Add back removed code. It still causes LLVM to miscompile. But not having it breaks other things.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151594 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Linker/LinkModules.cpp

@@ -581,6 +581,36 @@ void ModuleLinker::computeTypeMapping() {
       TypeMap.addTypeMapping(DGV->getType(), I->getType());
   }
 
+  // Incorporate types by name, scanning all the types in the source module.
+  // At this point, the destination module may have a type "%foo = { i32 }" for
+  // example.  When the source module got loaded into the same LLVMContext, if
+  // it had the same type, it would have been renamed to "%foo.42 = { i32 }".
+  // Though it isn't required for correctness, attempt to link these up to clean
+  // up the IR.
+  std::vector<StructType*> SrcStructTypes;
+  SrcM->findUsedStructTypes(SrcStructTypes);
+  
+  SmallPtrSet<StructType*, 32> SrcStructTypesSet(SrcStructTypes.begin(),
+                                                 SrcStructTypes.end());
+  
+  for (unsigned i = 0, e = SrcStructTypes.size(); i != e; ++i) {
+    StructType *ST = SrcStructTypes[i];
+    if (!ST->hasName()) continue;
+    
+    // Check to see if there is a dot in the name followed by a digit.
+    size_t DotPos = ST->getName().rfind('.');
+    if (DotPos == 0 || DotPos == StringRef::npos ||
+        ST->getName().back() == '.' || !isdigit(ST->getName()[DotPos+1]))
+      continue;
+    
+    // Check to see if the destination module has a struct with the prefix name.
+    if (StructType *DST = DstM->getTypeByName(ST->getName().substr(0, DotPos)))
+      // Don't use it if this actually came from the source module.  They're in
+      // the same LLVMContext after all.
+      if (!SrcStructTypesSet.count(DST))
+        TypeMap.addTypeMapping(DST, ST);
+  }
+
   // Don't bother incorporating aliases, they aren't generally typed well.
   
   // Now that we have discovered all of the type equivalences, get a body for

test/Linker/link-type-names.ll

@@ -1,10 +1,7 @@
 ; RUN: echo "%X = type { i32 } @G2 = global %X { i32 4 }" > %t.ll
 ; RUN: llvm-link %s %t.ll -S | FileCheck %s
-; XFAIL: *
 ; PR11464
 
-; FIXME: XFAIL until <rdar://problem/10913281> is addressed.
-
 %X = type { i32 }
 @G = global %X { i32 4 }