From: Uros Bizjak <ubizjak@gmail.com>
To: Paul_Koning@dell.com
Cc: gcc-patches@gcc.gnu.org, rdsandiford@googlemail.com,
ebotcazou@adacore.com
Subject: Re: [PATCH v2, rtl-optimization]: Fix PR54457, [x32] Fail to combine 64bit index + constant
Date: Thu, 27 Sep 2012 19:21:00 -0000 [thread overview]
Message-ID: <CAFULd4bSX2+V028LzMi30Pk4RyA1NKDC1skm3EBCCqeQcc-EAg@mail.gmail.com> (raw)
In-Reply-To: <C75A84166056C94F84D238A44AF9F6AD237AC0@AUSX10MPS303.AMER.DELL.COM>
On Thu, Sep 27, 2012 at 8:08 PM, <Paul_Koning@dell.com> wrote:
>>>>>> I agree (subreg:M (op:N A C) 0) to (op:M (subreg:N (A 0)) C) is
>>>>>> a good transformation, but why do we need to handle as special
>>>>>> the case where the subreg is itself the operand of a plus or minus?
>>>>>> I think it should happen regardless of where the subreg occurs.
>>>>>
>>>>> Don't we need to restrict this to the low part though?
>>>>
>>>> ...
>>
>> After some off-line discussion with Richard, attached is v2 of the patch.
>>
>> 2012-09-27 Uros Bizjak <ubizjak@gmail.com>
>>
>> PR rtl-optimization/54457
>> * simplify-rtx.c (simplify_subreg):
>> Simplify (subreg:SI (op:DI ((x:DI) (y:DI)), 0)
>> to (op:SI (subreg:SI (x:DI) 0) (subreg:SI (x:DI) 0)).
>> ...
>
> Is it just specific to DI -> SI, or is it for any large mode -> smaller mode, like SI -> HI?
Oh, I just copied v1 ChangeLog. The patch converts all modes where
size of mode M < size of mode N. Updated ChangeLog reads:
2012-09-27 Uros Bizjak <ubizjak@gmail.com>
PR rtl-optimization/54457
* simplify-rtx.c (simplify_subreg):
Simplify (subreg:M (op:N ((x:N) (y:N)), 0)
to (op:M (subreg:M (x:N) 0) (subreg:M (x:N) 0)), where
the outer subreg is effectively a truncation to the original mode M.
testsuite/ChangeLog:
2012-09-27 Uros Bizjak <ubizjak@gmail.com>
PR rtl-optimization/54457
* gcc.target/i386/pr54457.c: New test.
Uros.
next prev parent reply other threads:[~2012-09-27 18:13 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-25 8:04 [PATCH, " Uros Bizjak
2012-09-26 18:17 ` Richard Sandiford
2012-09-26 21:38 ` Eric Botcazou
2012-09-27 14:25 ` Uros Bizjak
2012-09-27 16:10 ` Richard Sandiford
2012-09-27 18:20 ` [PATCH v2, " Uros Bizjak
2012-09-27 18:35 ` Paul_Koning
2012-09-27 19:21 ` Uros Bizjak [this message]
2012-10-02 2:13 ` Andrew Pinski
2012-10-02 19:32 ` Richard Sandiford
2012-10-06 10:22 ` RFA: Simplifying truncation and integer lowpart subregs Richard Sandiford
2012-10-06 11:13 ` Eric Botcazou
2012-10-06 12:39 ` Richard Sandiford
2012-10-06 13:05 ` Eric Botcazou
2012-10-07 8:56 ` Richard Sandiford
2012-10-07 12:36 ` Eric Botcazou
2012-11-28 2:27 ` Ramana Radhakrishnan
2012-11-28 21:45 ` Richard Sandiford
2012-09-27 20:33 ` [PATCH v2, rtl-optimization]: Fix PR54457, [x32] Fail to combine 64bit index + constant Jakub Jelinek
2012-09-27 22:37 ` Richard Sandiford
2012-09-28 15:39 ` Uros Bizjak
2012-09-30 11:40 ` Richard Sandiford
2012-10-03 11:07 ` Paolo Bonzini
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