Is it possible to make gcc detect whether printf prints floating point numbers?

[Thierry Moreau]

Joseph S. Myers wrote:
> On Tue, 12 Jun 2012, Bin.Cheng wrote:
> 
>>>> I noticed that GCC now can check format string of printf functions, so
>>>> I am wondering if it is possible to take advantage of this utility, by
>>>> making gcc detect whether printf prints floating point number and then
>>>> generate assembly directive in backend to pull in floating point
>>>> functions only if necessary.
>>> Obviously this won't help if the program is using functions such as
>>> vprintf to print things with variable format strings....
>> One method is to analyze the type of arguments when format strings are
>> varying. Though this method might fail when user trying to output a
>> "long long" type int with conversion specifier "%f", I think it's not
>> a big deal.
> 
> That method won't help for vprintf (unless you do something more 
> complicated and interprocedural) since then you have just a (probably 
> nonconstant) format strict and a (definitely nonconstant) va_list so don't 
> know the types of the arguments at all.
> 

The original question does not belong to gcc development. It's an 
embedded software tools issue.

The straightforward solution is to supply the (library internal) 
...printf() function that ultimately handles any C-style output format 
string. I mean a variant of this function that does not support floating 
point output.

I used the word straightforward because embedded software development 
usually implies more intricate issues with the run-time support library 
(exception handling, dynamic memory, linker issues). The more serious 
the memory restrictions in the embedded environment, the more critical 
these issues become.

Let gcc development proceed as a great compiler technology!

Regards,

-- 
- Thierry Moreau

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