psm: add db property to selectively disconnect bpins

Signed-off-by: Peter Gadfort <[email protected]>

Author: gadfort

src/psm/README.md

@@ -156,6 +156,19 @@ set_pdnsim_source_settings
 | `-bump_interval` | Set the bump population interval, this is used to depopulate the bump grid to emulate signals and other power connections. The default bump pitch is 3. |
 | `-strap_track_pitch` | Sets the track pitck to use for moduling voltage sources as straps. The default is 10x. |
 
+#### Selectively diconencting sources
+
+If you need to be able to disconnect some of the terminals in the design, such as in the case of "what-if" analysis or different chip packaging options.
+This can be done by assigning `PSM_DISCONNECT` to a terminal or shape in a terminal will cause PDNSim to leave that object disconnected from the analysis.
+
+```tcl
+# Assumes bpin is the block pin to be disconnected
+odb::dbBoolProperty_create $bpin PSM_DISCONNECT 1
+
+# Assumes box the box shape in the bpin to be disconnected
+odb::dbBoolProperty_create $box PSM_DISCONNECT 1
+```
+
 ### Insert Decap Cells
 The `insert_decap` command inserts decap cells in the areas with the highest
 IR Drop. The number of decap cells inserted will be limited to the target

src/psm/src/ir_network.cpp

@@ -330,7 +330,7 @@ IRNetwork::generatePolygonsFromBTerms(std::vector<TerminalNode*>& terminals)
 
   for (auto* bterm : net_->getBTerms()) {
     for (auto* bpin : bterm->getBPins()) {
-      for (auto* geom : bpin->getBoxes()) {
+      for (odb::dbBox* geom : bpin->getBoxes()) {
         for (const auto& [layer, shapes] :
              generatePolygonsFromBox(geom, odb::dbTransform())) {
           shapes_by_layer[layer] += shapes;
@@ -345,7 +345,7 @@ IRNetwork::generatePolygonsFromBTerms(std::vector<TerminalNode*>& terminals)
 
         // create bpin nodes
         auto term = std::make_unique<TerminalNode>(pin_shape, layer);
-        auto pin_node = std::make_unique<BPinNode>(bpin, pin_shape, layer);
+        auto pin_node = std::make_unique<BPinNode>(bpin, geom, layer);
 
         connections_.push_back(
             std::make_unique<TermConnection>(term.get(), pin_node.get()));
@@ -1292,7 +1292,9 @@ Node::NodeSet IRNetwork::getBPinShapeNodes() const
 
   std::map<odb::dbTechLayer*, std::set<odb::Rect>> nodes;
   for (const auto& bpin : bpin_nodes_) {
-    nodes[bpin->getLayer()].insert(bpin->getShape());
+    if (bpin->shouldConnect()) {
+      nodes[bpin->getLayer()].insert(bpin->getShape());
+    }
   }
 
   Node::NodeSet pin_nodes;

src/psm/src/ir_solver.cpp

@@ -501,7 +501,7 @@ IRSolver::generateSourceNodesFromBTerms() const
 
   std::vector<std::unique_ptr<SourceNode>> src_nodes;
 
-  for (auto* root_node : network_->getBPinShapeNodes()) {
+  for (Node* root_node : network_->getBPinShapeNodes()) {
     src_nodes.push_back(std::make_unique<SourceNode>(root_node));
   }
 

src/psm/src/node.cpp

@@ -131,10 +131,8 @@ std::string ITermNode::describe(const std::string& prefix) const
 
 ////////////////////
 
-BPinNode::BPinNode(odb::dbBPin* pin,
-                   const odb::Rect& shape,
-                   odb::dbTechLayer* layer)
-    : TerminalNode(shape, layer), pin_(pin)
+BPinNode::BPinNode(odb::dbBPin* pin, odb::dbBox* box, odb::dbTechLayer* layer)
+    : TerminalNode(box->getBox(), layer), pin_(pin), box_(box)
 {
 }
 
@@ -143,4 +141,19 @@ int BPinNode::getTypeCompareInfo() const
   return pin_->getId();
 }
 
+bool BPinNode::shouldConnect() const
+{
+  if (auto prop = odb::dbBoolProperty::find(pin_, kDisconnectProperty)) {
+    if (prop != nullptr && prop->getValue()) {
+      return false;
+    }
+  }
+  if (auto prop = odb::dbBoolProperty::find(box_, kDisconnectProperty)) {
+    if (prop != nullptr && prop->getValue()) {
+      return false;
+    }
+  }
+  return true;
+}
+
 }  // namespace psm

src/psm/src/node.h

@@ -14,6 +14,7 @@
 #include "odb/geom_boost.h"
 
 namespace odb {
+class dbBox;
 class dbTechLayer;
 class dbBPin;
 class dbITerm;
@@ -125,9 +126,10 @@ class ITermNode : public TerminalNode
 class BPinNode : public TerminalNode
 {
  public:
-  BPinNode(odb::dbBPin* pin, const odb::Rect& shape, odb::dbTechLayer* layer);
+  BPinNode(odb::dbBPin* pin, odb::dbBox* box, odb::dbTechLayer* layer);
 
   const odb::dbBPin* getBPin() const { return pin_; }
+  bool shouldConnect() const;
 
  protected:
   NodeType getType() const override { return NodeType::kBPin; }
@@ -136,6 +138,9 @@ class BPinNode : public TerminalNode
 
  private:
   odb::dbBPin* pin_;
+  odb::dbBox* box_;
+
+  static constexpr const char* kDisconnectProperty = "PSM_DISCONNECT";
 };
 
 }  // namespace psm

src/psm/test/BUILD

@@ -9,6 +9,7 @@ COMPULSORY_TESTS = [
     "aes_asap7_vdd",
     "aes_test_bterms",
     "aes_test_multiple_bterms",
+    "aes_test_multiple_bterms_skipped",
     "aes_test_vdd",
     "aes_test_vss",
     "check_power_grid",

src/psm/test/CMakeLists.txt

@@ -4,6 +4,7 @@ or_integration_tests(
     aes_asap7_vdd
     aes_test_bterms
     aes_test_multiple_bterms
+    aes_test_multiple_bterms_skipped
     aes_test_vdd
     aes_test_vss
     check_power_grid

src/psm/test/aes_test_multiple_bterms_skipped.ok

@@ -0,0 +1,28 @@
+[INFO ODB-0227] LEF file: Nangate45/Nangate45.lef, created 22 layers, 27 vias, 135 library cells
+[INFO ODB-0128] Design: aes_cipher_top
+[INFO ODB-0130]     Created 390 pins.
+[INFO ODB-0131]     Created 19835 components and 101835 component-terminals.
+[INFO ODB-0132]     Created 2 special nets and 39670 connections.
+[INFO ODB-0133]     Created 18908 nets and 62165 connections.
+[INFO PSM-0040] All shapes on net VDD are connected.
+########## IR report #################
+Net              : VDD
+Corner           : default
+Supply voltage   : 1.10e+00 V
+Worstcase voltage: 1.10e+00 V
+Average voltage  : 1.10e+00 V
+Average IR drop  : 2.40e-04 V
+Worstcase IR drop: 2.55e-03 V
+Percentage drop  : 0.23 %
+######################################
+[INFO PSM-0040] All shapes on net VDD are connected.
+########## IR report #################
+Net              : VDD
+Corner           : default
+Supply voltage   : 1.10e+00 V
+Worstcase voltage: 1.10e+00 V
+Average voltage  : 1.10e+00 V
+Average IR drop  : 4.36e-04 V
+Worstcase IR drop: 3.52e-03 V
+Percentage drop  : 0.32 %
+######################################

src/psm/test/aes_test_multiple_bterms_skipped.tcl

@@ -0,0 +1,19 @@
+source "helpers.tcl"
+read_lef Nangate45/Nangate45.lef
+read_def Nangate45_data/aes_multi_bterms.def
+read_liberty Nangate45/Nangate45_typ.lib
+read_sdc Nangate45_data/aes.sdc
+
+analyze_power_grid -net VDD
+
+# Disconnect all metal6
+set bterm [[ord::get_db_block] findBTerm VDD]
+foreach bpin [$bterm getBPins] {
+    foreach box [$bpin getBoxes] {
+        if { [$box getTechLayer] == [[ord::get_db_tech] findLayer metal6]} {
+            odb::dbBoolProperty_create $box PSM_DISCONNECT 1
+        }
+    }
+}
+
+analyze_power_grid -net VDD