diff mbox series

MATCH: Simplify zero/sign extension bit operations [PR122848]

Message ID 20260707111950.1230436-1-eikansh.gupta@oss.qualcomm.com
State New
Headers
Series MATCH: Simplify zero/sign extension bit operations [PR122848] |

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Commit Message

Eikansh Gupta July 7, 2026, 11:19 a.m. UTC 
  Fold bitwise operations involving zero and sign extensions from the same
low-precision value.  The AND case folds to the zero extension, and the
OR case folds to the sign extension.

	PR tree-optimization/122848

gcc/ChangeLog:

	* match.pd (zero_extend & sign_extend -> zero_extend): New pattern.
	(zero_extend | sign_extend -> sign_extend): Likewise.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/pr122848.c: New test.

Signed-off-by: Eikansh Gupta <eikansh.gupta@oss.qualcomm.com>
---
 gcc/match.pd                             | 15 +++++
 gcc/testsuite/gcc.dg/tree-ssa/pr122848.c | 70 ++++++++++++++++++++++++
 2 files changed, 85 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr122848.c

Comments

Jeffrey Law July 9, 2026, 2:56 p.m. UTC | #1 
On 7/7/2026 5:19 AM, Eikansh Gupta wrote:
> Fold bitwise operations involving zero and sign extensions from the same
> low-precision value.  The AND case folds to the zero extension, and the
> OR case folds to the sign extension.
>
> 	PR tree-optimization/122848
>
> gcc/ChangeLog:
>
> 	* match.pd (zero_extend & sign_extend -> zero_extend): New pattern.
> 	(zero_extend | sign_extend -> sign_extend): Likewise.
>
> gcc/testsuite/ChangeLog:
>
> 	* gcc.dg/tree-ssa/pr122848.c: New test.
LGTM.  I had to convince myself the nop_conversion was needed, but it 
(like the convert nodes) is inherently needed for what you're trying to do.

Given match.pd isn't a strong area for me, I'd give others another 48hrs 
to chime in before committing.  Which raises the issue of commit privs.  
I'm pretty sure that Andrea and I have been pushing patches for you.  We 
should probably go ahead and get you commit privs so you can push 
approved patches.

This page as a link to a form you fill out:


https://gcc.gnu.org/gitwrite.html

List me as approving your request.  You can use any email for me you 
want :-)  The admins will likely recognize jeffreyalaw@gmail.com 
easiest, but again, any will work.  Once approved you'll create an entry 
in the MAINTAINERS file and push this patch if there aren't any change 
requests/objections in the next 48hrs.

Jeff
Eikansh Gupta July 10, 2026, 9:55 a.m. UTC | #2 
>
> Given match.pd isn't a strong area for me, I'd give others another 48hrs
> to chime in before committing.  Which raises the issue of commit privs.
> I'm pretty sure that Andrea and I have been pushing patches for you.  We
> should probably go ahead and get you commit privs so you can push
> approved patches.
>
> This page as a link to a form you fill out:
>
>
> https://gcc.gnu.org/gitwrite.html
>
> List me as approving your request.  You can use any email for me you
> want :-)  The admins will likely recognize jeffreyalaw@gmail.com
> easiest, but again, any will work.  Once approved you'll create an entry
> in the MAINTAINERS file and push this patch if there aren't any change
> requests/objections in the next 48hrs.
>

Thanks Jeff. I have filled out the form.

Regards
Eikansh
diff mbox series

Patch

diff --git a/gcc/match.pd b/gcc/match.pd
index a7cec25dbad..c9dff2341cc 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1472,6 +1472,21 @@  DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
        && bitwise_inverted_equal_p (@0, @1, wascmp))
    { wascmp ? constant_boolean_node (false, type) : build_zero_cst (type); })))
 
+/* zero_extend (X) & sign_extend (X) -> zero_extend (X) and
+   zero_extend (X) | sign_extend (X) -> sign_extend (X)  */
+(for bitop (bit_and bit_ior)
+ (simplify
+  (bitop:c (convert @0) (convert (nop_convert@1 @0)))
+  (if (INTEGRAL_TYPE_P (type)
+       && INTEGRAL_TYPE_P (TREE_TYPE (@0))
+       && INTEGRAL_TYPE_P (TREE_TYPE (@1))
+       && TYPE_UNSIGNED (TREE_TYPE (@0)) != TYPE_UNSIGNED (TREE_TYPE (@1))
+       && TYPE_PRECISION (TREE_TYPE (@0)) == TYPE_PRECISION (TREE_TYPE (@1))
+       && TYPE_PRECISION (TREE_TYPE (@0)) <= TYPE_PRECISION (type))
+   (if ((bitop == BIT_AND_EXPR) == TYPE_UNSIGNED (TREE_TYPE (@0)))
+    (convert @0)
+    (convert @1)))))
+
 /* PR71636: Transform x & ((1U << b) - 1) -> x & ~(~0U << b);  */
 (simplify
   (bit_and:c @0 (plus:s (lshift:s integer_onep @1) integer_minus_onep))
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr122848.c b/gcc/testsuite/gcc.dg/tree-ssa/pr122848.c
new file mode 100644
index 00000000000..363e000f43e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr122848.c
@@ -0,0 +1,70 @@ 
+/* PR tree-optimization/122848 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+int f1 (unsigned char a)
+{
+  int t = a;
+  int t1 = (signed char) a;
+  return t & t1;
+}
+
+int f2 (unsigned char a)
+{
+  int t = a;
+  int t1 = (signed char) a;
+  return t1 & t;
+}
+
+int f3 (unsigned char a)
+{
+  return (int) a & (int) (signed char) a;
+}
+
+int f4 (unsigned short a)
+{
+  return (int) a & (int) (short) a;
+}
+
+long f5 (unsigned int a)
+{
+  return (long) a & (long) (int) a;
+}
+
+unsigned int f6 (unsigned char a)
+{
+  return (unsigned int) a & (unsigned int) (signed char) a;
+}
+
+int f7 (unsigned char a)
+{
+  return (int) a | (int) (signed char) a;
+}
+
+int f8 (unsigned short a)
+{
+  return (int) a | (int) (short) a;
+}
+
+int f9 (signed char a)
+{
+  return (int) (unsigned char) a & (int) a;
+}
+
+int f10 (signed char a)
+{
+  return (int) a & (int) (unsigned char) a;
+}
+
+int f11 (signed char a)
+{
+  return (int) (unsigned char) a | (int) a;
+}
+
+int f12 (signed short a)
+{
+  return (int) (unsigned short) a | (int) a;
+}
+
+/* { dg-final { scan-tree-dump-not " & " "optimized" } } */
+/* { dg-final { scan-tree-dump-not " \\| " "optimized" } } */