tree-ssa-loop-niter.c (zero_p, nonzero_p): Removed.

	* tree-ssa-loop-niter.c (zero_p, nonzero_p): Removed.
	(number_of_iterations_ne, number_of_iterations_lt_to_ne,
	assert_no_overflow_lt, assert_loop_rolls_lt,
	number_of_iterations_lt, number_of_iterations_le,
	number_of_iterations_cond, tree_simplify_using_condition_1,
	number_of_iterations_exit, find_loop_niter, loop_niter_by_eval,
	implies_nonnegative_p, implies_ge_p, record_nonwrapping_iv,
	idx_infer_loop_bounds, n_of_executions_at_most, scev_probably_wraps_p):
	Do not use zero_p/nonzero_p.
	* tree-ssa-loop-manip.c (determine_exit_conditions): Ditto.
	* tree-ssa-loop-ivopts.c (niter_for_exit, determine_biv_step,
	find_interesting_uses_op, find_interesting_uses_cond,
	find_interesting_uses_address, find_interesting_uses_stmt,
	strip_offset_1, add_candidate_1, add_old_ivs_candidates,
	difference_cost, determine_use_iv_cost_condition,
	rewrite_use_compare, remove_unused_ivs): Ditto.
	* tree-ssa-address.c (tree_mem_ref_addr, create_mem_ref_raw): Ditto.
	* tree-ssa-loop-prefetch.c (idx_analyze_ref): Ditto.
	* tree-cfg.c (find_taken_edge_cond_expr): Ditto.
	* tree.h (zero_p): Declaration removed.
	(null_or_integer_zerop, nonnull_and_integer_nonzerop): New.

From-SVN: r120156

8 files changed, 126 insertions, 114 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4ceb90f..5314fc9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,27 @@
+2006-12-22  Zdenek Dvorak <dvorakz@suse.cz>
+
+	* tree-ssa-loop-niter.c (zero_p, nonzero_p): Removed.
+	(number_of_iterations_ne, number_of_iterations_lt_to_ne,
+	assert_no_overflow_lt, assert_loop_rolls_lt,
+	number_of_iterations_lt, number_of_iterations_le,
+	number_of_iterations_cond, tree_simplify_using_condition_1,
+	number_of_iterations_exit, find_loop_niter, loop_niter_by_eval,
+	implies_nonnegative_p, implies_ge_p, record_nonwrapping_iv,
+	idx_infer_loop_bounds, n_of_executions_at_most, scev_probably_wraps_p):
+	Do not use zero_p/nonzero_p.
+	* tree-ssa-loop-manip.c (determine_exit_conditions): Ditto.
+	* tree-ssa-loop-ivopts.c (niter_for_exit, determine_biv_step,
+	find_interesting_uses_op, find_interesting_uses_cond,
+	find_interesting_uses_address, find_interesting_uses_stmt,
+	strip_offset_1, add_candidate_1, add_old_ivs_candidates,
+	difference_cost, determine_use_iv_cost_condition,
+	rewrite_use_compare, remove_unused_ivs): Ditto.
+	* tree-ssa-address.c (tree_mem_ref_addr, create_mem_ref_raw): Ditto.
+	* tree-ssa-loop-prefetch.c (idx_analyze_ref): Ditto.
+	* tree-cfg.c (find_taken_edge_cond_expr): Ditto.
+	* tree.h (zero_p): Declaration removed.
+	(null_or_integer_zerop, nonnull_and_integer_nonzerop): New.
+
 2006-12-22  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
 
 	PR middle-end/7651
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index b85e38e..bdb1bce 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -2153,7 +2153,7 @@ find_taken_edge_cond_expr (basic_block bb, tree val)
   extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
 
   gcc_assert (TREE_CODE (val) == INTEGER_CST);
-  return (zero_p (val) ? false_edge : true_edge);
+  return (integer_zerop (val) ? false_edge : true_edge);
 }
 
 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
diff --git a/gcc/tree-ssa-address.c b/gcc/tree-ssa-address.c
index eb39370..3fffd1d 100644
--- a/gcc/tree-ssa-address.c
+++ b/gcc/tree-ssa-address.c
@@ -281,7 +281,7 @@ tree_mem_ref_addr (tree type, tree mem_ref)
 	addr = act_elem;
     }
 
-  if (!zero_p (offset))
+  if (offset && !integer_zerop (offset))
     {
       act_elem = fold_convert (type, offset);
 
@@ -325,7 +325,7 @@ create_mem_ref_raw (tree type, struct mem_address *addr)
   if (addr->step && integer_onep (addr->step))
     addr->step = NULL_TREE;
 
-  if (addr->offset && zero_p (addr->offset))
+  if (addr->offset && integer_zerop (addr->offset))
     addr->offset = NULL_TREE;
 
   return build7 (TARGET_MEM_REF, type,
diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c
index 1efaf99..5e70937 100644
--- a/gcc/tree-ssa-loop-ivopts.c
+++ b/gcc/tree-ssa-loop-ivopts.c
@@ -732,7 +732,7 @@ niter_for_exit (struct ivopts_data *data, edge exit)
 	 overlapping life ranges for them (PR 27283).  */
       if (number_of_iterations_exit (data->current_loop,
 				     exit, &desc, true)
-	  && zero_p (desc.may_be_zero)
+	  && integer_zerop (desc.may_be_zero)
      	  && !contains_abnormal_ssa_name_p (desc.niter))
 	nfe_desc->niter = desc.niter;
       else
@@ -904,7 +904,7 @@ determine_biv_step (tree phi)
   if (!simple_iv (loop, phi, name, &iv, true))
     return NULL_TREE;
 
-  return (zero_p (iv.step) ? NULL_TREE : iv.step);
+  return (null_or_integer_zerop (iv.step) ? NULL_TREE : iv.step);
 }
 
 /* Finds basic ivs.  */
@@ -1160,7 +1160,7 @@ find_interesting_uses_op (struct ivopts_data *data, tree op)
       return use;
     }
 
-  if (zero_p (iv->step))
+  if (null_or_integer_zerop (iv->step))
     {
       record_invariant (data, op, true);
       return NULL;
@@ -1224,21 +1224,23 @@ find_interesting_uses_cond (struct ivopts_data *data, tree stmt, tree *cond_p)
       (!iv0 || !iv1)
       /* Eliminating condition based on two ivs would be nontrivial.
 	 ??? TODO -- it is not really important to handle this case.  */
-      || (!zero_p (iv0->step) && !zero_p (iv1->step)))
+      || (!null_or_integer_zerop (iv0->step)
+	  && !null_or_integer_zerop (iv1->step)))
     {
       find_interesting_uses_op (data, *op0_p);
       find_interesting_uses_op (data, *op1_p);
       return;
     }
 
-  if (zero_p (iv0->step) && zero_p (iv1->step))
+  if (null_or_integer_zerop (iv0->step)
+      && null_or_integer_zerop (iv1->step))
     {
       /* If both are invariants, this is a work for unswitching.  */
       return;
     }
 
   civ = XNEW (struct iv);
-  *civ = zero_p (iv0->step) ? *iv1: *iv0;
+  *civ = null_or_integer_zerop (iv0->step) ? *iv1: *iv0;
   record_use (data, cond_p, civ, stmt, USE_COMPARE);
 }
 
@@ -1514,7 +1516,7 @@ find_interesting_uses_address (struct ivopts_data *data, tree stmt, tree *op_p)
 	    }
 	}
 
-      if (zero_p (step))
+      if (null_or_integer_zerop (step))
 	goto fail;
       base = tree_mem_ref_addr (type, base);
     }
@@ -1524,7 +1526,7 @@ find_interesting_uses_address (struct ivopts_data *data, tree stmt, tree *op_p)
       ifs_ivopts_data.stmt = stmt;
       ifs_ivopts_data.step_p = &step;
       if (!for_each_index (&base, idx_find_step, &ifs_ivopts_data)
-	  || zero_p (step))
+	  || null_or_integer_zerop (step))
 	goto fail;
 
       gcc_assert (TREE_CODE (base) != ALIGN_INDIRECT_REF);
@@ -1598,7 +1600,7 @@ find_interesting_uses_stmt (struct ivopts_data *data, tree stmt)
 
 	  iv = get_iv (data, lhs);
 
-	  if (iv && !zero_p (iv->step))
+	  if (iv && !null_or_integer_zerop (iv->step))
 	    return;
 	}
 
@@ -1644,7 +1646,7 @@ find_interesting_uses_stmt (struct ivopts_data *data, tree stmt)
       lhs = PHI_RESULT (stmt);
       iv = get_iv (data, lhs);
 
-      if (iv && !zero_p (iv->step))
+      if (iv && !null_or_integer_zerop (iv->step))
 	return;
     }
 
@@ -1758,7 +1760,7 @@ strip_offset_1 (tree expr, bool inside_addr, bool top_compref,
     {
     case INTEGER_CST:
       if (!cst_and_fits_in_hwi (expr)
-	  || zero_p (expr))
+	  || integer_zerop (expr))
 	return orig_expr;
 
       *offset = int_cst_value (expr);
@@ -1777,9 +1779,9 @@ strip_offset_1 (tree expr, bool inside_addr, bool top_compref,
 	  && op1 == TREE_OPERAND (expr, 1))
 	return orig_expr;
 
-      if (zero_p (op1))
+      if (integer_zerop (op1))
 	expr = op0;
-      else if (zero_p (op0))
+      else if (integer_zerop (op0))
 	{
 	  if (code == PLUS_EXPR)
 	    expr = op1;
@@ -1805,7 +1807,7 @@ strip_offset_1 (tree expr, bool inside_addr, bool top_compref,
       *offset = off1 * st;
 
       if (top_compref
-	  && zero_p (op1))
+	  && integer_zerop (op1))
 	{
 	  /* Strip the component reference completely.  */
 	  op0 = TREE_OPERAND (expr, 0);
@@ -1971,9 +1973,9 @@ add_candidate_1 (struct ivopts_data *data,
       if (!operand_equal_p (base, cand->iv->base, 0))
 	continue;
 
-      if (zero_p (cand->iv->step))
+      if (null_or_integer_zerop (cand->iv->step))
 	{
-	  if (zero_p (step))
+	  if (null_or_integer_zerop (step))
 	    break;
 	}
       else
@@ -2134,7 +2136,7 @@ add_old_ivs_candidates (struct ivopts_data *data)
   EXECUTE_IF_SET_IN_BITMAP (data->relevant, 0, i, bi)
     {
       iv = ver_info (data, i)->iv;
-      if (iv && iv->biv_p && !zero_p (iv->step))
+      if (iv && iv->biv_p && !null_or_integer_zerop (iv->step))
 	add_old_iv_candidates (data, iv);
     }
 }
@@ -3340,10 +3342,10 @@ difference_cost (struct ivopts_data *data,
       return 0;
     }
   *var_present = true;
-  if (zero_p (e2))
+  if (integer_zerop (e2))
     return force_var_cost (data, e1, depends_on);
 
-  if (zero_p (e1))
+  if (integer_zerop (e1))
     {
       cost = force_var_cost (data, e2, depends_on);
       cost += multiply_by_cost (-1, mode);
@@ -3730,7 +3732,8 @@ determine_use_iv_cost_condition (struct ivopts_data *data,
   if (TREE_CODE (cond) != SSA_NAME)
     {
       op = TREE_OPERAND (cond, 0);
-      if (TREE_CODE (op) == SSA_NAME && !zero_p (get_iv (data, op)->step))
+      if (TREE_CODE (op) == SSA_NAME
+	  && !null_or_integer_zerop (get_iv (data, op)->step))
 	op = TREE_OPERAND (cond, 1);
       if (TREE_CODE (op) == SSA_NAME)
 	{
@@ -5148,7 +5151,7 @@ rewrite_use_compare (struct ivopts_data *data,
   cond = *use->op_p;
   op_p = &TREE_OPERAND (cond, 0);
   if (TREE_CODE (*op_p) != SSA_NAME
-      || zero_p (get_iv (data, *op_p)->step))
+      || null_or_integer_zerop (get_iv (data, *op_p)->step))
     op_p = &TREE_OPERAND (cond, 1);
 
   op = force_gimple_operand (comp, &stmts, true, SSA_NAME_VAR (*op_p));
@@ -5219,7 +5222,7 @@ remove_unused_ivs (struct ivopts_data *data)
 
       info = ver_info (data, j);
       if (info->iv
-	  && !zero_p (info->iv->step)
+	  && !null_or_integer_zerop (info->iv->step)
 	  && !info->inv_id
 	  && !info->iv->have_use_for
 	  && !info->preserve_biv)
diff --git a/gcc/tree-ssa-loop-manip.c b/gcc/tree-ssa-loop-manip.c
index e68ca55..d27985f 100644
--- a/gcc/tree-ssa-loop-manip.c
+++ b/gcc/tree-ssa-loop-manip.c
@@ -706,7 +706,7 @@ determine_exit_conditions (struct loop *loop, struct tree_niter_desc *desc,
 	of the loop, i.e., BOUND - step * FACTOR does not overflow.
      3) # of iterations is at least FACTOR  */
 
-  if (!zero_p (desc->may_be_zero))
+  if (!integer_zerop (desc->may_be_zero))
     cond = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
 			invert_truthvalue (desc->may_be_zero),
 			cond);
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
index bff08a0..2187c2f 100644
--- a/gcc/tree-ssa-loop-niter.c
+++ b/gcc/tree-ssa-loop-niter.c
@@ -52,36 +52,6 @@ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
 
 */
 
-/* Returns true if ARG is either NULL_TREE or constant zero.  Unlike
-   integer_zerop, it does not care about overflow flags.  */
-
-bool
-zero_p (tree arg)
-{
-  if (!arg)
-    return true;
-
-  if (TREE_CODE (arg) != INTEGER_CST)
-    return false;
-
-  return (TREE_INT_CST_LOW (arg) == 0 && TREE_INT_CST_HIGH (arg) == 0);
-}
-
-/* Returns true if ARG a nonzero constant.  Unlike integer_nonzerop, it does
-   not care about overflow flags.  */
-
-static bool
-nonzero_p (tree arg)
-{
-  if (!arg)
-    return false;
-
-  if (TREE_CODE (arg) != INTEGER_CST)
-    return false;
-
-  return (TREE_INT_CST_LOW (arg) != 0 || TREE_INT_CST_HIGH (arg) != 0);
-}
-
 /* Returns inverse of X modulo 2^s, where MASK = 2^s-1.  */
 
 static tree
@@ -188,7 +158,7 @@ number_of_iterations_ne (tree type, affine_iv *iv, tree final,
       assumption = fold_build2 (FLOOR_MOD_EXPR, niter_type, c, d);
       assumption = fold_build2 (EQ_EXPR, boolean_type_node,
 				assumption, build_int_cst (niter_type, 0));
-      if (!nonzero_p (assumption))
+      if (!integer_nonzerop (assumption))
 	niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
 					  niter->assumptions, assumption);
     }
@@ -219,22 +189,22 @@ number_of_iterations_lt_to_ne (tree type, affine_iv *iv0, affine_iv *iv1,
 
   if (TREE_CODE (mod) != INTEGER_CST)
     return false;
-  if (nonzero_p (mod))
+  if (integer_nonzerop (mod))
     mod = fold_build2 (MINUS_EXPR, niter_type, step, mod);
   tmod = fold_convert (type, mod);
 
-  if (nonzero_p (iv0->step))
+  if (nonnull_and_integer_nonzerop (iv0->step))
     {
       /* The final value of the iv is iv1->base + MOD, assuming that this
 	 computation does not overflow, and that
 	 iv0->base <= iv1->base + MOD.  */
-      if (!iv1->no_overflow && !zero_p (mod))
+      if (!iv1->no_overflow && !integer_zerop (mod))
 	{
 	  bound = fold_build2 (MINUS_EXPR, type,
 			       TYPE_MAX_VALUE (type), tmod);
 	  assumption = fold_build2 (LE_EXPR, boolean_type_node,
 				    iv1->base, bound);
-	  if (zero_p (assumption))
+	  if (integer_zerop (assumption))
 	    return false;
 	}
       noloop = fold_build2 (GT_EXPR, boolean_type_node,
@@ -247,13 +217,13 @@ number_of_iterations_lt_to_ne (tree type, affine_iv *iv0, affine_iv *iv1,
       /* The final value of the iv is iv0->base - MOD, assuming that this
 	 computation does not overflow, and that
 	 iv0->base - MOD <= iv1->base. */
-      if (!iv0->no_overflow && !zero_p (mod))
+      if (!iv0->no_overflow && !integer_zerop (mod))
 	{
 	  bound = fold_build2 (PLUS_EXPR, type,
 			       TYPE_MIN_VALUE (type), tmod);
 	  assumption = fold_build2 (GE_EXPR, boolean_type_node,
 				    iv0->base, bound);
-	  if (zero_p (assumption))
+	  if (integer_zerop (assumption))
 	    return false;
 	}
       noloop = fold_build2 (GT_EXPR, boolean_type_node,
@@ -262,11 +232,11 @@ number_of_iterations_lt_to_ne (tree type, affine_iv *iv0, affine_iv *iv1,
 			    iv1->base);
     }
 
-  if (!nonzero_p (assumption))
+  if (!integer_nonzerop (assumption))
     niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
 				      niter->assumptions,
 				      assumption);
-  if (!zero_p (noloop))
+  if (!integer_zerop (noloop))
     niter->may_be_zero = fold_build2 (TRUTH_OR_EXPR, boolean_type_node,
 				      niter->may_be_zero,
 				      noloop);
@@ -286,7 +256,7 @@ assert_no_overflow_lt (tree type, affine_iv *iv0, affine_iv *iv1,
   tree bound, d, assumption, diff;
   tree niter_type = TREE_TYPE (step);
 
-  if (nonzero_p (iv0->step))
+  if (nonnull_and_integer_nonzerop (iv0->step))
     {
       /* for (i = iv0->base; i < iv1->base; i += iv0->step) */
       if (iv0->no_overflow)
@@ -333,9 +303,9 @@ assert_no_overflow_lt (tree type, affine_iv *iv0, affine_iv *iv1,
 				iv0->base, bound);
     }
 
-  if (zero_p (assumption))
+  if (integer_zerop (assumption))
     return false;
-  if (!nonzero_p (assumption))
+  if (!integer_nonzerop (assumption))
     niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
 				      niter->assumptions, assumption);
     
@@ -354,7 +324,7 @@ assert_loop_rolls_lt (tree type, affine_iv *iv0, affine_iv *iv1,
   tree assumption = boolean_true_node, bound, diff;
   tree mbz, mbzl, mbzr;
 
-  if (nonzero_p (iv0->step))
+  if (nonnull_and_integer_nonzerop (iv0->step))
     {
       diff = fold_build2 (MINUS_EXPR, type,
 			  iv0->step, build_int_cst (type, 1));
@@ -394,10 +364,10 @@ assert_loop_rolls_lt (tree type, affine_iv *iv0, affine_iv *iv1,
 
   mbz = fold_build2 (GT_EXPR, boolean_type_node, mbzl, mbzr);
 
-  if (!nonzero_p (assumption))
+  if (!integer_nonzerop (assumption))
     niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
 				      niter->assumptions, assumption);
-  if (!zero_p (mbz))
+  if (!integer_zerop (mbz))
     niter->may_be_zero = fold_build2 (TRUTH_OR_EXPR, boolean_type_node,
 				      niter->may_be_zero, mbz);
 }
@@ -414,7 +384,7 @@ number_of_iterations_lt (tree type, affine_iv *iv0, affine_iv *iv1,
   tree niter_type = unsigned_type_for (type);
   tree delta, step, s;
 
-  if (nonzero_p (iv0->step))
+  if (nonnull_and_integer_nonzerop (iv0->step))
     {
       niter->control = *iv0;
       niter->cmp = LT_EXPR;
@@ -433,9 +403,9 @@ number_of_iterations_lt (tree type, affine_iv *iv0, affine_iv *iv1,
 
   /* First handle the special case that the step is +-1.  */
   if ((iv0->step && integer_onep (iv0->step)
-       && zero_p (iv1->step))
+       && null_or_integer_zerop (iv1->step))
       || (iv1->step && integer_all_onesp (iv1->step)
-	  && zero_p (iv0->step)))
+	  && null_or_integer_zerop (iv0->step)))
     {
       /* for (i = iv0->base; i < iv1->base; i++)
 
@@ -451,7 +421,7 @@ number_of_iterations_lt (tree type, affine_iv *iv0, affine_iv *iv1,
       return true;
     }
 
-  if (nonzero_p (iv0->step))
+  if (nonnull_and_integer_nonzerop (iv0->step))
     step = fold_convert (niter_type, iv0->step);
   else
     step = fold_convert (niter_type,
@@ -509,21 +479,21 @@ number_of_iterations_le (tree type, affine_iv *iv0, affine_iv *iv1,
 
   if (!never_infinite)
     {
-      if (nonzero_p (iv0->step))
+      if (nonnull_and_integer_nonzerop (iv0->step))
 	assumption = fold_build2 (NE_EXPR, boolean_type_node,
 				  iv1->base, TYPE_MAX_VALUE (type));
       else
 	assumption = fold_build2 (NE_EXPR, boolean_type_node,
 				  iv0->base, TYPE_MIN_VALUE (type));
 
-      if (zero_p (assumption))
+      if (integer_zerop (assumption))
 	return false;
-      if (!nonzero_p (assumption))
+      if (!integer_nonzerop (assumption))
 	niter->assumptions = fold_build2 (TRUTH_AND_EXPR, boolean_type_node,
 					  niter->assumptions, assumption);
     }
 
-  if (nonzero_p (iv0->step))
+  if (nonnull_and_integer_nonzerop (iv0->step))
     iv1->base = fold_build2 (PLUS_EXPR, type,
 			     iv1->base, build_int_cst (type, 1));
   else
@@ -572,7 +542,7 @@ number_of_iterations_cond (tree type, affine_iv *iv0, enum tree_code code,
   /* Make < comparison from > ones, and for NE_EXPR comparisons, ensure that
      the control variable is on lhs.  */
   if (code == GE_EXPR || code == GT_EXPR
-      || (code == NE_EXPR && zero_p (iv0->step)))
+      || (code == NE_EXPR && null_or_integer_zerop (iv0->step)))
     {
       SWAP (iv0, iv1);
       code = swap_tree_comparison (code);
@@ -608,9 +578,9 @@ number_of_iterations_cond (tree type, affine_iv *iv0, enum tree_code code,
 
   /* If the control induction variable does not overflow, the loop obviously
      cannot be infinite.  */
-  if (!zero_p (iv0->step) && iv0->no_overflow)
+  if (!null_or_integer_zerop (iv0->step) && iv0->no_overflow)
     never_infinite = true;
-  else if (!zero_p (iv1->step) && iv1->no_overflow)
+  else if (!null_or_integer_zerop (iv1->step) && iv1->no_overflow)
     never_infinite = true;
   else
     never_infinite = false;
@@ -618,7 +588,7 @@ number_of_iterations_cond (tree type, affine_iv *iv0, enum tree_code code,
   /* We can handle the case when neither of the sides of the comparison is
      invariant, provided that the test is NE_EXPR.  This rarely occurs in
      practice, but it is simple enough to manage.  */
-  if (!zero_p (iv0->step) && !zero_p (iv1->step))
+  if (!null_or_integer_zerop (iv0->step) && !null_or_integer_zerop (iv1->step))
     {
       if (code != NE_EXPR)
 	return false;
@@ -633,7 +603,7 @@ number_of_iterations_cond (tree type, affine_iv *iv0, enum tree_code code,
   /* If the result of the comparison is a constant,  the loop is weird.  More
      precise handling would be possible, but the situation is not common enough
      to waste time on it.  */
-  if (zero_p (iv0->step) && zero_p (iv1->step))
+  if (null_or_integer_zerop (iv0->step) && null_or_integer_zerop (iv1->step))
     return false;
 
   /* Ignore loops of while (i-- < 10) type.  */
@@ -642,12 +612,12 @@ number_of_iterations_cond (tree type, affine_iv *iv0, enum tree_code code,
       if (iv0->step && tree_int_cst_sign_bit (iv0->step))
 	return false;
 
-      if (!zero_p (iv1->step) && !tree_int_cst_sign_bit (iv1->step))
+      if (!null_or_integer_zerop (iv1->step) && !tree_int_cst_sign_bit (iv1->step))
 	return false;
     }
 
   /* If the loop exits immediately, there is nothing to do.  */
-  if (zero_p (fold_build2 (code, boolean_type_node, iv0->base, iv1->base)))
+  if (integer_zerop (fold_build2 (code, boolean_type_node, iv0->base, iv1->base)))
     {
       niter->niter = build_int_cst (unsigned_type_for (type), 0);
       return true;
@@ -658,7 +628,7 @@ number_of_iterations_cond (tree type, affine_iv *iv0, enum tree_code code,
   switch (code)
     {
     case NE_EXPR:
-      gcc_assert (zero_p (iv1->step));
+      gcc_assert (null_or_integer_zerop (iv1->step));
       return number_of_iterations_ne (type, iv0, iv1->base, niter, never_infinite);
     case LT_EXPR:
       return number_of_iterations_lt (type, iv0, iv1, niter, never_infinite);
@@ -822,11 +792,11 @@ tree_simplify_using_condition_1 (tree cond, tree expr)
       /* We know that e0 == e1.  Check whether we cannot simplify expr
 	 using this fact.  */
       e = simplify_replace_tree (expr, e0, e1);
-      if (zero_p (e) || nonzero_p (e))
+      if (integer_zerop (e) || integer_nonzerop (e))
 	return e;
 
       e = simplify_replace_tree (expr, e1, e0);
-      if (zero_p (e) || nonzero_p (e))
+      if (integer_zerop (e) || integer_nonzerop (e))
 	return e;
     }
   if (TREE_CODE (expr) == EQ_EXPR)
@@ -836,10 +806,10 @@ tree_simplify_using_condition_1 (tree cond, tree expr)
 
       /* If e0 == e1 (EXPR) implies !COND, then EXPR cannot be true.  */
       e = simplify_replace_tree (cond, e0, e1);
-      if (zero_p (e))
+      if (integer_zerop (e))
 	return e;
       e = simplify_replace_tree (cond, e1, e0);
-      if (zero_p (e))
+      if (integer_zerop (e))
 	return e;
     }
   if (TREE_CODE (expr) == NE_EXPR)
@@ -849,10 +819,10 @@ tree_simplify_using_condition_1 (tree cond, tree expr)
 
       /* If e0 == e1 (!EXPR) implies !COND, then EXPR must be true.  */
       e = simplify_replace_tree (cond, e0, e1);
-      if (zero_p (e))
+      if (integer_zerop (e))
 	return boolean_true_node;
       e = simplify_replace_tree (cond, e1, e0);
-      if (zero_p (e))
+      if (integer_zerop (e))
 	return boolean_true_node;
     }
 
@@ -861,12 +831,12 @@ tree_simplify_using_condition_1 (tree cond, tree expr)
   /* Check whether COND ==> EXPR.  */
   notcond = invert_truthvalue (cond);
   e = fold_binary (TRUTH_OR_EXPR, boolean_type_node, notcond, te);
-  if (nonzero_p (e))
+  if (e && integer_nonzerop (e))
     return e;
 
   /* Check whether COND ==> not EXPR.  */
   e = fold_binary (TRUTH_AND_EXPR, boolean_type_node, cond, te);
-  if (e && zero_p (e))
+  if (e && integer_zerop (e))
     return e;
 
   return expr;
@@ -1129,8 +1099,8 @@ number_of_iterations_exit (struct loop *loop, edge exit,
   
       /* We can provide a more specific warning if one of the operator is
 	 constant and the other advances by +1 or -1.  */
-      if (!zero_p (iv1.step)
-	  ? (zero_p (iv0.step)
+      if (!null_or_integer_zerop (iv1.step)
+	  ? (null_or_integer_zerop (iv0.step)
 	     && (integer_onep (iv1.step) || integer_all_onesp (iv1.step)))
 	  : (iv0.step
 	     && (integer_onep (iv0.step) || integer_all_onesp (iv0.step))))
@@ -1176,7 +1146,7 @@ find_loop_niter (struct loop *loop, edge *exit)
       if (!number_of_iterations_exit (loop, ex, &desc, false))
 	continue;
 
-      if (nonzero_p (desc.may_be_zero))
+      if (integer_nonzerop (desc.may_be_zero))
 	{
 	  /* We exit in the first iteration through this exit.
 	     We won't find anything better.  */
@@ -1185,7 +1155,7 @@ find_loop_niter (struct loop *loop, edge *exit)
 	  break;
 	}
 
-      if (!zero_p (desc.may_be_zero))
+      if (!integer_zerop (desc.may_be_zero))
 	continue;
 
       aniter = desc.niter;
@@ -1415,7 +1385,7 @@ loop_niter_by_eval (struct loop *loop, edge exit)
 	aval[j] = get_val_for (op[j], val[j]);
 
       acnd = fold_binary (cmp, boolean_type_node, aval[0], aval[1]);
-      if (acnd && zero_p (acnd))
+      if (acnd && integer_zerop (acnd))
 	{
 	  if (dump_file && (dump_flags & TDF_DETAILS))
 	    fprintf (dump_file,
@@ -1489,14 +1459,14 @@ implies_nonnegative_p (tree cond, tree val)
   if (tree_expr_nonnegative_p (val))
     return true;
 
-  if (nonzero_p (cond))
+  if (integer_nonzerop (cond))
     return false;
 
   compare = fold_build2 (GE_EXPR,
 			 boolean_type_node, val, build_int_cst (type, 0));
   compare = tree_simplify_using_condition_1 (cond, compare);
 
-  return nonzero_p (compare);
+  return integer_nonzerop (compare);
 }
 
 /* Returns true if we can prove that COND ==> A >= B.  */
@@ -1506,15 +1476,15 @@ implies_ge_p (tree cond, tree a, tree b)
 {
   tree compare = fold_build2 (GE_EXPR, boolean_type_node, a, b);
 
-  if (nonzero_p (compare))
+  if (integer_nonzerop (compare))
     return true;
 
-  if (nonzero_p (cond))
+  if (integer_nonzerop (cond))
     return false;
 
   compare = tree_simplify_using_condition_1 (cond, compare);
 
-  return nonzero_p (compare);
+  return integer_nonzerop (compare);
 }
 
 /* Returns a constant upper bound on the value of expression VAL.  VAL
@@ -1711,7 +1681,7 @@ record_nonwrapping_iv (struct loop *loop, tree base, tree step, tree stmt,
   tree niter_bound, extreme, delta;
   tree type = TREE_TYPE (base), unsigned_type;
 
-  if (TREE_CODE (step) != INTEGER_CST || zero_p (step))
+  if (TREE_CODE (step) != INTEGER_CST || integer_zerop (step))
     return;
 
   if (dump_file && (dump_flags & TDF_DETAILS))
@@ -1808,7 +1778,7 @@ idx_infer_loop_bounds (tree base, tree *idx, void *dta)
   if (!init
       || !step
       || TREE_CODE (step) != INTEGER_CST
-      || zero_p (step)
+      || integer_zerop (step)
       || tree_contains_chrecs (init, NULL)
       || chrec_contains_symbols_defined_in_loop (init, loop->num))
     return true;
@@ -2070,7 +2040,7 @@ n_of_executions_at_most (tree stmt,
 			 tree niter)
 {
   double_int bound = niter_bound->bound;
-  tree nit_type = TREE_TYPE (niter);
+  tree nit_type = TREE_TYPE (niter), e;
   enum tree_code cmp;
 
   gcc_assert (TYPE_UNSIGNED (nit_type));
@@ -2117,9 +2087,9 @@ n_of_executions_at_most (tree stmt,
       cmp = GT_EXPR;
     }
 
-  return nonzero_p (fold_binary (cmp, boolean_type_node,
-				 niter,
-				 double_int_to_tree (nit_type, bound)));
+  e = fold_binary (cmp, boolean_type_node,
+		   niter, double_int_to_tree (nit_type, bound));
+  return e && integer_nonzerop (e);
 }
 
 /* Returns true if the arithmetics in TYPE can be assumed not to wrap.  */
@@ -2179,7 +2149,7 @@ scev_probably_wraps_p (tree base, tree step,
       || TREE_CODE (step) != INTEGER_CST)
     return true;
 
-  if (zero_p (step))
+  if (integer_zerop (step))
     return false;
 
   /* If we can use the fact that signed and pointer arithmetics does not
diff --git a/gcc/tree-ssa-loop-prefetch.c b/gcc/tree-ssa-loop-prefetch.c
index 5f39b8d..c8e6922 100644
--- a/gcc/tree-ssa-loop-prefetch.c
+++ b/gcc/tree-ssa-loop-prefetch.c
@@ -337,7 +337,7 @@ idx_analyze_ref (tree base, tree *index, void *data)
   ibase = iv.base;
   step = iv.step;
 
-  if (zero_p (step))
+  if (null_or_integer_zerop (step))
     istep = 0;
   else
     {
diff --git a/gcc/tree.h b/gcc/tree.h
index f88c244..87bce8b 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -4075,7 +4075,22 @@ extern int integer_pow2p (tree);
 
 extern int integer_nonzerop (tree);
 
-extern bool zero_p (tree);
+/* Returns true if X is either NULL or zero.  */
+
+static inline bool
+null_or_integer_zerop (tree x)
+{
+  return x == NULL_TREE || integer_zerop (x);
+}
+
+/* Returns true if X is non-NULL and non-zero.  */
+
+static inline bool
+nonnull_and_integer_nonzerop (tree x)
+{
+  return x != NULL_TREE && integer_nonzerop (x);
+}
+
 extern bool cst_and_fits_in_hwi (tree);
 extern tree num_ending_zeros (tree);