From 5d0233bea22a103b5ecb5a9b5453f1206f2defe0 Mon Sep 17 00:00:00 2001
From: Dylan McKay <dylanmckay34@gmail.com>
Date: Sat, 10 Dec 2016 10:16:13 +0000
Subject: [PATCH] [AVR] Support stores to undefined pointers

This would previously trigger an assertion error in AVRISelDAGToDAG.

llvm-svn: 289321
---
 llvm/lib/Target/AVR/AVRISelDAGToDAG.cpp |  3 ++-
 llvm/test/CodeGen/AVR/store-undef.ll    | 13 +++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/AVR/store-undef.ll

diff --git a/llvm/lib/Target/AVR/AVRISelDAGToDAG.cpp b/llvm/lib/Target/AVR/AVRISelDAGToDAG.cpp
index 098ee61b..9ef9874 100644
--- a/llvm/lib/Target/AVR/AVRISelDAGToDAG.cpp
+++ b/llvm/lib/Target/AVR/AVRISelDAGToDAG.cpp
@@ -328,7 +328,8 @@ template <> bool AVRDAGToDAGISel::select<ISD::STORE>(SDNode *N) {
   SDValue BasePtr = ST->getBasePtr();
 
   // Early exit when the base pointer is a frame index node or a constant.
-  if (isa<FrameIndexSDNode>(BasePtr) || isa<ConstantSDNode>(BasePtr)) {
+  if (isa<FrameIndexSDNode>(BasePtr) || isa<ConstantSDNode>(BasePtr) ||
+      BasePtr.isUndef()) {
     return false;
   }
 
diff --git a/llvm/test/CodeGen/AVR/store-undef.ll b/llvm/test/CodeGen/AVR/store-undef.ll
new file mode 100644
index 0000000..58ea500
--- /dev/null
+++ b/llvm/test/CodeGen/AVR/store-undef.ll
@@ -0,0 +1,13 @@
+; RUN: llc < %s -mattr=avr6 | FileCheck %s
+
+; This test checks that we can successfully lower a store
+; to an undefined pointer.
+
+; CHECK-LABEL: foo
+define void @foo() {
+
+  ; CHECK:      ldi [[SRC:r[0-9]+]], 0
+  ; CHECK-NEXT: st [[PTRREG:X|Y|Z]], [[SRC]]
+  store i8 0, i8* undef, align 4
+  ret void
+}
-- 
2.7.4