[PATCH] Fold REDUC_*_EXPR

[Jakub Jelinek]

Hi!

This patch folds REDUC_*_EXPR (e.g. on pr54877.c -Ofast -mavx
testcase we end up with unfolded REDUC_PLUS_EXPR till *.optimized).

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2012-10-10  Jakub Jelinek  <ja...@redhat.com>

        * fold-const.c (fold_unary_loc): Handle REDUC_MIN_EXPR,
        REDUC_MAX_EXPR and REDUC_PLUS_EXPR.

--- gcc/fold-const.c.jj 2012-10-09 13:42:30.000000000 +0200
+++ gcc/fold-const.c    2012-10-10 12:28:11.768999520 +0200
@@ -8294,6 +8294,40 @@ fold_unary_loc (location_t loc, enum tre
        return build_vector (type, elts);
       }
 
+    case REDUC_MIN_EXPR:
+    case REDUC_MAX_EXPR:
+    case REDUC_PLUS_EXPR:
+      {
+       unsigned int nelts = TYPE_VECTOR_SUBPARTS (type), i;
+       tree *elts;
+       enum tree_code subcode;
+
+       if (TREE_CODE (op0) != VECTOR_CST)
+         return NULL_TREE;
+
+       elts = XALLOCAVEC (tree, nelts);
+       if (!vec_cst_ctor_to_array (op0, elts))
+         return NULL_TREE;
+
+       switch (code)
+         {
+         case REDUC_MIN_EXPR: subcode = MIN_EXPR; break;
+         case REDUC_MAX_EXPR: subcode = MAX_EXPR; break;
+         case REDUC_PLUS_EXPR: subcode = PLUS_EXPR; break;
+         default: gcc_unreachable ();
+         }
+
+       for (i = 1; i < nelts; i++)
+         {
+           elts[0] = const_binop (subcode, elts[0], elts[i]);
+           if (elts[0] == NULL_TREE || !CONSTANT_CLASS_P (elts[0]))
+             return NULL_TREE;
+           elts[i] = build_zero_cst (TREE_TYPE (type));
+         }
+
+       return build_vector (type, elts);
+      }
+
     default:
       return NULL_TREE;
     } /* switch (code) */

        Jakub