rsz: Try multiple repairs per iteration

src/rsz/README.md

@@ -305,6 +305,7 @@ repair_timing
     [-skip_last_gasp]
     [-repair_tns tns_end_percent]
     [-max_passes passes]
+    [-max_repairs_per_iter max_repairs_per_iter]
     [-max_utilization util]
     [-max_buffer_percent buffer_percent]
     [-match_cell_footprint]

src/rsz/include/rsz/Resizer.hh

@@ -289,6 +289,7 @@ class Resizer : public dbStaState
   bool repairSetup(double setup_margin,
                    double repair_tns_end_percent,
                    int max_passes,
+                   int max_repairs_per_iter,
                    bool match_cell_footprint,
                    bool verbose,
                    bool skip_pin_swap,
@@ -622,9 +623,11 @@ class Resizer : public dbStaState
                    bool journal);
 
   void findResizeSlacks1();
-  bool removeBuffer(Instance* buffer,
-                    bool honorDontTouchFixed = true,
-                    bool recordJournal = false);
+  bool removeBufferIfPossible(Instance* buffer,
+                              bool honorDontTouchFixed = true,
+                              bool recordJournal = false);
+  bool canRemoveBuffer(Instance* buffer, bool honorDontTouchFixed = true);
+  void removeBuffer(Instance* buffer, bool recordJournal = false);
   Instance* makeInstance(LibertyCell* cell,
                          const char* name,
                          Instance* parent,

src/rsz/src/RepairSetup.cc

@@ -90,6 +90,7 @@ void RepairSetup::init()
 bool RepairSetup::repairSetup(const float setup_slack_margin,
                               const double repair_tns_end_percent,
                               const int max_passes,
+                              const int max_repairs_per_iter,
                               const bool verbose,
                               const bool skip_pin_swap,
                               const bool skip_gate_cloning,
@@ -100,6 +101,7 @@ bool RepairSetup::repairSetup(const float setup_slack_margin,
   bool repaired = false;
   init();
   constexpr int digits = 3;
+  max_repairs_per_iter_ = max_repairs_per_iter;
   inserted_buffer_count_ = 0;
   split_load_buffer_count_ = 0;
   resize_count_ = 0;
@@ -174,7 +176,12 @@ bool RepairSetup::repairSetup(const float setup_slack_margin,
     printProgress(opto_iteration, false, false, false, num_viols);
   }
   float fix_rate_threshold = inc_fix_rate_threshold_;
+  if (!violating_ends.empty()) {
+    min_viol_ = -violating_ends.back().second;
+    max_viol_ = -violating_ends.front().second;
+  }
   for (const auto& end_original_slack : violating_ends) {
+    fallback_ = false;
     Vertex* end = end_original_slack.first;
     Slack end_slack = sta_->vertexSlack(end, max_);
     Slack worst_slack;
@@ -325,6 +332,7 @@ bool RepairSetup::repairSetup(const float setup_slack_margin,
         // Progress, Save checkpoint so we can back up to here.
         resizer_->journalBegin();
       } else {
+        fallback_ = true;
         // Allow slack to increase to get out of local minima.
         // Do not update prev_end_slack so it saves the high water mark.
         decreasing_slack_passes++;
@@ -439,6 +447,7 @@ bool RepairSetup::repairSetup(const float setup_slack_margin,
 void RepairSetup::repairSetup(const Pin* end_pin)
 {
   init();
+  max_repairs_per_iter_ = 1;
   inserted_buffer_count_ = 0;
   resize_count_ = 0;
   swap_pin_count_ = 0;
@@ -495,7 +504,7 @@ bool RepairSetup::repairPath(PathRef& path,
                              const float setup_slack_margin)
 {
   PathExpanded expanded(&path, sta_);
-  bool changed = false;
+  int changed = 0;
 
   if (expanded.size() > 1) {
     const int path_length = expanded.size();
@@ -537,7 +546,26 @@ bool RepairSetup::repairPath(PathRef& path,
                  || (pair1.second == pair2.second && pair1.first > pair2.first);
         });
     // Attack gates with largest load delays first.
+    int repairs_per_iter = 1;
+    if (max_viol_ - min_viol_ != 0.0) {
+      repairs_per_iter
+          += std::round((max_repairs_per_iter_ - 1) * (-path_slack - min_viol_)
+                        / (max_viol_ - min_viol_));
+    }
+    if (fallback_) {
+      repairs_per_iter = 1;
+    }
+    debugPrint(logger_,
+               RSZ,
+               "repair_setup",
+               3,
+               "Path slack: {}, repairs: {}",
+               delayAsString(path_slack, sta_, 3),
+               repairs_per_iter);
     for (const auto& [drvr_index, ignored] : load_delays) {
+      if (changed >= repairs_per_iter) {
+        break;
+      }
       const PathRef* drvr_path = expanded.path(drvr_index);
       Vertex* drvr_vertex = drvr_path->vertex(sta_);
       const Pin* drvr_pin = drvr_vertex->pin();
@@ -561,21 +589,21 @@ bool RepairSetup::repairPath(PathRef& path,
                        drvr_index,
                        &expanded,
                        setup_slack_margin)) {
-          changed = true;
-          break;
+          changed++;
+          continue;
         }
       }
 
       if (upsizeDrvr(drvr_path, drvr_index, &expanded)) {
-        changed = true;
-        break;
+        changed++;
+        continue;
       }
 
       // Pin swapping
       if (!skip_pin_swap) {
         if (swapPins(drvr_path, drvr_index, &expanded)) {
-          changed = true;
-          break;
+          changed++;
+          continue;
         }
       }
 
@@ -597,8 +625,8 @@ bool RepairSetup::repairPath(PathRef& path,
                      network_->pathName(drvr_pin),
                      rebuffer_count);
           inserted_buffer_count_ += rebuffer_count;
-          changed = true;
-          break;
+          changed++;
+          continue;
         }
       }
 
@@ -609,8 +637,8 @@ bool RepairSetup::repairPath(PathRef& path,
                  db_network_->instance(drvr_pin))
                  == resizer_->inserted_buffer_set_.end()
           && cloneDriver(drvr_path, drvr_index, path_slack, &expanded)) {
-        changed = true;
-        break;
+        changed++;
+        continue;
       }
 
       if (!skip_buffering) {
@@ -620,13 +648,17 @@ bool RepairSetup::repairPath(PathRef& path,
           const int init_buffer_count = inserted_buffer_count_;
           splitLoads(drvr_path, drvr_index, path_slack, &expanded);
           split_load_buffer_count_ = inserted_buffer_count_ - init_buffer_count;
-          changed = true;
-          break;
+          changed++;
+          continue;
         }
       }
     }
+    for (auto inst : buf_to_remove_) {
+      resizer_->removeBuffer(inst, /* recordJournal */ true);
+    }
+    buf_to_remove_.clear();
   }
-  return changed;
+  return changed > 0;
 }
 
 void RepairSetup::debugCheckMultipleBuffers(PathRef& path,
@@ -858,8 +890,8 @@ bool RepairSetup::removeDrvr(const PathRef* drvr_path,
       return false;
     }
 
-    if (resizer_->removeBuffer(
-            drvr, /* honorDontTouch */ true, /* recordJournal */ true)) {
+    if (resizer_->canRemoveBuffer(drvr, /* honorDontTouch */ true)) {
+      buf_to_remove_.push_back(drvr);
       removed_buffer_count_++;
       return true;
     }
@@ -977,7 +1009,7 @@ bool RepairSetup::estimatedSlackOK(const SlackEstimatorParams& params)
                  "because side input pin {} will have a violating slack of {}:"
                  " old slack={}, slack margin={}, delay_degrad={}",
                  db_network_->name(params.driver),
-                 db_network_->name(side_input_pin), new_slack, old_slack, 
+                 db_network_->name(side_input_pin), new_slack, old_slack,
                  params.setup_slack_margin, delay_degrad);
       // clang-format on
       return false;
@@ -1917,6 +1949,7 @@ void RepairSetup::repairSetupLastGasp(const OptoParams& params, int& num_viols)
   float fix_rate_threshold = inc_fix_rate_threshold_;
 
   for (const auto& end_original_slack : violating_ends) {
+    fallback_ = false;
     Vertex* end = end_original_slack.first;
     Slack end_slack = sta_->vertexSlack(end, max_);
     Slack worst_slack;
@@ -2001,6 +2034,7 @@ void RepairSetup::repairSetupLastGasp(const OptoParams& params, int& num_viols)
         resizer_->journalEnd();
         resizer_->journalBegin();
       } else {
+        fallback_ = true;
         resizer_->journalRestore(resize_count_,
                                  inserted_buffer_count_,
                                  cloned_gate_count_,

src/rsz/src/RepairSetup.hh

@@ -129,6 +129,7 @@ class RepairSetup : public sta::dbStaState
                    // reduce tns (0.0-1.0).
                    double repair_tns_end_percent,
                    int max_passes,
+                   int max_repairs_per_iter,
                    bool verbose,
                    bool skip_pin_swap,
                    bool skip_gate_cloning,
@@ -235,12 +236,17 @@ class RepairSetup : public sta::dbStaState
                          int num_endpts);
   void repairSetupLastGasp(const OptoParams& params, int& num_viols);
 
+  std::vector<Instance*> buf_to_remove_;
   Logger* logger_ = nullptr;
   dbNetwork* db_network_ = nullptr;
   Resizer* resizer_;
   const Corner* corner_ = nullptr;
   LibertyPort* drvr_port_ = nullptr;
 
+  bool fallback_ = false;
+  float min_viol_ = 0.0;
+  float max_viol_ = 0.0;
+  int max_repairs_per_iter_ = 1;
   int resize_count_ = 0;
   int inserted_buffer_count_ = 0;
   int split_load_buffer_count_ = 0;