analyzer: avoid use of fold_build2

Various places in the analyzer use fold_build2, test the result, then
discard it.  It's more efficient to use fold_binary, which avoids
building and GC-ing a redundant tree for the cases where folding fails.

gcc/analyzer/ChangeLog:
	* constraint-manager.cc (range::constrained_to_single_element):
	Replace fold_build2 with fold_binary.  Remove unnecessary newline.
	(constraint_manager::get_or_add_equiv_class): Replace fold_build2
	with fold_binary in two places, and remove out-of-date comment.
	(constraint_manager::eval_condition): Replace fold_build2 with
	fold_binary.
	* region-model.cc (constant_svalue::eval_condition): Likewise.
	(region_model::on_assignment): Likewise.

gcc/analyzer/ChangeLog

 2020-02-03  David Malcolm  <dmalcolm@redhat.com>
 
+	* constraint-manager.cc (range::constrained_to_single_element):
+	Replace fold_build2 with fold_binary.  Remove unnecessary newline.
+	(constraint_manager::get_or_add_equiv_class): Replace fold_build2
+	with fold_binary in two places, and remove out-of-date comment.
+	(constraint_manager::eval_condition): Replace fold_build2 with
+	fold_binary.
+	* region-model.cc (constant_svalue::eval_condition): Likewise.
+	(region_model::on_assignment): Likewise.
+
+2020-02-03  David Malcolm  <dmalcolm@redhat.com>
+
 	PR analyzer/93544
 	* diagnostic-manager.cc
 	(diagnostic_manager::prune_for_sm_diagnostic): Bulletproof

gcc/analyzer/constraint-manager.cc

@@ -145,10 +145,9 @@ range::constrained_to_single_element (tree *out)
   m_upper_bound.ensure_closed (true);
 
   // Are they equal?
-  tree comparison
-    = fold_build2 (EQ_EXPR, boolean_type_node,
-		   m_lower_bound.m_constant,
-		   m_upper_bound.m_constant);
+  tree comparison = fold_binary (EQ_EXPR, boolean_type_node,
+				 m_lower_bound.m_constant,
+				 m_upper_bound.m_constant);
   if (comparison == boolean_true_node)
     {
       *out = m_lower_bound.m_constant;
@@ -932,7 +931,7 @@ constraint_manager::get_or_add_equiv_class (svalue_id sid)
 	    && types_compatible_p (TREE_TYPE (cst),
 				   TREE_TYPE (ec->m_constant)))
 	  {
-	    tree eq = fold_build2 (EQ_EXPR, boolean_type_node,
+	    tree eq = fold_binary (EQ_EXPR, boolean_type_node,
 				   cst, ec->m_constant);
 	    if (eq == boolean_true_node)
 	      {
@@ -969,10 +968,8 @@ constraint_manager::get_or_add_equiv_class (svalue_id sid)
 		 Determine the direction of the inequality, and record that
 		 fact.  */
 	      tree lt
-		= fold_build2 (LT_EXPR, boolean_type_node,
+		= fold_binary (LT_EXPR, boolean_type_node,
 			       new_ec->m_constant, other_ec.m_constant);
-	      //gcc_assert (lt == boolean_true_node || lt == boolean_false_node);
-	      // not true for int vs float comparisons
 	      if (lt == boolean_true_node)
 		add_constraint_internal (new_id, CONSTRAINT_LT, other_id);
 	      else if (lt == boolean_false_node)
@@ -1018,7 +1015,7 @@ constraint_manager::eval_condition (equiv_class_id lhs_ec,
   if (lhs_const && rhs_const)
     {
       tree comparison
-	= fold_build2 (op, boolean_type_node, lhs_const, rhs_const);
+	= fold_binary (op, boolean_type_node, lhs_const, rhs_const);
       if (comparison == boolean_true_node)
 	return tristate (tristate::TS_TRUE);
       if (comparison == boolean_false_node)

gcc/analyzer/region-model.cc

@@ -670,7 +670,7 @@ constant_svalue::eval_condition (constant_svalue *lhs,
   if (types_compatible_p (TREE_TYPE (lhs_const), TREE_TYPE (rhs_const)))
     {
       tree comparison
-	= fold_build2 (op, boolean_type_node, lhs_const, rhs_const);
+	= fold_binary (op, boolean_type_node, lhs_const, rhs_const);
       if (comparison == boolean_true_node)
 	return tristate (tristate::TS_TRUE);
       if (comparison == boolean_false_node)
@@ -4088,9 +4088,9 @@ region_model::on_assignment (const gassign *assign, region_model_context *ctxt)
 	if (tree rhs1_cst = maybe_get_constant (rhs1_sid))
 	  if (tree rhs2_cst = maybe_get_constant (rhs2_sid))
 	    {
-	      tree result = fold_build2 (op, TREE_TYPE (lhs),
+	      tree result = fold_binary (op, TREE_TYPE (lhs),
 					 rhs1_cst, rhs2_cst);
-	      if (CONSTANT_CLASS_P (result))
+	      if (result && CONSTANT_CLASS_P (result))
 		{
 		  svalue_id result_sid
 		    = get_or_create_constant_svalue (result);