Misc pyxl2 perf improvements continued

[undingen]

                                   upstream/master:      origin/pyxl2_2:
           django_template3.py             2.2s (4)             2.2s (2)  +0.7%
                 pyxl_bench.py             1.8s (4)             1.8s (2)  +0.4%
     sqlalchemy_imperative2.py             2.3s (4)             2.3s (2)  -0.2%
                pyxl_bench2.py             1.3s (4)             1.3s (2)  -1.3%
       django_template3_10x.py            14.2s (4)            14.4s (2)  +0.9%
             pyxl_bench_10x.py            14.3s (4)            14.2s (2)  -0.4%
 sqlalchemy_imperative2_10x.py            17.5s (4)            17.4s (2)  -0.5%
            pyxl_bench2_10x.py            12.2s (4)            11.5s (2)  -5.5%
                       geomean                 5.2s                 5.1s  -0.8%

[kmod]

I think we might need to make this rewrite_args = NULL instead, since it's not clearing a potential capi exception. I'm surprised that the change you made here helped, since I would have thought these guards would cause the rewrite to abort anyway.

[undingen]

It rewrites the case where we run into this case inside getattrInternalGeneric:

if (unlikely(rewrite_args && !descr && obj->cls != instancemethod_cls
         && rewrite_args->rewriter->aggressiveness() < 40
         && attr->interned_state == SSTATE_INTERNED_IMMORTAL)) {
    class Helper {
    public:
        static Box* call(Box* obj, BoxedString* attr) { return obj->getattr(attr); }
    };

    RewriterVar* r_rtn = rewrite_args->rewriter->call(
        false, (void*)Helper::call, rewrite_args->obj,
        rewrite_args->rewriter->loadConst((intptr_t)attr, Location::forArg(1)));
    rewrite_args->setReturn(r_rtn, ReturnConvention::NOEXC_POSSIBLE);
    return Helper::call(obj, attr);
}

the call is marked as having no side effects to the additional guard don't abort the rewrite.

[kmod]

oh ok, right :)