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From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Vineet Gupta <Vineet.Gupta1@synopsys.com>,
	"libc-alpha@sourceware.org" <libc-alpha@sourceware.org>
Cc: arcml <linux-snps-arc@lists.infradead.org>
Subject: Re: [PATCH v6 03/13] ARC: Thread Local Storage support
Date: Mon, 1 Jun 2020 15:53:27 -0300
Message-ID: <65de7a88-593f-faa0-4ce6-c62b91b04249@linaro.org> (raw)
In-Reply-To: <18a9ff31-baea-c916-4377-76b77976c169@synopsys.com>



On 27/05/2020 22:36, Vineet Gupta wrote:
> On 5/27/20 12:17 PM, Adhemerval Zanella via Libc-alpha wrote:
>>
>>
>> On 22/04/2020 22:41, Vineet Gupta via Libc-alpha wrote:
>>> This includes all 4 TLS addressing models
>>>
>>> Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
>>
>> As prior patch we do not use DCO, but rather copyright assignment.
>>
>> Looks ok in general, with some comments below.
> 
>>> +
>>> +register struct pthread *__thread_self __asm__("r25");
>>
>> This is used on other ports, but I am not sure if this is a valid definition
>> for a global variable. 
> 
> Not valid from gcc implementation POV ? The syntax seems to work alright in ARC
> linux kernel where we use r25 to cache the current task pointer.

The gcc documentation [1] does specify register global variables, but it
also states that 

"[...] it is recommended that you choose a register that is normally saved and 
restored by function calls on your machine, so that calls to library routines
will not clobber it."

So I see that the semantic of global register is kind fragile and since
it is usage is solely for asm inline argument I don't see a very compelling
reason to keep using it.

[1] https://gcc.gnu.org/onlinedocs/gcc/Local-Register-Variables.html

> 
>> Usually the register specifier is used as an input 
>> for inline assembly.  Do we really need this global on ARC port? Couldn't
>> we replace it with __builtin_thread_pointer where applicable?
> 
> We do use __builtin_thread_pointer and actually __thread_self is not used in ARC
> port :-) so I can just drop it

Ack.

> 
> Many thx for reviewing.
> -Vineet
> 

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  reply index

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-23  1:41 [PATCH v6 00/13] glibc port to ARC processors Vineet Gupta
2020-04-23  1:41 ` [PATCH v6 01/13] ARC: ABI Implementation Vineet Gupta
     [not found]   ` <88508d10-2d29-026a-bb54-ad607154ab87@linaro.org>
2020-05-27 22:15     ` Vineet Gupta
2020-05-29 13:56       ` Adhemerval Zanella
     [not found]     ` <a56a35d4-3e9e-9a88-4be5-8553d5f11ad3@synopsys.com>
     [not found]       ` <87mu5jxkv7.fsf@oldenburg2.str.redhat.com>
2020-06-04 19:01         ` Vineet Gupta
2020-06-04 23:56           ` Vineet Gupta
2020-04-23  1:41 ` [PATCH v6 02/13] ARC: startup and dynamic linking code Vineet Gupta
     [not found]   ` <17957ee6-2bc1-f43b-f184-f0703ba2765f@linaro.org>
2020-05-28  1:14     ` Vineet Gupta
2020-04-23  1:41 ` [PATCH v6 03/13] ARC: Thread Local Storage support Vineet Gupta
     [not found]   ` <4f7a67fb-6f96-57e6-b827-d1ab5dd6733f@linaro.org>
2020-05-28  1:36     ` Vineet Gupta
2020-06-01 18:53       ` Adhemerval Zanella [this message]
2020-04-23  1:41 ` [PATCH v6 04/13] ARC: Atomics and Locking primitives Vineet Gupta
     [not found]   ` <03f4a9b3-b1ca-90fa-0b6a-609a3135267d@linaro.org>
2020-04-24  7:23     ` Vineet Gupta
     [not found]     ` <20200427215938.14136-1-vgupta@synopsys.com>
2020-04-27 22:13       ` [PATCH] semaphore: consolidate arch headers into a generic one Vineet Gupta
     [not found]       ` <ac93c301-36d3-b20a-d31c-50c1f3264c68@linaro.org>
2020-05-05 22:59         ` Vineet Gupta
2020-05-08 13:32           ` Adhemerval Zanella
2020-04-23  1:41 ` [PATCH v6 05/13] ARC: math soft float support Vineet Gupta
2020-04-23  1:41 ` [PATCH v6 06/13] ARC: hardware floating point support Vineet Gupta
2020-05-29 14:12   ` Adhemerval Zanella
2020-05-29 22:28     ` Vineet Gupta
2020-05-29 23:50       ` Vineet Gupta
2020-06-02 17:51         ` Joseph Myers
     [not found]         ` <07887c48-7e07-9f89-035d-3f336a16f2da@synopsys.com>
2020-06-02 18:13           ` static inline math functions (was Re: [PATCH v6 06/13] ARC: hardware floating point support) Joseph Myers
2020-06-02 18:35             ` Adhemerval Zanella
2020-06-05  4:44         ` [PATCH v6 06/13] ARC: hardware floating point support Vineet Gupta
2020-06-05 17:22           ` Adhemerval Zanella
2020-06-02 17:48       ` Joseph Myers
2020-04-23  1:41 ` [PATCH v6 07/13] ARC: Linux Syscall Interface Vineet Gupta
2020-05-29 16:49   ` Adhemerval Zanella
2020-05-30  2:02     ` Vineet Gupta
2020-06-03 19:46     ` Vineet Gupta
2020-06-03 20:04       ` Adhemerval Zanella
2020-06-03 20:17         ` Vineet Gupta
2020-06-04 11:06           ` Adhemerval Zanella
2020-04-23  1:41 ` [PATCH v6 08/13] ARC: Linux ABI Vineet Gupta
2020-04-23  1:41 ` [PATCH v6 09/13] ARC: Linux Startup and Dynamic Loading Vineet Gupta
2020-04-23  1:41 ` [PATCH v6 10/13] ARC: ABI lists Vineet Gupta
2020-04-23  1:41 ` [PATCH v6 11/13] ARC: Build Infrastructure Vineet Gupta
2020-06-03 19:58   ` Adhemerval Zanella
2020-06-04 15:25     ` Vineet Gupta
2020-06-04 17:05       ` Adhemerval Zanella
2020-06-08  4:18         ` Vineet Gupta
2020-04-23  1:41 ` [PATCH v6 12/13] build-many-glibcs.py: Enable ARC builds Vineet Gupta
2020-04-23  1:41 ` [PATCH v6 13/13] Documentation for ARC port Vineet Gupta
2020-05-04 21:21 ` [PATCH v6 00/13] glibc port to ARC processors Vineet Gupta
2020-05-15  0:45   ` Vineet Gupta
2020-05-27  1:49     ` Vineet Gupta
     [not found]       ` <d7f1176c-87c6-90c6-161c-4705a47837ea@linaro.org>
2020-05-27 18:38         ` Vineet Gupta

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