[TypeChecker] Implement a per-module block list for disjunction optimizer

Allow enabling performance hacks via a block list action - `ShouldUseTypeCheckerPerfHacks`

include/swift/AST/TypeCheckRequests.h

@@ -5370,6 +5370,22 @@ public:
   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

@@ -637,3 +637,7 @@ 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

lib/Sema/TypeCheckConstraints.cpp

@@ -466,7 +466,11 @@ TypeChecker::typeCheckTarget(SyntacticElementTarget &target,
   if (options.contains(TypeCheckExprFlags::DisableMacroExpansions))
     csOptions |= ConstraintSystemFlags::DisableMacroExpansions;
 
-  if (Context.TypeCheckerOpts.EnableConstraintSolverPerformanceHacks)
+  if (Context.TypeCheckerOpts.EnableConstraintSolverPerformanceHacks ||
+      evaluateOrDefault(Context.evaluator,
+                        ModuleHasTypeCheckerPerformanceHacksEnabledRequest{
+                            dc->getParentModule()},
+                        false))
     csOptions |= ConstraintSystemFlags::EnablePerformanceHacks;
 
   ConstraintSystem cs(dc, csOptions, diagnosticTransaction);
@@ -2463,3 +2467,11 @@ void ConstraintSystem::forEachExpr(
 
   expr->walk(ChildWalker(*this, callback));
 }
+
+bool ModuleHasTypeCheckerPerformanceHacksEnabledRequest::evaluate(
+    Evaluator &evaluator, const ModuleDecl *module) const {
+  auto name = module->getRealName().str();
+  return module->getASTContext().blockListConfig.hasBlockListAction(
+      name, BlockListKeyKind::ModuleName,
+      BlockListAction::ShouldUseTypeCheckerPerfHacks);
+}

test/Constraints/perf_hacks_with_block_list.swift

@@ -0,0 +1,16 @@
+// RUN: %empty-directory(%t)
+// RUN: split-file %s %t
+
+// RUN: %target-swift-frontend -typecheck -module-name Test -debug-constraints -blocklist-file %t/blocklist.yaml -verify %t/main.swift 2>%t.err
+// RUN: %FileCheck %t/main.swift < %t.err
+
+//--- blocklist.yaml
+---
+ShouldUseTypeCheckerPerfHacks:
+  ModuleName:
+    - Test
+
+//--- main.swift
+_ = 1 + 2 + 3
+
+// CHECK: [favored] {{.*}} bound to decl Swift.(file).Int extension.+ : (Int.Type) -> (Int, Int) -> Int