Error: Type constraint application shouldn't fail!

Hi list,

I’m trying to match a particular pattern into the SDag which looks like this:

// non-commutative multiplication
def ncmul : SDNode<“ISD::MUL” , SDTIntBinOp,

def mula_pat : PatFrag<(ops node:$a, node:$b),
(sext (i16 (extractelt node:$a, (i32 0)))),
(sext (i16 (extractelt node:$b, (i32 1))))
(sext (i16 (extractelt node:$a, (i32 1)))),
(sext (i16 (extractelt node:$b, (i32 0))))


def ADDMULv : InstSP< (outs IntRegs:$dst), (ins IntRegs:$a, IntRegs:$b),
“muladd $a, $b, $dst”,
[(set (i32 IntRegs:$dst), (mula_pat (v2i16 IntRegs:$a), (v2i16 IntRegs:$b)))]>;

IntRegs is class with a type list of [i32, v2i16]

But I get the following error when llvm building system try to generate the ISelector

llvm[3]: Building DAG instruction selector implementation with tblgen
vtInt: (vt:Other)<<P:Predicate_vtInt>>
Type constraint application shouldn’t fail!0 llvm-tblgen 0x081d6de7
1 llvm-tblgen 0x081d6b74
2 0x4001d400 __kernel_sigreturn + 0
3 0x401b8a82 abort + 386
4 llvm-tblgen 0x0810a4ab
5 llvm-tblgen 0x0810a38f
6 llvm-tblgen 0x0810dd72
7 llvm-tblgen 0x080f8d98
8 llvm-tblgen 0x08176f49
9 llvm-tblgen 0x08184519
10 llvm-tblgen 0x081760e5
11 0x401a1bd6 __libc_start_main + 230
12 llvm-tblgen 0x0804cb51

Any clue where it may come from ?