+/* Fold the RHS of an assignment statement and return it as a tree.
+ May return NULL_TREE if no simplification is possible. */
+
+static tree
+fold_assignment_stmt (gimple stmt)
+{
+ enum tree_code subcode = gimple_assign_rhs_code (stmt);
+
+ switch (get_gimple_rhs_class (subcode))
+ {
+ case GIMPLE_SINGLE_RHS:
+ {
+ tree rhs = gimple_assign_rhs1 (stmt);
+
+ if (TREE_CODE (rhs) == COND_EXPR)
+ {
+ /* Sadly, we have to handle conditional assignments specially
+ here, because fold expects all the operands of an expression
+ to be folded before the expression itself is folded, but we
+ can't just substitute the folded condition here. */
+ tree cond = fold (COND_EXPR_COND (rhs));
+ if (cond == boolean_true_node)
+ rhs = COND_EXPR_THEN (rhs);
+ else if (cond == boolean_false_node)
+ rhs = COND_EXPR_ELSE (rhs);
+ }
+
+ return fold (rhs);
+ }
+ break;
+ case GIMPLE_UNARY_RHS:
+ {
+ tree lhs = gimple_assign_lhs (stmt);
+ tree op0 = gimple_assign_rhs1 (stmt);
+ return fold_unary (subcode, TREE_TYPE (lhs), op0);
+ }
+ break;
+ case GIMPLE_BINARY_RHS:
+ {
+ tree lhs = gimple_assign_lhs (stmt);
+ tree op0 = gimple_assign_rhs1 (stmt);
+ tree op1 = gimple_assign_rhs2 (stmt);
+ return fold_binary (subcode, TREE_TYPE (lhs), op0, op1);
+ }
+ break;
+ default:
+ gcc_unreachable ();
+ }
+}
+
OSDN Git Service
