Re: [PATCH] Simplify "1 - bool_val" to "bool_val ^ 1"

[Jeff Law <jeffreyalaw@gmail.com>]

On 1/31/23 18:21, Andrew Pinski via Gcc-patches wrote:
> For bool values, it is easier to deal with
> xor 1 rather than having 1 - a. This is because
> we are more likely to simplify the xor further in many
> cases.
> 
> This is a special case for (MASK - b) where MASK
> is a powerof2 - 1 and b <= MASK but only for bool
> ranges ([0,1]) as that is the main case where the
> difference comes into play.
> 
> Note this is enabled for gimple folding only
> as the ranges are only know while doing gimple
> folding and cfun is not always set when fold is called.
> 
> OK? Bootstrapped and tested on x86_64-linux-gnu with no
> regressions.
> 
> gcc/ChangeLog:
> 
> 	PR tree-optimization/108355
> 	PR tree-optimization/96921
> 	* match.pd: Add pattern for "1 - bool_val".
> 
> gcc/testsuite/ChangeLog:
> 
> 	PR tree-optimization/108355
> 	PR tree-optimization/96921
> 	* gcc.dg/tree-ssa/bool-minus-1.c: New test.
> 	* gcc.dg/tree-ssa/bool-minus-2.c: New test.
> 	* gcc.dg/tree-ssa/pr108354-1.c: New test.
OK.
jeff