utl: add mechanism to make it easier to handle operation-specific settings

src/rsz/src/Resizer.cc

@@ -66,6 +66,7 @@
 #include "sta/TimingModel.hh"
 #include "sta/Units.hh"
 #include "utl/Logger.h"
+#include "utl/scope.h"
 
 // http://vlsicad.eecs.umich.edu/BK/Slots/cache/dropzone.tamu.edu/~zhuoli/GSRC/fast_buffer_insertion.html
 
@@ -2689,14 +2690,9 @@ void Resizer::repairNet(Net* net,
 void Resizer::repairClkNets(double max_wire_length)
 {
   resizePreamble();
-
-  // Use the buffers that were selected by CTS.
-  buffer_cells_ = clk_buffers_;
+  utl::SetAndRestore<LibertyCellSeq> set_buffers(buffer_cells_, clk_buffers_);
 
   repair_design_->repairClkNets(max_wire_length);
-
-  // Reset so that the next preamble select data buffers again.
-  buffer_cells_.clear();
 }
 
 ////////////////////////////////////////////////////////////////
@@ -2864,13 +2860,16 @@ void Resizer::repairHold(
     int max_passes,
     bool verbose)
 {
-  buffer_cells_.clear();
-
   // Some technologies such as nangate45 don't have delay cells. Hence,
   // until we have a better approach, it's better to consider clock buffers
   // for hold violation repairing as these buffers' delay may be slighty
   // higher and we'll need fewer insertions.
-  exclude_clock_buffers_ = false;
+  // Obs: We need to clear the buffer list for the preamble to select
+  // buffers again excluding the clock ones.
+  utl::SetAndRestore<bool> set_exclude_clk_buffers(exclude_clock_buffers_,
+                                                   false);
+  utl::SetAndRestore<LibertyCellSeq> set_buffers(buffer_cells_,
+                                                 LibertyCellSeq());
 
   resizePreamble();
   if (parasitics_src_ == ParasiticsSrc::global_routing) {
@@ -2882,10 +2881,6 @@ void Resizer::repairHold(
                            max_buffer_percent,
                            max_passes,
                            verbose);
-
-  // Reset buffer selection strategy for the subsequent RSZ operation.
-  exclude_clock_buffers_ = true;
-  buffer_cells_.clear();
 }
 
 void Resizer::repairHold(const Pin* end_pin,
@@ -2895,10 +2890,11 @@ void Resizer::repairHold(const Pin* end_pin,
                          float max_buffer_percent,
                          int max_passes)
 {
-  buffer_cells_.clear();
-
-  // See comments on previous method.
-  exclude_clock_buffers_ = false;
+  // See comment on the method above.
+  utl::SetAndRestore<bool> set_exclude_clk_buffers(exclude_clock_buffers_,
+                                                   false);
+  utl::SetAndRestore<LibertyCellSeq> set_buffers(buffer_cells_,
+                                                 LibertyCellSeq());
 
   resizePreamble();
   repair_hold_->repairHold(end_pin,
@@ -2907,10 +2903,6 @@ void Resizer::repairHold(const Pin* end_pin,
                            allow_setup_violations,
                            max_buffer_percent,
                            max_passes);
-
-  // Ditto.
-  exclude_clock_buffers_ = true;
-  buffer_cells_.clear();
 }
 
 int Resizer::holdBufferCount() const

src/utl/include/utl/scope.h

@@ -0,0 +1,58 @@
+/////////////////////////////////////////////////////////////////////////////
+//
+// Copyright (c) 2024, Precision Innovations Inc
+// All rights reserved.
+//
+// BSD 3-Clause License
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice, this
+//   list of conditions and the following disclaimer.
+//
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+//
+// * Neither the name of the copyright holder nor the names of its
+//   contributors may be used to endorse or promote products derived from
+//   this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#pragma once
+
+namespace utl {
+
+// RAII mechanism to facilitate using operation-specific settings.
+template <typename T>
+class SetAndRestore
+{
+ public:
+  SetAndRestore(T& storage, const T& new_value)
+      : storage_(storage), old_value_(storage)
+  {
+    storage_ = new_value;
+  }
+
+  ~SetAndRestore() { storage_ = old_value_; }
+
+ private:
+  T& storage_;
+  T old_value_;
+};
+
+}  // namespace utl