/**
* Pre-block-walker: calculate the control dependence
*/
static void cdep_pre(ir_node *node, void *ctx)
{
(void)ctx;
for (int i = get_Block_n_cfgpreds(node); i-- > 0; ) {
ir_node *pred = get_Block_cfgpred_block(node, i);
if (is_Bad(pred))
continue;
ir_node *pdom = get_Block_ipostdom(pred);
for (ir_node *dependee = node; dependee != pdom;
dependee = get_Block_ipostdom(dependee)) {
assert(!is_Bad(pdom));
add_cdep(dependee, pred);
}
}
}
/**
* Computes the predecessors for the real phi node, and then
* allocates and returns this node. The routine called to allocate the
* node might optimize it away and return a real value.
* This function must be called with an in-array of proper size.
*/
static ir_node *set_phi_arguments(ir_node *phi, int pos)
{
ir_node *block = get_nodes_block(phi);
ir_graph *irg = get_irn_irg(block);
int arity = get_irn_arity(block);
ir_node **in = ALLOCAN(ir_node*, arity);
ir_mode *mode = get_irn_mode(phi);
/* This loop goes to all predecessor blocks of the block the Phi node
* is in and there finds the operands of the Phi node by calling
* get_r_value_internal. */
for (int i = 0; i < arity; ++i) {
ir_node *cfgpred = get_Block_cfgpred_block(block, i);
ir_node *value;
if (cfgpred == NULL) {
value = new_r_Bad(irg, mode);
} else {
value = get_r_value_internal(cfgpred, pos, mode);
}
in[i] = value;
}
phi->attr.phi.u.backedge = new_backedge_arr(get_irg_obstack(irg), arity);
set_irn_in(phi, arity, in);
verify_new_node(phi);
try_remove_unnecessary_phi(phi);
/* To solve the problem of (potentially) endless loops being observable
* behaviour we add a keep-alive edge too all PhiM nodes. */
if (mode == mode_M && !is_Id(phi)) {
phi->attr.phi.loop = true;
keep_alive(phi);
}
return phi;
}
