Re: [PATCH] For the `-A CMP -B -> B CMP A` pattern allow EQ/NE for all integer types

[Jeff Law <jeffreyalaw@gmail.com>]

On 6/6/23 15:07, Andrew Pinski via Gcc-patches wrote:
> I noticed while looking at some code generation issue, that forwprop
> was not handling `-a == 0` for unsigned types and I was confused why
> it was not.
> r6-1814-g66e1cacf608045 removed these from fold because they
> were supposed to be already handled by the match.pd patterns
> but it was missed that the match.pd patterns checked
> TYPE_OVERFLOW_UNDEFINED while fold didn't do that for NE/EQ.
> This patch removes the restriction on NE/EQ on TYPE_OVERFLOW_UNDEFINED.
> 
> OK? Bootstrapped and tested on x86_64-linux-gnu.
> 
> gcc/ChangeLog:
> 
> 	PR tree-optimization/110134
> 	* match.pd (-A CMP -B -> B CMP A): Allow EQ/NE for all integer
> 	types.
> 	(-A CMP CST -> B CMP (-CST)): Likewise.
> 
> gcc/testsuite/ChangeLog:
> 
> 	PR tree-optimization/110134
> 	* gcc.dg/tree-ssa/negneq-1.c: New test.
> 	* gcc.dg/tree-ssa/negneq-2.c: New test.
> 	* gcc.dg/tree-ssa/negneq-3.c: New test.
> 	* gcc.dg/tree-ssa/negneq-4.c: New test.
OK.
jeff