Re: [arm] Tweak C++ guard variables

[Mark Mitchell <mark at codesourcery dot com>]

Paul Brook wrote:

> The patch below changes guard variables for static one-time construction in 
> line with the arm c++ eabi.
> It consists of two changes:
> - The guard variable is a (32-bit) int, not long long.
> - It sets/tests the least significant bit, rather than the first byte.
>
> Technically the g++ and libstdc++ changes are independent because the compiler 
> doesn't use the helper function, but it makes sense to keep them in sync.
>
> I've enabled the changes unconditionally (on arm targets). I'm not sure if 
> this is desirable, or if they should only be enables when an eabi based abi 
> is used.
>  
I think they should only be used when the EABI is enabled so that ARM 
GNU/Linux (for example) doesn't see an ABI change.

These two functions need comments:

> +static tree
> +arm_cxx_guard_type (void)
> +{
> +  return integer_type_node;
> +}
> +
> +static bool
> +arm_cxx_guard_mask_bit (void)
> +{
> +  return TRUE;
> +}
>  
>
> Index: libstdc++-v3/libsupc++/cxxabi.h
> ===================================================================
> RCS file: /var/cvsroot/gcc-cvs/gcc/libstdc++-v3/libsupc++/cxxabi.h,v
> retrieving revision 1.16
> diff -u -p -r1.16 cxxabi.h
> --- libstdc++-v3/libsupc++/cxxabi.h	22 May 2004 21:07:28 -0000	1.16
> +++ libstdc++-v3/libsupc++/cxxabi.h	24 Jun 2004 14:32:52 -0000
> @@ -44,6 +44,11 @@
>
> #include <stddef.h>
>  
> +/* ??? We should probably define this in the compiler.  */
>  
Yes, we should, but this is probably OK for now.

OK with those changes.

Thanks,

--
Mark Mitchell
CodeSourcery, LLC
(916) 791-8304
mark@codesourcery.com