[PATCH] Turn constant vector CONSTRUCTORs to VECTOR_CSTs

[Richard Guenther]

Not turning constant vector CONSTRUCTORs to VECTOR_CSTs pervents
constant propagation and folding in VIEW_CONVERT_EXPRs.  The following
patch teaches CCP and fold_stmt to properly do that which fixes the
cases originating from both inlining and CCP.

This makes the testcase in PR40122 constant fold properly.

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

Richard.

2009-05-26  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/40122
	* tree-ssa-ccp.c (ccp_fold): Fold vector CONSTRUCTORs to
	VECTOR_CSTs if possible.
	(fold_gimple_assign): Likewise.

Index: gcc/tree-ssa-ccp.c
===================================================================
*** gcc/tree-ssa-ccp.c	(revision 147862)
--- gcc/tree-ssa-ccp.c	(working copy)
*************** ccp_fold (gimple stmt)
*** 958,963 ****
--- 958,987 ----
  			}
  		    }
  		}
+ 	      else if (TREE_CODE (rhs) == CONSTRUCTOR
+ 		       && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE
+ 		       && (CONSTRUCTOR_NELTS (rhs)
+ 			   == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs))))
+ 		{
+ 		  unsigned i;
+ 		  tree val, list;
+ 
+ 		  list = NULL_TREE;
+ 		  FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
+ 		    {
+ 		      if (TREE_CODE (val) == SSA_NAME
+ 			  && get_value (val)->lattice_val == CONSTANT)
+ 			val = get_value (val)->value;
+ 		      if (TREE_CODE (val) == INTEGER_CST
+ 			  || TREE_CODE (val) == REAL_CST
+ 			  || TREE_CODE (val) == FIXED_CST)
+ 			list = tree_cons (NULL_TREE, val, list);
+ 		      else
+ 			return NULL_TREE;
+ 		    }
+ 
+ 		  return build_vector (TREE_TYPE (rhs), nreverse (list));
+ 		}
  
                if (kind == tcc_reference)
  		{
*************** fold_gimple_assign (gimple_stmt_iterator
*** 2654,2659 ****
--- 2678,2702 ----
  				     build_fold_addr_expr (tem));
  	  }
  
+ 	else if (TREE_CODE (rhs) == CONSTRUCTOR
+ 		 && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE
+ 		 && (CONSTRUCTOR_NELTS (rhs)
+ 		     == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs))))
+ 	  {
+ 	    /* Fold a constant vector CONSTRUCTOR to VECTOR_CST.  */
+ 	    unsigned i;
+ 	    tree val;
+ 
+ 	    FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
+ 	      if (TREE_CODE (val) != INTEGER_CST
+ 		  && TREE_CODE (val) != REAL_CST
+ 		  && TREE_CODE (val) != FIXED_CST)
+ 		return NULL_TREE;
+ 
+ 	    return build_vector_from_ctor (TREE_TYPE (rhs),
+ 					   CONSTRUCTOR_ELTS (rhs));
+ 	  }
+ 
          /* If we couldn't fold the RHS, hand over to the generic
             fold routines.  */
          if (result == NULL_TREE)