On Thu, Nov 21, 2013 at 1:01 PM, Richard Biener <richard.guent...@gmail.com> wrote: > Wei Mi <w...@google.com> wrote: >>On Thu, Nov 21, 2013 at 11:36 AM, Richard Biener >><richard.guent...@gmail.com> wrote: >>> Wei Mi <w...@google.com> wrote: >>>>> So what you are doing is basically not only rewriting memory >>>>references >>>>> to possibly use TARGET_MEM_REF but also address uses to use >>>>> &TARGET_MEM_REF. I think this is a good thing in general >>>>> (given instructions like x86 lea) and I would not bother >>>>distinguishing >>>>> the different kind of uses. >>>>> >>>>> Richard. >>>>> >>>> >>>>You mean to change normal expr to &TMR(expr) form in order to utilize >>>>x86 lea type instructions as much as possible. It is interesting. I >>>>can experiment that idea later. I am not sure if it could simply >>work. >>>>My concern is x86 lea still has some limitation (such as three >>>>operands lea will have longer latency and can only be issued to >>>>port1), if we change some expr to &TMR(expr), will it inhitbit cse >>>>opportunity if codegen find out it is not good to use lea? >>> >>> That needs to be determined. Over all it might be because ivopts >>runs so early. At rtl level there should not be big differences apart >>from better initial address computations. >>> >>> Did I misunderstand what your patch does? >>> >>> Richard. >>> >> >>My patch wants to address the issue that iv uses using as memory >>reference actuals for load/store/prefetch builtins are treated as >>non-linear iv uses instead of address iv uses, and the result of >>determine_use_iv_cost is wrong. After we change those uses to address >>uses, less ivs may be used, TMR will be generated for those iv uses >>and efficent addressing mode could be utilized. > > But are not all pointer typed uses address uses?! > > Richard. >
If a pointer typed use is plainly value passed to a func call, it is not an address use, right? But as you said, x86 lea may help here. Thanks, Wei.
