[PATCH] Fold more vector constants early

[Richard Biener]

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.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

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

	* gimplify.cc (gimplify_init_constructor): First gimplify,
	then simplify the result to a VECTOR_CST.
---
 gcc/gimplify.cc | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
index 2588824dce2..f052d9f970c 100644
--- 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);
       }
-- 
2.35.3