From e8d452c1e1fc2035ab18f011f4c3fd7db0ab8ced Mon Sep 17 00:00:00 2001
From: Krzysztof Bieganski <kbieganski@antmicro.com>
Date: Thu, 7 Nov 2024 11:46:40 +0100
Subject: [PATCH] rsz: Number of repairs based on path slack, fallback to 1

Signed-off-by: Krzysztof Bieganski <kbieganski@antmicro.com>
---
 src/rsz/src/RepairSetup.cc | 48 ++++++++++++++++++++++++--------------
 src/rsz/src/RepairSetup.hh |  1 +
 2 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/src/rsz/src/RepairSetup.cc b/src/rsz/src/RepairSetup.cc
index 8de7b5a0b00..752e24d6c67 100644
--- a/src/rsz/src/RepairSetup.cc
+++ b/src/rsz/src/RepairSetup.cc
@@ -175,6 +175,7 @@ bool RepairSetup::repairSetup(const float setup_slack_margin,
   }
   float fix_rate_threshold = inc_fix_rate_threshold_;
   for (const auto& end_original_slack : violating_ends) {
+    max_repairs_per_iter_ = 10;
     Vertex* end = end_original_slack.first;
     Slack end_slack = sta_->vertexSlack(end, max_);
     Slack worst_slack;
@@ -325,6 +326,7 @@ bool RepairSetup::repairSetup(const float setup_slack_margin,
         // Progress, Save checkpoint so we can back up to here.
         resizer_->journalBegin();
       } else {
+        max_repairs_per_iter_ = 1;
         // 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++;
@@ -495,7 +497,7 @@ 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 +539,19 @@ bool RepairSetup::repairPath(PathRef& path,
                  || (pair1.second == pair2.second && pair1.first > pair2.first);
         });
     // Attack gates with largest load delays first.
+    int repairs_per_iter = std::round(std::max(-path_slack * 10e9f, 1.0f));
+    repairs_per_iter = std::min(repairs_per_iter, max_repairs_per_iter_);
+    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();
@@ -561,24 +575,21 @@ bool RepairSetup::repairPath(PathRef& path,
                        drvr_index,
                        &expanded,
                        setup_slack_margin)) {
-          Pin* drvr_pin = drvr_path->pin(this);
-          Instance* drvr = network_->instance(drvr_pin);
-          buf_to_remove_.push_back(drvr);
-          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;
         }
       }
 
@@ -600,8 +611,8 @@ bool RepairSetup::repairPath(PathRef& path,
                      network_->pathName(drvr_pin),
                      rebuffer_count);
           inserted_buffer_count_ += rebuffer_count;
-          changed = true;
-          break;
+          changed++;
+          continue;
         }
       }
 
@@ -612,8 +623,8 @@ 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) {
@@ -623,8 +634,8 @@ 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;
         }
       }
     }
@@ -633,7 +644,7 @@ bool RepairSetup::repairPath(PathRef& path,
     }
     buf_to_remove_.clear();
   }
-  return changed;
+  return changed > 0;
 }
 
 void RepairSetup::debugCheckMultipleBuffers(PathRef& path,
@@ -866,6 +877,7 @@ bool RepairSetup::removeDrvr(const PathRef* drvr_path,
     }
 
     if (resizer_->canRemoveBuffer(drvr, /* honorDontTouch */ true)) {
+      buf_to_remove_.push_back(drvr);
       removed_buffer_count_++;
       return true;
     }
@@ -1923,6 +1935,7 @@ 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) {
+    max_repairs_per_iter_ = 10;
     Vertex* end = end_original_slack.first;
     Slack end_slack = sta_->vertexSlack(end, max_);
     Slack worst_slack;
@@ -2007,6 +2020,7 @@ void RepairSetup::repairSetupLastGasp(const OptoParams& params, int& num_viols)
         resizer_->journalEnd();
         resizer_->journalBegin();
       } else {
+        max_repairs_per_iter_ = 1;
         resizer_->journalRestore(resize_count_,
                                  inserted_buffer_count_,
                                  cloned_gate_count_,
diff --git a/src/rsz/src/RepairSetup.hh b/src/rsz/src/RepairSetup.hh
index 9c627bcd16d..a3167eba9f7 100644
--- a/src/rsz/src/RepairSetup.hh
+++ b/src/rsz/src/RepairSetup.hh
@@ -242,6 +242,7 @@ class RepairSetup : public sta::dbStaState
   const Corner* corner_ = nullptr;
   LibertyPort* drvr_port_ = nullptr;
 
+  int max_repairs_per_iter_ = 1;
   int resize_count_ = 0;
   int inserted_buffer_count_ = 0;
   int split_load_buffer_count_ = 0;