Index: llvm/trunk/lib/Target/Sparc/SparcInstrAliases.td
===================================================================
--- llvm/trunk/lib/Target/Sparc/SparcInstrAliases.td
+++ llvm/trunk/lib/Target/Sparc/SparcInstrAliases.td
@@ -476,6 +476,9 @@
 // flush -> flush %g0
 def : InstAlias<"flush", (FLUSH), 0>;
 
+// unimp -> unimp 0
+def : InstAlias<"unimp", (UNIMP 0), 0>;
+
 def : MnemonicAlias<"iflush", "flush">;
 
 def : MnemonicAlias<"stub", "stb">;
Index: llvm/trunk/test/MC/Sparc/sparc-misc-instructions.s
===================================================================
--- llvm/trunk/test/MC/Sparc/sparc-misc-instructions.s
+++ llvm/trunk/test/MC/Sparc/sparc-misc-instructions.s
@@ -0,0 +1,8 @@
+! RUN: llvm-mc %s -arch=sparc   -show-encoding | FileCheck %s
+! RUN: llvm-mc %s -arch=sparcv9 -show-encoding | FileCheck %s
+
+        ! CHECK: unimp 0   ! encoding: [0x00,0x00,0x00,0x00]
+        unimp
+
+        ! CHECK: unimp 0   ! encoding: [0x00,0x00,0x00,0x00]
+        unimp 0