Re: [PATCH] ifcvt.cc: Prevent excessive if-conversion for conditional moves

[Jeff Law <jeffreyalaw@gmail.com>]

On 1/10/23 21:20, Takayuki 'January June' Suwa via Gcc-patches wrote:
> Currently, cond_move_process_if_block() does the conversion without
> balancing the cost of the converted sequence with the original one, but
> this should be checked by calling targetm.noce_conversion_profitable_p().
> 
> Doing so allows us to provide a way based on the target-specific cost
> estimate, to prevent unwanted size growth due to excessive conditional
> moves on optimizing for size.
> 
> On optimizing for speed, default_noce_conversion_profitable_p() allows
> plenty of headroom, so this patch has little impact.
> 
> Also, if the target-specific cost estimate is accurate or allows for
> margins, the impact should be similarly small.
> 
> gcc/ChangeLog:
> 
> 	* ifcvt.cc (cond_move_process_if_block):
> 	Consider the result of targetm.noce_conversion_profitable_p()
> 	when replacing the original sequence with the converted one.
This is OK for gcc-14 when stage1 opens.  The only way I see including 
it in gcc-13 would be if it fixes a regression.

jeff