[PATCH] Improve folding of COND_EXPRs in tree-if-conv.c (PR tree-optimization/70916)

[Jakub Jelinek]

Hi!

This allows us to better fold the COND_EXPR, so that _1 = 1 ? &foo : _2;
is folded to _1 = &foo.  There is another bug, the 1 in this case is wrong,
but it could appear on some other code too.

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

2016-05-03  Jakub Jelinek  <ja...@redhat.com>

        PR tree-optimization/70916
        * tree-if-conv.c (constant_or_ssa_name): Removed.
        (fold_build_cond_expr): Use is_gimple_val instead of
        constant_or_ssa_name.

--- gcc/tree-if-conv.c.jj       2016-04-26 18:03:15.850034179 +0200
+++ gcc/tree-if-conv.c  2016-05-03 11:04:19.378939463 +0200
@@ -408,24 +408,6 @@ fold_or_predicates (location_t loc, tree
   return fold_build2_loc (loc, TRUTH_OR_EXPR, boolean_type_node, c1, c2);
 }
 
-/* Returns true if N is either a constant or a SSA_NAME.  */
-
-static bool
-constant_or_ssa_name (tree n)
-{
-  switch (TREE_CODE (n))
-    {
-      case SSA_NAME:
-      case INTEGER_CST:
-      case REAL_CST:
-      case COMPLEX_CST:
-      case VECTOR_CST:
-       return true;
-      default:
-       return false;
-    }
-}
-
 /* Returns either a COND_EXPR or the folded expression if the folded
    expression is a MIN_EXPR, a MAX_EXPR, an ABS_EXPR,
    a constant or a SSA_NAME. */
@@ -446,22 +428,21 @@ fold_build_cond_expr (tree type, tree co
          && (integer_zerop (op1)))
        cond = op0;
     }
-  cond_expr = fold_ternary (COND_EXPR, type, cond,
-                           rhs, lhs);
+  cond_expr = fold_ternary (COND_EXPR, type, cond, rhs, lhs);
 
   if (cond_expr == NULL_TREE)
     return build3 (COND_EXPR, type, cond, rhs, lhs);
 
   STRIP_USELESS_TYPE_CONVERSION (cond_expr);
 
-  if (constant_or_ssa_name (cond_expr))
+  if (is_gimple_val (cond_expr))
     return cond_expr;
 
   if (TREE_CODE (cond_expr) == ABS_EXPR)
     {
       rhs1 = TREE_OPERAND (cond_expr, 1);
       STRIP_USELESS_TYPE_CONVERSION (rhs1);
-      if (constant_or_ssa_name (rhs1))
+      if (is_gimple_val (rhs1))
        return build1 (ABS_EXPR, type, rhs1);
     }
 
@@ -472,8 +453,7 @@ fold_build_cond_expr (tree type, tree co
       STRIP_USELESS_TYPE_CONVERSION (lhs1);
       rhs1 = TREE_OPERAND (cond_expr, 1);
       STRIP_USELESS_TYPE_CONVERSION (rhs1);
-      if (constant_or_ssa_name (rhs1)
-         && constant_or_ssa_name (lhs1))
+      if (is_gimple_val (rhs1) && is_gimple_val (lhs1))
        return build2 (TREE_CODE (cond_expr), type, lhs1, rhs1);
     }
   return build3 (COND_EXPR, type, cond, rhs, lhs);

        Jakub