Don't crash on redefinitions.

One error we were not deleting the alias or putting it in the Module. The
end result is that there was an use left of the aliasee when the module was
deleted.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208447 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 14 insertions, 5 deletions

diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 32037df958..892cff6f8f 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -673,9 +673,8 @@ bool LLParser::ParseAlias(const std::string &Name, LocTy NameLoc,
     return Error(AliaseeLoc, "alias must have pointer type");
 
   // Okay, create the alias but do not insert it into the module yet.
-  GlobalAlias* GA = new GlobalAlias(Aliasee->getType(),
-                                    (GlobalValue::LinkageTypes)Linkage, Name,
-                                    Aliasee);
+  std::unique_ptr<GlobalAlias> GA(new GlobalAlias(
+      Aliasee->getType(), (GlobalValue::LinkageTypes)Linkage, Name, Aliasee));
   GA->setVisibility((GlobalValue::VisibilityTypes)Visibility);
   GA->setDLLStorageClass((GlobalValue::DLLStorageClassTypes)DLLStorageClass);
 
@@ -697,15 +696,18 @@ bool LLParser::ParseAlias(const std::string &Name, LocTy NameLoc,
 
     // If they agree, just RAUW the old value with the alias and remove the
     // forward ref info.
-    Val->replaceAllUsesWith(GA);
+    Val->replaceAllUsesWith(GA.get());
     Val->eraseFromParent();
     ForwardRefVals.erase(I);
   }
 
   // Insert into the module, we know its name won't collide now.
-  M->getAliasList().push_back(GA);
+  M->getAliasList().push_back(GA.get());
   assert(GA->getName() == Name && "Should not be a name conflict!");
 
+  // The module owns this now
+  GA.release();
+
   return false;
 }
 
diff --git a/test/Assembler/alias-redefinition.ll b/test/Assembler/alias-redefinition.ll
new file mode 100644
index 0000000000..19ad85bf5f
--- /dev/null
+++ b/test/Assembler/alias-redefinition.ll
@@ -0,0 +1,7 @@
+; RUN: not llvm-as %s 2>&1 | FileCheck %s
+
+; CHECK: error: redefinition of global named '@bar'
+
+@foo = global i32 0
+@bar = alias i32* @foo
+@bar = alias i32* @foo