static unsigned
get_stmt_uid (tree stmt)
{
if (TREE_CODE (stmt) == PHI_NODE)
return SSA_NAME_VERSION (PHI_RESULT (stmt)) + max_stmt_uid;
return stmt_ann (stmt)->uid;
}
enum move_pos
movement_possibility (tree stmt)
{
tree lhs, rhs;
if (flag_unswitch_loops
&& TREE_CODE (stmt) == COND_EXPR)
{
/* If we perform unswitching, force the operands of the invariant
condition to be moved out of the loop. */
return MOVE_POSSIBLE;
}
if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT)
return MOVE_IMPOSSIBLE;
if (stmt_ends_bb_p (stmt))
return MOVE_IMPOSSIBLE;
if (stmt_ann (stmt)->has_volatile_ops)
return MOVE_IMPOSSIBLE;
lhs = GIMPLE_STMT_OPERAND (stmt, 0);
if (TREE_CODE (lhs) == SSA_NAME
&& SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
return MOVE_IMPOSSIBLE;
rhs = GIMPLE_STMT_OPERAND (stmt, 1);
if (TREE_SIDE_EFFECTS (rhs)
|| tree_could_throw_p (rhs))
return MOVE_IMPOSSIBLE;
if (TREE_CODE (lhs) != SSA_NAME
|| tree_could_trap_p (rhs))
return MOVE_PRESERVE_EXECUTION;
if (get_call_expr_in (stmt))
{
/* While pure or const call is guaranteed to have no side effects, we
cannot move it arbitrarily. Consider code like
char *s = something ();
while (1)
{
if (s)
t = strlen (s);
else
t = 0;
}
Here the strlen call cannot be moved out of the loop, even though
s is invariant. In addition to possibly creating a call with
invalid arguments, moving out a function call that is not executed
may cause performance regressions in case the call is costly and
not executed at all. */
return MOVE_PRESERVE_EXECUTION;
}
return MOVE_POSSIBLE;
}
