Viewing file:  SSI.cpp (2.02 KB) -rw-rw-r--
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#include "optimize/ssa/HSSA.h"
#include "optimize/ssa/Phi.h"
#include "optimize/ssa/SSA_ops.h"
#include "optimize/Basic_block.h"
#include "optimize/Def_use_web.h"
#include "SSI.h"
SSI::SSI(Whole_program* wp, CFG* cfg) : HSSA(wp, cfg) {
check_ssi = true;
}
void SSI::insert_nodes() {
bool changed = false;
// Always try to insert phi nodes.
insert_phi_nodes();
// First round may insert sigma nodes even if no phi nodes are inserted.
changed = insert_sigma_nodes();
// Insert phi and sigma nodes until a fix-point is reached.
while (changed) {
changed = insert_phi_nodes();
if (changed)
changed = insert_sigma_nodes();
}
}
bool SSI::insert_sigma_nodes() {
bool changed = false;
BB_list *worklist = cfg->get_all_bbs_bottom_up();
BB_list::iterator i = worklist->begin();
while (i != worklist->end()) {
// Analyze basic block bb.
Basic_block *bb = *i;
// Find basic block's dominance frontier.
BB_list *rev_frontier_list = bb->get_reverse_dominance_frontier();
// Collect uses only if there is at least one basic blocks
// in the reverse dominance frontier.
if (rev_frontier_list->size() > 0) {
// Get all uses.
SSA_use_list *uses = cfg->duw->get_block_uses(bb);
// Sigma can also add uses.
foreach (SSA_name sigma_rhs, *bb->get_sigma_rhss())
uses->push_back(new SSA_use(bb, new SSA_name(sigma_rhs), SSA_BB));
// Add a sigma node for each basic block in the dominance frontier for
// each use, unless it is already present.
foreach (Basic_block *rev_frontier, *rev_frontier_list) {
bool use_added = false;
foreach (SSA_use *use, *uses) {
if (!rev_frontier->has_sigma_node(*use->name)) {
rev_frontier->add_sigma_node(*use->name);
use_added = true;
}
}
// This adds a new use, which requires us to iterate.
if (use_added) {
worklist->push_back(rev_frontier);
changed = true;
}
}
}
i++;
}
return changed;
}
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