[gcc r14-2697] tree-optimization/110742 - fix latent issue with permuting existing vectors

[gcc r14-2697] tree-optimization/110742 - fix latent issue with permuting existing vectors

[Richard Biener]

https://gcc.gnu.org/g:9a8782e63790842d1bfa03e12eecf73c4aaeb1f8

commit r14-2697-g9a8782e63790842d1bfa03e12eecf73c4aaeb1f8
Author: Richard Biener <rguenther@suse.de>
Date:   Thu Jul 20 13:09:17 2023 +0200

    tree-optimization/110742 - fix latent issue with permuting existing vectors
    
    When we materialize a layout we push edge permutes to constant/external
    defs without checking we can actually do so.  For externals defined
    by vector stmts rather than scalar components we can't.
    
            PR tree-optimization/110742
            * tree-vect-slp.cc (vect_optimize_slp_pass::get_result_with_layout):
            Do not materialize an edge permutation in an external node with
            vector defs.
            (vect_slp_analyze_node_operations_1): Guard purely internal
            nodes better.
    
            * g++.dg/torture/pr110742.C: New testcase.

Diff:
---
 gcc/testsuite/g++.dg/torture/pr110742.C | 47 +++++++++++++++++++++++++++++++++
 gcc/tree-vect-slp.cc                    |  7 +++--
 2 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/gcc/testsuite/g++.dg/torture/pr110742.C b/gcc/testsuite/g++.dg/torture/pr110742.C
new file mode 100644
index 00000000000..d41ac0479d2
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr110742.C
@@ -0,0 +1,47 @@
+// { dg-do compile }
+
+struct HARD_REG_SET {
+  HARD_REG_SET operator~() const {
+    HARD_REG_SET res;
+    for (unsigned int i = 0; i < (sizeof(elts) / sizeof((elts)[0])); ++i)
+      res.elts[i] = ~elts[i];
+    return res;
+  }
+  HARD_REG_SET operator&(const HARD_REG_SET &other) const {
+    HARD_REG_SET res;
+    for (unsigned int i = 0; i < (sizeof(elts) / sizeof((elts)[0])); ++i)
+      res.elts[i] = elts[i] & other.elts[i];
+    return res;
+  }
+  unsigned long elts[4];
+};
+typedef const HARD_REG_SET &const_hard_reg_set;
+inline bool hard_reg_set_subset_p(const_hard_reg_set x, const_hard_reg_set y) {
+  unsigned long bad = 0;
+  for (unsigned int i = 0; i < (sizeof(x.elts) / sizeof((x.elts)[0])); ++i)
+    bad |= (x.elts[i] & ~y.elts[i]);
+  return bad == 0;
+}
+inline bool hard_reg_set_empty_p(const_hard_reg_set x) {
+  unsigned long bad = 0;
+  for (unsigned int i = 0; i < (sizeof(x.elts) / sizeof((x.elts)[0])); ++i)
+    bad |= x.elts[i];
+  return bad == 0;
+}
+extern HARD_REG_SET rr[2];
+extern int t[2];
+extern HARD_REG_SET nn;
+static HARD_REG_SET mm;
+void setup_reg_class_relations(void) {
+  HARD_REG_SET intersection_set, union_set, temp_set2;
+  for (int cl2 = 0; cl2 < 2; cl2++) {
+    temp_set2 = rr[cl2] & ~nn;
+    if (hard_reg_set_empty_p(mm) && hard_reg_set_empty_p(temp_set2)) {
+      mm = rr[0] & nn;
+      if (hard_reg_set_subset_p(mm, intersection_set))
+        if (!hard_reg_set_subset_p(mm, temp_set2) ||
+            hard_reg_set_subset_p(rr[0], rr[t[cl2]]))
+          t[cl2] = 0;
+    }
+  }
+}
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index 693621ca990..f4adbb28761 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -5198,7 +5198,9 @@ vect_optimize_slp_pass::get_result_with_layout (slp_tree node,
     return result;
 
   if (SLP_TREE_DEF_TYPE (node) == vect_constant_def
-      || SLP_TREE_DEF_TYPE (node) == vect_external_def)
+      || (SLP_TREE_DEF_TYPE (node) == vect_external_def
+	  /* We can't permute vector defs in place.  */
+	  && SLP_TREE_VEC_DEFS (node).is_empty ()))
     {
       /* If the vector is uniform or unchanged, there's nothing to do.  */
       if (to_layout_i == 0 || vect_slp_tree_uniform_p (node))
@@ -5944,7 +5946,8 @@ vect_slp_analyze_node_operations_1 (vec_info *vinfo, slp_tree node,
      calculated by the recursive call).  Otherwise it is the number of
      scalar elements in one scalar iteration (DR_GROUP_SIZE) multiplied by
      VF divided by the number of elements in a vector.  */
-  if (!STMT_VINFO_DATA_REF (stmt_info)
+  if (SLP_TREE_CODE (node) != VEC_PERM_EXPR
+      && !STMT_VINFO_DATA_REF (stmt_info)
       && REDUC_GROUP_FIRST_ELEMENT (stmt_info))
     {
       for (unsigned i = 0; i < SLP_TREE_CHILDREN (node).length (); ++i)