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Re: [PATCH] Builtins handling in IVOPT
- From: Richard Biener <richard dot guenther at gmail dot com>
- To: Wei Mi <wmi at google dot com>
- Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>,Zdenek Dvorak <rakdver at kam dot mff dot cuni dot cz>,David Li <davidxl at google dot com>
- Date: Thu, 21 Nov 2013 20:36:59 +0100
- Subject: Re: [PATCH] Builtins handling in IVOPT
- Authentication-results: sourceware.org; auth=none
- References: <CA+4CFy7_1JO7r3eq8TWzotR1L6oGKkecZx24OvBd8yeXKcshWQ at mail dot gmail dot com> <CAFiYyc192S2FxNiaeOd6tCvOi0XBfi2arCd4Obf+sckkfwja3g at mail dot gmail dot com> <CA+4CFy6Qcsd1H=zm=LXGJ1c=E_aTcDU-WXAn0eXHmqBAC3z6PA at mail dot gmail dot com>
Wei Mi <email@example.com> wrote:
>> So what you are doing is basically not only rewriting memory
>> 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
>> the different kind of uses.
>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?