--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/CodeGen/AMDGPU/subreg-coalescer-undef-use.ll	Tue Oct 13 17:48:58 2015 +0900
@@ -0,0 +1,37 @@
+; RUN: llc -march=amdgcn -mcpu=SI -o - %s | FileCheck %s
+; Don't crash when the use of an undefined value is only detected by the
+; register coalescer because it is hidden with subregister insert/extract.
+target triple="amdgcn--"
+
+; CHECK-LABEL: foobar:
+; CHECK: s_load_dword s2, s[0:1], 0x9
+; CHECK-NEXT: s_load_dwordx2 s[4:5], s[0:1], 0xb
+; CHECK-NEXT: s_waitcnt lgkmcnt(0)
+; CHECK-NEXT: v_mov_b32_e32 v0, s2
+; CHECK-NEXT: s_and_saveexec_b64 s[2:3], s[0:1]
+; CHECK-NEXT: s_xor_b64 s[2:3], exec, s[2:3]
+; BB0_1:
+; CHECK: s_load_dword s6, s[0:1], 0xa
+; CHECK-NEXT: s_waitcnt lgkmcnt(0)
+; CHECK-NEXT: v_mov_b32_e32 v0, s6
+; BB0_2:
+; CHECK: s_or_b64 exec, exec, s[2:3]
+; CHECK-NEXT: s_mov_b32 s7, 0xf000
+; CHECK-NEXT: s_mov_b32 s6, -1
+; CHECK-NEXT: buffer_store_dword v1, s[4:7], 0
+; CHECK-NEXT: s_endpgm
+define void @foobar(float %a0, float %a1, float addrspace(1)* %out) nounwind {
+entry:
+  %v0 = insertelement <4 x float> undef, float %a0, i32 0
+  br i1 undef, label %ift, label %ife
+
+ift:
+  %v1 = insertelement <4 x float> undef, float %a1, i32 0
+  br label %ife
+
+ife:
+  %val = phi <4 x float> [ %v1, %ift ], [ %v0, %entry ]
+  %v2 = extractelement <4 x float> %val, i32 1
+  store float %v2, float addrspace(1)* %out, align 4
+  ret void
+}