Fold more vector constants early

In PR105049 we had

  return VIEW_CONVERT_EXPR<U>( VEC_PERM_EXPR < {<<< Unknown tree: compound_literal_expr
        V D.1984 = { 0 }; >>>, { 0 }} , {<<< Unknown tree: compound_literal_expr
        V D.1985 = { 0 }; >>>, { 0 }} , { 0, 0 } >  & {(short int) SAVE_EXPR <c>, (short int) SAVE_EXPR <c>});

where we gimplify the init CTORs to

  _1 = {{ 0 }, { 0 }};
  _2 = {{ 0 }, { 0 }};

instead of to vector constants.  The following makes sure to simplify the
CTORs to VECTOR_CSTs during gimplification by re-ordering the simplification
to after CTOR flag recomputation and gimplification of the elements.

2022-03-25  Richard Biener  <rguenther@suse.de>

	* gimplify.cc (gimplify_init_constructor): First gimplify,
	then simplify the result to a VECTOR_CST.

diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
index 2588824..f052d9f 100644 (file)
--- a/gcc/gimplify.cc
+++ b/gcc/gimplify.cc
@@ -5432,6 +5432,22 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
        if (notify_temp_creation)
          return GS_OK;
 
+       /* Vector types use CONSTRUCTOR all the way through gimple
+          compilation as a general initializer.  */
+       FOR_EACH_VEC_SAFE_ELT (elts, ix, ce)
+         {
+           enum gimplify_status tret;
+           tret = gimplify_expr (&ce->value, pre_p, post_p, is_gimple_val,
+                                 fb_rvalue);
+           if (tret == GS_ERROR)
+             ret = GS_ERROR;
+           else if (TREE_STATIC (ctor)
+                    && !initializer_constant_valid_p (ce->value,
+                                                      TREE_TYPE (ce->value)))
+             TREE_STATIC (ctor) = 0;
+         }
+       recompute_constructor_flags (ctor);
+
        /* Go ahead and simplify constant constructors to VECTOR_CST.  */
        if (TREE_CONSTANT (ctor))
          {
@@ -5454,25 +5470,8 @@ gimplify_init_constructor (tree *expr_p, gimple_seq *pre_p, gimple_seq *post_p,
                TREE_OPERAND (*expr_p, 1) = build_vector_from_ctor (type, elts);
                break;
              }
-
-           TREE_CONSTANT (ctor) = 0;
          }
 
-       /* Vector types use CONSTRUCTOR all the way through gimple
-          compilation as a general initializer.  */
-       FOR_EACH_VEC_SAFE_ELT (elts, ix, ce)
-         {
-           enum gimplify_status tret;
-           tret = gimplify_expr (&ce->value, pre_p, post_p, is_gimple_val,
-                                 fb_rvalue);
-           if (tret == GS_ERROR)
-             ret = GS_ERROR;
-           else if (TREE_STATIC (ctor)
-                    && !initializer_constant_valid_p (ce->value,
-                                                      TREE_TYPE (ce->value)))
-             TREE_STATIC (ctor) = 0;
-         }
-       recompute_constructor_flags (ctor);
        if (!is_gimple_reg (TREE_OPERAND (*expr_p, 0)))
          TREE_OPERAND (*expr_p, 1) = get_formal_tmp_var (ctor, pre_p);
       }