func buildShift(b *builder, ret, A, B *ref, op string) {
if types.IsSigned(A.Type()) {
b.b.Arith(ret.IR(), A.IR(), op, B.IR())
} else {
if op == ">>" {
b.b.Arith(ret.IR(), A.IR(), "u>>", B.IR())
} else {
b.b.Arith(ret.IR(), A.IR(), op, B.IR())
}
}
}
func checkArrayIndex(b *builder, index *ref) ir.Ref {
t := index.Type()
if types.IsSigned(t) {
neg := b.newCond()
b.b.Arith(neg, nil, "<0", index.IR())
negPanic := b.f.NewBlock(b.b)
after := b.f.NewBlock(negPanic)
b.b.JumpIfNot(neg, after)
b.b = negPanic
callPanic(b, "index is negative")
b.b = after
}
return index.IR()
}