Re: [PATCH][5/n] Remove GENERIC stmt combining from SCCVN

[Marc Glisse <marc.glisse@inria.fr>]

On Fri, 26 Jun 2015, Richard Biener wrote:

> + /* Equality compare simplifications from fold_binary  */
> + (for cmp (eq ne)
> +
> +  /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
> +     Similarly for NE_EXPR.  */
> +  (simplify
> +   (cmp (convert?@3 (bit_ior @0 INTEGER_CST@1)) INTEGER_CST@2)
> +   (if (tree_nop_conversion_p (TREE_TYPE (@3), TREE_TYPE (@0))
> +        && wi::bit_and_not (@1, @2) != 0)
> +    { constant_boolean_node (cmp == NE_EXPR, type); }))
> +
> +  /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y.  */
> +  (simplify
> +   (cmp (bit_xor @0 @1) integer_zerop)
> +   (cmp @0 @1))
> +
> +  /* (X ^ Y) == Y becomes X == 0.
> +     Likewise (X ^ Y) == X becomes Y == 0.  */
> +  (simplify
> +   (cmp (bit_xor:c @0 @1) @0)

Don't you need cmp:c for this one? The transformation still somehow 
happens through forward_propagate_into_comparison, but it looks like an 
accident.

> +   (cmp @1 { build_zero_cst (TREE_TYPE (@1)); }))
> +
> +  /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2).  */
> +  (simplify
> +   (cmp (convert?@3 (bit_xor @0 INTEGER_CST@1)) INTEGER_CST@2)
> +   (if (tree_nop_conversion_p (TREE_TYPE (@3), TREE_TYPE (@0)))
> +    (cmp @0 (bit_xor @1 (convert @2))))))

I guess we'll have to generalize this to vectors at some point...

-- 
Marc Glisse