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Re: Is it possible to make gcc detect whether printf prints floating point numbers?
- From: "Bin.Cheng" <amker dot cheng at gmail dot com>
- To: Andrew Haley <aph at redhat dot com>
- Cc: "gcc-help at gcc dot gnu dot org" <gcc-help at gcc dot gnu dot org>
- Date: Fri, 8 Jun 2012 17:57:15 +0800
- Subject: Re: Is it possible to make gcc detect whether printf prints floating point numbers?
- References: <CAHFci29a5rfe+5BeyHmfzXcV7T=mQkQW9XXtTo=7CvpM5=-zWQ@mail.gmail.com> <4FD1C262.20907@redhat.com>
On Fri, Jun 8, 2012 at 5:14 PM, Andrew Haley <aph@redhat.com> wrote:
> [Redirect to gcc-help]
>
> On 06/08/2012 09:54 AM, Bin.Cheng wrote:
>> In micro-controller applications, code size is critical and the size
>> problem is worse if library is linked.
>> For example, most c programs call printf to format output data, that
>> means floating point code get linked even the program only want to
>> output non-floating point numbers. Currently, we rely on end-user to
>> call iprintf if the program does not want floating point.
>>
>> 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.
>
> It wouldn't be at all difficult, but you'd have to change gcc.
>
Thanks Andrew.
How about the question:
The check is done in front end, so how should I expose the check
result to back-end. Is there any hook utility?
Thanks.
--
Best Regards.