diff --git a/gcc/match.pd b/gcc/match.pd
index c2fed9b..753c392 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -7800,6 +7800,22 @@ and,
  (if (TREE_CODE (@0) == SSA_NAME && num_imm_uses (@0) == 2)
   (minus (mult (vec_perm @1 @1 @3) @2) @4)))
 
+/* VEC_UNPACK_LO_EXPR and friends.  */
+(for unpack (vec_unpack_lo vec_unpack_float_lo vec_unpack_fix_trunc_lo
+	     vec_unpack_hi vec_unpack_float_hi vec_unpack_fix_trunc_hi)
+     opcode (convert float fix_trunc convert float fix_trunc)
+ (simplify
+  (unpack CONSTRUCTOR@0)
+  (with { tree ctor = (TREE_CODE (@0) == SSA_NAME
+		    ? gimple_assign_rhs1 (SSA_NAME_DEF_STMT (@0)) : @0);
+	  tree elt = uniform_vector_p (ctor);
+	  tree eltype = TREE_TYPE (type); }
+   (if (elt)
+    (vec_duplicate (opcode:eltype { elt; })))))
+ (simplify
+  (unpack (vec_duplicate @0))
+  (with { tree eltype = TREE_TYPE (type); }
+   (vec_duplicate (opcode:eltype @0)))))
 
 /* Match count trailing zeroes for simplify_count_trailing_zeroes in fwprop.
    The canonical form is array[((x & -x) * C) >> SHIFT] where C is a magic
diff --git a/gcc/testsuite/g++.dg/vect/pr105621.cc b/gcc/testsuite/g++.dg/vect/pr105621.cc
new file mode 100644
index 0000000..98e8fcd
--- /dev/null
+++ b/gcc/testsuite/g++.dg/vect/pr105621.cc
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+bool d;
+
+void test(unsigned short a, int b, unsigned c) {
+  for (int i = 2; i < 24; i += 3)
+    d = b ? a ? c : 2086607777901731118 : 0;
+}
+
+/* { dg-final { scan-tree-dump-not "vec_unpack" "optimized" } } */