Re: Recursive calloc() due to optimization

[Marc Glisse <marc dot glisse at inria dot fr>]

On Wed, 25 Mar 2015, Sebastian Huber wrote:

> Hello,
>
> I updated to GCC 5 and now it turns the RTEMS calloc() implementation into
>
> Disassembly of section .text:
>
> 00000000 <calloc>:
>   0:   fb01 f000       mul.w   r0, r1, r0
>   4:   2101            movs    r1, #1
>   6:   f7ff bffe       b.w     0 <calloc>
>   a:   bf00            nop
>
> on ARM. How can I disable this optimization? I tried
>
> __attribute__((__optimize__("-fno-builtin")))
> void *calloc(
>  size_t nelem,
>  size_t elsize
> )
> {
>  char   *cptr;
>  size_t  length;
>
>  length = nelem * elsize;
>  cptr = malloc( length );
>  if ( cptr )
>    memset( cptr, '\0', length );
>
>  return cptr;
> }
>
> but this doesn't work. It this one of the -fno-tree-* options?

-fno-builtin is good, but you cannot use it in an optimize attribute.

--
Marc Glisse