It's possible to speed up opcodes that use toBoolean conversion in a number of ways: 1) Make JSValue::toBoolean nonvirtual and completely inline by making use of the StructureID type field. 2) Make JSValue::toBoolean not take an ExecState; doesn't need it. 3) Make op_not, op_loop_if_true and op_jtrue not read the ExecState (toBoolean doesn't need it any more) and not check exceptions (toBoolean can't throw).
Created attachment 24116 [details] speedup patch
Comment on attachment 24116 [details] speedup patch r=me. Please include the perf delta in the ChangeLog.