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

[Khem Raj]

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