From d21e55abce305c0c567c05b769e69c3cb0e2d36c Mon Sep 17 00:00:00 2001
From: Eli Friedman <eli.friedman@gmail.com>
Date: Fri, 31 Jul 2009 19:36:47 +0000
Subject: [PATCH] PR4662: Fix a crash introduced by the recent LLVMContext
 changes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77716 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/TailDuplication.cpp      |  3 ++-
 test/Transforms/TailDup/2009-07-31-phicrash.ll | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 test/Transforms/TailDup/2009-07-31-phicrash.ll

diff --git a/lib/Transforms/Scalar/TailDuplication.cpp b/lib/Transforms/Scalar/TailDuplication.cpp
index dccc3e6ffb3..5e54a69bfa1 100644
--- a/lib/Transforms/Scalar/TailDuplication.cpp
+++ b/lib/Transforms/Scalar/TailDuplication.cpp
@@ -360,7 +360,8 @@ void TailDup::eliminateUnconditionalBranch(BranchInst *Branch) {
       Instruction *Inst = BI++;
       if (isInstructionTriviallyDead(Inst))
         Inst->eraseFromParent();
-      else if (Constant *C = ConstantFoldInstruction(Inst, BI->getContext())) {
+      else if (Constant *C = ConstantFoldInstruction(Inst,
+                                                     Inst->getContext())) {
         Inst->replaceAllUsesWith(C);
         Inst->eraseFromParent();
       }
diff --git a/test/Transforms/TailDup/2009-07-31-phicrash.ll b/test/Transforms/TailDup/2009-07-31-phicrash.ll
new file mode 100644
index 00000000000..6abd2a5bd69
--- /dev/null
+++ b/test/Transforms/TailDup/2009-07-31-phicrash.ll
@@ -0,0 +1,14 @@
+; RUN: llvm-as < %s | opt -tailduplicate -disable-output
+; PR4662
+
+define void @a() {
+BB:
+	br label %BB6
+
+BB6:
+	%tmp9 = phi i64 [ 0, %BB ], [ 5, %BB34 ]
+	br label %BB34
+
+BB34:
+	br label %BB6
+}
-- 
2.34.1