Set the body of a new struct as soon as it is created.

This changes the order in which different types are passed to get, but
one order is not inherently better than the other.

The main motivation is that this simplifies linkDefinedTypeBodies now that
it is only linking "real" opaque types. It is also means that we only have to
call it once and that we don't need getImpl.

A small change in behavior is that we don't copy type names when resolving
opaque types. This is an improvement IMHO, but it can be added back if
desired. A test is included with the new behavior.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222764 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Linker/LinkModules.cpp

@@ -87,7 +87,6 @@ public:
   }
 
 private:
-  Type *getImpl(Type *T);
   Type *remapType(Type *SrcTy) override { return get(SrcTy); }
 
   bool areTypesIsomorphic(Type *DstTy, Type *SrcTy);
@@ -205,54 +204,22 @@ bool TypeMapTy::areTypesIsomorphic(Type *DstTy, Type *SrcTy) {
 
 void TypeMapTy::linkDefinedTypeBodies() {
   SmallVector<Type*, 16> Elements;
-  SmallString<16> TmpName;
+  for (StructType *SrcSTy : SrcDefinitionsToResolve) {
-
-  // Note that processing entries in this loop (calling 'get') can add new
-  // entries to the SrcDefinitionsToResolve vector.
-  while (!SrcDefinitionsToResolve.empty()) {
-    StructType *SrcSTy = SrcDefinitionsToResolve.pop_back_val();
     StructType *DstSTy = cast<StructType>(MappedTypes[SrcSTy]);
-
+    assert(DstSTy->isOpaque());
-    // TypeMap is a many-to-one mapping, if there were multiple types that
-    // provide a body for DstSTy then previous iterations of this loop may have
-    // already handled it.  Just ignore this case.
-    if (!DstSTy->isOpaque()) continue;
-    assert(!SrcSTy->isOpaque() && "Not resolving a definition?");
 
     // Map the body of the source type over to a new body for the dest type.
     Elements.resize(SrcSTy->getNumElements());
     for (unsigned I = 0, E = Elements.size(); I != E; ++I)
-      Elements[I] = getImpl(SrcSTy->getElementType(I));
+      Elements[I] = get(SrcSTy->getElementType(I));
 
     DstSTy->setBody(Elements, SrcSTy->isPacked());
-
-    // If DstSTy has no name or has a longer name than STy, then viciously steal
-    // STy's name.
-    if (!SrcSTy->hasName()) continue;
-    StringRef SrcName = SrcSTy->getName();
-
-    if (!DstSTy->hasName() || DstSTy->getName().size() > SrcName.size()) {
-      TmpName.insert(TmpName.end(), SrcName.begin(), SrcName.end());
-      SrcSTy->setName("");
-      DstSTy->setName(TmpName.str());
-      TmpName.clear();
-    }
   }
-
+  SrcDefinitionsToResolve.clear();
   DstResolvedOpaqueTypes.clear();
 }
 
 Type *TypeMapTy::get(Type *Ty) {
-  Type *Result = getImpl(Ty);
-
-  // If this caused a reference to any struct type, resolve it before returning.
-  if (!SrcDefinitionsToResolve.empty())
-    linkDefinedTypeBodies();
-  return Result;
-}
-
-/// This is the recursive version of get().
-Type *TypeMapTy::getImpl(Type *Ty) {
   // If we already have an entry for this type, return it.
   Type **Entry = &MappedTypes[Ty];
   if (*Entry)
@@ -271,7 +238,7 @@ Type *TypeMapTy::getImpl(Type *Ty) {
     SmallVector<Type*, 4> ElementTypes;
     ElementTypes.resize(Ty->getNumContainedTypes());
     for (unsigned I = 0, E = Ty->getNumContainedTypes(); I != E; ++I) {
-      ElementTypes[I] = getImpl(Ty->getContainedType(I));
+      ElementTypes[I] = get(Ty->getContainedType(I));
       AnyChange |= ElementTypes[I] != Ty->getContainedType(I);
     }
 
@@ -342,15 +309,27 @@ Type *TypeMapTy::getImpl(Type *Ty) {
     return *Entry = STy;
   }
 
-  // Otherwise we create a new type and resolve its body later.  This will be
+  // Otherwise we create a new type.
-  // resolved by the top level of get().
-  SrcDefinitionsToResolve.push_back(STy);
   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);
-  DstResolvedOpaqueTypes.insert(DTy);
+  *Entry = DTy;
-  return *Entry = DTy;
+
+  SmallVector<Type*, 4> ElementTypes;
+  ElementTypes.resize(STy->getNumElements());
+  for (unsigned I = 0, E = ElementTypes.size(); I != E; ++I)
+    ElementTypes[I] = get(STy->getElementType(I));
+  DTy->setBody(ElementTypes, STy->isPacked());
+
+  // Steal STy's name.
+  if (STy->hasName()) {
+    SmallString<16> TmpName = STy->getName();
+    STy->setName("");
+    DTy->setName(TmpName);
+  }
+
+  return DTy;
 }
 
 //===----------------------------------------------------------------------===//
@@ -1590,10 +1569,6 @@ bool ModuleLinker::run() {
     }
   } while (LinkedInAnyFunctions);
 
-  // Now that all of the types from the source are used, resolve any structs
-  // copied over to the dest that didn't exist there.
-  TypeMap.linkDefinedTypeBodies();
-
   return false;
 }
 

test/Linker/Inputs/type-unique-name.ll

@@ -0,0 +1,5 @@
+%t = type { i8 }
+
+define %t* @f() {
+  ret %t* null
+}

test/Linker/type-unique-name.ll

@@ -0,0 +1,13 @@
+; RUN: llvm-link -S %s %p/Inputs/type-unique-name.ll | FileCheck %s
+
+; Test that we keep the type name
+; CHECK: %abc = type { i8 }
+
+%abc = type opaque
+
+declare %abc* @f()
+
+define %abc* @g() {
+  %x = call %abc* @f()
+  ret %abc* %x
+}