From: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
To: Alan Modra <amodra@gmail.com>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Nemanja Ivanovic <nemanjai@ca.ibm.com>, libc-alpha@sourceware.org
Subject: Re: [PATCH] powerpc: Define USE_PPC64_NOTOC iff compiler and linker also supports it
Date: Tue, 16 Nov 2021 17:20:21 -0300 [thread overview]
Message-ID: <87wnl73la2.fsf@linux.ibm.com> (raw)
In-Reply-To: <87zgq33n1k.fsf@linux.ibm.com>
Tulio Magno Quites Machado Filho via Libc-alpha <libc-alpha@sourceware.org> writes:
> Alan Modra via Libc-alpha <libc-alpha@sourceware.org> writes:
>
>> I have a question about powerpc64/ppc-mcount.S. Why is the assembly
>> wrapper using ENTRY and a NOTOC call? By using ENTRY you are saying
>> that calls to _mcount must have r2 valid. Given that r2 is valid, why
>> then use NOTOC?
>
> I wouldn't be surprised if that was a misinterpretation of the ABI on my part.
>
> Looking at table 2.20 "Protocols for Local Function Calls", I think this is a
> scenario that falls to the last row of this table, where we have:
OK, I should be looking at table 2.19 because this is not a call within the
same compilation unit.
I guess that answers my previous question and all these calls should have nop
after the branch.
--
Tulio Magno
next prev parent reply other threads:[~2021-11-16 20:20 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-08 11:33 Adhemerval Zanella
2021-11-08 22:48 ` Fangrui Song
2021-11-09 11:05 ` Alan Modra
2021-11-16 19:42 ` Tulio Magno Quites Machado Filho
2021-11-16 20:20 ` Tulio Magno Quites Machado Filho [this message]
2021-11-16 20:48 ` Florian Weimer
2021-11-16 22:12 ` Fāng-ruì Sòng
2021-11-16 22:46 ` Bill Schmidt
2021-11-17 2:16 ` Alan Modra
2021-11-17 2:30 ` Alan Modra
2021-11-09 13:03 ` Adhemerval Zanella
2021-11-09 17:44 ` Fangrui Song
2021-11-09 18:44 ` Adhemerval Zanella
2021-11-19 15:52 ` Tulio Magno Quites Machado Filho
2021-11-22 17:54 ` Adhemerval Zanella
2021-11-25 17:02 ` Tulio Magno Quites Machado Filho
2021-11-25 17:16 ` Adhemerval Zanella
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