Re: [PATCH 07/12] mode-switching: Allow targets to set the mode for EH handlers

[Jeff Law <jeffreyalaw@gmail.com>]

On 11/5/23 11:48, Richard Sandiford wrote:
> The mode-switching pass already had hooks to say what mode
> an entity is in on entry to a function and what mode it must
> be in on return.  For SME, we also want to say what mode an
> entity is guaranteed to be in on entry to an exception handler.
> 
> gcc/
> 	* target.def (mode_switching.eh_handler): New hook.
> 	* doc/tm.texi.in (TARGET_MODE_EH_HANDLER): New @hook.
> 	* doc/tm.texi: Regenerate.
> 	* mode-switching.cc (optimize_mode_switching): Use eh_handler
> 	to get the mode on entry to an exception handler.
Can we ever have a path to the exception handler triggered by a normal 
control flow and if so, presumably we want this to apply in that case too?

It looks like that's the semantics of the implementation by way to using 
bb_has_eh_pred.  Just want to make sure that's the semantics you want in 
that oddball case.

Assuming it is the semantics you want, it's OK for the trunk, though you 
might want to twiddle the docs slightly to mention that case.

jeff