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fix for analysis in previous commit

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Properly distinguish between vertices that will get set after the cyclic
from vertices that may get set alongside the cyclic
This commit is contained in:
Alex Coyte 2016-10-07 10:06:46 +11:00 committed by Matthew Barr
parent 47f53f63a7
commit 779bebfd12
1 changed files with 27 additions and 0 deletions
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27
src/nfagraph/ng_misc_opt.cpp
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@ -604,6 +604,18 @@ flat_set<NFAVertex> findDependentVertices(const NGHolder &g, NFAVertex v) {
return rv;
}
static
bool willBeEnabledConcurrently(NFAVertex main_cyclic, NFAVertex v,
const NGHolder &g) {
return is_subset_of(preds(main_cyclic, g), preds(v, g));
}
static
bool sometimesEnabledConcurrently(NFAVertex main_cyclic, NFAVertex v,
const NGHolder &g) {
return has_intersection(preds(main_cyclic, g), preds(v, g));
}
static
bool pruneUsingSuccessors(NGHolder &g, NFAVertex u, som_type som) {
if (som && (is_virtual_start(u, g) || u == g.startDs)) {
@ -628,6 +640,10 @@ bool pruneUsingSuccessors(NGHolder &g, NFAVertex u, som_type som) {
});
for (NFAVertex v : u_succs) {
DEBUG_PRINTF(" using %u as killer\n", g[v].index);
/* Need to distinguish between vertices that are switched on after the
* cyclic vs vertices that are switched on concurrently with the cyclic
* if (subject to a suitable reach) */
bool v_peer_of_cyclic = willBeEnabledConcurrently(u, v, g);
set<NFAEdge> dead;
for (NFAVertex s : adjacent_vertices_range(v, g)) {
DEBUG_PRINTF(" looking at preds of %u\n", g[s].index);
@ -642,6 +658,17 @@ bool pruneUsingSuccessors(NGHolder &g, NFAVertex u, som_type som) {
DEBUG_PRINTF("%u bad reports\n", g[p].index);
continue;
}
/* the out-edges of a vertex that may be enabled on the same
* byte as the cyclic can only be killed by the out-edges of a
* peer vertex which will be enabled with the cyclic (a non-peer
* may not be switched on until another byte is processed). */
if (!v_peer_of_cyclic
&& sometimesEnabledConcurrently(u, p, g)) {
DEBUG_PRINTF("%u can only be squashed by a proper peer\n",
g[p].index);
continue;
}
if (g[p].char_reach.isSubsetOf(g[v].char_reach)) {
dead.insert(e);
changed = true;