[patch ping] C6X unwinding/exception handling

[Jonathan Wakely]

On 1 September 2011 12:07, Paul Brook wrote:
> Ping for libstdc++ bits?

If it really is that or an ABI bump, then I guess we want that :-)

I'd feel more comfortable with another maintainer approving it though,
I'm not competent to review the EH code.


> (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.
>
>