Revert "Prevent alias from pointing to weak aliases."

This reverts commit r204781.

I will follow up to with msan folks to see what is what they
were trying to do with aliases to weak aliases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204784 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 24 insertions, 21 deletions

diff --git a/lib/IR/Globals.cpp b/lib/IR/Globals.cpp
index f338dd76aa..11152d5d6c 100644
--- a/lib/IR/Globals.cpp
+++ b/lib/IR/Globals.cpp
@@ -236,10 +236,10 @@ void GlobalAlias::setAliasee(Constant *Aliasee) {
   setOperand(0, Aliasee);
 }
 
-static GlobalValue *getAliaseeGV(GlobalAlias *GA) {
-  Constant *C = GA->getAliasee();
-  assert(C && "Must alias something");
-
+GlobalValue *GlobalAlias::getAliasedGlobal() {
+  Constant *C = getAliasee();
+  if (C == 0) return 0;
+  
   if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
     return GV;
 
@@ -248,23 +248,30 @@ static GlobalValue *getAliaseeGV(GlobalAlias *GA) {
           CE->getOpcode() == Instruction::AddrSpaceCast ||
           CE->getOpcode() == Instruction::GetElementPtr) &&
          "Unsupported aliasee");
-
+  
   return cast<GlobalValue>(CE->getOperand(0));
 }
 
-GlobalValue *GlobalAlias::getAliasedGlobal() {
+GlobalValue *GlobalAlias::resolveAliasedGlobal(bool stopOnWeak) {
   SmallPtrSet<GlobalValue*, 3> Visited;
 
-  GlobalAlias *GA = this;
+  // Check if we need to stop early.
+  if (stopOnWeak && mayBeOverridden())
+    return this;
+
+  GlobalValue *GV = getAliasedGlobal();
+  Visited.insert(GV);
+
+  // Iterate over aliasing chain, stopping on weak alias if necessary.
+  while (GlobalAlias *GA = dyn_cast<GlobalAlias>(GV)) {
+    if (stopOnWeak && GA->mayBeOverridden())
+      break;
+
+    GV = GA->getAliasedGlobal();
 
-  for (;;) {
-    GlobalValue *GV = getAliaseeGV(GA);
     if (!Visited.insert(GV))
       return 0;
-
-    // Iterate over aliasing chain.
-    GA = dyn_cast<GlobalAlias>(GV);
-    if (!GA)
-      return GV;
   }
+
+  return GV;
 }
diff --git a/lib/IR/Verifier.cpp b/lib/IR/Verifier.cpp
index f5c8ac623b..50c6ae204e 100644
--- a/lib/IR/Verifier.cpp
+++ b/lib/IR/Verifier.cpp
@@ -502,14 +502,10 @@ void Verifier::visitGlobalAlias(const GlobalAlias &GA) {
     }
   }
   Assert1(!GV->isDeclaration(), "Alias must point to a definition", &GA);
-  if (const GlobalAlias *GAAliasee = dyn_cast<GlobalAlias>(GV)) {
-    Assert1(!GAAliasee->mayBeOverridden(), "Alias cannot point to a weak alias",
-            &GA);
-  }
 
-  const GlobalValue *AG = GA.getAliasedGlobal();
-  Assert1(AG, "Aliasing chain should end with function or global variable",
-          &GA);
+  const GlobalValue* Resolved = GA.resolveAliasedGlobal(/*stopOnWeak*/ false);
+  Assert1(Resolved,
+          "Aliasing chain should end with function or global variable", &GA);
 
   visitGlobalValue(GA);
 }