Remove copy and accidental detach.

Change-Id: Iedd751424ff0b651ba9e00a30f50e197ecd7967d
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
V4 IR: replace hashes by vectors.

Speeds up the register allocation by another 20%.

Change-Id: I8c638d09e1b96f400e3e101a000bc73b02d79165
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>