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Re: [patch ping] C6X unwinding/exception handling
- From: Jonathan Wakely <jwakely dot gcc at gmail dot com>
- To: Paul Brook <paul at codesourcery dot com>
- Cc: libstdc++ at gcc dot gnu dot org
- Date: Thu, 1 Sep 2011 12:44:04 +0100
- Subject: Re: [patch ping] C6X unwinding/exception handling
- References: <201108041531.58790.paul@codesourcery.com> <201109011207.28361.paul@codesourcery.com>
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.
>
>