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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/110111] bool patterns that should produce a?b:c
Date: Tue, 29 Aug 2023 05:27:05 +0000	[thread overview]
Message-ID: <bug-110111-4-gcR7S1BR74@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-110111-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110111

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
f1:
  _6 = b_2(D) ^ c_3(D);
  _7 = a_1(D) & _6;
  _4 = c_3(D) ^ _7;

Which was done due to:
/* (x & ~m) | (y & m) -> ((x ^ y) & m) ^ x */
(simplify
 (bit_ior:c (bit_and:cs @0 (bit_not @2)) (bit_and:cs @1 @2))
 (bit_xor (bit_and (bit_xor @0 @1) @2) @0))

Note if we move this over to bitwise_inverted_equal_p (which we should), we
will lose also:
```
bool f(int a, int b, int t)
{
  bool x = a == 0;
  bool y = b == 1;
  bool m = t == 2;
  bool mp = !m;
  return (x & mp) | (y & m);
}
```
Which is currently handled.
We should check for `element_precision (type) == 1` too.

So something like:

(simplify
 (bit_ior (bit_and:c@and1 @0 @3) (bit_and:c@and2 @1 @2))
 (with { bool wascmp; }
  (if (bitwise_inverted_equal_p (@0, @2, wascmp))
   (switch
    /* For 1bit, wascmp can be true and we can just convert it into `m ? y : x`
*/
    (if (INTEGRAL_TYPE_P (type) && element_precision (type) == 1)
     (cond @3 @0 @1))
    (if (!wascmp && element_precision (type) != 1
         && single_use (@and1) && single_use (@and2))
     (bit_xor (bit_and (bit_xor @0 @1) @2) @0))
    )
   )
  )
 )
)

/* 1bit `((x ^ y) & m) ^ x` should just be convert into `m ? y : x` early */
(simplify
 (bit_xor:c (bit_and:c (bit_xor:c @0 @1) @2) @0)
 (if (INTEGRAL_TYPE_P (type) && element_precision (type) == 1)
  (cond @2 @0 @1)))

  parent reply	other threads:[~2023-08-29  5:27 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-04  8:15 [Bug tree-optimization/110111] New: " pinskia at gcc dot gnu.org
2023-07-12  6:20 ` [Bug tree-optimization/110111] " pinskia at gcc dot gnu.org
2023-08-24  6:47 ` pinskia at gcc dot gnu.org
2023-08-29  5:27 ` pinskia at gcc dot gnu.org [this message]
2023-08-29  8:10 ` pinskia at gcc dot gnu.org

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