[PATCH] Do not consider vector CONSTRUCTORs is_gimple_constant

[PATCH] Do not consider vector CONSTRUCTORs is_gimple_constant

[Richard Biener]

I've seen unfolded CONSTRUCTORs like { 1, 2, 3, 4 } being propagated
into binary stmt operands where they will sit forever, not being
folded (to VECTOR_CSTs) nor being considered for any constant folding
(which operates on VECTOR_CSTs only).  There is no reason to allow
those unfolded CONSTRUCTORs as gimple operands - we don't allow
an unfolded 1 + 2 expression either (that is, either allow
everything TREE_CONSTANT or nothing but tcc_constant).

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2013-04-12  Richard Biener  <rguenther@suse.de>

	* gimple.c (is_gimple_constant): Vector CONSTRUCTORs should
	not be considered a gimple constant.

Index: gcc/gimple.c
===================================================================
*** gcc/gimple.c	(revision 197802)
--- gcc/gimple.c	(working copy)
*************** is_gimple_constant (const_tree t)
*** 2592,2604 ****
      case VECTOR_CST:
        return true;
  
-     /* Vector constant constructors are gimple invariant.  */
-     case CONSTRUCTOR:
-       if (TREE_TYPE (t) && TREE_CODE (TREE_TYPE (t)) == VECTOR_TYPE)
- 	return TREE_CONSTANT (t);
-       else
- 	return false;
- 
      default:
        return false;
      }
--- 2592,2597 ----