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Avoid erroneous fanout-size and primary output updates #397

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Merged
merged 6 commits into from
Nov 15, 2020
Merged

Avoid erroneous fanout-size and primary output updates #397

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588ddd2
bugfix: avoid recursive fanout-size updates when double deleting a node.
hriener Nov 15, 2020
c759d67
ensure that `create_and` never returns a dead node.
hriener Nov 15, 2020
6681525
bugfix: do not propagate updates of dead nodes to the primary outputs.
hriener Nov 15, 2020
4b212ca
coding style changes.
hriener Nov 15, 2020
c10d59d
bugix: do not update dead nodes.
hriener Nov 15, 2020
6fb481f
comments.
hriener Nov 15, 2020
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10 changes: 7 additions & 3 deletions include/mockturtle/networks/aig.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -312,6 +312,7 @@ class aig_network
const auto it = _storage->hash.find( node );
if ( it != _storage->hash.end() )
{
assert( !is_dead( it->second ) );
return {it->second, 0};
}

Expand Down Expand Up @@ -510,6 +511,9 @@ class aig_network

void replace_in_outputs( node const& old_node, signal const& new_signal )
{
if ( is_dead( old_node ) )
return;

for ( auto& output : _storage->outputs )
{
if ( output.index == old_node )
Expand All @@ -525,8 +529,8 @@ class aig_network

void take_out_node( node const& n )
{
/* we cannot delete CIs or constants */
if ( n == 0 || is_ci( n ) )
/* we cannot delete CIs, constants, or already dead nodes */
if ( n == 0 || is_ci( n ) || is_dead( n ) )
return;

auto& nobj = _storage->nodes[n];
Expand Down Expand Up @@ -568,7 +572,7 @@ class aig_network

for ( auto idx = 1u; idx < _storage->nodes.size(); ++idx )
{
if ( is_ci( idx ) )
if ( is_ci( idx ) || is_dead( idx ) )
continue; /* ignore CIs */

if ( const auto repl = replace_in_node( idx, _old, _new ); repl )
Expand Down
28 changes: 28 additions & 0 deletions test/networks/aig.cpp
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Expand Up @@ -783,3 +783,31 @@ TEST_CASE( "substitute node by constant in NAND-based XOR circuit (test case 2)"
CHECK( aig.fanout_size( aig.get_node( f3 ) ) == 0u );
CHECK( aig.fanout_size( aig.get_node( f4 ) ) == 1u );
}

TEST_CASE( "invoke take_out_node two times on the same node", "[aig]" )
{
aig_network aig;
const auto x1 = aig.create_pi();
const auto x2 = aig.create_pi();

const auto f1 = aig.create_and( x1, x2 );
const auto f2 = aig.create_or( x1, x2 );
(void)f2;

CHECK( aig.fanout_size( aig.get_node( x1 ) ) == 2u );
CHECK( aig.fanout_size( aig.get_node( x2 ) ) == 2u );

/* delete node */
CHECK( !aig.is_dead( aig.get_node( f1 ) ) );
aig.take_out_node( aig.get_node( f1 ) );
CHECK( aig.is_dead( aig.get_node( f1 ) ) );
CHECK( aig.fanout_size( aig.get_node( x1 ) ) == 1u );
CHECK( aig.fanout_size( aig.get_node( x2 ) ) == 1u );

/* ensure that double-deletion has no effect on the fanout-size of x1 and x2 */
CHECK( aig.is_dead( aig.get_node( f1 ) ) );
aig.take_out_node( aig.get_node( f1 ) );
CHECK( aig.is_dead( aig.get_node( f1 ) ) );
CHECK( aig.fanout_size( aig.get_node( x1 ) ) == 1u );
CHECK( aig.fanout_size( aig.get_node( x2 ) ) == 1u );
}