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Re: [PATCH 1/3][GCC] Add new target hook asm_post_cfi_startproc


On 11/5/18 10:18 AM, Sam Tebbs wrote:

> On 11/05/2018 07:54 AM, Richard Biener wrote:
>> On Fri, 2 Nov 2018, Sam Tebbs wrote:
>>
>>> On 11/02/2018 05:28 PM, Sam Tebbs wrote:
>>>
>>>> Hi all,
>>>>
>>>> This patch adds a new target hook called "asm_post_cfi_startproc". This hook is
>>>> intended to be used by the aarch64 backend to emit a directive that enables
>>>> support for unwinding frames signed with the pointer authentication B-key. This
>>>> hook is triggered after the ".cfi_startproc" directive is emitted in
>>>> gcc/dwarf2out.c.
>>>>
>>>> Bootstrapped on aarch64-none-linux-gnu and tested on aarch64-none-elf with no regressions.
>>>>
>>>> Ok for trunk?
>> Can you explain why existing prologue/cfi emission points are not
>> enough?
> I couldn't find any target hooks that were triggered at the
> assembly-printing level at the correct point in time (after
> .cfi_startproc is emitted), please do point me to one if that is not the
> case.
>
> An alternative could have been to implement a new reg_note but that
> would have meant adding target-specific code to target-agnostic files
> and wouldn't have been as flexible.
>
> Sam
>
>>>> gcc/
>>>> 2018-11-02  Sam Tebbs<sam.tebbs@arm.com>
>>>>
>>>> 	* doc/tm.texi (TARGET_ASM_POST_CFI_STARTPROC): Define.
>>>> 	* doc/tm.texi.in (TARGET_ASM_POST_CFI_STARTPROC): Define.
>>>> 	* dwarf2out.c (dwarf2out_do_cfi_startproc): Trigger the hook.
>>>> 	* hooks.c (hook_void_FILEptr_tree): Define.
>>>> 	* hooks.h (hook_void_FILEptr_tree): Define.
>>>> 	* target.def (post_cfi_startproc): Define.
>>> CCing global reviewers and dwarf maintainers.
>>>
>>>
>>>
ping 4. There are previous pings in another thread with more maintainers 
CC'ed, but pinging here as this is where the conversation has been.

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