Re: [PATCH 2/2] Add match patterns for `a ? onezero : onezero` where one of the two operands are constant

[Jeff Law <jeffreyalaw@gmail.com>]

On 6/6/23 18:17, Andrew Pinski via Gcc-patches wrote:
> This adds a match pattern that are for boolean values
> that optimizes `a ? onezero : 0` to `a & onezero` and
> `a ? 1 : onezero` to `a | onezero`.
> 
> This was reported a few times and I thought I would finally
> add the match pattern for this.
> 
> This hits a few times in GCC itself too.
> 
> Notes on the testcases:
> * phi-opt-2.c: This now is optimized to `a & b` in phiopt rather than ifcombine
> * phi-opt-25b.c: The test part that was failing was parity which now gets `x & y` treatment.
> * ssa-thread-21.c: there is no longer a threading opportunity, so need to disable phiopt.
>    Note PR 109957 is filed for the now missing optimization in that testcase too.
> 
> gcc/ChangeLog:
> 
> 	PR tree-optimization/89263
> 	PR tree-optimization/99069
> 	PR tree-optimization/20083
> 	PR tree-optimization/94898
> 	* match.pd: Add patterns to optimize `a ? onezero : onezero` with
> 	one of the operands are constant.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.dg/tree-ssa/phi-opt-2.c: Adjust the testcase.
> 	* gcc.dg/tree-ssa/phi-opt-25b.c: Adjust the testcase.
> 	* gcc.dg/tree-ssa/ssa-thread-21.c: Disable phiopt.
> 	* gcc.dg/tree-ssa/phi-opt-27.c: New test.
> 	* gcc.dg/tree-ssa/phi-opt-28.c: New test.
> 	* gcc.dg/tree-ssa/phi-opt-29.c: New test.
> 	* gcc.dg/tree-ssa/phi-opt-30.c: New test.
> 	* gcc.dg/tree-ssa/phi-opt-31.c: New test.
> 	* gcc.dg/tree-ssa/phi-opt-32.c: New test.
OK.

tbird rendered the bool0^1 as bool0 to the first power, so I was briefly 
confused before I realized what was going on.

jeff