Eliminate getForwardingSubstitutions().

Use the SubstitutionMap version everywhere.

Author: DougGregor

include/swift/AST/GenericEnvironment.h

@@ -171,7 +171,6 @@ class alignas(1 << DeclAlignInBits) GenericEnvironment final
   Type getSugaredType(Type type) const;
 
   SubstitutionMap getForwardingSubstitutionMap() const;
-  SubstitutionList getForwardingSubstitutions() const;
 
   void dump(raw_ostream &os) const;
 

include/swift/SIL/SILFunction.h

@@ -121,9 +121,6 @@ class SILFunction
   /// Only set if this function is a specialization of another function.
   const GenericSpecializationInformation *SpecializationInfo;
 
-  /// The forwarding substitutions, lazily computed.
-  Optional<SubstitutionList> ForwardingSubs;
-
   /// The forwarding substitution map, lazily computed.
   SubstitutionMap ForwardingSubMap;
 
@@ -684,10 +681,6 @@ class SILFunction
   /// Converts the given function definition to a declaration.
   void convertToDeclaration();
 
-  /// Return the identity substitutions necessary to forward this call if it is
-  /// generic.
-  SubstitutionList getForwardingSubstitutions();
-
   /// Return the identity substitutions necessary to forward this call if it is
   /// generic.
   SubstitutionMap getForwardingSubstitutionMap();

lib/AST/GenericEnvironment.cpp

@@ -225,15 +225,6 @@ SubstitutionMap GenericEnvironment::getForwardingSubstitutionMap() const {
     MakeAbstractConformanceForGenericType());
 }
 
-SubstitutionList
-GenericEnvironment::getForwardingSubstitutions() const {
-  auto *genericSig = getGenericSignature();
-
-  SmallVector<Substitution, 4> result;
-  genericSig->getSubstitutions(getForwardingSubstitutionMap(), result);
-  return genericSig->getASTContext().AllocateCopy(result);
-}
-
 std::pair<Type, ProtocolConformanceRef>
 GenericEnvironment::mapConformanceRefIntoContext(GenericEnvironment *genericEnv,
                                            Type conformingType,

lib/IRGen/GenKeyPath.cpp

@@ -230,8 +230,7 @@ getAccessorForComputedComponent(IRGenModule &IGM,
     // Use the bound generic metadata to form a call to the original generic
     // accessor.
     WitnessMetadata ignoreWitnessMetadata;
-    auto forwardingSubs = genericEnv->getGenericSignature()->getSubstitutionMap(
-      genericEnv->getForwardingSubstitutions());
+    auto forwardingSubs = genericEnv->getForwardingSubstitutionMap();
     emitPolymorphicArguments(IGF, accessor->getLoweredFunctionType(),
                              forwardingSubs,
                              &ignoreWitnessMetadata,

lib/SIL/SILFunction.cpp

@@ -482,18 +482,6 @@ void SILFunction::convertToDeclaration() {
   getBlocks().clear();
 }
 
-SubstitutionList SILFunction::getForwardingSubstitutions() {
-  if (ForwardingSubs)
-    return *ForwardingSubs;
-
-  auto *env = getGenericEnvironment();
-  if (!env)
-    return {};
-
-  ForwardingSubs = env->getForwardingSubstitutions();
-  return *ForwardingSubs;
-}
-
 SubstitutionMap SILFunction::getForwardingSubstitutionMap() {
   if (ForwardingSubMap)
     return ForwardingSubMap;

lib/SIL/SILVerifier.cpp

@@ -2440,7 +2440,7 @@ class SILVerifier : public SILVerifierBase<SILVerifier> {
 
     // Map interface types to archetypes.
     if (auto *env = constantInfo.GenericEnv) {
-      auto subs = env->getForwardingSubstitutions();
+      auto subs = env->getForwardingSubstitutionMap();
       methodTy = methodTy->substGenericArgs(F.getModule(), subs);
     }
     assert(!methodTy->isPolymorphic());

lib/SILGen/SILGenDecl.cpp

@@ -144,10 +144,6 @@ namespace {
   };
 } // end anonymous namespace
 
-SubstitutionList SILGenFunction::getForwardingSubstitutions() {
-  return F.getForwardingSubstitutions();
-}
-
 SubstitutionMap SILGenFunction::getForwardingSubstitutionMap() {
   return F.getForwardingSubstitutionMap();
 }

lib/SILGen/SILGenFunction.h

@@ -1813,10 +1813,6 @@ class LLVM_LIBRARY_VISIBILITY SILGenFunction
     }
   };
 
-  /// Return forwarding substitutions for the archetypes in the current
-  /// function.
-  SubstitutionList getForwardingSubstitutions();
-
   /// Return forwarding substitutions for the archetypes in the current
   /// function.
   SubstitutionMap getForwardingSubstitutionMap();

lib/SILGen/SILGenPoly.cpp

@@ -2655,8 +2655,7 @@ buildThunkSignature(SILGenFunction &SGF,
   if (openedExistential == nullptr) {
     auto genericSig = SGF.F.getLoweredFunctionType()->getGenericSignature();
     genericEnv = SGF.F.getGenericEnvironment();
-    auto subsArray = SGF.F.getForwardingSubstitutions();
-    interfaceSubs = genericSig->getSubstitutionMap(subsArray);
+    interfaceSubs = SGF.F.getForwardingSubstitutionMap();
     contextSubs = interfaceSubs;
     return genericSig;
   }
@@ -3015,7 +3014,7 @@ SILGenFunction::createWithoutActuallyEscapingClosure(
   }
 
   CanSILFunctionType substFnType = thunkType->substGenericArgs(
-      F.getModule(), thunk->getForwardingSubstitutions());
+      F.getModule(), thunk->getForwardingSubstitutionMap());
 
   // Create it in our current function.
   auto thunkValue = B.createFunctionRef(loc, thunk);

lib/Sema/CalleeCandidateInfo.cpp

@@ -65,7 +65,7 @@ UncurriedCandidate::UncurriedCandidate(ValueDecl *decl, unsigned level)
     auto *DC = decl->getInnermostDeclContext();
     if (auto *GFT = entityType->getAs<GenericFunctionType>()) {
       auto subs = DC->getGenericEnvironmentOfContext()
-      ->getForwardingSubstitutions();
+      ->getForwardingSubstitutionMap();
       entityType = GFT->substGenericArgs(subs);
     } else {
       // FIXME: look through unforced IUOs here?