNamingIndex(const NamedDecl *RD);
+  /// A SourceLocation to store whether we have evaluated a kernel name already,
+  /// and where it happened.  If so, we need to diagnose an illegal use of the
+  /// builtin.
+  llvm::MapVector<const SYCLUniqueStableNameExpr *, std::string>
+      SYCLUniqueStableNameEvaluatedValues;
+
 private:
   /// All OMPTraitInfo objects live in this collection, one per
   /// `pragma omp [begin] declare variant` directive.
   SmallVector<std::unique_ptr<OMPTraitInfo>, 4> OMPTraitInfoVector;
+
+  /// A list of the (right now just lambda decls) declarations required to
+  /// name all the SYCL kernels in the translation unit, so that we can get the
+  /// correct kernel name, as well as implement
+  /// __builtin_sycl_unique_stable_name.
+  llvm::DenseMap<const DeclContext *,
+                 llvm::SmallPtrSet<const CXXRecordDecl *, 4>>
+      SYCLKernelNamingTypes;
+  std::unique_ptr<ItaniumMangleContext> SYCLKernelFilterContext;
+  void FilterSYCLKernelNamingDecls(
+      const CXXRecordDecl *RD,
+      llvm::SmallVectorImpl<const CXXRecordDecl *> &Decls);
 };
 
 /// Insertion operator for diagnostics.

clang/include/clang/AST/ComputeDependence.h

@@ -78,6 +78,7 @@ class MaterializeTemporaryExpr;
 class CXXFoldExpr;
 class TypeTraitExpr;
 class ConceptSpecializationExpr;
+class SYCLUniqueStableNameExpr;
 class PredefinedExpr;
 class CallExpr;
 class OffsetOfExpr;
@@ -165,6 +166,7 @@ ExprDependence computeDependence(TypeTraitExpr *E);
 ExprDependence computeDependence(ConceptSpecializationExpr *E,
                                  bool ValueDependent);
 
+ExprDependence computeDependence(SYCLUniqueStableNameExpr *E);
 ExprDependence computeDependence(PredefinedExpr *E);
 ExprDependence computeDependence(CallExpr *E, llvm::ArrayRef<Expr *> PreArgs);
 ExprDependence computeDependence(OffsetOfExpr *E);

clang/include/clang/AST/Expr.h

@@ -1948,17 +1948,13 @@ class StringLiteral final
 /// [C99 6.4.2.2] - A predefined identifier such as __func__.
 class PredefinedExpr final
     : public Expr,
-      private llvm::TrailingObjects<PredefinedExpr, Stmt *, Expr *,
-                                    TypeSourceInfo *> {
+      private llvm::TrailingObjects<PredefinedExpr, Stmt *> {
   friend class ASTStmtReader;
   friend TrailingObjects;
 
   // PredefinedExpr is optionally followed by a single trailing
   // "Stmt *" for the predefined identifier. It is present if and only if
   // hasFunctionName() is true and is always a "StringLiteral *".
-  // It can also be followed by a Expr* in the case of a
-  // __builtin_unique_stable_name with an expression, or TypeSourceInfo * if
-  // __builtin_unique_stable_name with a type.
 
 public:
   enum IdentKind {
@@ -1971,18 +1967,12 @@ class PredefinedExpr final
     PrettyFunction,
     /// The same as PrettyFunction, except that the
     /// 'virtual' keyword is omitted for virtual member functions.
-    PrettyFunctionNoVirtual,
-    UniqueStableNameType,
-    UniqueStableNameExpr,
+    PrettyFunctionNoVirtual
   };
 
 private:
   PredefinedExpr(SourceLocation L, QualType FNTy, IdentKind IK,
                  StringLiteral *SL);
-  PredefinedExpr(SourceLocation L, QualType FNTy, IdentKind IK,
-                 TypeSourceInfo *Info);
-  PredefinedExpr(SourceLocation L, QualType FNTy, IdentKind IK,
-                 Expr *E);
 
   explicit PredefinedExpr(EmptyShell Empty, bool HasFunctionName);
 
@@ -1995,39 +1985,10 @@ class PredefinedExpr final
     *getTrailingObjects<Stmt *>() = SL;
   }
 
-  void setTypeSourceInfo(TypeSourceInfo *Info) {
-    assert(!hasFunctionName() && getIdentKind() == UniqueStableNameType &&
-           "TypeSourceInfo only valid for UniqueStableName of a Type");
-    *getTrailingObjects<TypeSourceInfo *>() = Info;
-  }
-
-  void setExpr(Expr *E) {
-    assert(!hasFunctionName() && getIdentKind() == UniqueStableNameExpr &&
-           "TypeSourceInfo only valid for UniqueStableName of n Expression.");
-    *getTrailingObjects<Expr *>() = E;
-  }
-
-  size_t numTrailingObjects(OverloadToken<Stmt *>) const {
-    return hasFunctionName();
-  }
-
-  size_t numTrailingObjects(OverloadToken<TypeSourceInfo *>) const {
-    return getIdentKind() == UniqueStableNameType && !hasFunctionName();
-  }
-  size_t numTrailingObjects(OverloadToken<Expr *>) const {
-    return getIdentKind() == UniqueStableNameExpr && !hasFunctionName();
-  }
-
 public:
   /// Create a PredefinedExpr.
   static PredefinedExpr *Create(const ASTContext &Ctx, SourceLocation L,
                                 QualType FNTy, IdentKind IK, StringLiteral *SL);
-  static PredefinedExpr *Create(const ASTContext &Ctx, SourceLocation L,
-                                QualType FNTy, IdentKind IK, StringLiteral *SL,
-                                TypeSourceInfo *Info);
-  static PredefinedExpr *Create(const ASTContext &Ctx, SourceLocation L,
-                                QualType FNTy, IdentKind IK, StringLiteral *SL,
-                                Expr *E);
 
   /// Create an empty PredefinedExpr.
   static PredefinedExpr *CreateEmpty(const ASTContext &Ctx,
@@ -2052,38 +2013,12 @@ class PredefinedExpr final
                : nullptr;
   }
 
-  TypeSourceInfo *getTypeSourceInfo() {
-    assert(!hasFunctionName() && getIdentKind() == UniqueStableNameType &&
-           "TypeSourceInfo only valid for UniqueStableName of a Type");
-    return *getTrailingObjects<TypeSourceInfo *>();
-  }
-
-  const TypeSourceInfo *getTypeSourceInfo() const {
-    assert(!hasFunctionName() && getIdentKind() == UniqueStableNameType &&
-           "TypeSourceInfo only valid for UniqueStableName of a Type");
-    return *getTrailingObjects<TypeSourceInfo *>();
-  }
-
-  Expr *getExpr() {
-    assert(!hasFunctionName() && getIdentKind() == UniqueStableNameExpr &&
-           "TypeSourceInfo only valid for UniqueStableName of n Expression.");
-    return *getTrailingObjects<Expr *>();
-  }
-
-  const Expr *getExpr() const {
-    assert(!hasFunctionName() && getIdentKind() == UniqueStableNameExpr &&
-           "TypeSourceInfo only valid for UniqueStableName of n Expression.");
-    return *getTrailingObjects<Expr *>();
-  }
-
   static StringRef getIdentKindName(IdentKind IK);
   StringRef getIdentKindName() const {
     return getIdentKindName(getIdentKind());
   }
 
   static std::string ComputeName(IdentKind IK, const Decl *CurrentDecl);
-  static std::string ComputeName(ASTContext &Context, IdentKind IK,
-                                 const QualType Ty);
 
   SourceLocation getBeginLoc() const { return getLocation(); }
   SourceLocation getEndLoc() const { return getLocation(); }
@@ -2104,6 +2039,64 @@ class PredefinedExpr final
   }
 };
 
+// This represents a use of the __builtin_sycl_unique_stable_name, which takes a
+// type-id, and at CodeGen time emits a unique string representation of the
+// type in a way that permits us to properly encode information about the SYCL
+// kernels.
+class SYCLUniqueStableNameExpr final : public Expr {
+  friend class ASTStmtReader;
+  SourceLocation OpLoc, LParen, RParen;
+  TypeSourceInfo *TypeInfo;
+
+  SYCLUniqueStableNameExpr(EmptyShell Empty, QualType ResultTy);
+  SYCLUniqueStableNameExpr(SourceLocation OpLoc, SourceLocation LParen,
+                           SourceLocation RParen, QualType ResultTy,
+                           TypeSourceInfo *TSI);
+
+  void setTypeSourceInfo(TypeSourceInfo *Ty) { TypeInfo = Ty; }
+
+  void setLocation(SourceLocation L) { OpLoc = L; }
+  void setLParenLocation(SourceLocation L) { LParen = L; }
+  void setRParenLocation(SourceLocation L) { RParen = L; }
+
+public:
+  TypeSourceInfo *getTypeSourceInfo() { return TypeInfo; }
+
+  const TypeSourceInfo *getTypeSourceInfo() const { return TypeInfo; }
+
+  static SYCLUniqueStableNameExpr *
+  Create(const ASTContext &Ctx, SourceLocation OpLoc, SourceLocation LParen,
+         SourceLocation RParen, TypeSourceInfo *TSI);
+
+  static SYCLUniqueStableNameExpr *CreateEmpty(const ASTContext &Ctx);
+
+  SourceLocation getBeginLoc() const { return getLocation(); }
+  SourceLocation getEndLoc() const { return RParen; }
+  SourceLocation getLocation() const { return OpLoc; }
+  SourceLocation getLParenLocation() const { return LParen; }
+  SourceLocation getRParenLocation() const { return RParen; }
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == SYCLUniqueStableNameExprClass;
+  }
+
+  // Iterators
+  child_range children() {
+    return child_range(child_iterator(), child_iterator());
+  }
+
+  const_child_range children() const {
+    return const_child_range(const_child_iterator(), const_child_iterator());
+  }
+
+  // Convenience function to generate the name of the currently stored type.
+  std::string ComputeName(ASTContext &Context) const;
+
+  // Get the generated name of the type.  Note that this only works after all
+  // kernels have been instantiated.
+  static std::string ComputeName(ASTContext &Context, QualType Ty);
+};
+
 /// ParenExpr - This represents a parethesized expression, e.g. "(1)".  This
 /// AST node is only formed if full location information is requested.
 class ParenExpr : public Expr {

clang/include/clang/AST/JSONNodeDumper.h

@@ -263,6 +263,7 @@ class JSONNodeDumper
   void VisitBlockDecl(const BlockDecl *D);
 
   void VisitDeclRefExpr(const DeclRefExpr *DRE);
+  void VisitSYCLUniqueStableNameExpr(const SYCLUniqueStableNameExpr *E);
   void VisitPredefinedExpr(const PredefinedExpr *PE);
   void VisitUnaryOperator(const UnaryOperator *UO);
   void VisitBinaryOperator(const BinaryOperator *BO);

clang/include/clang/AST/Mangle.h

@@ -107,9 +107,6 @@ class MangleContext {
   virtual bool shouldMangleCXXName(const NamedDecl *D) = 0;
   virtual bool shouldMangleStringLiteral(const StringLiteral *SL) = 0;
 
-  virtual bool isDeviceMangleContext() const { return false; }
-  virtual void setDeviceMangleContext(bool) {}
-
   virtual bool isUniqueInternalLinkageDecl(const NamedDecl *ND) {
     return false;
   }
@@ -172,14 +169,11 @@ class MangleContext {
 };
 
 class ItaniumMangleContext : public MangleContext {
-  bool IsUniqueNameMangler = false;
 public:
+  using DiscriminatorOverrideTy =
+      llvm::Optional<unsigned> (*)(ASTContext &, const NamedDecl *);
   explicit ItaniumMangleContext(ASTContext &C, DiagnosticsEngine &D)
       : MangleContext(C, D, MK_Itanium) {}
-  explicit ItaniumMangleContext(ASTContext &C, DiagnosticsEngine &D,
-                                bool IsUniqueNameMangler)
-      : MangleContext(C, D, MK_Itanium),
-        IsUniqueNameMangler(IsUniqueNameMangler) {}
 
   virtual void mangleCXXVTable(const CXXRecordDecl *RD, raw_ostream &) = 0;
   virtual void mangleCXXVTT(const CXXRecordDecl *RD, raw_ostream &) = 0;
@@ -200,15 +194,18 @@ class ItaniumMangleContext : public MangleContext {
 
   virtual void mangleDynamicStermFinalizer(const VarDecl *D, raw_ostream &) = 0;
 
-  bool isUniqueNameMangler() { return IsUniqueNameMangler; }
-
+  // This has to live here, otherwise the CXXNameMangler won't have access to
+  // it.
+  virtual DiscriminatorOverrideTy getDiscriminatorOverride() const = 0;
   static bool classof(const MangleContext *C) {
     return C->getKind() == MK_Itanium;
   }
 
+  static ItaniumMangleContext *create(ASTContext &Context,
+                                      DiagnosticsEngine &Diags);
   static ItaniumMangleContext *create(ASTContext &Context,
                                       DiagnosticsEngine &Diags,
-                                      bool IsUniqueNameMangler = false);
+                                      DiscriminatorOverrideTy Discriminator);
 };
 
 class MicrosoftMangleContext : public MangleContext {

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -2651,6 +2651,9 @@ DEF_TRAVERSE_STMT(ObjCBridgedCastExpr, {
 DEF_TRAVERSE_STMT(ObjCAvailabilityCheckExpr, {})
 DEF_TRAVERSE_STMT(ParenExpr, {})
 DEF_TRAVERSE_STMT(ParenListExpr, {})
+DEF_TRAVERSE_STMT(SYCLUniqueStableNameExpr, {
+  TRY_TO(TraverseTypeLoc(S->getTypeSourceInfo()->getTypeLoc()));
+})
 DEF_TRAVERSE_STMT(PredefinedExpr, {})
 DEF_TRAVERSE_STMT(ShuffleVectorExpr, {})
 DEF_TRAVERSE_STMT(ConvertVectorExpr, {})