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Re: [PATCH] Rework -fno-omit-frame-pointer support on i386
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Fri, 17 Feb 2017 09:44:22 -0800
- Subject: Re: [PATCH] Rework -fno-omit-frame-pointer support on i386
- Authentication-results: sourceware.org; auth=none
- References: <1483966550-21038-1-git-send-email-adhemerval.zanella@linaro.org> <CAMe9rOpsn6_y3MY6X=j-L7FncmWdkoQkQazvxRQUz=W_msRCeQ@mail.gmail.com> <0e80c379-4c5b-9d00-7331-6c4035fac5e2@linaro.org> <CAMe9rOpj4wh=ZGNBr47==hT=EaNavveFvbF5RQJsuMbFqF7eBA@mail.gmail.com> <0b7b1364-25da-d5b7-367d-7684efaa7766@linaro.org>
On Fri, Feb 17, 2017 at 9:08 AM, Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>>> -#if __GNUC_PREREQ (5,0) && !defined PROF
>>> + profiling or when -fno-omit-frame-pointer is used since asm ("ebp")
>>> + can't be used to put the 6th argument in %ebp for syscall. */
>>> +#if __GNUC_PREREQ (5,0) && !defined PROF && CAN_USE_REGISTER_ASM_EBP
>>
>> Should it be "defined CAN_USE_REGISTER_ASM_EBP"
>> since CAN_USE_REGISTER_ASM_EBP may not be defined.
>
> In fact since it is defined in config.h.in as default being 0, it will
> always be defined (also I check with -O2 and -Os without --disable-werror
> to confirm it.
>
>>
>>> # define OPTIMIZE_FOR_GCC_5
>>> #endif
>>>
>>> @@ -611,7 +611,8 @@ struct libc_do_syscall_args
>>> #endif
>>>
>>> /* Consistency check for position-independent code. */
>>> -#if defined __PIC__ && !defined OPTIMIZE_FOR_GCC_5
>>> +#if defined __PIC__ && !defined OPTIMIZE_FOR_GCC_5 \
>>> + && !CAN_USE_REGISTER_ASM_EBP
>>
>> No need for this. If CAN_USE_REGISTER_ASM_EBP
>> isn't defined, OPTIMIZE_FOR_GCC_5 won't be defined.
>>
>>> # define check_consistency() \
>>> ({ int __res; \
>>> __asm__ __volatile__ \
>>> --
>>> 2.7.4
>>>
>
> Right, I will remove it. I presume with this fix it is ok to commit.
Yes, it is OK with this change.
Thanks for working on this.
--
H.J.