IRGen: Emit method descriptors

Author: slavapestov

lib/IRGen/GenMeta.cpp

@@ -550,12 +550,14 @@ namespace {
     Optional<ConstantAggregateBuilderBase::PlaceholderPosition>
       NumRequirementsInSignature,
       NumRequirements;
+
+    bool Resilient;
+
   public:
     ProtocolDescriptorBuilder(IRGenModule &IGM, ProtocolDecl *Proto,
                                      SILDefaultWitnessTable *defaultWitnesses)
-      : super(IGM), Proto(Proto), DefaultWitnesses(defaultWitnesses)
-    {
-    }
+      : super(IGM), Proto(Proto), DefaultWitnesses(defaultWitnesses),
+        Resilient(IGM.isResilient(Proto, ResilienceExpansion::Minimal)) {}
 
     void layout() {
       super::layout();
@@ -649,7 +651,7 @@ namespace {
 
       // Look up the dispatch thunk if the protocol is resilient.
       llvm::Constant *thunk = nullptr;
-      if (IGM.isResilient(Proto, ResilienceExpansion::Minimal))
+      if (Resilient)
         thunk = IGM.emitDispatchThunk(func);
 
       // Classify the function.
@@ -668,6 +670,15 @@ namespace {
                                pi.getNumWitnesses());
 
       for (auto &entry : pi.getWitnessEntries()) {
+        if (Resilient && entry.isFunction()) {
+          // Define the method descriptor.
+          SILDeclRef func(entry.getFunction());
+          auto *descriptor =
+            B.getAddrOfCurrentPosition(
+              IGM.ProtocolRequirementStructTy);
+          IGM.defineMethodDescriptor(func, Proto, descriptor);
+        }
+
         auto reqt = B.beginStruct(IGM.ProtocolRequirementStructTy);
 
         auto info = getRequirementInfo(entry);
@@ -1207,13 +1218,13 @@ namespace {
 
     SILVTable *VTable = nullptr;
     unsigned VTableSize = 0;
-    bool isResilient;
+    bool Resilient;
 
   public:
     ClassContextDescriptorBuilder(IRGenModule &IGM, ClassDecl *Type,
                                   RequireMetadata_t requireMetadata)
       : super(IGM, Type, requireMetadata),
-        isResilient(IGM.isResilient(Type, ResilienceExpansion::Minimal)) {
+        Resilient(IGM.isResilient(Type, ResilienceExpansion::Minimal)) {
 
       if (getType()->isForeign()) return;
 
@@ -1309,6 +1320,12 @@ namespace {
     void addMethod(SILDeclRef fn) {
       assert(VTable && "no vtable?!");
 
+      // Define the method descriptor to point to the current position in the
+      // nominal type descriptor.
+      IGM.defineMethodDescriptor(fn, Type,
+                      B.getAddrOfCurrentPosition(IGM.MethodDescriptorStructTy));
+
+      // Actually build the descriptor.
       auto *func = cast<AbstractFunctionDecl>(fn.getDecl());
       auto descriptor = B.beginStruct(IGM.MethodDescriptorStructTy);
 
@@ -1343,7 +1360,7 @@ namespace {
       descriptor.finishAndAddTo(B);
 
       // Emit method dispatch thunk if the class is resilient.
-      if (isResilient &&
+      if (Resilient &&
           func->getEffectiveAccess() >= AccessLevel::Public) {
         IGM.emitDispatchThunk(fn);
       }

lib/IRGen/GenThunk.cpp

@@ -115,3 +115,10 @@ llvm::Function *IRGenModule::emitDispatchThunk(SILDeclRef declRef) {
 
   return f;
 }
+
+llvm::GlobalValue *IRGenModule::defineMethodDescriptor(SILDeclRef declRef,
+                                                       NominalTypeDecl *nominalDecl,
+                                                       llvm::Constant *definition) {
+  auto entity = LinkEntity::forMethodDescriptor(declRef);
+  return defineAlias(entity, definition);
+}

lib/IRGen/IRGenModule.h

@@ -1149,6 +1149,11 @@ private:                            \
   llvm::GlobalValue *defineAlias(LinkEntity entity,
                                  llvm::Constant *definition);
 
+  llvm::GlobalValue *defineMethodDescriptor(SILDeclRef declRef,
+                                            NominalTypeDecl *nominalDecl,
+                                            llvm::Constant *definition);
+
+
   Address getAddrOfEnumCase(EnumElementDecl *Case,
                             ForDefinition_t forDefinition);
   Address getAddrOfFieldOffset(VarDecl *D, ForDefinition_t forDefinition);

test/IRGen/generic_vtable.swift

@@ -107,6 +107,17 @@ public class Concrete : Derived<Int> {
 // CHECK-SAME: }>, align
 
 
+//// Method descriptors
+
+// CHECK-LABEL: @"$S14generic_vtable4BaseC2m1yyFTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.method_descriptor, getelementptr inbounds (<{{.*}}>* @"$S14generic_vtable4BaseCMn", i32 0, i32 13)
+// CHECK-LABEL: @"$S14generic_vtable4BaseC2m2yyFTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.method_descriptor, getelementptr inbounds (<{{.*}}* @"$S14generic_vtable4BaseCMn", i32 0, i32 14)
+// CHECK-LABEL: @"$S14generic_vtable4BaseCACycfcTq" = hidden alias %swift.method_descriptor, getelementptr inbounds (<{{.*}}* @"$S14generic_vtable4BaseCMn", i32 0, i32 15)
+
+// CHECK-LABEL: @"$S14generic_vtable7DerivedC2m3yyFTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.method_descriptor, getelementptr inbounds (<{{.*}}>* @"$S14generic_vtable7DerivedCMn", i32 0, i32 23)
+
+// CHECK-LABEL: @"$S14generic_vtable8ConcreteC2m4yyFTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.method_descriptor, getelementptr inbounds (<{{.*}}>* @"$S14generic_vtable8ConcreteCMn", i32 0, i32 16)
+
+
 //// Metadata initialization function for 'Derived' copies superclass vtable
 //// and installs overrides for 'm2()' and 'init()'.
 

test/IRGen/protocol_resilience_thunks.swift

@@ -7,6 +7,17 @@
 
 import resilient_protocol
 
+// Method descriptors
+
+// CHECK-LABEL: @"$S26protocol_resilience_thunks19MyResilientProtocolP11returnsVoid1xySb_tFTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.protocol_requirement, getelementptr inbounds (<{{.*}}>* @"$S26protocol_resilience_thunks19MyResilientProtocolMp", i32 0, i32 6)
+// CHECK-LABEL: @"$S26protocol_resilience_thunks19MyResilientProtocolP11returnsBoolSbyFTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.protocol_requirement, getelementptr inbounds (<{{.*}}>* @"$S26protocol_resilience_thunks19MyResilientProtocolMp", i32 0, i32 7)
+// CHECK-LABEL: @"$S26protocol_resilience_thunks19MyResilientProtocolP10returnsAnyypyFTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.protocol_requirement, getelementptr inbounds (<{{.*}}>* @"$S26protocol_resilience_thunks19MyResilientProtocolMp", i32 0, i32 8)
+// CHECK-LABEL: @"$S26protocol_resilience_thunks19MyResilientProtocolP12throwingFuncyyKFTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.protocol_requirement, getelementptr inbounds (<{{.*}}>* @"$S26protocol_resilience_thunks19MyResilientProtocolMp", i32 0, i32 9)
+// CHECK-LABEL: @"$S26protocol_resilience_thunks19MyResilientProtocolP11genericFuncyqd__qd__lFTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.protocol_requirement, getelementptr inbounds (<{{.*}}>* @"$S26protocol_resilience_thunks19MyResilientProtocolMp", i32 0, i32 10)
+// CHECK-LABEL: @"$S26protocol_resilience_thunks19MyResilientProtocolP8propertySbvgTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.protocol_requirement, getelementptr inbounds (<{{.*}}>* @"$S26protocol_resilience_thunks19MyResilientProtocolMp", i32 0, i32 11)
+// CHECK-LABEL: @"$S26protocol_resilience_thunks19MyResilientProtocolP8propertySbvsTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.protocol_requirement, getelementptr inbounds (<{{.*}}>* @"$S26protocol_resilience_thunks19MyResilientProtocolMp", i32 0, i32 12)
+// CHECK-LABEL: @"$S26protocol_resilience_thunks19MyResilientProtocolP8propertySbvMTq" ={{( dllexport)?}}{{( protected)?}} alias %swift.protocol_requirement, getelementptr inbounds (<{{.*}}>* @"$S26protocol_resilience_thunks19MyResilientProtocolMp", i32 0, i32 13)
+
 // CHECK-LABEL: define{{( dllexport)?}}{{( protected)?}} swiftcc void @"$S26protocol_resilience_thunks26callResilientWitnessMethodyyx010resilient_A00E12BaseProtocolRzlF"(%swift.opaque* noalias nocapture, %swift.type* %T, i8** %T.ResilientBaseProtocol)
 // CHECK: call swiftcc [[INT]] @"$S18resilient_protocol21ResilientBaseProtocolP11requirementSiyFTj"(%swift.opaque* noalias nocapture swiftself %0, %swift.type* %T, i8** %T.ResilientBaseProtocol)
 // CHECK: ret void