when they are changed -- if this has to be done, the lowering routine must
do it explicitly. DATA is passed through the recursion. */
-void
+static void
lower_stmt_body (tree expr, struct lower_data *data)
{
tree_stmt_iterator tsi;
tsi_delink (tsi);
}
+/* Try to determine whether a TRY_CATCH expression can fall through.
+ This is a subroutine of block_may_fallthru. */
+
+static bool
+try_catch_may_fallthru (tree stmt)
+{
+ tree_stmt_iterator i;
+
+ /* If the TRY block can fall through, the whole TRY_CATCH can
+ fall through. */
+ if (block_may_fallthru (TREE_OPERAND (stmt, 0)))
+ return true;
+
+ i = tsi_start (TREE_OPERAND (stmt, 1));
+ switch (TREE_CODE (tsi_stmt (i)))
+ {
+ case CATCH_EXPR:
+ /* We expect to see a sequence of CATCH_EXPR trees, each with a
+ catch expression and a body. The whole TRY_CATCH may fall
+ through iff any of the catch bodies falls through. */
+ for (; !tsi_end_p (i); tsi_next (&i))
+ {
+ if (block_may_fallthru (CATCH_BODY (tsi_stmt (i))))
+ return true;
+ }
+ return false;
+
+ case EH_FILTER_EXPR:
+ /* The exception filter expression only matters if there is an
+ exception. If the exception does not match EH_FILTER_TYPES,
+ we will execute EH_FILTER_FAILURE, and we will fall through
+ if that falls through. If the exception does match
+ EH_FILTER_TYPES, the stack unwinder will continue up the
+ stack, so we will not fall through. We don't know whether we
+ will throw an exception which matches EH_FILTER_TYPES or not,
+ so we just ignore EH_FILTER_TYPES and assume that we might
+ throw an exception which doesn't match. */
+ return block_may_fallthru (EH_FILTER_FAILURE (tsi_stmt (i)));
+
+ default:
+ /* This case represents statements to be executed when an
+ exception occurs. Those statements are implicitly followed
+ by a RESX_EXPR to resume execution after the exception. So
+ in this case the TRY_CATCH never falls through. */
+ return false;
+ }
+}
+
/* Try to determine if we can fall out of the bottom of BLOCK. This guess
need not be 100% accurate; simply be conservative and return true if we
don't know. This is used only to avoid stupidly generating extra code.
branch to a selected label and hence can not fall through.
Otherwise SWITCH_BODY is set, and the switch can fall
through. */
- return SWITCH_LABELS (stmt) != NULL_TREE;
+ return SWITCH_LABELS (stmt) == NULL_TREE;
case COND_EXPR:
if (block_may_fallthru (COND_EXPR_THEN (stmt)))
case BIND_EXPR:
return block_may_fallthru (BIND_EXPR_BODY (stmt));
+ case TRY_CATCH_EXPR:
+ return try_catch_may_fallthru (stmt);
+
case TRY_FINALLY_EXPR:
- return block_may_fallthru (TREE_OPERAND (stmt, 1));
+ /* The finally clause is always executed after the try clause,
+ so if it does not fall through, then the try-finally will not
+ fall through. Otherwise, if the try clause does not fall
+ through, then when the finally clause falls through it will
+ resume execution wherever the try clause was going. So the
+ whole try-finally will only fall through if both the try
+ clause and the finally clause fall through. */
+ return (block_may_fallthru (TREE_OPERAND (stmt, 0))
+ && block_may_fallthru (TREE_OPERAND (stmt, 1)));
case MODIFY_EXPR:
if (TREE_CODE (TREE_OPERAND (stmt, 1)) == CALL_EXPR)