[PR91504] Inlining misses some logical operation folding

Message ID CABKRkgjqsRUyH+c_yWgaQfzo4a-aBxqQdG+Hb07eeJVNgMok-w@mail.gmail.com
State New
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  • [PR91504] Inlining misses some logical operation folding
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Commit Message

kamlesh kumar Aug. 26, 2019, 7:06 a.m.
2019-08-26  Kamlesh Kumar  <kamleshbhalui@gmail.com>

        * gcc/match.pd: Added simplification
        pattern.
        * gcc.dg/tree-ssa/pr91504.c: New test.

Comments

Richard Biener Aug. 26, 2019, 12:04 p.m. | #1
On Mon, 26 Aug 2019, kamlesh kumar wrote:

> 2019-08-26  Kamlesh Kumar  <kamleshbhalui@gmail.com>

> 

>         * gcc/match.pd: Added simplification

>         pattern.

>         * gcc.dg/tree-ssa/pr91504.c: New test.

> ====================

> 

> diff --git a/gcc/match.pd b/gcc/match.pd

> index 93dcef9..b3734f8 100644

> --- a/gcc/match.pd

> +++ b/gcc/match.pd

> @@ -831,6 +831,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)

>   (bit_xor:c (bit_and:cs @0 (bit_not @1)) (bit_not @0))

>   (bit_not (bit_and @0 @1)))

> 

> +/* (~a & b) ^ a  -->   (a | b)   */

> +(simplify

> + (bit_xor:c (bit_and:cs (bit_not @0) @1) @0)

> + (bit_ior @0 @1))

> +


Are you sure?

(~1804289383 & 846930886) ^ 1804289383 != 1804289383 | 846930886

#include <stdio.h>
#include <stdlib.h>
int main ()
{
  while (1)
    {
      int a = random();
      int b = random();
      if ((~a & b) ^ a != a | b)
        {
          fprintf (stderr, "%d, %d\n", a, b);
          abort ();
        }
    }
}


>  /* (a | b) & ~(a ^ b)  -->  a & b  */

>  (simplify

>   (bit_and:c (bit_ior @0 @1) (bit_not (bit_xor:c @0 @1)))

> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr91504.c

> b/gcc/testsuite/gcc.dg/tree-ssa/pr91504.c

> new file mode 100644

> index 0000000..a52dea4

> --- /dev/null

> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr91504.c

> @@ -0,0 +1,18 @@

> +/* { dg-do compile } */

> +/* { dg-options "-O -fdump-tree-optimized-raw" } */

> +

> +static inline unsigned deposit32(unsigned value, int start, int length,

> +                                 unsigned fieldval)

> +{

> +    unsigned mask = (~0U >> (32 - length)) << start;

> +    return (value & ~mask) | ((fieldval << start) & mask);

> +}

> +

> +unsigned foo(unsigned value)

> +{

> +   return deposit32(value, 10, 1, 1);

> +}

> +

> +/* { dg-final { scan-tree-dump-not "bit_and_expr" "optimized" } } */

> +/* { dg-final { scan-tree-dump-not "bit_xor_expr" "optimized" } } */

> +/* { dg-final { scan-tree-dump-not "bit_not_expr" "optimized" } } */

> 


-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 247165 (AG München)
Segher Boessenkool Aug. 26, 2019, 3:01 p.m. | #2
On Mon, Aug 26, 2019 at 02:04:25PM +0200, Richard Biener wrote:
> On Mon, 26 Aug 2019, kamlesh kumar wrote:

> > +/* (~a & b) ^ a  -->   (a | b)   */

> > +(simplify

> > + (bit_xor:c (bit_and:cs (bit_not @0) @1) @0)

> > + (bit_ior @0 @1))

> > +

> 

> Are you sure?

> 

> (~1804289383 & 846930886) ^ 1804289383 != 1804289383 | 846930886


Both are hex 7bfb67e7.

a|b = a|(b&~a) = a^(b&~a)

>       if ((~a & b) ^ a != a | b)


!= has higher precedence than ^ and | (and &).


Segher
Richard Biener Aug. 27, 2019, 7:14 a.m. | #3
On Mon, 26 Aug 2019, Segher Boessenkool wrote:

> On Mon, Aug 26, 2019 at 02:04:25PM +0200, Richard Biener wrote:

> > On Mon, 26 Aug 2019, kamlesh kumar wrote:

> > > +/* (~a & b) ^ a  -->   (a | b)   */

> > > +(simplify

> > > + (bit_xor:c (bit_and:cs (bit_not @0) @1) @0)

> > > + (bit_ior @0 @1))

> > > +

> > 

> > Are you sure?

> > 

> > (~1804289383 & 846930886) ^ 1804289383 != 1804289383 | 846930886

> 

> Both are hex 7bfb67e7.

> 

> a|b = a|(b&~a) = a^(b&~a)

> 

> >       if ((~a & b) ^ a != a | b)

> 

> != has higher precedence than ^ and | (and &).


Oops.  Need more coffee (and -Wall).

Patch is OK.

Thanks,
Richard.
Jeff Law Sept. 3, 2019, 8:13 p.m. | #4
On 8/26/19 1:06 AM, kamlesh kumar wrote:
> 2019-08-26  Kamlesh Kumar  <kamleshbhalui@gmail.com>

> 

>         * gcc/match.pd: Added simplification

>         pattern.

>         * gcc.dg/tree-ssa/pr91504.c: New test.

Thanks.  I've installed this on the trunk.
jeff

Patch

====================

diff --git a/gcc/match.pd b/gcc/match.pd
index 93dcef9..b3734f8 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -831,6 +831,11 @@  DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (bit_xor:c (bit_and:cs @0 (bit_not @1)) (bit_not @0))
  (bit_not (bit_and @0 @1)))

+/* (~a & b) ^ a  -->   (a | b)   */
+(simplify
+ (bit_xor:c (bit_and:cs (bit_not @0) @1) @0)
+ (bit_ior @0 @1))
+
 /* (a | b) & ~(a ^ b)  -->  a & b  */
 (simplify
  (bit_and:c (bit_ior @0 @1) (bit_not (bit_xor:c @0 @1)))
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr91504.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr91504.c
new file mode 100644
index 0000000..a52dea4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr91504.c
@@ -0,0 +1,18 @@ 
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized-raw" } */
+
+static inline unsigned deposit32(unsigned value, int start, int length,
+                                 unsigned fieldval)
+{
+    unsigned mask = (~0U >> (32 - length)) << start;
+    return (value & ~mask) | ((fieldval << start) & mask);
+}
+
+unsigned foo(unsigned value)
+{
+   return deposit32(value, 10, 1, 1);
+}
+
+/* { dg-final { scan-tree-dump-not "bit_and_expr" "optimized" } } */
+/* { dg-final { scan-tree-dump-not "bit_xor_expr" "optimized" } } */
+/* { dg-final { scan-tree-dump-not "bit_not_expr" "optimized" } } */