See these:

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070319/046143.html
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070319/046144.html

-bw

Now get this error:

Assertion failed: (0 && "Don't support illegal by-val vector arguments yet!"), function LowerArguments,
file /Volumes/Gir/devel/llvm/llvm.src/lib/CodeGen
/SelectionDAG/SelectionDAGISel.cpp, line 3158.
mmx-3.cpp:157: internal compiler error: Abort trap
Please submit a full bug report,
with preprocessed source if appropriate.
See URL:http://llvm.org/bugs for instructions.

.abort

-bw

Assertion was caused by:

define void @​main() {
entry:
%tmp1314.2 = tail call <8 x i8> @​llvm.x86.mmx.packuswb( <4 x i16>
zeroinitializer,
<4 x i16>
bitcast (i64 0 to <4 x i16>) )
ret void
}

declare <8 x i8> @​llvm.x86.mmx.packuswb(<4 x i16>, <4 x i16>)

Interesting: this looks related to Bug 1172. I can make this constant fold to a zero vector, but I don't
know if that will fix the original problem or just the reduced testcase.

We support MMX now. Try it out!