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. Thanks, Wei.
