From 7b98e46ac352e625be2d8da9b12e7252ed5179d5 Mon Sep 17 00:00:00 2001 From: Clifford Wolf Date: Sun, 20 Jul 2014 11:41:57 +0200 Subject: [PATCH] Added removing of always inactive cells to "share" pass --- passes/sat/share.cc | 50 +++++++++++++++++++++++++++++++++++++-------- 1 file changed, 42 insertions(+), 8 deletions(-) diff --git a/passes/sat/share.cc b/passes/sat/share.cc index a1510a599..fd48b9012 100644 --- a/passes/sat/share.cc +++ b/passes/sat/share.cc @@ -41,6 +41,8 @@ struct ShareWorker CellTypes fwd_ct, cone_ct; ModWalker modwalker; + std::set cells_to_remove; + // ------------------------------------------------------------------------------ // Find terminal bits -- i.e. bits that do not (exclusively) feed into a mux tree @@ -229,7 +231,7 @@ struct ShareWorker std::map>> activation_patterns_cache; - bool sort_check_pattern(std::pair &p) + bool sort_check_activation_pattern(std::pair &p) { std::map p_bits; @@ -253,7 +255,13 @@ struct ShareWorker return true; } - const std::set> &find_cell_activation_patterns(RTLIL::Cell *cell) + void optimize_activation_patterns(std::set> & /* patterns */) + { + // TODO: Remove patterns that are contained in other patterns + // TODO: Consolidate pairs of patterns that only differ in the value for one signal bit + } + + const std::set> &find_cell_activation_patterns(RTLIL::Cell *cell, const char *indent) { if (activation_patterns_cache.count(cell)) return activation_patterns_cache.at(cell); @@ -276,7 +284,7 @@ struct ShareWorker for (auto c : driven_cells) { - const std::set> &c_patterns = find_cell_activation_patterns(c); + const std::set> &c_patterns = find_cell_activation_patterns(c, indent); if (c->type == "$mux" || c->type == "$pmux") { @@ -300,14 +308,14 @@ struct ShareWorker for (auto p : c_patterns) { for (int i = 0; i < SIZE(sig_s); i++) p.first.append_bit(sig_s[i]), p.second.bits.push_back(RTLIL::State::S0); - if (sort_check_pattern(p)) + if (sort_check_activation_pattern(p)) activation_patterns_cache[cell].insert(p); } for (int idx : used_in_b_parts) for (auto p : c_patterns) { p.first.append_bit(sig_s[idx]), p.second.bits.push_back(RTLIL::State::S1); - if (sort_check_pattern(p)) + if (sort_check_activation_pattern(p)) activation_patterns_cache[cell].insert(p); } } @@ -319,6 +327,12 @@ struct ShareWorker } } + optimize_activation_patterns(activation_patterns_cache[cell]); + if (activation_patterns_cache[cell].empty()) { + log("%sFound cell that is never activated: %s\n", indent, log_id(cell)); + cells_to_remove.insert(cell); + } + return activation_patterns_cache[cell]; } @@ -375,9 +389,14 @@ struct ShareWorker log(" Analyzing resource sharing options for %s:\n", log_id(cell)); - const std::set> &cell_activation_patterns = find_cell_activation_patterns(cell); + const std::set> &cell_activation_patterns = find_cell_activation_patterns(cell, " "); RTLIL::SigSpec cell_activation_signals = bits_from_activation_patterns(cell_activation_patterns); + if (cell_activation_patterns.empty()) { + log (" Cell is never active. Sharing is pointless, we simply remove it.\n"); + continue; + } + if (cell_activation_patterns.count(std::pair())) { log (" Cell is always active. Therefore no sharing is possible.\n"); continue; @@ -402,11 +421,17 @@ struct ShareWorker { log(" Analyzing resource sharing with %s:\n", log_id(other_cell)); - const std::set> &other_cell_activation_patterns = find_cell_activation_patterns(other_cell); + const std::set> &other_cell_activation_patterns = find_cell_activation_patterns(other_cell, " "); RTLIL::SigSpec other_cell_activation_signals = bits_from_activation_patterns(other_cell_activation_patterns); + if (other_cell_activation_patterns.empty()) { + log (" Cell is never active. Sharing is pointless, we simply remove it.\n"); + shareable_cells.erase(other_cell); + continue; + } + if (other_cell_activation_patterns.count(std::pair())) { - log (" Cell is always active. Therefore no sharing is possible.\n"); + log (" Cell is always active. Therefore no sharing is possible.\n"); continue; } @@ -484,6 +509,15 @@ struct ShareWorker break; } } + + if (!cells_to_remove.empty()) { + log("Removing %d cells in module %s:\n", SIZE(cells_to_remove), log_id(module)); + for (auto c : cells_to_remove) { + log(" Removing cell %s (%s).\n", log_id(c), log_id(c->type)); + module->cells.erase(c->name); + delete c; + } + } } }; -- 2.30.2