From cde89e48b23f80899225e91b3eedf3b6e7388d8d Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Sat, 25 Apr 2009 21:23:19 +0000
Subject: [PATCH] Allow aliasee to be a GEP or bitcast instead of just a
 bitcast. The real fix for this whole mess is to require the operand of the
 alias to be a *GlobalValue* (not a general constant, including constant
 exprs) but allow the operand and the alias type to be unrelated.

This fixes PR4066

llvm-svn: 70079
---
 llvm/lib/VMCore/AsmWriter.cpp | 12 ++++++------
 llvm/lib/VMCore/Verifier.cpp  |  4 +++-
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/VMCore/AsmWriter.cpp b/llvm/lib/VMCore/AsmWriter.cpp
index f007c7645cc0..742931e8fd80 100644
--- a/llvm/lib/VMCore/AsmWriter.cpp
+++ b/llvm/lib/VMCore/AsmWriter.cpp
@@ -1317,12 +1317,12 @@ void AssemblyWriter::printAlias(const GlobalAlias *GA) {
     Out << ' ';
     PrintLLVMName(Out, GA);
   } else {
-    const ConstantExpr *CE = 0;
-    if ((CE = dyn_cast<ConstantExpr>(Aliasee)) &&
-        (CE->getOpcode() == Instruction::BitCast)) {
-      writeOperand(CE, false);    
-    } else
-      assert(0 && "Unsupported aliasee");
+    const ConstantExpr *CE = cast<ConstantExpr>(Aliasee);
+    // The only valid GEP is an all zero GEP.
+    assert((CE->getOpcode() == Instruction::BitCast ||
+            CE->getOpcode() == Instruction::GetElementPtr) &&
+           "Unsupported aliasee");
+    writeOperand(CE, false);
   }
   
   printInfoComment(*GA);
diff --git a/llvm/lib/VMCore/Verifier.cpp b/llvm/lib/VMCore/Verifier.cpp
index df9aceec0241..5e1137f32db2 100644
--- a/llvm/lib/VMCore/Verifier.cpp
+++ b/llvm/lib/VMCore/Verifier.cpp
@@ -427,7 +427,9 @@ void Verifier::visitGlobalAlias(GlobalAlias &GA) {
 
   if (!isa<GlobalValue>(GA.getAliasee())) {
     const ConstantExpr *CE = dyn_cast<ConstantExpr>(GA.getAliasee());
-    Assert1(CE && CE->getOpcode() == Instruction::BitCast &&
+    Assert1(CE && 
+            (CE->getOpcode() == Instruction::BitCast ||
+             CE->getOpcode() == Instruction::GetElementPtr) &&
             isa<GlobalValue>(CE->getOperand(0)),
             "Aliasee should be either GlobalValue or bitcast of GlobalValue",
             &GA);