From 86c5abb4c0edfffdd24729e142a62b9b949f025d Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Tue, 20 Apr 2010 01:25:01 +0000
Subject: [PATCH] The visitXOR method can return the same SDNode. If so, we
 don't want to delete it as it's not dead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101855 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/DAGCombiner.cpp      |  2 +-
 .../CodeGen/X86/2010-04-19-DAGCombineCrash.ll | 58 +++++++++++++++++++
 2 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 test/CodeGen/X86/2010-04-19-DAGCombineCrash.ll

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index f15c121668f..7ece6e85216 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4911,7 +4911,7 @@ SDValue DAGCombiner::visitBRCOND(SDNode *N) {
     if (Op0.getOpcode() == Op1.getOpcode()) {
       // Avoid missing important xor optimizations.
       SDValue Tmp = visitXOR(TheXor);
-      if (Tmp.getNode()) {
+      if (Tmp.getNode() && Tmp.getNode() != TheXor) {
         DEBUG(dbgs() << "\nReplacing.8 ";
               TheXor->dump(&DAG);
               dbgs() << "\nWith: ";
diff --git a/test/CodeGen/X86/2010-04-19-DAGCombineCrash.ll b/test/CodeGen/X86/2010-04-19-DAGCombineCrash.ll
new file mode 100644
index 00000000000..4d73c648433
--- /dev/null
+++ b/test/CodeGen/X86/2010-04-19-DAGCombineCrash.ll
@@ -0,0 +1,58 @@
+; RUN: llc < %s -mtriple=i386-apple-darwin
+; rdar://7869290
+
+%struct.anon = type { float }
+
+define void @func() nounwind ssp {
+entry:
+  br label %bb66
+
+bb:                                               ; preds = %bb66
+  br i1 undef, label %bb65, label %bb2
+
+bb2:                                              ; preds = %bb
+  br i1 undef, label %bb65, label %bb3
+
+bb3:                                              ; preds = %bb2
+  br i1 undef, label %bb65, label %bb4
+
+bb4:                                              ; preds = %bb3
+  br i1 undef, label %bb65, label %bb5
+
+bb5:                                              ; preds = %bb4
+  br i1 undef, label %bb65, label %bb6
+
+bb6:                                              ; preds = %bb5
+  br i1 undef, label %bb65, label %bb11
+
+bb11:                                             ; preds = %bb6
+  br i1 undef, label %bb65, label %bb12
+
+bb12:                                             ; preds = %bb11
+  br i1 undef, label %bb65, label %bb13
+
+bb13:                                             ; preds = %bb12
+  br i1 undef, label %bb65, label %bb14
+
+bb14:                                             ; preds = %bb13
+  %0 = trunc i16 undef to i1                      ; <i1> [#uses=1]
+  %1 = load i8* undef, align 8                    ; <i8> [#uses=1]
+  %2 = shl i8 %1, 4                               ; <i8> [#uses=1]
+  %3 = lshr i8 %2, 7                              ; <i8> [#uses=1]
+  %4 = trunc i8 %3 to i1                          ; <i1> [#uses=1]
+  %5 = icmp ne i1 %0, %4                          ; <i1> [#uses=1]
+  br i1 %5, label %bb65, label %bb15
+
+bb15:                                             ; preds = %bb14
+  %6 = load %struct.anon** undef, align 8         ; <%struct.anon*> [#uses=0]
+  br label %bb65
+
+bb65:                                             ; preds = %bb15, %bb14, %bb13, %bb12, %bb11, %bb6, %bb5, %bb4, %bb3, %bb2, %bb
+  br label %bb66
+
+bb66:                                             ; preds = %bb65, %entry
+  br i1 undef, label %bb, label %bb67
+
+bb67:                                             ; preds = %bb66
+  ret void
+}