static tree
make_phi_node (tree var, int len)
{
tree phi;
int capacity, i;
capacity = ideal_phi_node_len (len);
phi = allocate_phi_node (capacity);
/* We need to clear the entire PHI node, including the argument
portion, because we represent a "missing PHI argument" by placing
NULL_TREE in PHI_ARG_DEF. */
memset (phi, 0, (sizeof (struct tree_phi_node) - sizeof (struct phi_arg_d)
+ sizeof (struct phi_arg_d) * len));
TREE_SET_CODE (phi, PHI_NODE);
PHI_NUM_ARGS (phi) = len;
PHI_ARG_CAPACITY (phi) = capacity;
TREE_TYPE (phi) = TREE_TYPE (var);
if (TREE_CODE (var) == SSA_NAME)
SET_PHI_RESULT (phi, var);
else
SET_PHI_RESULT (phi, make_ssa_name (var, phi));
for (i = 0; i < capacity; i++)
{
use_operand_p imm;
imm = &(PHI_ARG_IMM_USE_NODE (phi, i));
imm->use = &(PHI_ARG_DEF_TREE (phi, i));
imm->prev = NULL;
imm->next = NULL;
imm->stmt = phi;
}
return phi;
}
static void
resize_phi_node (tree *phi, int len)
{
int old_size, i;
tree new_phi;
gcc_assert (len > PHI_ARG_CAPACITY (*phi));
/* The garbage collector will not look at the PHI node beyond the
first PHI_NUM_ARGS elements. Therefore, all we have to copy is a
portion of the PHI node currently in use. */
old_size = (sizeof (struct tree_phi_node)
+ (PHI_NUM_ARGS (*phi) - 1) * sizeof (struct phi_arg_d));
new_phi = allocate_phi_node (len);
memcpy (new_phi, *phi, old_size);
for (i = 0; i < PHI_NUM_ARGS (new_phi); i++)
{
use_operand_p imm, old_imm;
imm = &(PHI_ARG_IMM_USE_NODE (new_phi, i));
old_imm = &(PHI_ARG_IMM_USE_NODE (*phi, i));
imm->use = &(PHI_ARG_DEF_TREE (new_phi, i));
relink_imm_use_stmt (imm, old_imm, new_phi);
}
PHI_ARG_CAPACITY (new_phi) = len;
for (i = PHI_NUM_ARGS (new_phi); i < len; i++)
{
use_operand_p imm;
imm = &(PHI_ARG_IMM_USE_NODE (new_phi, i));
imm->use = &(PHI_ARG_DEF_TREE (new_phi, i));
imm->prev = NULL;
imm->next = NULL;
imm->stmt = new_phi;
}
*phi = new_phi;
}
static unsigned int
tree_ssa_phiopt (void)
{
basic_block bb;
basic_block *bb_order;
unsigned n, i;
bool cfgchanged = false;
/* Search every basic block for COND_EXPR we may be able to optimize.
We walk the blocks in order that guarantees that a block with
a single predecessor is processed before the predecessor.
This ensures that we collapse inner ifs before visiting the
outer ones, and also that we do not try to visit a removed
block. */
bb_order = blocks_in_phiopt_order ();
n = n_basic_blocks - NUM_FIXED_BLOCKS;
for (i = 0; i < n; i++)
{
tree cond_expr;
tree phi;
basic_block bb1, bb2;
edge e1, e2;
tree arg0, arg1;
bb = bb_order[i];
cond_expr = last_stmt (bb);
/* Check to see if the last statement is a COND_EXPR. */
if (!cond_expr
|| TREE_CODE (cond_expr) != COND_EXPR)
continue;
e1 = EDGE_SUCC (bb, 0);
bb1 = e1->dest;
e2 = EDGE_SUCC (bb, 1);
bb2 = e2->dest;
/* We cannot do the optimization on abnormal edges. */
if ((e1->flags & EDGE_ABNORMAL) != 0
|| (e2->flags & EDGE_ABNORMAL) != 0)
continue;
/* If either bb1's succ or bb2 or bb2's succ is non NULL. */
if (EDGE_COUNT (bb1->succs) == 0
|| bb2 == NULL
|| EDGE_COUNT (bb2->succs) == 0)
continue;
/* Find the bb which is the fall through to the other. */
if (EDGE_SUCC (bb1, 0)->dest == bb2)
;
else if (EDGE_SUCC (bb2, 0)->dest == bb1)
{
basic_block bb_tmp = bb1;
edge e_tmp = e1;
bb1 = bb2;
bb2 = bb_tmp;
e1 = e2;
e2 = e_tmp;
}
else
continue;
e1 = EDGE_SUCC (bb1, 0);
/* Make sure that bb1 is just a fall through. */
if (!single_succ_p (bb1)
|| (e1->flags & EDGE_FALLTHRU) == 0)
continue;
/* Also make sure that bb1 only have one predecessor and that it
is bb. */
if (!single_pred_p (bb1)
|| single_pred (bb1) != bb)
continue;
phi = phi_nodes (bb2);
/* Check to make sure that there is only one PHI node.
TODO: we could do it with more than one iff the other PHI nodes
have the same elements for these two edges. */
if (!phi || PHI_CHAIN (phi) != NULL)
continue;
arg0 = PHI_ARG_DEF_TREE (phi, e1->dest_idx);
arg1 = PHI_ARG_DEF_TREE (phi, e2->dest_idx);
/* Something is wrong if we cannot find the arguments in the PHI
node. */
gcc_assert (arg0 != NULL && arg1 != NULL);
/* Do the replacement of conditional if it can be done. */
if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
cfgchanged = true;
else if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
cfgchanged = true;
else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
cfgchanged = true;
else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1))
cfgchanged = true;
}
free (bb_order);
/* If the CFG has changed, we should cleanup the CFG. */
return cfgchanged ? TODO_cleanup_cfg : 0;
}
