Re: [PATCH] FreeBSD arm support, EABI.

[Richard Earnshaw <rearnsha at arm dot com>]

On 02/11/14 22:11, Andreas Tobler wrote:
> Hello all,
> 
> this is a patch which brings support for arm*-*-freebsd* to trunk.
> The architectures supported are arm-*-*freebsd*, armv6-*-freebsd* and 
> armv6hf-*-freebsd*.
> armv6 stands for ARM_ARCH == 6, arm stands for ARM_ARCH < 6.
> 
> There is kernel development for armv8 aka. aarch64 ongoing but this is 
> not covered here. This patch only covers 32-bit arm in a basic manner.
> 
> The patch is built and tested against armv6, armv6hf and arm. The former 
> two tests (lots of) were done on a WANDBOARD-QUAD, the latter on a 
> MARVELL board with 256MB Ram and 200MHz cpu.... (around 72h+ for a build 
> and test.....)
> 
> Results for armv6hf are on the list. Only one entry but locally I ran 
> several dozens runs...
> 
> Once if this patch is accepted a few test suite additions will follow.
> (arm*-*-*eabi* -> arm_eabi)
> 
> The patch itself is also prepared for arm*eb*-*-freebsd*, but I could 
> not test since I lack the HW.
> 
> I appreciate comments, questions and also an ack if this patch is ok for 
> trunk.
> 
> TIA,
> 
> Andreas
> 
> toplevel:
> 
> 2014-11-02  Andreas Tobler  <andreast@gcc.gnu.org>
> 
> 	* configure.ac: Don't add ${libgcj} for arm*-*-freebsd*.
> 	* configure: Regenerate.
> 
> gcc:
> 
> 2014-11-02  Andreas Tobler  <andreast@gcc.gnu.org>
> 
> 	* config.gcc (arm*-*-freebsd*): New configuration.
> 	* config/arm/freebsd.h: New file.
> 	* config.host: A extras components for arm*-*-freebsd*.
> 	* config/arm/arm.c (arm_init_libfuncs): FreeBSD does not support 8 byte
> 	atomics for __ARM_ARCH__ < 6 yet.
> 	(arm_option_override): FreeBSD has not yet implemented unaligned access.
> 
> libgcc:
> 
> 2014-11-02  Andreas Tobler  <andreast@gcc.gnu.org>
> 
> 	* config.host (arm*-*-freebsd*): Add new configuration for
> 	arm*-*-freebsd*.
> 	* config/arm/freebsd-atomic.c: New file.
> 	* config/arm/t-freebsd: Likewise.
> 	* config/arm/unwind-arm.h: Add __FreeBSD__ to the list of 'PC-relative
> 	indirect' OS's.
> 
> libstdc++:
> 
> 2014-11-02  Andreas Tobler  <andreast@gcc.gnu.org>
> 
> 	* configure.host: Add arm*-*-freebsd* port_specific_symbol_files.
> 
> 

This mostly looks OK, but a couple of nits.


> Index: gcc/config/arm/arm.c
> ===================================================================
> --- gcc/config/arm/arm.c	(revision 217020)
> +++ gcc/config/arm/arm.c	(working copy)
> @@ -2202,7 +2202,11 @@
>  {
>    /* For Linux, we have access to kernel support for atomic operations.  */
>    if (arm_abi == ARM_ABI_AAPCS_LINUX)
> +#ifndef __FreeBSD__
>      init_sync_libfuncs (2 * UNITS_PER_WORD);
> +#else
> +    init_sync_libfuncs (UNITS_PER_WORD);
> +#endif

This would be better handled by some refactoring, so that we can
eliminate the conditionalized code in the main function.  Define
something like MAX_SYNC_LIBFUNC_SIZE and then override it in the
FreeBSD-specific header.

> @@ -3036,6 +3040,9 @@
>        warning (0, "target CPU does not support unaligned accesses");
>        unaligned_access = 0;
>      }
> +#ifdef __FreeBSD__
> +      unaligned_access = 0;
> +#endif
>  

This really should be fixed in the OS; you're not really supporting the
architecture properly if you don't allow this on v6 or later.  In the
mean time, the code should be moved to SUBTARGET_OVERRIDE_OPTIONS.

> Index: gcc/config/arm/freebsd.h
> ===================================================================
> --- gcc/config/arm/freebsd.h	(revision 0)
> +++ gcc/config/arm/freebsd.h	(working copy)

> +
> +/*  Use the AAPCS type for wchar_t, override the one from config/freebsd.h.  */
> +#undef  WCHAR_TYPE
> +#define WCHAR_TYPE (TARGET_AAPCS_BASED ? "unsigned int" : "long int")

I don't think you should really be targeting anything that is not AAPCS
based; so this should surely collapse to 'unsigned int'.