I assume this is due to Dan's recent patches:

$ llvm-as < test.ll | llc -march=ppc32 -mcpu=g5
..
/Volumes/ProjectsDisk/cvs/llvm/include/llvm/Target/TargetLowering.h:123: failed assertion `!
MVT::isExtendedValueType(VT)'


target datalayout = "E-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-
v64:64:64-v128:128:128-a0:0:64"
target triple = "powerpc-apple-darwin8.8.0"

define i32 @main() {
entry:
        br label %bb

bb:             ; preds = %bb, %entry
        br i1 false, label %bb15, label %bb

bb15:           ; preds = %bb15, %bb
        %tmp21 = add <8 x double> zeroinitializer, zeroinitializer              ; <<8 x double>> [#uses=1]
        br i1 false, label %bb15, label %bb30

bb30:           ; preds = %bb15
        store <8 x double> %tmp21, <8 x double>* null
        ret i32 0
}