-
-/* Perform any modifications to EXPR required when it is unsaved. Does
- not recurse into EXPR's subtrees. */
-
-void
-unsave_expr_1 (tree expr)
-{
- switch (TREE_CODE (expr))
- {
- case TARGET_EXPR:
- /* Don't mess with a TARGET_EXPR that hasn't been expanded.
- It's OK for this to happen if it was part of a subtree that
- isn't immediately expanded, such as operand 2 of another
- TARGET_EXPR. */
- if (TREE_OPERAND (expr, 1))
- break;
-
- TREE_OPERAND (expr, 1) = TREE_OPERAND (expr, 3);
- TREE_OPERAND (expr, 3) = NULL_TREE;
- break;
-
- default:
- break;
- }
-}
-
-/* Return 0 if it is safe to evaluate EXPR multiple times,
- return 1 if it is safe if EXPR is unsaved afterward, or
- return 2 if it is completely unsafe.
-
- This assumes that CALL_EXPRs and TARGET_EXPRs are never replicated in
- an expression tree, so that it safe to unsave them and the surrounding
- context will be correct.
-
- SAVE_EXPRs basically *only* appear replicated in an expression tree,
- occasionally across the whole of a function. It is therefore only
- safe to unsave a SAVE_EXPR if you know that all occurrences appear
- below the UNSAVE_EXPR. */
-
-int
-unsafe_for_reeval (tree expr)
-{
- int unsafeness = 0;
- enum tree_code code;
- int i, tmp, tmp2;
- tree exp;
- int first_rtl;
-
- if (expr == NULL_TREE)
- return 1;
-
- code = TREE_CODE (expr);
- first_rtl = first_rtl_op (code);
-
- switch (code)
- {
- case SAVE_EXPR:
- return 2;
-
- /* A label can only be emitted once. */
- case LABEL_EXPR:
- return 1;
-
- case BIND_EXPR:
- unsafeness = 1;
- break;
-
- case TREE_LIST:
- for (exp = expr; exp != 0; exp = TREE_CHAIN (exp))
- {
- tmp = unsafe_for_reeval (TREE_VALUE (exp));
- unsafeness = MAX (tmp, unsafeness);
- }
-
- return unsafeness;
-
- case CALL_EXPR:
- tmp2 = unsafe_for_reeval (TREE_OPERAND (expr, 0));
- tmp = unsafe_for_reeval (TREE_OPERAND (expr, 1));
- return MAX (MAX (tmp, 1), tmp2);
-
- case TARGET_EXPR:
- unsafeness = 1;
- break;
-
- case EXIT_BLOCK_EXPR:
- /* EXIT_BLOCK_LABELED_BLOCK, a.k.a. TREE_OPERAND (expr, 0), holds
- a reference to an ancestor LABELED_BLOCK, so we need to avoid
- unbounded recursion in the 'e' traversal code below. */
- exp = EXIT_BLOCK_RETURN (expr);
- return exp ? unsafe_for_reeval (exp) : 0;
-
- default:
- tmp = lang_hooks.unsafe_for_reeval (expr);
- if (tmp >= 0)
- return tmp;
- break;
- }
-
- switch (TREE_CODE_CLASS (code))
- {
- case 'c': /* a constant */
- case 't': /* a type node */
- case 'x': /* something random, like an identifier or an ERROR_MARK. */
- case 'd': /* A decl node */
- return 0;
-
- case 'e': /* an expression */
- case 'r': /* a reference */
- case 's': /* an expression with side effects */
- case '<': /* a comparison expression */
- case '2': /* a binary arithmetic expression */
- case '1': /* a unary arithmetic expression */
- for (i = first_rtl - 1; i >= 0; i--)
- {
- tmp = unsafe_for_reeval (TREE_OPERAND (expr, i));
- unsafeness = MAX (tmp, unsafeness);
- }
-
- return unsafeness;
-
- default:
- return 2;
- }
-}