uint IndexSet::lrg_union(uint lr1, uint lr2,
const uint fail_degree,
const PhaseIFG *ifg,
const RegMask &mask ) {
IndexSet *one = ifg->neighbors(lr1);
IndexSet *two = ifg->neighbors(lr2);
LRG &lrg1 = ifg->lrgs(lr1);
LRG &lrg2 = ifg->lrgs(lr2);
#ifdef ASSERT
assert(_max_elements == one->_max_elements, "max element mismatch");
check_watch("union destination");
one->check_watch("union source");
two->check_watch("union source");
#endif
// Compute the degree of the combined live-range. The combined
// live-range has the union of the original live-ranges' neighbors set as
// well as the neighbors of all intermediate copies, minus those neighbors
// that can not use the intersected allowed-register-set.
// Copy the larger set. Insert the smaller set into the larger.
if (two->count() > one->count()) {
IndexSet *temp = one;
one = two;
two = temp;
}
clear();
// Used to compute degree of register-only interferences. Infinite-stack
// neighbors do not alter colorability, as they can always color to some
// other color. (A variant of the Briggs assertion)
uint reg_degree = 0;
uint element;
// Load up the combined interference set with the neighbors of one
IndexSetIterator elements(one);
while ((element = elements.next()) != 0) {
LRG &lrg = ifg->lrgs(element);
if (mask.overlap(lrg.mask())) {
insert(element);
if( !lrg.mask().is_AllStack() ) {
reg_degree += lrg1.compute_degree(lrg);
if( reg_degree >= fail_degree ) return reg_degree;
} else {
// !!!!! Danger! No update to reg_degree despite having a neighbor.
// A variant of the Briggs assertion.
// Not needed if I simplify during coalesce, ala George/Appel.
assert( lrg.lo_degree(), "" );
}
}
}
// Add neighbors of two as well
IndexSetIterator elements2(two);
while ((element = elements2.next()) != 0) {
LRG &lrg = ifg->lrgs(element);
if (mask.overlap(lrg.mask())) {
if (insert(element)) {
if( !lrg.mask().is_AllStack() ) {
reg_degree += lrg2.compute_degree(lrg);
if( reg_degree >= fail_degree ) return reg_degree;
} else {
// !!!!! Danger! No update to reg_degree despite having a neighbor.
// A variant of the Briggs assertion.
// Not needed if I simplify during coalesce, ala George/Appel.
assert( lrg.lo_degree(), "" );
}
}
}
}
return reg_degree;
}
