static rtx_expr_list *
extract_mentioned_regs (rtx x)
{
rtx_expr_list *mentioned_regs = NULL;
subrtx_var_iterator::array_type array;
FOR_EACH_SUBRTX_VAR (iter, array, x, NONCONST)
{
rtx x = *iter;
if (REG_P (x))
mentioned_regs = alloc_EXPR_LIST (0, x, mentioned_regs);
}
/* Unswitch single LOOP. COND_CHECKED holds list of conditions we already
unswitched on and are therefore known to be true in this LOOP. NUM is
number of unswitchings done; do not allow it to grow too much, it is too
easy to create example on that the code would grow exponentially.
Returns true LOOP was unswitched. */
static bool
unswitch_single_loop (struct loop *loop, rtx cond_checked, int num)
{
basic_block *bbs;
struct loop *nloop;
unsigned i;
rtx cond, rcond = NULL_RTX, conds, rconds, acond, cinsn;
int repeat;
edge e;
HOST_WIDE_INT iterations;
/* Do not unswitch too much. */
if (num > PARAM_VALUE (PARAM_MAX_UNSWITCH_LEVEL))
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching anymore, hit max level\n");
return false;
}
/* Only unswitch innermost loops. */
if (loop->inner)
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching, not innermost loop\n");
return false;
}
/* We must be able to duplicate loop body. */
if (!can_duplicate_loop_p (loop))
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching, can't duplicate loop\n");
return false;
}
/* The loop should not be too large, to limit code growth. */
if (num_loop_insns (loop) > PARAM_VALUE (PARAM_MAX_UNSWITCH_INSNS))
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching, loop too big\n");
return false;
}
/* Do not unswitch in cold areas. */
if (optimize_loop_for_size_p (loop))
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching, not hot area\n");
return false;
}
/* Nor if the loop usually does not roll. */
iterations = estimated_loop_iterations_int (loop);
if (iterations >= 0 && iterations <= 1)
{
if (dump_file)
fprintf (dump_file, ";; Not unswitching, loop iterations < 1\n");
return false;
}
do
{
repeat = 0;
cinsn = NULL_RTX;
/* Find a bb to unswitch on. */
bbs = get_loop_body (loop);
iv_analysis_loop_init (loop);
for (i = 0; i < loop->num_nodes; i++)
if ((cond = may_unswitch_on (bbs[i], loop, &cinsn)))
break;
if (i == loop->num_nodes)
{
free (bbs);
return false;
}
if (cond != const0_rtx
&& cond != const_true_rtx)
{
rcond = reversed_condition (cond);
if (rcond)
rcond = canon_condition (rcond);
/* Check whether the result can be predicted. */
for (acond = cond_checked; acond; acond = XEXP (acond, 1))
simplify_using_condition (XEXP (acond, 0), &cond, NULL);
}
if (cond == const_true_rtx)
{
/* Remove false path. */
e = FALLTHRU_EDGE (bbs[i]);
remove_path (e);
free (bbs);
repeat = 1;
}
else if (cond == const0_rtx)
{
/* Remove true path. */
e = BRANCH_EDGE (bbs[i]);
remove_path (e);
free (bbs);
repeat = 1;
}
} while (repeat);
/* We found the condition we can unswitch on. */
conds = alloc_EXPR_LIST (0, cond, cond_checked);
if (rcond)
rconds = alloc_EXPR_LIST (0, rcond, cond_checked);
else
rconds = cond_checked;
if (dump_file)
fprintf (dump_file, ";; Unswitching loop\n");
/* Unswitch the loop on this condition. */
nloop = unswitch_loop (loop, bbs[i], copy_rtx_if_shared (cond), cinsn);
gcc_assert (nloop);
/* Invoke itself on modified loops. */
unswitch_single_loop (nloop, rconds, num + 1);
unswitch_single_loop (loop, conds, num + 1);
free_EXPR_LIST_node (conds);
if (rcond)
free_EXPR_LIST_node (rconds);
free (bbs);
return true;
}