Partial revert of r222986.

The explicit set of destination types is not fully redundant when lazy loading
since the TypeFinder will not find types used only in function bodies.

This keeps the logic to drop the name of mapped types since it still helps
with avoiding further renaming.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223043 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Linker/Linker.h

@@ -46,6 +46,7 @@ public:
 private:
   void init(Module *M, DiagnosticHandlerFunction DiagnosticHandler);
   Module *Composite;
+  SmallPtrSet<StructType *, 32> IdentifiedStructTypes;
   DiagnosticHandlerFunction DiagnosticHandler;
 };
 

lib/Linker/LinkModules.cpp

@@ -58,8 +58,9 @@ class TypeMapTy : public ValueMapTypeRemapper {
   SmallPtrSet<StructType*, 16> DstResolvedOpaqueTypes;
 
 public:
-  TypeMapTy() {}
+  TypeMapTy(TypeSet &Set) : DstStructTypesSet(Set) {}
 
+  TypeSet &DstStructTypesSet;
   /// Indicate that the specified type in the destination module is conceptually
   /// equivalent to the specified type in the source module.
   void addTypeMapping(Type *DstTy, Type *SrcTy);
@@ -225,6 +226,13 @@ void TypeMapTy::linkDefinedTypeBodies() {
 }
 
 Type *TypeMapTy::get(Type *Ty) {
+#ifndef NDEBUG
+  for (auto &Pair : MappedTypes) {
+    assert(!(Pair.first != Ty && Pair.second == Ty) &&
+           "mapping to a source type");
+  }
+#endif
+
   // If we already have an entry for this type, return it.
   Type **Entry = &MappedTypes[Ty];
   if (*Entry)
@@ -310,6 +318,7 @@ Type *TypeMapTy::get(Type *Ty) {
   if (STy->isOpaque()) {
     // A named structure type from src module is used. Add it to the Set of
     // identified structs in the destination module.
+    DstStructTypesSet.insert(STy);
     return *Entry = STy;
   }
 
@@ -317,6 +326,7 @@ Type *TypeMapTy::get(Type *Ty) {
   StructType *DTy = StructType::create(STy->getContext());
   // A new identified structure type was created. Add it to the set of
   // identified structs in the destination module.
+  DstStructTypesSet.insert(DTy);
   *Entry = DTy;
 
   SmallVector<Type*, 4> ElementTypes;
@@ -402,9 +412,9 @@ class ModuleLinker {
   Linker::DiagnosticHandlerFunction DiagnosticHandler;
 
 public:
-  ModuleLinker(Module *dstM, Module *srcM,
+  ModuleLinker(Module *dstM, TypeSet &Set, Module *srcM,
                Linker::DiagnosticHandlerFunction DiagnosticHandler)
-      : DstM(dstM), SrcM(srcM),
+      : DstM(dstM), SrcM(srcM), TypeMap(Set),
         ValMaterializer(TypeMap, DstM, LazilyLinkFunctions),
         DiagnosticHandler(DiagnosticHandler) {}
 
@@ -816,7 +826,7 @@ void ModuleLinker::computeTypeMapping() {
       // we prefer to take the '%C' version. So we are then left with both
       // '%C.1' and '%C' being used for the same types. This leads to some
       // variables using one type and some using the other.
-      if (!SrcStructTypesSet.count(DST))
+      if (!SrcStructTypesSet.count(DST) && TypeMap.DstStructTypesSet.count(DST))
         TypeMap.addTypeMapping(DST, ST);
   }
 
@@ -1578,6 +1588,10 @@ bool ModuleLinker::run() {
 void Linker::init(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
   this->Composite = M;
   this->DiagnosticHandler = DiagnosticHandler;
+
+  TypeFinder StructTypes;
+  StructTypes.run(*M, true);
+  IdentifiedStructTypes.insert(StructTypes.begin(), StructTypes.end());
 }
 
 Linker::Linker(Module *M, DiagnosticHandlerFunction DiagnosticHandler) {
@@ -1599,7 +1613,8 @@ void Linker::deleteModule() {
 }
 
 bool Linker::linkInModule(Module *Src) {
-  ModuleLinker TheLinker(Composite, Src, DiagnosticHandler);
+  ModuleLinker TheLinker(Composite, IdentifiedStructTypes, Src,
+                         DiagnosticHandler);
   return TheLinker.run();
 }
 

test/Linker/type-unique-src-type.ll

@@ -0,0 +1,22 @@
+; RUN: llvm-as %s -o %t.bc
+; RUN: llvm-link -S %t.bc -o - | FileCheck %s
+; RUN: llvm-link -S %s -o - | FileCheck %s
+
+; Test that we don't try to map %C.0 and C and then try to map %C to a new type.
+; This used to happen when lazy loading since we wouldn't then identify %C
+; as a destination type until it was too late.
+
+; CHECK: %C.0 = type { %B }
+; CHECK-NEXT: %B = type { %A }
+; CHECK-NEXT: %A = type { i8 }
+; CHECK-NEXT: %C = type { %B }
+
+%A   = type { i8 }
+%B   = type { %A }
+%C   = type { %B }
+%C.0 = type { %B }
+define void @f1() {
+  getelementptr %C* null, i64 0, i32 0, i32 0
+  ret void
+}
+@g1 = external global %C.0