Re: [PATCH] [PR116831] match.pd: Check trunc_mod vector obtap before folding.

[Jennifer Schmitz]

> On 8 Oct 2024, at 10:31, Richard Biener <rguent...@suse.de> wrote:
> 
> External email: Use caution opening links or attachments
> 
> 
> On Fri, 4 Oct 2024, Jennifer Schmitz wrote:
> 
>> As in https://gcc.gnu.org/pipermail/gcc-patches/2024-September/663185.html,
>> this patch guards the simplification x / y * y == x -> x % y == 0 in
>> match.pd for vector types by a check for:
>> 1) Support of the mod optab for vectors OR
>> 2) Application before vector lowering for non-VL vectors.
>> 
>> The patch was bootstrapped and tested with no regression on
>> aarch64-linux-gnu and x86_64-linux-gnu.
>> OK for mainline?
> 
> -  (if (TREE_CODE (TREE_TYPE (@0)) != COMPLEX_TYPE)
> +  (if (TREE_CODE (TREE_TYPE (@0)) != COMPLEX_TYPE
> +       || (VECTOR_INTEGER_TYPE_P (type)
> +          && ((optimize_vectors_before_lowering_p ()
> +               && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST)
> +              || target_supports_op_p (type, TRUNC_MOD_EXPR,
> +                                       optab_vector))))
> 
> this looks a bit odd, VECTOR_INTEGER_TYPE_P (type) checks the
> result type of the comparison.  I think the whole condition is
> better written as
> 
> (if (TREE_CODE (TREE_TYPE (@0)) != COMPLEX_TYPE
>      && (!VECTOR_MODE_P (TYPE_MODE (TREE_TYPE (@0)))
>          || !target_supports_op_p (TREE_TYPE (@0), TRUNC_DIV_EXPR,
>                                    optab_vector)
>          || target_supports_op_p (TREE_TYPE (@0), TRUNC_MOD_EXPR,
>                                    optab_vector)))
> 
> when we have non-vector mode we're before lowering, likewise when
> the target doesn't support the division.  Even before lowering
> we shouldn't replace a supported division (and multiplication)
> with an unsupported modulo.
Dear Richard,
thanks for the review. I updated the patch with your suggestion and 
re-validated on aarch64 and x86_64.
Best,
Jennifer

This patch guards the simplification x / y * y == x -> x % y == 0 in
match.pd by a check for:
1) Non-vector mode of x OR
2) Lack of support for vector division OR
3) Support of vector modulo

The patch was bootstrapped and tested with no regression on
aarch64-linux-gnu and x86_64-linux-gnu.
OK for mainline?

Signed-off-by: Jennifer Schmitz <jschm...@nvidia.com>

gcc/
        PR tree-optimization/116831
        * match.pd: Guard simplification to trunc_mod with check for
        mod optab support.

gcc/testsuite/
        PR tree-optimization/116831
        * gcc.dg/torture/pr116831.c: New test.
---
 gcc/match.pd                            |  9 +++++++--
 gcc/testsuite/gcc.dg/torture/pr116831.c | 10 ++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr116831.c

diff --git a/gcc/match.pd b/gcc/match.pd
index ba83f0f29e6..9b59b5c12f1 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -5380,8 +5380,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 /* x / y * y == x -> x % y == 0.  */
 (simplify
   (eq:c (mult:c (trunc_div:s @0 @1) @1) @0)
-  (if (TREE_CODE (TREE_TYPE (@0)) != COMPLEX_TYPE)
-    (eq (trunc_mod @0 @1) { build_zero_cst (TREE_TYPE (@0)); })))
+  (if (TREE_CODE (TREE_TYPE (@0)) != COMPLEX_TYPE
+       && (!VECTOR_MODE_P (TYPE_MODE (TREE_TYPE (@0)))
+          || !target_supports_op_p (TREE_TYPE (@0), TRUNC_DIV_EXPR,
+                                    optab_vector)
+          || target_supports_op_p (TREE_TYPE (@0), TRUNC_MOD_EXPR,
+                                   optab_vector)))
+   (eq (trunc_mod @0 @1) { build_zero_cst (TREE_TYPE (@0)); })))
 
 /* ((X /[ex] A) +- B) * A  -->  X +- A * B.  */
 (for op (plus minus)
diff --git a/gcc/testsuite/gcc.dg/torture/pr116831.c 
b/gcc/testsuite/gcc.dg/torture/pr116831.c
new file mode 100644
index 00000000000..92b2a130e69
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr116831.c
@@ -0,0 +1,10 @@
+/* { dg-additional-options "-mcpu=neoverse-v2" { target aarch64*-*-* } } */
+
+long a;
+int b, c;
+void d (int e[][5], short f[][5][5][5]) 
+{
+  for (short g; g; g += 4)
+    a = c ?: e[6][0] % b ? 0 : f[0][0][0][g];
+}
+
-- 
2.44.0


> 
> Richard.
> 
> 
>> Signed-off-by: Jennifer Schmitz <jschm...@nvidia.com>
>> 
>> gcc/
>>      PR tree-optimization/116831
>>      * match.pd: Guard simplification to trunc_mod with check for
>>      mod optab support.
>> 
>> gcc/testsuite/
>>      PR tree-optimization/116831
>>      * gcc.dg/torture/pr116831.c: New test.
>> 
> 
> --
> Richard Biener <rguent...@suse.de>
> SUSE Software Solutions Germany GmbH,
> Frankenstrasse 146, 90461 Nuernberg, Germany;
> GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)

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