[LEDE-DEV] [PATCH] gcc: 7.2: remove mips patch causing broken code

[Hauke Mehrtens]

On 12/18/2017 11:38 PM, Hauke Mehrtens wrote:
> On 12/18/2017 03:07 PM, Kevin Darbyshire-Bryant wrote:
>>
>>
>>> On 18 Dec 2017, at 10:12, Felix Fietkau <nbd at nbd.name> wrote:
>>>
>>> On 2017-12-18 11:07, Kevin Darbyshire-Bryant wrote:
>>>> Hi Felix,
>>>>
>>>> Thanks for explaining that.  I suspect you’re right that there’s an underlying bug in gcc mips.  So ideally we need some code that exposes the bug when using -O2 (or even just -funroll_loops) Looking at FS 814 there’s a hint in there that uhttpd was similarly affected…and not solved by the patch drop.  So what to do if there’s a bug just lurking to bite us?
>>>
>>> If possible, reproduce it on uhttpd with an unmodified upstream version
>>> of GCC and open up a bug report.
>>>
>>> - Felix
>>
>> Sadly I’m unable to reproduce the uhttpd issue - frustrating.
>>
>> Cheers,
>>
>> Kevin D-B
> 
> Hi,
> 
> The attached patch also made the problem disappear.
> This patch builds the code with -funroll-loops in addition, otherwise
> only the default settings are used.
> 
> Hauke

I can reproduce this problem also without Felix's gcc patch.
When I compile libtommath from dropbear with "-mbranch-cost=1" I get the
same broken code. This is one of the changes Felix's patch does.

Hauke

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