Commit b933d37c authored by Saar Raz's avatar Saar Raz
Browse files

[Concepts] Constraint Satisfaction Caching 

Add a simple cache for constraint satisfaction results. Whether or not this simple caching
would be permitted in final C++2a is currently being discussed but it is required for
acceptable performance so we use it in the meantime, with the possibility of adding some
cache invalidation mechanisms later.

Differential Revision: https://reviews.llvm.org/D72552
parent a156da5f

clang/include/clang/AST/ASTConcept.h

+24 −6
Original line number Diff line number Diff line
@@ -24,9 +24,23 @@ namespace clang { 
class ConceptDecl;

class ConceptSpecializationExpr;



/// \brief The result of a constraint satisfaction check, containing the

/// necessary information to diagnose an unsatisfied constraint.

struct ConstraintSatisfaction {

/// The result of a constraint satisfaction check, containing the necessary

/// information to diagnose an unsatisfied constraint.

class ConstraintSatisfaction : public llvm::FoldingSetNode {

  // The template-like entity that 'owns' the constraint checked here (can be a

  // constrained entity or a concept).

  NamedDecl *ConstraintOwner = nullptr;

  llvm::SmallVector<TemplateArgument, 4> TemplateArgs;



public:



  ConstraintSatisfaction() = default;



  ConstraintSatisfaction(NamedDecl *ConstraintOwner,

                         ArrayRef<TemplateArgument> TemplateArgs) :

      ConstraintOwner(ConstraintOwner), TemplateArgs(TemplateArgs.begin(),

                                                     TemplateArgs.end()) { }



  using SubstitutionDiagnostic = std::pair<SourceLocation, StringRef>;

  using Detail = llvm::PointerUnion<Expr *, SubstitutionDiagnostic *>;
@@ -38,9 +52,13 @@ struct ConstraintSatisfaction { 
  /// invalid expression.

  llvm::SmallVector<std::pair<const Expr *, Detail>, 4> Details;



  // This can leak if used in an AST node, use ASTConstraintSatisfaction

  // instead.

  void *operator new(size_t bytes, ASTContext &C) = delete;

  void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &C) {

    Profile(ID, C, ConstraintOwner, TemplateArgs);

  }



  static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &C,

                      NamedDecl *ConstraintOwner,

                      ArrayRef<TemplateArgument> TemplateArgs);

};



/// Pairs of unsatisfied atomic constraint expressions along with the

clang/include/clang/Basic/LangOptions.def

+1 −0
Original line number Diff line number Diff line
@@ -238,6 +238,7 @@ LANGOPT(AlignedAllocation , 1, 0, "aligned allocation") 
LANGOPT(AlignedAllocationUnavailable, 1, 0, "aligned allocation functions are unavailable")

LANGOPT(NewAlignOverride  , 32, 0, "maximum alignment guaranteed by '::operator new(size_t)'")

LANGOPT(ConceptsTS , 1, 0, "enable C++ Extensions for Concepts")

LANGOPT(ConceptSatisfactionCaching , 1, 1, "enable satisfaction caching for C++2a Concepts")

BENIGN_LANGOPT(ModulesCodegen , 1, 0, "Modules code generation")

BENIGN_LANGOPT(ModulesDebugInfo , 1, 0, "Modules debug info")

BENIGN_LANGOPT(ElideConstructors , 1, 1, "C++ copy constructor elision")

clang/include/clang/Driver/CC1Options.td

+3 −0
Original line number Diff line number Diff line
@@ -557,6 +557,9 @@ def ftest_module_file_extension_EQ : 
           "The argument is parsed as blockname:major:minor:hashed:user info">;

def fconcepts_ts : Flag<["-"], "fconcepts-ts">,

  HelpText<"Enable C++ Extensions for Concepts.">;

def fno_concept_satisfaction_caching : Flag<["-"],

                                            "fno-concept-satisfaction-caching">,

  HelpText<"Disable satisfaction caching for C++2a Concepts.">;



let Group = Action_Group in {

clang/include/clang/Sema/Sema.h

+9 −17
Original line number Diff line number Diff line
@@ -6232,6 +6232,9 @@ private: 
  llvm::DenseMap<NamedDecl *, NormalizedConstraint *>

      NormalizationCache;













  llvm::ContextualFoldingSet<ConstraintSatisfaction, const ASTContext &>













      SatisfactionCache;



























public:















  const NormalizedConstraint *















  getNormalizedAssociatedConstraints(









@@ -6258,6 +6261,8 @@ public:



























  /// \brief Check whether the given list of constraint expressions are















  /// satisfied (as if in a 'conjunction') given template arguments.













  /// \param Template the template-like entity that triggered the constraints













  /// check (either a concept or a constrained entity).















  /// \param ConstraintExprs a list of constraint expressions, treated as if















  /// they were 'AND'ed together.















  /// \param TemplateArgs the list of template arguments to substitute into the









@@ -6269,23 +6274,10 @@ public:













  /// expression.















  /// \returns true if an error occurred and satisfaction could not be checked,















  /// false otherwise.













  bool CheckConstraintSatisfaction(TemplateDecl *Template,













                                   ArrayRef<const Expr *> ConstraintExprs,













                                   ArrayRef<TemplateArgument> TemplateArgs,













                                   SourceRange TemplateIDRange,













                                   ConstraintSatisfaction &Satisfaction);

























  bool CheckConstraintSatisfaction(ClassTemplatePartialSpecializationDecl *TD,













                                   ArrayRef<const Expr *> ConstraintExprs,













  bool CheckConstraintSatisfaction(













      NamedDecl *Template, ArrayRef<const Expr *> ConstraintExprs,















      ArrayRef<TemplateArgument> TemplateArgs,













                                   SourceRange TemplateIDRange,













                                   ConstraintSatisfaction &Satisfaction);

























  bool CheckConstraintSatisfaction(VarTemplatePartialSpecializationDecl *TD,













                                   ArrayRef<const Expr *> ConstraintExprs,













                                   ArrayRef<TemplateArgument> TemplateArgs,













                                   SourceRange TemplateIDRange,













                                   ConstraintSatisfaction &Satisfaction);













      SourceRange TemplateIDRange, ConstraintSatisfaction &Satisfaction);





























  /// \brief Check whether the given non-dependent constraint expression is















  /// satisfied. Returns false and updates Satisfaction with the satisfaction

































clang/include/clang/Sema/TemplateDeduction.h



+1
−0






























Original line number
Diff line number
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@@ -15,6 +15,7 @@













#define LLVM_CLANG_SEMA_TEMPLATEDEDUCTION_H































#include "clang/Sema/Ownership.h"













#include "clang/Sema/SemaConcept.h"















#include "clang/AST/ASTConcept.h"















#include "clang/AST/DeclAccessPair.h"















#include "clang/AST/DeclTemplate.h"