This is the mail archive of the
cygwin@cygwin.com
mailing list for the Cygwin project.
Re:Strange behaviour of gcc
- From: Danny Smith <danny_r_smith_2001 at yahoo dot co dot nz>
- To: cygwin at cygwin dot com
- Cc: fabrizio_ge-wolit at tiscali dot it
- Date: Tue, 24 Dec 2002 16:11:34 +1100 (EST)
- Subject: Re:Strange behaviour of gcc
fabrizio_ge-wolit@tiscali.it wrote:
> Can somebody explain why gcc (version 3.2 20020927) on Cygwin does
> this? Type this simple C program
>
> void func(void){
> struct {unsigned char data[3985];}var;
> }
>
> and compile with
>
> gcc -c filename.c
>
> Then type
>
> nm filename.o
>
> The output is
>
> 00000000 b .bss
> 00000000 d .data
> 00000000 t .text
> U __alloca
> 00000000 T _func
>
> Why on earth is the symbol __alloca doing there?
>
> Just change the program to
>
> void func(void){
> struct {unsigned char data[3984];}var;
> }
>
> and compile it. This time, nm's output is
>
> 00000000 b .bss
> 00000000 d .data
> 00000000 t .text
> 00000000 T _func
>
> as it should. Is there a reason why the symbol __alloca appears?
GCC's __builtin_alloca uses a helper function called _alloca to check the stack
whenever allocating more that 4000 bytes in one go.
Danny
http://movies.yahoo.com.au - Yahoo! Movies
- What's on at your local cinema?
--
Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
Bug reporting: http://cygwin.com/bugs.html
Documentation: http://cygwin.com/docs.html
FAQ: http://cygwin.com/faq/