[gcc r16-3078] tree-optimization/121454 - ICE building libgo

[Richard Biener via Gcc-cvs]

https://gcc.gnu.org/g:43949a5271b6c0b14076b736d0c609235d36f7df

commit r16-3078-g43949a5271b6c0b14076b736d0c609235d36f7df
Author: Richard Biener <rguent...@suse.de>
Date:   Fri Aug 8 08:57:58 2025 +0200

    tree-optimization/121454 - ICE building libgo
    
    The following avoids building BIT_FIELD_REFs of reference trees
    that are unexpected by nonoverlapping_refs_since_match_p and
    while being there also those declared invalid by IL verification.
    
            PR tree-optimization/121454
            * tree-ssa-sccvn.cc (visit_nary_op): Avoid unexpected
            BIT_FIELD_REFs.

Diff:
---
 gcc/tree-ssa-sccvn.cc | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index 1c113f848ebb..ccd80806263b 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -5643,15 +5643,24 @@ visit_nary_op (tree lhs, gassign *stmt)
              && vn_get_stmt_kind (ass) == VN_REFERENCE)
            {
              tree last_vuse = gimple_vuse (ass);
-             tree op = build3 (BIT_FIELD_REF, TREE_TYPE (rhs1),
-                               gimple_assign_rhs1 (ass),
-                               TREE_OPERAND (rhs1, 1), TREE_OPERAND (rhs1, 2));
-             tree result = vn_reference_lookup (op, gimple_vuse (ass),
-                                                default_vn_walk_kind,
-                                                NULL, true, &last_vuse);
-             if (result
-                 && useless_type_conversion_p (type, TREE_TYPE (result)))
-               return set_ssa_val_to (lhs, result);
+             tree op = gimple_assign_rhs1 (ass);
+             /* Avoid building invalid and unexpected refs.  */
+             if (TREE_CODE (op) != TARGET_MEM_REF
+                 && TREE_CODE (op) != BIT_FIELD_REF
+                 && TREE_CODE (op) != REALPART_EXPR
+                 && TREE_CODE (op) != IMAGPART_EXPR)
+               {
+                 tree op = build3 (BIT_FIELD_REF, TREE_TYPE (rhs1),
+                                   gimple_assign_rhs1 (ass),
+                                   TREE_OPERAND (rhs1, 1),
+                                   TREE_OPERAND (rhs1, 2));
+                 tree result = vn_reference_lookup (op, gimple_vuse (ass),
+                                                    default_vn_walk_kind,
+                                                    NULL, true, &last_vuse);
+                 if (result
+                     && useless_type_conversion_p (type, TREE_TYPE (result)))
+                   return set_ssa_val_to (lhs, result);
+               }
            }
        }
       break;