tree-optimization/103864 - SLP reduction of reductions with conversions

This generalizes the fix for PR103544 to also cover reductions that
are not reduction chains and does not consider reductions wrapped in
sign conversions for SLP reduction handling.

2022-01-04  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/103864
	PR tree-optimization/103544
	* tree-vect-slp.c (vect_analyze_slp_instance): Exclude
	reductions wrapped in conversions from SLP handling.
	(vect_analyze_slp): Revert PR103544 change.

	* gcc.dg/vect/pr103864.c: New testcase.

diff --git a/gcc/testsuite/gcc.dg/vect/pr103864.c b/gcc/testsuite/gcc.dg/vect/pr103864.c
new file mode 100644 (file)
index 0000000..464d573
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr103864.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-O3 -fno-tree-reassoc" } */
+
+void
+crash_me (short int *crash_me_result, int i, char crash_me_ptr_0)
+{
+  while (i < 1)
+    {
+      int j;
+
+      for (j = 0; j < 2; ++j)
+        crash_me_result[j] += crash_me_ptr_0 + 1;
+
+      i += 3;
+    }
+}

diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
index 3566752c6574c07c1bb579ba298d36001bf5728c..c3a1681d7c6495ae98084288bf335956effd6893 100644 (file)
--- a/gcc/tree-vect-slp.c
+++ b/gcc/tree-vect-slp.c
@@ -3325,8 +3325,13 @@ vect_analyze_slp_instance (vec_info *vinfo,
        = as_a <loop_vec_info> (vinfo)->reductions;
       scalar_stmts.create (reductions.length ());
       for (i = 0; reductions.iterate (i, &next_info); i++)
-       if (STMT_VINFO_RELEVANT_P (next_info)
-           || STMT_VINFO_LIVE_P (next_info))
+       if ((STMT_VINFO_RELEVANT_P (next_info)
+            || STMT_VINFO_LIVE_P (next_info))
+           /* ???  Make sure we didn't skip a conversion around a reduction
+              path.  In that case we'd have to reverse engineer that conversion
+              stmt following the chain using reduc_idx and from the PHI
+              using reduc_def.  */
+           && STMT_VINFO_DEF_TYPE (next_info) == vect_reduction_def)
          scalar_stmts.quick_push (next_info);
       /* If less than two were relevant/live there's nothing to SLP.  */
       if (scalar_stmts.length () < 2)
@@ -3419,13 +3424,8 @@ vect_analyze_slp (vec_info *vinfo, unsigned max_tree_size)
                vinfo = next;
              }
            STMT_VINFO_DEF_TYPE (first_element) = vect_internal_def;
-           /* It can be still vectorized as part of an SLP reduction.
-              ???  But only if we didn't skip a conversion around the group.
-              In that case we'd have to reverse engineer that conversion
-              stmt following the chain using reduc_idx and from the PHI
-              using reduc_def.  */
-           if (STMT_VINFO_DEF_TYPE (last) == vect_reduction_def)
-             loop_vinfo->reductions.safe_push (last);
+           /* It can be still vectorized as part of an SLP reduction.  */
+           loop_vinfo->reductions.safe_push (last);
          }
 
       /* Find SLP sequences starting from groups of reductions.  */