From: Tamar Christina <tamar.christina@arm.com>
Date: Wed, 9 Jul 2025 07:42:02 +0000 (+0100)
Subject: middle-end: Use rounding division for ranges for partial vectors [PR120922]
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=963d5362c598d48ee7a896e674d2a68c41179785;p=thirdparty%2Fgcc.git

middle-end: Use rounding division for ranges for partial vectors [PR120922]

This patch adds support for niters ranges for partial
vector loops.

Due to the last iteration being partial the bounds should
be at least 1 but niters // vf as the max.

gcc/ChangeLog:

	PR tree-optimization/120922
	* tree-vect-loop-manip.cc (vect_gen_vector_loop_niters): Support range
	for partial vectors.
---

diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
index 9c58a6a01d7..2d01a4b0ed1 100644
--- a/gcc/tree-vect-loop-manip.cc
+++ b/gcc/tree-vect-loop-manip.cc
@@ -2857,11 +2857,21 @@ vect_gen_vector_loop_niters (loop_vec_info loop_vinfo, tree niters,
 	 we set range information to make niters analyzer's life easier.
 	 Note the number of latch iteration value can be TYPE_MAX_VALUE so
 	 we have to represent the vector niter TYPE_MAX_VALUE + 1 / vf.  */
-      if (stmts != NULL
-	  && const_vf > 0
-	  && !LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo))
+      if (stmts != NULL && const_vf > 0)
 	{
-	  if (niters_no_overflow)
+	  if (niters_no_overflow
+	      && LOOP_VINFO_USING_PARTIAL_VECTORS_P (loop_vinfo))
+	    {
+	      int_range<1> vr (type,
+			       wi::one (TYPE_PRECISION (type)),
+			       wi::div_ceil (wi::max_value
+							(TYPE_PRECISION (type),
+							 TYPE_SIGN (type)),
+					     const_vf,
+					     TYPE_SIGN (type)));
+	      set_range_info (niters_vector, vr);
+	    }
+	  else if (niters_no_overflow)
 	    {
 	      int_range<1> vr (type,
 			       wi::one (TYPE_PRECISION (type)),