Merge pull request #8502 from luis201420/cts_add_option_skip_nets

maliberty · web-flow · commit c9cc993123e2 · 2025-10-02T20:08:34.000Z
Cts: Add option to skip nets
diff --git a/src/cts/README.md b/src/cts/README.md
@@ -151,6 +151,7 @@ set_cts_config
     [-sink_clustering_levels levels]
     [-sink_clustering_max_diameter max_diameter]
     [-sink_clustering_size cluster_size]
+    [-skip_nets <list_of_clk_nets_to_skip>]
     [-tree_buf <buf>]
     [-wire_unit wire_unit]
 ```
@@ -176,6 +177,7 @@ set_cts_config
 | `-sink_clustering_max_diameter` | Specifies maximum diameter (in microns) of sink cluster for the register tree. The allowed values are integers `[0, MAX_INT]`. If this is not specified the diameter will be automatically chosen between `50, 100 or 200`, based on the tree buffer max cap. |
 | `-sink_clustering_size` | Specifies the maximum number of sinks per cluster for the register tree. The allowed values are integers `[0, MAX_INT]`. If this is not specified the size will be automatically chosen between `10, 20 or 30` based on the tree buffer max cap. |
 | `-sink_clustering_levels` | ... |
+| `-skip_nets` | Tcl list containing the clock nets to be skipped (e.g. `{net1, net2}`). If the net is a root clock net, the whole clock is skipped, otherwise only the subnet specified is skipped. |
 | `-wire_unit` | Minimum unit distance between buffers for a specific wire. If this parameter is omitted, the code gets the value from ten times the height of `-root_buffer`. |
 
 ### Report CTS configuration
@@ -208,6 +210,7 @@ reset_cts_config
     [-sink_clustering_levels]
     [-sink_clustering_max_diameter]
     [-sink_clustering_size]
+    [-skip_nets]
     [-tree_buf]
     [-wire_unit]
 ```
diff --git a/src/cts/src/CtsOptions.h b/src/cts/src/CtsOptions.h
@@ -125,6 +125,17 @@ class CtsOptions : public odb::dbBlockCallBackObj
     clockNetsObjs_ = nets;
   }
   std::vector<odb::dbNet*> getClockNetsObjs() const { return clockNetsObjs_; }
+  void setSkipNets(odb::dbNet* nets) { skipNets_.push_back(nets); }
+  std::vector<odb::dbNet*> getSkipNets() const { return skipNets_; }
+  std::string getSkipNetsToString() const
+  {
+    std::ostringstream skip_nets_names;
+    for (const odb::dbNet* db_net : skipNets_) {
+      skip_nets_names << db_net->getConstName() << " ";
+    }
+    return skip_nets_names.str();
+  }
+  void resetSkipNets() { skipNets_.clear(); }
   void setMetricsFile(const std::string& metricFile)
   {
     metricFile_ = metricFile;
@@ -394,6 +405,7 @@ class CtsOptions : public odb::dbBlockCallBackObj
   unsigned numStaticLayers_ = 0;
   std::vector<std::string> bufferList_;
   std::vector<odb::dbNet*> clockNetsObjs_;
+  std::vector<odb::dbNet*> skipNets_;
   utl::Logger* logger_ = nullptr;
   stt::SteinerTreeBuilder* sttBuilder_ = nullptr;
   bool obsAware_ = true;
diff --git a/src/cts/src/TritonCTS.cpp b/src/cts/src/TritonCTS.cpp
@@ -302,9 +302,16 @@ void TritonCTS::initOneClockTree(odb::dbNet* driverNet,
                                  TreeBuilder* parent)
 {
   TreeBuilder* clockBuilder = nullptr;
+  std::vector<odb::dbNet*> skipNets = options_->getSkipNets();
   if (driverNet->isSpecial()) {
     logger_->info(
         CTS, 116, "Special net \"{}\" skipped.", driverNet->getName());
+  } else if (std::find(skipNets.begin(), skipNets.end(), driverNet)
+             != skipNets.end()) {
+    logger_->warn(CTS,
+                  44,
+                  "Skipping net {}, specified by the user...",
+                  driverNet->getName());
   } else {
     clockBuilder = initClock(driverNet, clkInputNet, sdcClockName, parent);
   }
@@ -1959,12 +1966,20 @@ bool TritonCTS::masterExists(const std::string& master) const
 void TritonCTS::findClockRoots(sta::Clock* clk,
                                std::set<odb::dbNet*>& clockNets)
 {
+  std::vector<odb::dbNet*> skipNets = options_->getSkipNets();
   for (const sta::Pin* pin : clk->leafPins()) {
     odb::dbITerm* instTerm;
     odb::dbBTerm* port;
     odb::dbModITerm* moditerm;
     network_->staToDb(pin, instTerm, port, moditerm);
     odb::dbNet* net = instTerm ? instTerm->getNet() : port->getNet();
+    if (std::find(skipNets.begin(), skipNets.end(), net) != skipNets.end()) {
+      logger_->warn(CTS,
+                    42,
+                    "Skipping root net {}, specified by the user...",
+                    net->getName());
+      continue;
+    }
     clockNets.insert(net);
   }
 }
diff --git a/src/cts/src/TritonCTS.i b/src/cts/src/TritonCTS.i
@@ -222,6 +222,12 @@ set_clock_nets(const char* names)
   return getTritonCts()->setClockNets(names);
 }
 
+void
+set_skip_clock_nets(odb::dbNet* net)
+{
+  getTritonCts()->getParms()->setSkipNets(net);
+}
+
 void
 set_buffer_list(const char* buffers)
 {
@@ -376,6 +382,11 @@ get_sink_clustering_size()
   return getTritonCts()->getParms()->getSinkClusteringSize();
 }
 
+std::string
+get_skip_nets()
+{
+  return getTritonCts()->getParms()->getSkipNetsToString();
+}
 std::string
 get_tree_buf()
 {
@@ -479,6 +490,11 @@ reset_sink_clustering_size()
   getTritonCts()->getParms()->resetSinkClusteringSize();
 }
 void
+reset_skip_nets()
+{
+  getTritonCts()->getParms()->resetSkipNets();
+}
+void
 reset_tree_buf()
 {
   getTritonCts()->getParms()->resetTreeBuffer();
diff --git a/src/cts/src/TritonCTS.tcl b/src/cts/src/TritonCTS.tcl
@@ -52,6 +52,7 @@ sta::define_cmd_args "set_cts_config" {[-apply_ndr strategy] \
                                        [-sink_clustering_levels levels] \
                                        [-sink_clustering_max_diameter] \
                                        [-sink_clustering_size] \
+				       [-skip_nets] \
                                        [-tree_buf buf] \
 	                               [-wire_unit unit]
 }
@@ -60,8 +61,8 @@ proc set_cts_config { args } {
     keys {-apply_ndr -branching_point_buffers_distance -buf_list -clustering_exponent \
            -clustering_unbalance_ratio -delay_buffer_derate -distance_between_buffers \
            -library -macro_clustering_max_diameter -macro_clustering_size \
-           -num_static_layers -sink_buffer_max_cap_derate -sink_clustering_levels -root_buf\
-           -sink_clustering_max_diameter -sink_clustering_size -tree_buf -wire_unit} \
+           -num_static_layers -sink_buffer_max_cap_derate -sink_clustering_levels -root_buf \
+           -sink_clustering_max_diameter -sink_clustering_size -skip_nets -tree_buf -wire_unit} \
     flags {}
 
   sta::check_argc_eq0 "set_cts_config" $args
@@ -136,6 +137,12 @@ proc set_cts_config { args } {
     set size $keys(-sink_clustering_size)
     cts::set_sink_clustering_size $size
   }
+  if { [info exists keys(-skip_nets)] } {
+    foreach net [get_nets $keys(-skip_nets)] {
+      set db_net [sta::sta_to_db_net $net]
+      cts::set_skip_clock_nets $db_net
+    }
+  }
   if { [info exists keys(-tree_buf)] } {
     set buf $keys(-tree_buf)
     cts::set_tree_buf $buf
@@ -186,6 +193,10 @@ proc report_cts_config { args } {
   set sink_clustering_levels [cts::get_sink_clustering_levels]
   set sink_max_diameter [cts::get_sink_clustering_max_diameter]
   set sink_cluster_size [cts::get_sink_clustering_size]
+  set skip_nets_list [cts::get_skip_nets]
+  if { $skip_nets_list eq "" } {
+    set skip_nets_list "undefined"
+  }
   set tree_buffer [cts::get_tree_buf]
   if { $tree_buffer eq "" } {
     set tree_buffer "undefined"
@@ -211,6 +222,7 @@ proc report_cts_config { args } {
   puts "-sink_clustering_levels:             $sink_clustering_levels"
   puts "-sink_clustering_max_diameter:       $sink_max_diameter"
   puts "-sink_clustering_size:               $sink_cluster_size"
+  puts "-skip_nets:                          $skip_nets_list"
   puts "-tree_buf:                           $tree_buffer"
   puts "-wire_unit:                          $wire_segment_unit"
   puts "****'***************************************"
@@ -232,6 +244,7 @@ sta::define_cmd_args "reset_cts_config" {[-apply_ndr] \
                                          [-sink_clustering_levels] \
                                          [-sink_clustering_max_diameter] \
                                          [-sink_clustering_size] \
+					 [-skip_nets] \
                                          [-tree_buf] \
 	                                 [-wire_unit]}
 
@@ -242,7 +255,7 @@ proc reset_cts_config { args } {
            -clustering_unbalance_ratio -delay_buffer_derate -distance_between_buffers \
            -library -macro_clustering_max_diameter -macro_clustering_size \
            -num_static_layers -root_buf -sink_buffer_max_cap_derate -sink_clustering_levels \
-           -sink_clustering_max_diameter -sink_clustering_size -tree_buf -wire_unit}
+           -sink_clustering_max_diameter -sink_clustering_size -skip_nets -tree_buf -wire_unit}
 
   set reset_all [expr { [array size flags] == 0 }]
 
@@ -310,13 +323,17 @@ proc reset_cts_config { args } {
     cts::reset_sink_clustering_size
     utl::info CTS 226 "Sink clustering size has been removed."
   }
+  if { $reset_all || [info exists flags(-skip_nets)] } {
+    cts::reset_skip_nets
+    utl::info CTS 227 "Skip nets has been removed."
+  }
   if { $reset_all || [info exists flags(-tree_buf)] } {
     cts::reset_tree_buf
-    utl::info CTS 227 "Tree buffer has been removed."
+    utl::info CTS 228 "Tree buffer has been removed."
   }
   if { $reset_all || [info exists flags(-wire_unit)] } {
     cts::reset_wire_segment_distance_unit
-    utl::info CTS 228 "Wire segment unit has been removed."
+    utl::info CTS 229 "Wire segment unit has been removed."
   }
 }
 
diff --git a/src/cts/test/BUILD b/src/cts/test/BUILD
@@ -42,6 +42,7 @@ COMPULSORY_TESTS = [
     "simple_test_clustered",
     "simple_test_clustered_max_cap",
     "simple_test_hier",
+    "skip_nets",
     "twice",
 ]
 
diff --git a/src/cts/test/CMakeLists.txt b/src/cts/test/CMakeLists.txt
@@ -43,6 +43,7 @@ or_integration_tests(
     simple_test_clustered
     simple_test_clustered_max_cap
     simple_test_hier
+    skip_nets
     twice
 )
 
diff --git a/src/cts/test/skip_nets.ok b/src/cts/test/skip_nets.ok
@@ -0,0 +1,160 @@
+[INFO ODB-0227] LEF file: Nangate45/Nangate45.lef, created 22 layers, 27 vias, 135 library cells
+[INFO ODB-0128] Design: multi_sink
+[INFO ODB-0130]     Created 1 pins.
+[INFO ODB-0131]     Created 291 components and 1743 component-terminals.
+[INFO ODB-0133]     Created 4 nets and 294 connections.
+*******************************************
+CTS config:
+-apply_ndr:                          HALF
+-buf_list:                           CLKBUF_X3 
+-branching_point_buffers_distance:   480000
+-clustering_exponent:                4
+-clustering_unbalance_ratio:         0.6
+-delay_buffer_derate:                1.0
+-distance_between_buffers:           200000
+-library:                            undefined
+-macro_clustering_max_diameter:      50.0
+-macro_clustering_size:              4
+-num_static_layers:                  1
+-root_buf:                           CLKBUF_X3 
+-sink_buffer_max_cap_derate:         0.01
+-sink_clustering_levels:             0
+-sink_clustering_max_diameter:       50.0
+-sink_clustering_size:               20
+-skip_nets:                          gclk1 gclk3 
+-tree_buf:                           undefined
+-wire_unit:                          20
+****'***************************************
+[INFO CTS-0050] Root buffer is CLKBUF_X3.
+[INFO CTS-0051] Sink buffer is CLKBUF_X3.
+[INFO CTS-0052] The following clock buffers will be used for CTS:
+                    CLKBUF_X3
+[INFO CTS-0049] Characterization buffer is CLKBUF_X3.
+[INFO CTS-0007] Net "clk" found for clock "clk".
+[INFO CTS-0011]  Clock net "clk" for macros has 2 sinks.
+[INFO CTS-0011]  Clock net "clk_regs" for registers has 144 sinks.
+[WARNING CTS-0044] Skipping net gclk1, specified by the user...
+[INFO CTS-0010]  Clock net "gclk2" has 36 sinks.
+[WARNING CTS-0044] Skipping net gclk3, specified by the user...
+[INFO CTS-0008] TritonCTS found 3 clock nets.
+[INFO CTS-0097] Characterization used 1 buffer(s) types.
+[INFO CTS-0201] 0 blockages from hard placement blockages and placed macros will be used.
+[INFO CTS-0027] Generating H-Tree topology for net clk.
+[INFO CTS-0028]  Total number of sinks: 2.
+[INFO CTS-0029]  Macro  sinks will be clustered in groups of up to 4 and with maximum cluster diameter of 50.0 um.
+[INFO CTS-0030]  Number of static layers: 1.
+[INFO CTS-0020]  Wire segment unit: 14000  dbu (7 um).
+[INFO CTS-0021]  Distance between buffers: 7 units (100 um).
+[INFO CTS-0023]  Original sink region: [(53595, 151620), (147835, 166180)].
+[INFO CTS-0024]  Normalized sink region: [(3.82821, 10.83), (10.5596, 11.87)].
+[INFO CTS-0025]     Width:  6.7314.
+[INFO CTS-0026]     Height: 1.0400.
+ Level 1
+    Direction: Horizontal
+    Sinks per sub-region: 1
+    Sub-region size: 3.3657 X 1.0400
+[INFO CTS-0034]     Segment length (rounded): 1.
+[INFO CTS-0032]  Stop criterion found. Max number of sinks is 15.
+[INFO CTS-0035]  Number of sinks covered: 2.
+[INFO CTS-0201] 0 blockages from hard placement blockages and placed macros will be used.
+[INFO CTS-0027] Generating H-Tree topology for net clk_regs.
+[INFO CTS-0028]  Total number of sinks: 144.
+[INFO CTS-0090]  Sinks will be clustered based on buffer max cap.
+[INFO CTS-0030]  Number of static layers: 1.
+[INFO CTS-0020]  Wire segment unit: 14000  dbu (7 um).
+[INFO CTS-0021]  Distance between buffers: 7 units (100 um).
+[INFO CTS-0023]  Original sink region: [(8930, 7170), (196650, 85570)].
+[INFO CTS-0024]  Normalized sink region: [(0.637857, 0.512143), (14.0464, 6.11214)].
+[INFO CTS-0025]     Width:  13.4086.
+[INFO CTS-0026]     Height: 5.6000.
+ Level 1
+    Direction: Horizontal
+    Sinks per sub-region: 72
+    Sub-region size: 6.7043 X 5.6000
+[INFO CTS-0034]     Segment length (rounded): 4.
+ Level 2
+    Direction: Vertical
+    Sinks per sub-region: 36
+    Sub-region size: 6.7043 X 2.8000
+[INFO CTS-0034]     Segment length (rounded): 1.
+ Level 3
+    Direction: Horizontal
+    Sinks per sub-region: 18
+    Sub-region size: 3.3521 X 2.8000
+[INFO CTS-0034]     Segment length (rounded): 1.
+ Level 4
+    Direction: Vertical
+    Sinks per sub-region: 9
+    Sub-region size: 3.3521 X 1.4000
+[INFO CTS-0034]     Segment length (rounded): 1.
+[INFO CTS-0032]  Stop criterion found. Max number of sinks is 15.
+[INFO CTS-0035]  Number of sinks covered: 144.
+[INFO CTS-0201] 0 blockages from hard placement blockages and placed macros will be used.
+[INFO CTS-0027] Generating H-Tree topology for net gclk2.
+[INFO CTS-0028]  Total number of sinks: 36.
+[INFO CTS-0090]  Sinks will be clustered based on buffer max cap.
+[INFO CTS-0030]  Number of static layers: 1.
+[INFO CTS-0020]  Wire segment unit: 14000  dbu (7 um).
+[INFO CTS-0021]  Distance between buffers: 7 units (100 um).
+[INFO CTS-0023]  Original sink region: [(8930, 96770), (97850, 130370)].
+[INFO CTS-0024]  Normalized sink region: [(0.637857, 6.91214), (6.98929, 9.31214)].
+[INFO CTS-0025]     Width:  6.3514.
+[INFO CTS-0026]     Height: 2.4000.
+ Level 1
+    Direction: Horizontal
+    Sinks per sub-region: 18
+    Sub-region size: 3.1757 X 2.4000
+[INFO CTS-0034]     Segment length (rounded): 1.
+ Level 2
+    Direction: Vertical
+    Sinks per sub-region: 9
+    Sub-region size: 3.1757 X 1.2000
+[INFO CTS-0034]     Segment length (rounded): 1.
+[INFO CTS-0032]  Stop criterion found. Max number of sinks is 15.
+[INFO CTS-0035]  Number of sinks covered: 36.
+[INFO CTS-0018]     Created 3 clock buffers.
+[INFO CTS-0012]     Minimum number of buffers in the clock path: 2.
+[INFO CTS-0013]     Maximum number of buffers in the clock path: 2.
+[INFO CTS-0015]     Created 3 clock nets.
+[INFO CTS-0016]     Fanout distribution for the current clock = 1:2..
+[INFO CTS-0017]     Max level of the clock tree: 1.
+[INFO CTS-0018]     Created 17 clock buffers.
+[INFO CTS-0012]     Minimum number of buffers in the clock path: 2.
+[INFO CTS-0013]     Maximum number of buffers in the clock path: 2.
+[INFO CTS-0015]     Created 17 clock nets.
+[INFO CTS-0016]     Fanout distribution for the current clock = 6:1, 7:3, 8:2, 9:4, 10:2, 11:3, 12:1..
+[INFO CTS-0017]     Max level of the clock tree: 4.
+[INFO CTS-0018]     Created 5 clock buffers.
+[INFO CTS-0012]     Minimum number of buffers in the clock path: 2.
+[INFO CTS-0013]     Maximum number of buffers in the clock path: 2.
+[INFO CTS-0015]     Created 5 clock nets.
+[INFO CTS-0016]     Fanout distribution for the current clock = 8:1, 9:2, 10:1..
+[INFO CTS-0017]     Max level of the clock tree: 2.
+[INFO CTS-0098] Clock net "clk"
+[INFO CTS-0099]  Sinks 3
+[INFO CTS-0100]  Leaf buffers 0
+[INFO CTS-0101]  Average sink wire length 57.59 um
+[INFO CTS-0102]  Path depth 2 - 2
+[INFO CTS-0207]  Leaf load cells 18
+[INFO CTS-0098] Clock net "clk_regs"
+[INFO CTS-0099]  Sinks 159
+[INFO CTS-0100]  Leaf buffers 0
+[INFO CTS-0101]  Average sink wire length 45.22 um
+[INFO CTS-0102]  Path depth 2 - 2
+[INFO CTS-0207]  Leaf load cells 18
+[INFO CTS-0098] Clock net "gclk2"
+[INFO CTS-0099]  Sinks 39
+[INFO CTS-0100]  Leaf buffers 0
+[INFO CTS-0101]  Average sink wire length 29.38 um
+[INFO CTS-0102]  Path depth 2 - 2
+[INFO CTS-0207]  Leaf load cells 18
+[DEBUG CTS-insertion delay] top buffer delay for macro tree clkbuf_0_clk is 2.666e-11
+[DEBUG CTS-insertion delay] top buffer delay for register tree clkbuf_regs_0_clk is 2.480e-11
+[DEBUG CTS-insertion delay] top buffer delay for register tree clkbuf_0_gclk2 is 3.492e-11
+[INFO CTS-0033] Balancing latency for clock clk
+[DEBUG CTS-insertion delay] new delay buffer delaybuf_0_clk is inserted at (100608 169407)
+[DEBUG CTS-insertion delay] new delay buffer delaybuf_1_clk is inserted at (101216 138954)
+[DEBUG CTS-insertion delay] new delay buffer delaybuf_2_clk is inserted at (101824 108501)
+[DEBUG CTS-insertion delay] new delay buffer delaybuf_3_clk is inserted at (102432 78048)
+[INFO CTS-0036]  inserted 4 delay buffers
+[INFO CTS-0037] Total number of delay buffers: 4
diff --git a/src/cts/test/skip_nets.tcl b/src/cts/test/skip_nets.tcl

Original file line number	Diff line number	Diff line change
`@@ -222,6 +222,12 @@ set_clock_nets(const char* names)`
`222`	`222`	`return getTritonCts()->setClockNets(names);`
`223`	`223`	`}`
`224`	`224`
	`225`	`+void`
	`226`	`+set_skip_clock_nets(odb::dbNet* net)`
	`227`	`+{`
	`228`	`+ getTritonCts()->getParms()->setSkipNets(net);`
	`229`	`+}`
	`230`	`+`
`225`	`231`	`void`
`226`	`232`	`set_buffer_list(const char* buffers)`
`227`	`233`	`{`
`@@ -376,6 +382,11 @@ get_sink_clustering_size()`
`376`	`382`	`return getTritonCts()->getParms()->getSinkClusteringSize();`
`377`	`383`	`}`
`378`	`384`
	`385`	`+std::string`
	`386`	`+get_skip_nets()`
	`387`	`+{`
	`388`	`+ return getTritonCts()->getParms()->getSkipNetsToString();`
	`389`	`+}`
`379`	`390`	`std::string`
`380`	`391`	`get_tree_buf()`
`381`	`392`	`{`
`@@ -479,6 +490,11 @@ reset_sink_clustering_size()`
`479`	`490`	`getTritonCts()->getParms()->resetSinkClusteringSize();`
`480`	`491`	`}`
`481`	`492`	`void`
	`493`	`+reset_skip_nets()`
	`494`	`+{`
	`495`	`+ getTritonCts()->getParms()->resetSkipNets();`
	`496`	`+}`
	`497`	`+void`
`482`	`498`	`reset_tree_buf()`
`483`	`499`	`{`
`484`	`500`	`getTritonCts()->getParms()->resetTreeBuffer();`
Original file line number	Diff line number	Diff line change
`@@ -42,6 +42,7 @@ COMPULSORY_TESTS = [`
`42`	`42`	`"simple_test_clustered",`
`43`	`43`	`"simple_test_clustered_max_cap",`
`44`	`44`	`"simple_test_hier",`
	`45`	`+ "skip_nets",`
`45`	`46`	`"twice",`
`46`	`47`	`]`
`47`	`48`
Original file line number	Diff line number	Diff line change
`@@ -43,6 +43,7 @@ or_integration_tests(`
`43`	`43`	`simple_test_clustered`
`44`	`44`	`simple_test_clustered_max_cap`
`45`	`45`	`simple_test_hier`
	`46`	`+ skip_nets`
`46`	`47`	`twice`
`47`	`48`	`)`
`48`	`49`