[U-Boot] Discussion topics / issues

[Jeroen Hofstee]

Hello Albert,

On 10-10-14 21:51, Albert ARIBAUD wrote:
> Hi Jeroen,
>
> On Fri, 10 Oct 2014 18:09:19 +0200, Jeroen Hofstee
> <jeroen at myspectrum.nl> wrote:
>
>> Hello Marek,
>>
>> On 10-10-14 16:26, Marek Vasut wrote:
>>> On Friday, October 10, 2014 at 04:04:40 PM, Jeroen Hofstee wrote:
>>>> Hello Wolfgang,
>>>>
>>>> On 10-10-14 14:22, Wolfgang Denk wrote:
>>>>>> It does not mention puts() vs. printf(), if it is indeed meant to be
>>>>>> u-boot policy.
>>>>> This is not just U-Boot philosophy, but something that I would
>>>>> consider a matter of course when writing code - using the appropriate
>>>>> tools for the task at hand.  If all you want to do is sendout a
>>>>> constant string to the utput device, there is no need to invoke a
>>>>> function that provides fancy formatting options.
>>>>>
>>>>> Don't we always try to use the smallest, most efficient tool that is
>>>>> suited for a task?
>>>> calling printf("%s\n", "string") gets translated into puts by the
>>>> compiler. There should be no difference in the binary
>>> Is this LLVM specific or does GCC do that too ? This is interesting information.
>> I was talking about gcc, it has been doing such since ages ago
>> (unless you purposely disable it). clang does it as well.
> That's a good thing, but generally speaking, I think that just because
> the compiler is being clever doesn't mean we are allowed to rely on
> that, because if we do take a habit of relying on the compiler being
> clever, two things will happen:

Why can't this be relied on, I gave up digging if this is a gcc 3 or 2
feature. It is old at least, museum stuff if it is not supported.

> 1) we will keep thinking the compiler is being clever even when for
> some reason it will stop being clever -- for instance, because someone
> decided to disable the clever feature;

If you ask to disable it, it is good if it does so, don't see a problem
with that. Anyway, it is not an u-boot issue, anything below -O2 is not
supported anyway.

> 2) we will begin thinking the compiler is clever in situations where it
> never has and never will.

I would almost take this as an insult, I hope u-boot folks know or at
least check before they assume a compiler does XYZ. And yes
compilers will replace simple printf call with their simpler equivalent
and has been doing so for quite a while (and that is an understatement).

> IMO, a quick cost/benefit comparison of choosing between manually
> turning printf() into puts whenever doable vs letting the compiler do
> the changes automatically, the manual option wins -- it's bit like
> Pascal's Wager: you don't lose much but you can only win.

No it is the other way around; why on earth do you want demand
patch submitters to make changes which result in the exactly same
binary; you waste time of reviewers / patch submitter and it doesn't
serve a goal.

So to turn it around: just use printf: "you don't lose much but you
can only win."

Regards,
Jeroen