1 files changed, 38 insertions, 0 deletions
diff --git a/test/CodeGen/MIR/X86/unreachable-mbb-undef-phi.mir b/test/CodeGen/MIR/X86/unreachable-mbb-undef-phi.mir
new file mode 100644
index 00000000000..1abfb19d638
--- /dev/null
+++ b/test/CodeGen/MIR/X86/unreachable-mbb-undef-phi.mir
@@ -0,0 +1,38 @@
+# RUN: llc %s -o - -run-pass=processimpdefs -run-pass=unreachable-mbb-elimination | FileCheck %s
+---
+name:            f
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: gr32, preferred-register: '' }
+  - { id: 1, class: gr32, preferred-register: '' }
+  - { id: 2, class: gr32, preferred-register: '' }
+body:             |
+  bb.0:
+    %0 = IMPLICIT_DEF
+    JMP_1 %bb.1
+
+  bb.1:
+    %1 = PHI %0, %bb.0, %2, %bb.2
+    %2 = ADD32ri8 killed %1, 1, implicit-def %eflags
+    JMP_1 %bb.3
+
+  bb.2:
+    JMP_1 %bb.1
+
+  bb.3:
+...
+
+# bb2 above is dead and should be removed and the PHI should be replaced with a
+# COPY from an undef value since the bb0 value in the PHI is undef.
+
+# CHECK:  bb.0:
+# CHECK:    successors: %bb.1
+# CHECK:    JMP_1 %bb.1
+
+# CHECK:  bb.1:
+# CHECK:    successors: %bb.2
+# CHECK:    [[TMP1:%[0-9]+]] = COPY undef %{{[0-9]+}}
+# CHECK:    %{{[0-9]+}} = ADD32ri8 killed [[TMP1]], 1
+# CHECK:    JMP_1 %bb.2
+
+# CHECK:  bb.2: