From: Sriraman Tallam <tmsriram@google.com>
To: Richard Henderson <rth@redhat.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>,
David Li <davidxl@google.com>,
Cary Coutant <ccoutant@google.com>,
Ian Lance Taylor <iant@google.com>,
Paul Pluzhnikov <ppluzhnikov@google.com>
Subject: Re: [PATCH x86_64] Optimize access to globals in "-fpie -pie" builds with copy relocations
Date: Mon, 06 Oct 2014 20:43:00 -0000 [thread overview]
Message-ID: <CAAs8HmzjrSiXRPa9Y4PMshxAQ6B5RG5JL0b7tzjJBeyo45Xv5Q@mail.gmail.com> (raw)
In-Reply-To: <CAAs8Hmyuc20qTsPrfsa2Ct8rhvMAs_ZTC-LLbjD-tOk_BPoV3g@mail.gmail.com>
Ping.
On Mon, Sep 29, 2014 at 10:57 AM, Sriraman Tallam <tmsriram@google.com> wrote:
> Ping.
>
> On Fri, Sep 19, 2014 at 2:11 PM, Sriraman Tallam <tmsriram@google.com> wrote:
>> Hi Richard,
>>
>> I also ran the gcc testsuite with
>> RUNTESTFLAGS="--tool_opts=-mcopyrelocs" to check for issues. The only
>> test that failed was g++.dg/tsan/default_options.C. It uses -fpie
>> -pie and BFD ld to link. Since BFD ld does not support copy
>> relocations with -pie, it does not link. I linked with gold to make
>> the test pass.
>>
>> Could you please take another look at this patch?
>>
>> Thanks
>> Sri
>>
>> On Mon, Sep 8, 2014 at 3:19 PM, Sriraman Tallam <tmsriram@google.com> wrote:
>>> On Tue, Sep 2, 2014 at 1:40 PM, Richard Henderson <rth@redhat.com> wrote:
>>>> On 06/20/2014 05:17 PM, Sriraman Tallam wrote:
>>>>> Index: config/i386/i386.c
>>>>> ===================================================================
>>>>> --- config/i386/i386.c (revision 211826)
>>>>> +++ config/i386/i386.c (working copy)
>>>>> @@ -12691,7 +12691,9 @@ legitimate_pic_address_disp_p (rtx disp)
>>>>> return true;
>>>>> }
>>>>> else if (!SYMBOL_REF_FAR_ADDR_P (op0)
>>>>> - && SYMBOL_REF_LOCAL_P (op0)
>>>>> + && (SYMBOL_REF_LOCAL_P (op0)
>>>>> + || (TARGET_64BIT && ix86_copyrelocs && flag_pie
>>>>> + && !SYMBOL_REF_FUNCTION_P (op0)))
>>>>> && ix86_cmodel != CM_LARGE_PIC)
>>>>> return true;
>>>>> break;
>>>>
>>>> This is the wrong place to patch.
>>>>
>>>> You ought to be adjusting SYMBOL_REF_LOCAL_P, by providing a modified
>>>> TARGET_BINDS_LOCAL_P.
>>>
>>> I have done this in the new attached patch, I added a new function
>>> i386_binds_local_p which will check for this and call
>>> default_binds_local_p otherwise.
>>>
>>>>
>>>> Note in particular that I believe that you are doing the wrong thing with weak
>>>> and COMMON symbols, in that you probably ought not force a copy reloc there.
>>>
>>> I added an extra check to not do this for WEAK symbols. I also added a
>>> check for DECL_EXTERNAL so I believe this will also not be called for
>>> COMMON symbols.
>>>
>>>>
>>>> Note the complexity of default_binds_local_p_1, and the fact that all you
>>>> really want to modify is
>>>>
>>>> /* If PIC, then assume that any global name can be overridden by
>>>> symbols resolved from other modules. */
>>>> else if (shlib)
>>>> local_p = false;
>>>>
>>>> near the bottom of that function.
>>>
>>> I did not understand what you mean here? Were you suggesting an
>>> alternative way of doing this?
>>>
>>> Thanks for reviewing
>>> Sri
>>>
>>>>
>>>>
>>>> r~
next prev parent reply other threads:[~2014-10-06 20:43 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-15 18:34 Sriraman Tallam
2014-05-19 18:11 ` Sriraman Tallam
2014-06-09 22:55 ` Sriraman Tallam
2014-06-21 0:17 ` Sriraman Tallam
2014-06-26 17:55 ` Sriraman Tallam
2014-07-11 17:42 ` Sriraman Tallam
2014-09-02 18:15 ` Sriraman Tallam
2014-09-02 20:40 ` Richard Henderson
2014-09-03 7:25 ` Bernhard Reutner-Fischer
2014-09-08 22:19 ` Sriraman Tallam
2014-09-19 21:11 ` Sriraman Tallam
2014-09-29 17:57 ` Sriraman Tallam
2014-10-06 20:43 ` Sriraman Tallam [this message]
2014-11-10 23:35 ` Sriraman Tallam
2014-12-02 18:01 ` Sriraman Tallam
2014-12-02 19:06 ` H.J. Lu
2014-12-02 19:19 Uros Bizjak
2014-12-02 19:39 ` H.J. Lu
2014-12-02 19:40 ` H.J. Lu
2014-12-02 20:01 ` Uros Bizjak
2014-12-02 20:43 ` H.J. Lu
2014-12-02 20:19 ` Jakub Jelinek
2014-12-02 22:14 ` H.J. Lu
2014-12-02 23:21 ` H.J. Lu
2014-12-03 13:47 ` H.J. Lu
2014-12-03 15:01 ` H.J. Lu
2014-12-03 21:35 ` H.J. Lu
2014-12-04 12:44 ` Uros Bizjak
2014-12-04 16:46 ` H.J. Lu
2014-12-04 19:32 ` Uros Bizjak
2015-02-03 19:25 ` Sriraman Tallam
2015-02-03 19:26 ` Sriraman Tallam
2015-02-03 19:36 ` Jakub Jelinek
2015-02-03 21:20 ` Sriraman Tallam
2015-02-03 21:29 ` H.J. Lu
2015-02-03 21:36 ` Sriraman Tallam
2015-02-03 22:03 ` H.J. Lu
2015-02-03 22:19 ` Jakub Jelinek
2015-02-04 1:16 ` H.J. Lu
2015-02-04 18:27 ` Sriraman Tallam
2015-02-04 18:31 ` Jakub Jelinek
2015-02-04 18:38 ` H.J. Lu
2015-02-04 18:42 ` Jakub Jelinek
2015-02-04 18:45 ` H.J. Lu
2015-02-04 18:51 ` Sriraman Tallam
2015-02-04 18:57 ` H.J. Lu
2015-02-04 21:53 ` Sriraman Tallam
2015-02-04 22:37 ` H.J. Lu
2015-02-04 22:47 ` Bernhard Reutner-Fischer
2015-02-04 23:10 ` H.J. Lu
2015-02-04 23:29 ` H.J. Lu
2015-02-05 16:57 ` Bernhard Reutner-Fischer
2015-02-05 18:54 ` Richard Henderson
2015-02-05 19:01 ` H.J. Lu
2015-02-05 19:59 ` Richard Henderson
2015-02-05 22:05 ` Sriraman Tallam
2015-02-05 22:47 ` H.J. Lu
2015-02-05 22:48 ` Sriraman Tallam
2015-02-06 16:25 ` H.J. Lu
2015-02-27 23:39 ` H.J. Lu
2015-02-27 23:46 ` H.J. Lu
2014-12-04 22:19 Dominique Dhumieres
2014-12-04 23:54 ` H.J. Lu
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