On 6/7/23 17:05, Andrew Pinski wrote:
On Wed, Jun 7, 2023 at 3:57 PM Jeff Law via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
On 6/7/23 15:32, Andrew Pinski via Gcc-patches wrote:
Since there is a pattern to convert `(-zero_one) & z` into `zero_one * z`
already,
it is better if we don't do a secondary transformation. This reduces the extra
statements produced by match-and-simplify on the gimple level too.
gcc/ChangeLog:
* match.pd (`zero_one ==/!= 0) ? y : z <op> y`): Use
multiply rather than negation/bit_and.
Don't you need to check the types in a manner similar to what the A & -Y
-> X * Y pattern does before you make this transformation?
No, because the convert is in a different order than in that
transformation; a very subtle difference which makes it work.
In A & -Y it was matching:
(bit_and (convert? (negate
But here we have:
(bit_and (negate (convert
Notice the convert is in a different location, in the `A & -Y` case,
the convert needs to be a sign extending (or a truncation) of the
negative value. Here we are converting the one_zero_value to the new
type so we get zero_one in the new type and then doing the negation
getting us 0 or -1 value.
THanks for the clarification. OK for the trunk.
jeff
