From: Jennifer Schmitz <jschmitz@nvidia.com>
Date: Thu, 5 Sep 2024 15:10:02 +0000 (-0700)
Subject: match.pd: Check trunc_mod vector obtap before folding.
X-Git-Tag: basepoints/gcc-16~5870
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6f3b6a451771cd54c98768e7db3c5d58aab2b6aa;p=thirdparty%2Fgcc.git

match.pd: Check trunc_mod vector obtap before folding.

In the pattern X - (X / Y) * Y to X % Y, this patch guards the
simplification 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.
This is to prevent reverting vectorization of modulo to div/mult/sub
if the target does not support vector mod optab.

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 <jschmitz@nvidia.com>

gcc/
	PR tree-optimization/116569
	* match.pd: Guard simplification to trunc_mod with check for
	mod optab support.

gcc/testsuite/
	PR tree-optimization/116569
	* gcc.dg/torture/pr116569.c: New test.
---

diff --git a/gcc/match.pd b/gcc/match.pd
index 5566c0e4c41..4aa610e2270 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -894,7 +894,12 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 /* X - (X / Y) * Y is the same as X % Y.  */
 (simplify
  (minus (convert1? @0) (convert2? (mult:c (trunc_div @@0 @@1) @1)))
- (if (INTEGRAL_TYPE_P (type) || VECTOR_INTEGER_TYPE_P (type))
+ (if (INTEGRAL_TYPE_P (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))))
   (convert (trunc_mod @0 @1))))
 
 /* x * (1 + y / x) - y -> x - y % x */
diff --git a/gcc/testsuite/gcc.dg/torture/pr116569.c b/gcc/testsuite/gcc.dg/torture/pr116569.c
new file mode 100644
index 00000000000..b74c749721b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr116569.c
@@ -0,0 +1,18 @@
+/* { dg-additional-options "-mcpu=neoverse-v2" { target aarch64*-*-* } } */
+int a;
+short b, c, e;
+long d, f;
+long g (long h)
+{
+  if (h)
+    return h;
+  return d;
+}
+void i (int h[][0][0][0])
+{
+  for (short j; j; j += 3)
+    {
+      a = g(h[1][2] ? 0 : h[1][1][1][1]);
+      b = e ?: f % c;
+    }
+}