How to know default gcc flags ?

[Pravin Shedage]

Hi Pritam,

You can use -frecord-gcc-switches.
This switch causes the command line that was used to invoke the compiler to
be recorded into the object file that is being created.

$ gcc -O2 -frecord-gcc-switches -g -o test test.c
$ <pravin at pravin-VirtualBox:/tmp$> readelf -p .GCC.command.line test
String dump of section '.GCC.command.line':
  [     0]  test.c
  [     7]  -D_FORTIFY_SOURCE=2
  [    1b]  -mtune=generic
  [    2a]  -march=i686
  [    36]  -g
  [    39]  -O2
  [    3d]  -frecord-gcc-switches
  [    53]  -fstack-protector<-fstack-protectorpravin at pravin-VirtualBox:/tmp$>
$
$ readelf --debug-dump test

<-fstack-protectorpravin at pravin-VirtualBox:/tmp$>
checkout the  *.debug_info* section of readelf output.


Thanks & Regards,
        PraviN


On Thu, Aug 23, 2012 at 7:50 PM, Mulyadi Santosa
<mulyadi.santosa at gmail.com>wrote:

> Hi..
>
> On Thu, Aug 23, 2012 at 4:37 PM, Pritam Bankar
> <pritambankar1988 at gmail.com> wrote:
> > How to know default flags used in specific gcc version ? I am looking
> > for difference between 3.4.3 and 4.1.1 These two have some difference
> > regarding -nosse option but how can I find this ?
>
> try something like:
> echo "" | gcc -E -v - 2>&1 | grep -i cc
>
> and find the line like below:
>
> /usr/lib/gcc/i686-linux-gnu/4.6/cc1 -E -quiet -v -imultilib .
> -imultiarch i386-linux-gnu - -mtune=generic -march=i686
> -fstack-protector
>
> (that's mine on Core Duo, Linux Mint 13 32 bit)
>
> --
> regards,
>
> Mulyadi Santosa
> Freelance Linux trainer and consultant
>
> blog: the-hydra.blogspot.com
> training: mulyaditraining.blogspot.com
>
> _______________________________________________
> Kernelnewbies mailing list
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>



-- 
Thanks & Regards,*
---------PraviN---------*
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