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share: Keep filtered activation patterns for the supercell

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The previous commit introduced code that optimizes the activation
patterns to be able to generate smaller activation logic. The resulting
supercell was then enqueued as shareable using those optimized
activation patterns. The condition represented by the optimized patterns
is an over-approximation of the actual activiation condition. This means
using it as activiation for the supercell loses precision and pessimises
sharing of the supercell with further cells, breaking the sat/share
test.

This commit fixes that by using the optimized activiation patterns only
for the generation of activation logic and using the original patterns
for enqueuing the supercell.
This commit is contained in:
Jannis Harder 2025-04-15 10:25:39 +02:00
parent 6dff9e7787
commit 27ed77ea24
1 changed files with 10 additions and 7 deletions
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17
passes/opt/share.cc
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@ -1365,6 +1365,9 @@ struct ShareWorker
continue;
}
pool<ssc_pair_t> optimized_cell_activation_patterns = filtered_cell_activation_patterns;
pool<ssc_pair_t> optimized_other_cell_activation_patterns = filtered_other_cell_activation_patterns;
if (pattern_only_solve) {
qcsat.ez->non_incremental();
@ -1389,12 +1392,12 @@ struct ShareWorker
log(" According to the SAT solver this pair of cells can be shared.\n");
} else {
log(" According to the SAT solver this pair of cells can be shared. (Pattern only case)\n");
restrict_activiation_patterns(filtered_cell_activation_patterns, filtered_other_cell_activation_patterns);
restrict_activiation_patterns(optimized_cell_activation_patterns, optimized_other_cell_activation_patterns);
for (auto &p : filtered_cell_activation_patterns)
for (auto &p : optimized_cell_activation_patterns)
log(" Simplified activation pattern for cell %s: %s = %s\n", log_id(cell), log_signal(p.first), log_signal(p.second));
for (auto &p : filtered_other_cell_activation_patterns)
for (auto &p : optimized_other_cell_activation_patterns)
log(" Simplified activation pattern for cell %s: %s = %s\n", log_id(other_cell), log_signal(p.first), log_signal(p.second));
}
@ -1413,20 +1416,20 @@ struct ShareWorker
int cell_select_score = 0;
int other_cell_select_score = 0;
for (auto &p : filtered_cell_activation_patterns)
for (auto &p : optimized_cell_activation_patterns)
cell_select_score += p.first.size();
for (auto &p : filtered_other_cell_activation_patterns)
for (auto &p : optimized_other_cell_activation_patterns)
other_cell_select_score += p.first.size();
RTLIL::Cell *supercell;
pool<RTLIL::Cell*> supercell_aux;
if (cell_select_score <= other_cell_select_score) {
RTLIL::SigSpec act = make_cell_activation_logic(filtered_cell_activation_patterns, supercell_aux);
RTLIL::SigSpec act = make_cell_activation_logic(optimized_cell_activation_patterns, supercell_aux);
supercell = make_supercell(cell, other_cell, act, supercell_aux);
log(" Activation signal for %s: %s\n", log_id(cell), log_signal(act));
} else {
RTLIL::SigSpec act = make_cell_activation_logic(filtered_other_cell_activation_patterns, supercell_aux);
RTLIL::SigSpec act = make_cell_activation_logic(optimized_other_cell_activation_patterns, supercell_aux);
supercell = make_supercell(other_cell, cell, act, supercell_aux);
log(" Activation signal for %s: %s\n", log_id(other_cell), log_signal(act));
}