More maybe_fold_reference TLC

This adjusts maybe_fold_reference to adhere to its desired behavior
of performing constant folding and thus explicitely avoid returning
unfolded reference trees.

2021-05-11  Richard Biener  <rguenther@suse.de>

	* gimple-fold.c (maybe_fold_reference): Only return
	is_gimple_min_invariant values.

diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index 6beb4f3..74ec36e 100644 (file)
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -311,27 +311,28 @@ get_symbol_constant_value (tree sym)
 static tree
 maybe_fold_reference (tree expr)
 {
-  tree result;
+  tree result = NULL_TREE;
 
   if ((TREE_CODE (expr) == VIEW_CONVERT_EXPR
        || TREE_CODE (expr) == REALPART_EXPR
        || TREE_CODE (expr) == IMAGPART_EXPR)
       && CONSTANT_CLASS_P (TREE_OPERAND (expr, 0)))
-    return fold_unary_loc (EXPR_LOCATION (expr),
-                          TREE_CODE (expr),
-                          TREE_TYPE (expr),
-                          TREE_OPERAND (expr, 0));
-  else if (TREE_CODE (expr) == BIT_FIELD_REF
-          && CONSTANT_CLASS_P (TREE_OPERAND (expr, 0)))
-    return fold_ternary_loc (EXPR_LOCATION (expr),
+    result = fold_unary_loc (EXPR_LOCATION (expr),
                             TREE_CODE (expr),
                             TREE_TYPE (expr),
-                            TREE_OPERAND (expr, 0),
-                            TREE_OPERAND (expr, 1),
-                            TREE_OPERAND (expr, 2));
+                            TREE_OPERAND (expr, 0));
+  else if (TREE_CODE (expr) == BIT_FIELD_REF
+          && CONSTANT_CLASS_P (TREE_OPERAND (expr, 0)))
+    result = fold_ternary_loc (EXPR_LOCATION (expr),
+                              TREE_CODE (expr),
+                              TREE_TYPE (expr),
+                              TREE_OPERAND (expr, 0),
+                              TREE_OPERAND (expr, 1),
+                              TREE_OPERAND (expr, 2));
+  else
+    result = fold_const_aggregate_ref (expr);
 
-  if ((result = fold_const_aggregate_ref (expr))
-      && is_gimple_min_invariant (result))
+  if (result && is_gimple_min_invariant (result))
     return result;
 
   return NULL_TREE;