291 lines
7.5 KiB
C
291 lines
7.5 KiB
C
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#include "allocate.h"
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#include "analyze.h"
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#include "internal.h"
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#include "logging.h"
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#include "print.h"
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#include "proprobe.h"
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#include "report.h"
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#include "terminate.h"
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#include "trail.h"
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#include "transitive.h"
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#include <stddef.h>
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static void
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transitive_assign (kissat * solver, unsigned lit)
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{
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LOG ("transitive assign %s", LOGLIT (lit));
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value *values = solver->values;
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const unsigned not_lit = NOT (lit);
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assert (!values[lit]);
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assert (!values[not_lit]);
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values[lit] = 1;
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values[not_lit] = -1;
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PUSH_STACK (solver->trail, lit);
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}
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static void
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transitive_backtrack (kissat * solver, unsigned saved)
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{
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assert (saved <= SIZE_STACK (solver->trail));
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value *values = solver->values;
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while (SIZE_STACK (solver->trail) > saved)
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{
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const unsigned lit = POP_STACK (solver->trail);
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LOG ("transitive unassign %s", LOGLIT (lit));
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const unsigned not_lit = NOT (lit);
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assert (values[lit] > 0);
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assert (values[not_lit] < 0);
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values[lit] = values[not_lit] = 0;
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}
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solver->propagated = saved;
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solver->level = 0;
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}
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static void
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prioritize_binaries (kissat * solver)
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{
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assert (solver->watching);
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statches large;
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INIT_STACK (large);
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watches *all_watches = solver->watches;
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for (all_literals (lit))
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{
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assert (EMPTY_STACK (large));
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watches *watches = all_watches + lit;
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watch *begin_watches = BEGIN_WATCHES (*watches), *q = begin_watches;
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const watch *end_watches = END_WATCHES (*watches), *p = q;
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while (p != end_watches)
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{
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const watch head = *q++ = *p++;
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if (head.type.binary)
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continue;
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const watch tail = *p++;
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PUSH_STACK (large, head);
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PUSH_STACK (large, tail);
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q--;
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}
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const watch *end_large = END_STACK (large);
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const watch *r = BEGIN_STACK (large);
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while (r != end_large)
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*q++ = *r++;
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assert (q == end_watches);
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CLEAR_STACK (large);
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}
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RELEASE_STACK (large);
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}
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static bool
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transitive_reduce (kissat * solver,
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unsigned src, uint64_t limit,
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uint64_t * reduced_ptr, unsigned *units)
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{
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bool res = false;
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assert (!VALUE (src));
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LOG ("transitive reduce %s", LOGLIT (src));
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watches *all_watches = solver->watches;
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watches *src_watches = all_watches + src;
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watch *end_src = END_WATCHES (*src_watches);
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watch *begin_src = BEGIN_WATCHES (*src_watches);
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unsigned ticks = kissat_cache_lines (src_watches->size, sizeof (watch));
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ADD (transitive_ticks, ticks + 1);
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const unsigned not_src = NOT (src);
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unsigned reduced = 0;
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bool failed = false;
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for (watch * p = begin_src; p != end_src; p++)
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{
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const watch src_watch = *p;
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if (!src_watch.type.binary)
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break;
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const unsigned dst = src_watch.binary.lit;
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if (dst < src)
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continue;
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if (VALUE (dst))
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continue;
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assert (solver->propagated == SIZE_STACK (solver->trail));
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unsigned saved = solver->propagated;
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assert (!solver->level);
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solver->level = 1;
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transitive_assign (solver, not_src);
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const bool redundant = src_watch.binary.redundant;
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bool transitive = false;
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unsigned propagated = 0;
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while (!transitive && !failed &&
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solver->propagated < SIZE_STACK (solver->trail))
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{
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const unsigned lit = PEEK_STACK (solver->trail, solver->propagated);
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solver->propagated++;
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propagated++;
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LOG ("transitive propagate %s", LOGLIT (lit));
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assert (VALUE (lit) > 0);
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const unsigned not_lit = NOT (lit);
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watches *lit_watches = all_watches + not_lit;
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const watch *end_lit = END_WATCHES (*lit_watches);
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const watch *begin_lit = BEGIN_WATCHES (*lit_watches);
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ticks = kissat_cache_lines (lit_watches->size, sizeof (watch));
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ADD (transitive_ticks, ticks + 1);
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for (const watch * q = begin_lit; q != end_lit; q++)
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{
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if (p == q)
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continue;
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const watch lit_watch = *q;
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if (!lit_watch.type.binary)
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break;
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if (not_lit == src && lit_watch.binary.lit == ILLEGAL_LIT)
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continue;
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if (!redundant && lit_watch.binary.redundant)
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continue;
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const unsigned other = lit_watch.binary.lit;
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if (other == dst)
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{
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transitive = true;
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break;
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}
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const value value = VALUE (other);
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if (value < 0)
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{
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LOG ("both %s and %s reachable from %s",
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LOGLIT (NOT (other)), LOGLIT (other), LOGLIT (src));
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failed = true;
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break;
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}
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if (!value)
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transitive_assign (solver, other);
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}
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}
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assert (solver->probing);
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ADD (propagations, propagated);
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ADD (probing_propagations, propagated);
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ADD (transitive_propagations, propagated);
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transitive_backtrack (solver, saved);
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if (transitive)
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{
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LOGBINARY (src, dst, "transitive reduce");
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INC (transitive_reduced);
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watches *dst_watches = all_watches + dst;
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watch dst_watch = src_watch;
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assert (dst_watch.binary.lit == dst);
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assert (dst_watch.binary.redundant == redundant);
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dst_watch.binary.lit = src;
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REMOVE_WATCHES (*dst_watches, dst_watch);
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kissat_delete_binary (solver,
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src_watch.binary.redundant,
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src_watch.binary.hyper, src, dst);
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p->binary.lit = ILLEGAL_LIT;
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reduced++;
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res = true;
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}
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if (failed)
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break;
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if (solver->statistics.transitive_ticks > limit)
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break;
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if (TERMINATED (16))
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break;
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}
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if (reduced)
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{
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*reduced_ptr += reduced;
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assert (begin_src == BEGIN_WATCHES (WATCHES (src)));
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assert (end_src == END_WATCHES (WATCHES (src)));
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watch *q = begin_src;
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for (const watch * p = begin_src; p != end_src; p++)
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{
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const watch src_watch = *q++ = *p;
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if (!src_watch.type.binary)
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{
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*q++ = *++p;
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continue;
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}
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if (src_watch.binary.lit == ILLEGAL_LIT)
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q--;
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}
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assert (end_src - q == (ptrdiff_t) reduced);
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SET_END_OF_WATCHES (*src_watches, q);
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}
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if (failed)
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{
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LOG ("transitive failed literal %s", LOGLIT (not_src));
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INC (failed);
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*units += 1;
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res = true;
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kissat_assign_unit (solver, src);
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CHECK_AND_ADD_UNIT (src);
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ADD_UNIT_TO_PROOF (src);
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clause *conflict = kissat_probing_propagate (solver, 0);
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if (conflict)
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{
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(void) kissat_analyze (solver, conflict);
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assert (solver->inconsistent);
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}
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else
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{
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assert (solver->unflushed);
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kissat_flush_trail (solver);
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}
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}
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return res;
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}
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void
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kissat_transitive_reduction (kissat * solver)
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{
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if (solver->inconsistent)
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return;
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assert (solver->watching);
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assert (solver->probing);
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assert (!solver->level);
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if (!GET_OPTION (transitive))
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return;
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if (TERMINATED (17))
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return;
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START (transitive);
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prioritize_binaries (solver);
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bool success = false;
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uint64_t reduced = 0;
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unsigned units = 0;
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SET_EFFICIENCY_BOUND (limit, transitive, transitive_ticks, search_ticks, 0);
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assert (solver->transitive < LITS);
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const unsigned end = solver->transitive;
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#ifndef QUIET
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const unsigned active = solver->active;
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#endif
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unsigned probed = 0;
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do
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{
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const unsigned lit = solver->transitive++;
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if (solver->transitive == LITS)
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solver->transitive = 0;
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if (!ACTIVE (IDX (lit)))
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continue;
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probed++;
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if (transitive_reduce (solver, lit, limit, &reduced, &units))
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success = true;
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if (solver->inconsistent)
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break;
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if (solver->statistics.transitive_ticks > limit)
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break;
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if (TERMINATED (18))
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break;
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}
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while (solver->transitive != end);
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kissat_phase (solver, "transitive", GET (probings),
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"probed %u (%.0f%%): reduced %" PRIu64 ", units %u",
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probed, kissat_percent (probed, 2 * active), reduced, units);
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STOP (transitive);
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REPORT (!success, 't');
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#ifdef QUIET
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(void) success;
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#endif
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}
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