Merge pull request swiftlang#82574 from xedin/solver-perf-behind-a-flag

[ConstraintSystem] Implement disjunction favoring algorithm behind a flag

Author: xedin

include/swift/AST/KnownStdlibTypes.def

@@ -70,6 +70,7 @@ KNOWN_STDLIB_TYPE_DECL(WritableKeyPath, NominalTypeDecl, 2)
 KNOWN_STDLIB_TYPE_DECL(ReferenceWritableKeyPath, NominalTypeDecl, 2)
 
 KNOWN_STDLIB_TYPE_DECL(Optional, EnumDecl, 1)
+KNOWN_STDLIB_TYPE_DECL(_OptionalNilComparisonType, NominalTypeDecl, 0)
 
 KNOWN_STDLIB_TYPE_DECL(OptionSet, NominalTypeDecl, 1)
 

include/swift/AST/TypeCheckRequests.h

@@ -5389,6 +5389,22 @@ class DefaultIsolationInSourceFileRequest
   bool isCached() const { return true; }
 };
 
+class ModuleHasTypeCheckerPerformanceHacksEnabledRequest
+    : public SimpleRequest<ModuleHasTypeCheckerPerformanceHacksEnabledRequest,
+                           bool(const ModuleDecl *),
+                           RequestFlags::Cached> {
+public:
+  using SimpleRequest::SimpleRequest;
+
+private:
+  friend SimpleRequest;
+
+  bool evaluate(Evaluator &evaluator, const ModuleDecl *module) const;
+
+public:
+  bool isCached() const { return true; }
+};
+
 #define SWIFT_TYPEID_ZONE TypeChecker
 #define SWIFT_TYPEID_HEADER "swift/AST/TypeCheckerTypeIDZone.def"
 #include "swift/Basic/DefineTypeIDZone.h"

include/swift/AST/TypeCheckerTypeIDZone.def

@@ -640,3 +640,7 @@ SWIFT_REQUEST(TypeChecker, SemanticAvailabilitySpecRequest,
 SWIFT_REQUEST(TypeChecker, DefaultIsolationInSourceFileRequest,
               std::optional<DefaultIsolation>(const SourceFile *),
               Cached, NoLocationInfo)
+
+SWIFT_REQUEST(TypeChecker, ModuleHasTypeCheckerPerformanceHacksEnabledRequest,
+              bool(const ModuleDecl *),
+              Cached, NoLocationInfo)

include/swift/Basic/BlockListAction.def

@@ -26,5 +26,6 @@ BLOCKLIST_ACTION(ShouldUseLayoutStringValueWitnesses)
 BLOCKLIST_ACTION(ShouldDisableOwnershipVerification)
 BLOCKLIST_ACTION(SkipEmittingFineModuleTrace)
 BLOCKLIST_ACTION(SkipIndexingModule)
+BLOCKLIST_ACTION(ShouldUseTypeCheckerPerfHacks)
 
 #undef BLOCKLIST_ACTION

include/swift/Basic/LangOptions.h

@@ -986,8 +986,8 @@ namespace swift {
     /// Enable experimental operator designated types feature.
     bool EnableOperatorDesignatedTypes = false;
 
-    /// Disable constraint system performance hacks.
-    bool DisableConstraintSolverPerformanceHacks = false;
+    /// Enable old constraint system performance hacks.
+    bool EnableConstraintSolverPerformanceHacks = false;
 
     /// See \ref FrontendOptions.PrintFullConvention
     bool PrintFullConvention = false;

include/swift/Option/FrontendOptions.td

@@ -862,8 +862,8 @@ def solver_trail_threshold_EQ : Joined<["-"], "solver-trail-threshold=">,
 def solver_disable_splitter : Flag<["-"], "solver-disable-splitter">,
   HelpText<"Disable the component splitter phase of expression type checking">;
 
-def disable_constraint_solver_performance_hacks : Flag<["-"], "disable-constraint-solver-performance-hacks">,
-  HelpText<"Disable all the hacks in the constraint solver">;
+def enable_constraint_solver_performance_hacks : Flag<["-"], "enable-constraint-solver-performance-hacks">,
+  HelpText<"Enable all the old hacks in the constraint solver">;
 
 def enable_operator_designated_types :
   Flag<["-"], "enable-operator-designated-types">,

include/swift/Sema/CSBindings.h

@@ -527,6 +527,12 @@ class BindingSet {
   void forEachLiteralRequirement(
       llvm::function_ref<void(KnownProtocolKind)> callback) const;
 
+  void forEachAdjacentVariable(
+      llvm::function_ref<void(TypeVariableType *)> callback) const {
+    for (auto *typeVar : AdjacentVars)
+      callback(typeVar);
+  }
+
   /// Return a literal requirement that has the most impact on the binding
   /// score.
   LiteralBindingKind getLiteralForScore() const;

include/swift/Sema/ConstraintSystem.h

@@ -491,6 +491,18 @@ class TypeVariableType::Implementation {
   /// literal (represented by `ArrayExpr` and `DictionaryExpr` in AST).
   bool isCollectionLiteralType() const;
 
+  /// Determine whether this type variable represents a literal such
+  /// as an integer value, a floating-point value with and without a sign.
+  bool isNumberLiteralType() const;
+
+  /// Determine whether this type variable represents a result type of a
+  /// function call.
+  bool isFunctionResult() const;
+
+  /// Determine whether this type variable represents a type of the ternary
+  /// operator.
+  bool isTernary() const;
+
   /// Retrieve the representative of the equivalence class to which this
   /// type variable belongs.
   ///
@@ -1952,6 +1964,9 @@ enum class ConstraintSystemFlags {
 
   /// Disable macro expansions.
   DisableMacroExpansions = 0x80,
+
+  /// Enable old type-checker performance hacks.
+  EnablePerformanceHacks = 0x100,
 };
 
 /// Options that affect the constraint system as a whole.
@@ -3591,11 +3606,10 @@ class ConstraintSystem {
     return Options.contains(ConstraintSystemFlags::ForCodeCompletion);
   }
 
-  /// Check whether type-checker performance hacks has been explicitly
-  /// disabled by a flag.
+  /// Check whether old type-checker performance hacks has been explicitly
+  /// enabled.
   bool performanceHacksEnabled() const {
-    return !getASTContext()
-                .TypeCheckerOpts.DisableConstraintSolverPerformanceHacks;
+    return Options.contains(ConstraintSystemFlags::EnablePerformanceHacks);
   }
 
   /// Log and record the application of the fix. Return true iff any
@@ -5397,8 +5411,12 @@ class ConstraintSystem {
 
   /// Pick a disjunction from the InactiveConstraints list.
   ///
-  /// \returns The selected disjunction.
-  Constraint *selectDisjunction();
+  /// \returns The selected disjunction and a set of it's favored choices.
+  std::optional<std::pair<Constraint *, llvm::TinyPtrVector<Constraint *>>>
+  selectDisjunction();
+
+  /// The old method that is only used when performance hacks are enabled.
+  Constraint *selectDisjunctionWithHacks();
 
   /// Pick a conjunction from the InactiveConstraints list.
   ///
@@ -6098,6 +6116,12 @@ class DisjunctionChoice {
     return false;
   }
 
+  bool isDisfavored() const {
+    if (auto *decl = getOverloadChoiceDecl(Choice))
+      return decl->getAttrs().hasAttribute<DisfavoredOverloadAttr>();
+    return false;
+  }
+
   bool isBeginningOfPartition() const { return IsBeginningOfPartition; }
 
   // FIXME: All three of the accessors below are required to support
@@ -6332,7 +6356,8 @@ class DisjunctionChoiceProducer : public BindingProducer<DisjunctionChoice> {
 public:
   using Element = DisjunctionChoice;
 
-  DisjunctionChoiceProducer(ConstraintSystem &cs, Constraint *disjunction)
+  DisjunctionChoiceProducer(ConstraintSystem &cs, Constraint *disjunction,
+                            llvm::TinyPtrVector<Constraint *> &favorites)
       : BindingProducer(cs, disjunction->shouldRememberChoice()
                                 ? disjunction->getLocator()
                                 : nullptr),
@@ -6342,6 +6367,11 @@ class DisjunctionChoiceProducer : public BindingProducer<DisjunctionChoice> {
     assert(disjunction->getKind() == ConstraintKind::Disjunction);
     assert(!disjunction->shouldRememberChoice() || disjunction->getLocator());
 
+    // Mark constraints as favored. This information
+    // is going to be used by partitioner.
+    for (auto *choice : favorites)
+      cs.favorConstraint(choice);
+
     // Order and partition the disjunction choices.
     partitionDisjunction(Ordering, PartitionBeginning);
   }
@@ -6386,8 +6416,9 @@ class DisjunctionChoiceProducer : public BindingProducer<DisjunctionChoice> {
   // Partition the choices in the disjunction into groups that we will
   // iterate over in an order appropriate to attempt to stop before we
   // have to visit all of the options.
-  void partitionDisjunction(SmallVectorImpl<unsigned> &Ordering,
-                            SmallVectorImpl<unsigned> &PartitionBeginning);
+  void
+  partitionDisjunction(SmallVectorImpl<unsigned> &Ordering,
+                       SmallVectorImpl<unsigned> &PartitionBeginning);
 
   /// Partition the choices in the range \c first to \c last into groups and
   /// order the groups in the best order to attempt based on the argument

lib/Frontend/CompilerInvocation.cpp

@@ -2009,8 +2009,8 @@ static bool ParseTypeCheckerArgs(TypeCheckerOptions &Opts, ArgList &Args,
         SWIFT_ONONE_SUPPORT);
   }
 
-  Opts.DisableConstraintSolverPerformanceHacks |=
-      Args.hasArg(OPT_disable_constraint_solver_performance_hacks);
+  Opts.EnableConstraintSolverPerformanceHacks |=
+      Args.hasArg(OPT_enable_constraint_solver_performance_hacks);
 
   Opts.EnableOperatorDesignatedTypes |=
       Args.hasArg(OPT_enable_operator_designated_types);

lib/Sema/CMakeLists.txt

@@ -14,6 +14,7 @@ add_swift_host_library(swiftSema STATIC
   CSStep.cpp
   CSTrail.cpp
   CSFix.cpp
+  CSOptimizer.cpp
   CSDiagnostics.cpp
   CodeSynthesis.cpp
   CodeSynthesisDistributedActor.cpp