Re: [PATCH] match.pd: Optimize (x & y) == x into (x & ~y) == 0 [PR94589]

[Richard Biener]

On Tue, 11 May 2021, Jakub Jelinek wrote:

> On Thu, May 06, 2021 at 09:42:41PM +0200, Marc Glisse wrote:
> > We can probably do it in 2 steps, first something like
> > 
> > (for cmp (eq ne)
> >  (simplify
> >   (cmp (bit_and:c @0 @1) @0)
> >   (cmp (@0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); })))
> > 
> > to get rid of the double use, and then simplify X==0 to X<=~C if C is a
> > mask 111...000 (I thought we already had a function to detect such masks, or
> > the 000...111, but I can't find them anymore).
> 
> Ok, here is the first step then.
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 
> Or should it have cmp:c too given that == and != are commutative too?

I think so.  OK with that change.

Richard.

> 2021-05-11  Jakub Jelinek  
>   Marc Glisse  
> 
>   PR tree-optimization/94589
>   * match.pd ((X & Y) == Y -> (X & ~Y) == 0,
>   (X | Y) == Y -> (X & ~Y) == 0): New GIMPLE simplifications.
> 
>   * gcc.dg/tree-ssa/pr94589-1.c: New test.
> 
> --- gcc/match.pd.jj   2021-04-27 14:46:56.583716888 +0200
> +++ gcc/match.pd  2021-05-10 22:31:49.726870421 +0200
> @@ -4764,6 +4764,18 @@ (define_operator_list COND_TERNARY
>(cmp:c (bit_xor:c @0 @1) @0)
>(cmp @1 { build_zero_cst (TREE_TYPE (@1)); }))
>  
> +#if GIMPLE
> + /* (X & Y) == X becomes (X & ~Y) == 0.  */
> + (simplify
> +  (cmp (bit_and:c @0 @1) @0)
> +  (cmp (bit_and @0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); }))
> +
> + /* (X | Y) == Y becomes (X & ~Y) == 0.  */
> + (simplify
> +  (cmp (bit_ior:c @0 @1) @1)
> +  (cmp (bit_and @0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); }))
> +#endif
> +
>   /* (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)
> --- gcc/testsuite/gcc.dg/tree-ssa/pr94589-1.c.jj  2021-05-10 
> 22:36:10.574130179 +0200
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr94589-1.c 2021-05-10 22:36:17.789054362 
> +0200
> @@ -0,0 +1,21 @@
> +/* PR tree-optimization/94589 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +int
> +foo (int x)
> +{
> +  return (x & 23) == x;
> +/* { dg-final { scan-tree-dump " & -24;" "optimized" } } */
> +/* { dg-final { scan-tree-dump-not " & 23;" "optimized" } } */
> +/* { dg-final { scan-tree-dump " == 0" "optimized" } } */
> +}
> +
> +int
> +bar (int x)
> +{
> +  return (x | 137) != 137;
> +/* { dg-final { scan-tree-dump " & -138;" "optimized" } } */
> +/* { dg-final { scan-tree-dump-not " \\| 137;" "optimized" } } */
> +/* { dg-final { scan-tree-dump " != 0" "optimized" } } */
> +}
> 
> 
>   Jakub
> 
> 

-- 
Richard Biener 
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)

Re: [PATCH] match.pd: Optimize (x & y) == x into (x & ~y) == 0 [PR94589]

[Marc Glisse]

On Tue, 11 May 2021, Jakub Jelinek via Gcc-patches wrote:


On Thu, May 06, 2021 at 09:42:41PM +0200, Marc Glisse wrote:

We can probably do it in 2 steps, first something like

(for cmp (eq ne)
 (simplify
  (cmp (bit_and:c @0 @1) @0)
  (cmp (@0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); })))

to get rid of the double use, and then simplify X==0 to X<=~C if C is a
mask 111...000 (I thought we already had a function to detect such masks, or
the 000...111, but I can't find them anymore).


Ok, here is the first step then.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Or should it have cmp:c too given that == and != are commutative too?


Ah, yes, you are right, good point on the cmp:c, thank you.


2021-05-11  Jakub Jelinek  
Marc Glisse  

PR tree-optimization/94589
* match.pd ((X & Y) == Y -> (X & ~Y) == 0,

   ^

X?


(X | Y) == Y -> (X & ~Y) == 0): New GIMPLE simplifications.

* gcc.dg/tree-ssa/pr94589-1.c: New test.

--- gcc/match.pd.jj 2021-04-27 14:46:56.583716888 +0200
+++ gcc/match.pd2021-05-10 22:31:49.726870421 +0200
@@ -4764,6 +4764,18 @@ (define_operator_list COND_TERNARY
  (cmp:c (bit_xor:c @0 @1) @0)
  (cmp @1 { build_zero_cst (TREE_TYPE (@1)); }))

+#if GIMPLE
+ /* (X & Y) == X becomes (X & ~Y) == 0.  */
+ (simplify
+  (cmp (bit_and:c @0 @1) @0)
+  (cmp (bit_and @0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); }))
+
+ /* (X | Y) == Y becomes (X & ~Y) == 0.  */
+ (simplify
+  (cmp (bit_ior:c @0 @1) @1)
+  (cmp (bit_and @0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); }))
+#endif
+
 /* (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)
--- gcc/testsuite/gcc.dg/tree-ssa/pr94589-1.c.jj2021-05-10 
22:36:10.574130179 +0200
+++ gcc/testsuite/gcc.dg/tree-ssa/pr94589-1.c   2021-05-10 22:36:17.789054362 
+0200
@@ -0,0 +1,21 @@
+/* PR tree-optimization/94589 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+int
+foo (int x)
+{
+  return (x & 23) == x;
+/* { dg-final { scan-tree-dump " & -24;" "optimized" } } */
+/* { dg-final { scan-tree-dump-not " & 23;" "optimized" } } */
+/* { dg-final { scan-tree-dump " == 0" "optimized" } } */
+}
+
+int
+bar (int x)
+{
+  return (x | 137) != 137;
+/* { dg-final { scan-tree-dump " & -138;" "optimized" } } */
+/* { dg-final { scan-tree-dump-not " \\| 137;" "optimized" } } */
+/* { dg-final { scan-tree-dump " != 0" "optimized" } } */
+}


Jakub


--
Marc Glisse

[PATCH] match.pd: Optimize (x & y) == x into (x & ~y) == 0 [PR94589]

[Jakub Jelinek via Gcc-patches]

On Thu, May 06, 2021 at 09:42:41PM +0200, Marc Glisse wrote:
> We can probably do it in 2 steps, first something like
> 
> (for cmp (eq ne)
>  (simplify
>   (cmp (bit_and:c @0 @1) @0)
>   (cmp (@0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); })))
> 
> to get rid of the double use, and then simplify X==0 to X<=~C if C is a
> mask 111...000 (I thought we already had a function to detect such masks, or
> the 000...111, but I can't find them anymore).

Ok, here is the first step then.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Or should it have cmp:c too given that == and != are commutative too?

2021-05-11  Jakub Jelinek  
Marc Glisse  

PR tree-optimization/94589
* match.pd ((X & Y) == Y -> (X & ~Y) == 0,
(X | Y) == Y -> (X & ~Y) == 0): New GIMPLE simplifications.

* gcc.dg/tree-ssa/pr94589-1.c: New test.

--- gcc/match.pd.jj 2021-04-27 14:46:56.583716888 +0200
+++ gcc/match.pd2021-05-10 22:31:49.726870421 +0200
@@ -4764,6 +4764,18 @@ (define_operator_list COND_TERNARY
   (cmp:c (bit_xor:c @0 @1) @0)
   (cmp @1 { build_zero_cst (TREE_TYPE (@1)); }))
 
+#if GIMPLE
+ /* (X & Y) == X becomes (X & ~Y) == 0.  */
+ (simplify
+  (cmp (bit_and:c @0 @1) @0)
+  (cmp (bit_and @0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); }))
+
+ /* (X | Y) == Y becomes (X & ~Y) == 0.  */
+ (simplify
+  (cmp (bit_ior:c @0 @1) @1)
+  (cmp (bit_and @0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); }))
+#endif
+
  /* (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)
--- gcc/testsuite/gcc.dg/tree-ssa/pr94589-1.c.jj2021-05-10 
22:36:10.574130179 +0200
+++ gcc/testsuite/gcc.dg/tree-ssa/pr94589-1.c   2021-05-10 22:36:17.789054362 
+0200
@@ -0,0 +1,21 @@
+/* PR tree-optimization/94589 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+int
+foo (int x)
+{
+  return (x & 23) == x;
+/* { dg-final { scan-tree-dump " & -24;" "optimized" } } */
+/* { dg-final { scan-tree-dump-not " & 23;" "optimized" } } */
+/* { dg-final { scan-tree-dump " == 0" "optimized" } } */
+}
+
+int
+bar (int x)
+{
+  return (x | 137) != 137;
+/* { dg-final { scan-tree-dump " & -138;" "optimized" } } */
+/* { dg-final { scan-tree-dump-not " \\| 137;" "optimized" } } */
+/* { dg-final { scan-tree-dump " != 0" "optimized" } } */
+}


Jakub