[patch ping] C6X unwinding/exception handling

[Paul Brook]

Ping for libstdc++ bits?

(Tested on arm-linux-gnueabi and c6x-elf, lightly tested on i686-linux)

http://gcc.gnu.org/ml/libstdc++/2011-08/msg00013.html

> C6X uses an unwinding/exception handling echeme very similar to that
> defined by the ARM EABI.  The core of the unwinder is the same, so I've
> pulled it out into a common file.
> 
> Other than the obvious target specific bits, the main compiler visible
> difference is that the C6X assembler generates the unwinding tables from
> DWARF .cfi directives, rather than the separate set of directives used by
> the ARM assembler.
> 
> The libstdc++ changes probably deserve a bit of explanation. The ttype_base
> field was clearly used in an early draft of the ARM EABI, and the current
> ARM definition is a compatible subset of that used by C6X.
> _GLIBCXX_OVERRIDE_TTYPE_ENCODING is an unfortunate hack because when doing
> the ARM implementation I failed to realise ttype_encoding was the same
> thing as R_ARM_TARGET2.  We now have a lot of ARM binaries floating around
> with that field set incorrectly, so it's either this or an ABI bump.
> 
> Ok?
> 
> Paul
> 
> 2011-08-04  Paul Brook  <paul@codesourcery.com>
> ...
> 
> 	libstdc++-v3/
> 	* libsupc++/eh_arm.cc (__cxa_end_cleanup): Add C6X implementation.
> 	* libsupc++/eh_call.cc (__cxa_call_unexpected): Set rtti_base.
> 	* libsupc++/eh_personality.cc (NO_SIZE_OF_ENCODED_VALUE): Remove
> 	__ARM_EABI_UNWINDER__ check.
> 	(parse_lsda_header): Check _GLIBCXX_OVERRIDE_TTYPE_ENCODING.
> 	(get_ttype_entry): Use generic implementation on ARM EABI.
> 	(check_exception_spec): Use _Unwind_decode_typeinfo_ptr and
> 	UNWIND_STACK_REG.
> 	(PERSONALITY_FUNCTION): Set ttype_base.  Use UNWIND_STACK_REG and
> 	UNWIND_POINTER_REG.