[oe] [OE-core] [RFT] GCC 8.1

[Khem Raj]

On Thu, May 10, 2018 at 6:11 PM, Andre McCurdy <armccurdy at gmail.com> wrote:
> On Thu, May 10, 2018 at 6:06 PM, Khem Raj <raj.khem at gmail.com> wrote:
>> On Thu, May 10, 2018 at 6:00 PM, Andre McCurdy <armccurdy at gmail.com> wrote:
>>> On Thu, May 10, 2018 at 5:55 PM, Khem Raj <raj.khem at gmail.com> wrote:
>>>> On Thu, May 10, 2018 at 4:11 PM, Andre McCurdy <armccurdy at gmail.com> wrote:
>>>>> On Thu, May 10, 2018 at 3:50 PM, Martin Jansa <martin.jansa at gmail.com> wrote:
>>>>>> On Thu, May 10, 2018 at 03:40:53PM -0700, Andre McCurdy wrote:
>>>>>>> On Thu, May 10, 2018 at 3:38 PM, Martin Jansa <martin.jansa at gmail.com> wrote:
>>>>>>> > see
>>>>>>> > http://lists.openembedded.org/pipermail/openembedded-core/2018-May/150654.html
>>>>>>>
>>>>>>> Removing -fno-omit-frame-pointer isn't the same as adding
>>>>>>> -fomit-frame-pointer. Frame pointers may get enabled depending on the
>>>>>>> optimisation level etc (ie not only by -fno-omit-frame-pointer).
>>>>>>
>>>>>> Should I send v2 adding -fomit-frame-pointer instead of removing
>>>>>> -fno-omit-frame-pointer?
>>>>>>
>>>>>> The v1 fixes the issue for me with default config + DEBUG_BUILD.
>>>>>
>>>>> The v1 patch isn't wrong, it's just incomplete (the problem could come
>>>>> back if someone changes optimisation level or switches gcc to clang,
>>>>> etc).
>>>>>
>>>>> My choice would be a v2 patch which adds -fomit-frame-pointer to
>>>>> CFLAGS unconditionally for all ARM builds when Thumb is enabled. That
>>>>> should fix the problem for all optimisation levels etc and avoids
>>>>> building the main strace binary differently depending on whether or
>>>>> not ptest is enabled.
>>>>
>>>> explicitly adding this option is a poor choice especially for debug
>>>> builds where we should
>>>> let the -On level decide and not explicitly ask for either
>>>> enable/disable frame-pointers
>>>> that will also make it compiler proof.
>>>
>>> Of course, we should let the compiler decide whenever it's possible to do so.
>>>
>>> Unfortunately there are cases like this one where frame pointers clash
>>> with inline assembler and we need to over-rule the compiler's choice.
>>
>> Here we are adding -fno-omit-frame-pointer via global opt flags that
>> is the issue
>> where we have fallouts from default O options I agree we should teach
>> this to build
>> system and help the compiler
>
> Since there's NO situation where enabling frame pointers is going to
> work for this code + ARM + Thumb, I don't see the advantage of leaving
> anything up to chance. Just explicitly disabling frame pointers is the
> safest and cleanest option.

In that case what we are saying is that strace has wrong assumptions
I would think its best to change strace build system to demand this
option override instead of injecting it externally.