From a46a66c2c468b93e6314e60540e8041d7df16689 Mon Sep 17 00:00:00 2001
From: Stan Lee <135666755+stanminlee@users.noreply.github.com>
Date: Thu, 21 May 2026 16:28:51 -0700
Subject: [PATCH 01/23] everything minus tcl wrapper

---
 include/sta/ExceptionPath.hh | 31 +++++++++++++++++++
 include/sta/PathEnd.hh       |  3 ++
 include/sta/Sdc.hh           |  6 ++++
 include/sta/SdcClass.hh      |  1 +
 include/sta/Sta.hh           |  6 ++++
 sdc/ExceptionPath.cc         | 59 ++++++++++++++++++++++++++++++++++++
 sdc/Sdc.cc                   | 19 ++++++++++--
 sdc/Sdc.i                    | 11 +++++++
 sdc/WriteSdc.cc              |  8 +++++
 search/PathEnd.cc            | 39 ++++++++++++++++++++++--
 search/ReportPath.cc         |  4 +++
 search/Sta.cc                | 14 ++++++++-
 search/VisitPathEnds.cc      | 21 +++++++------
 13 files changed, 207 insertions(+), 15 deletions(-)

diff --git a/include/sta/ExceptionPath.hh b/include/sta/ExceptionPath.hh
index c1c099781..327ea046c 100644
--- a/include/sta/ExceptionPath.hh
+++ b/include/sta/ExceptionPath.hh
@@ -63,6 +63,7 @@ public:
   virtual bool isLoop() const { return false; }
   virtual bool isMultiCycle() const { return false; }
   virtual bool isPathDelay() const { return false; }
+  virtual bool isPathMargin() const { return false; }
   virtual bool isGroupPath() const { return false; }
   virtual bool isFilter() const { return false; }
   virtual ExceptionPathType type() const = 0;
@@ -97,6 +98,7 @@ public:
   static int pathDelayPriority() { return 3000; }
   static int multiCyclePathPriority() { return 2000; }
   static int filterPathPriority() { return 1000; }
+  static int pathMarginPriority() { return 500; }
   static int groupPathPriority() { return 0; }
   // Compare the value (path delay or cycle count) to another exception
   // of the same priority.  Because the exception "values" are floats,
@@ -126,6 +128,7 @@ public:
   virtual bool useEndClk() const { return false; }
   virtual int pathMultiplier() const { return 0; }
   virtual float delay() const { return 0.0; }
+  virtual float margin() const { return 0.0; }
   virtual const char *name() const { return nullptr; }
   virtual bool isDefault() const { return false; }
   virtual bool ignoreClkLatency() const { return false; }
@@ -224,6 +227,34 @@ protected:
   float delay_;
 };
 
+// set_path_margin
+class PathMargin : public ExceptionPath
+{
+public:
+  PathMargin(ExceptionFrom *from,
+	     ExceptionThruSeq *thrus,
+	     ExceptionTo *to,
+	     const MinMaxAll *min_max,
+	     float margin,
+	     bool own_pts,
+	     const char *comment);
+  virtual ExceptionPath *clone(ExceptionFrom *from,
+			       ExceptionThruSeq *thrus,
+			       ExceptionTo *to,
+			       bool own_pts);
+  virtual bool isPathMargin() const { return true; }
+  virtual ExceptionPathType type() const { return ExceptionPathType::path_margin; }
+  virtual const char *typeString() const;
+  virtual bool mergeable(ExceptionPath *exception) const;
+  virtual bool overrides(ExceptionPath *exception) const;
+  virtual float margin() const { return margin_; }
+  virtual int typePriority() const;
+  virtual bool tighterThan(ExceptionPath *exception) const;
+
+protected:
+  float margin_;
+};
+
 // set_multicycle_path
 class MultiCyclePath : public ExceptionPath
 {
diff --git a/include/sta/PathEnd.hh b/include/sta/PathEnd.hh
index c61eb16ae..bc57985e4 100644
--- a/include/sta/PathEnd.hh
+++ b/include/sta/PathEnd.hh
@@ -137,6 +137,8 @@ public:
   // Target clock uncertainty + inter-clk uncertainty.
   virtual float targetClkUncertainty(const StaState *sta) const;
   virtual float targetClkMcpAdjustment(const StaState *sta) const;
+  // Target clock path margin.
+  virtual float targetClkPathMargin(const StaState *sta) const;
   virtual const TimingRole *checkRole(const StaState *sta) const;
   const TimingRole *checkGenericRole(const StaState *sta) const;
   virtual bool pathDelayMarginIsExternal() const;
@@ -257,6 +259,7 @@ public:
   virtual float targetNonInterClkUncertainty(const StaState *sta) const;
   virtual float interClkUncertainty(const StaState *sta) const;
   virtual float targetClkUncertainty(const StaState *sta) const;
+  virtual float targetClkPathMargin(const StaState *sta) const;
   virtual Crpr crpr(const StaState *sta) const;
   virtual Required requiredTime(const StaState *sta) const;
   virtual Slack slack(const StaState *sta) const;
diff --git a/include/sta/Sdc.hh b/include/sta/Sdc.hh
index e4f32afec..215117e4f 100644
--- a/include/sta/Sdc.hh
+++ b/include/sta/Sdc.hh
@@ -762,6 +762,12 @@ public:
                      bool break_path,
 		     float delay,
 		     const char *comment);
+  void makePathMargin(ExceptionFrom *from,
+		      ExceptionThruSeq *thrus,
+		      ExceptionTo *to,
+		      const MinMaxAll *min_max,
+		      float margin,
+		      const char *comment);
   bool pathDelaysWithoutTo() const { return path_delays_without_to_; }
   // Delete matching false/multicycle/path_delay exceptions.
   // Caller owns from, thrus, to exception points (and must delete them).
diff --git a/include/sta/SdcClass.hh b/include/sta/SdcClass.hh
index 2fece7b36..8e05222c2 100644
--- a/include/sta/SdcClass.hh
+++ b/include/sta/SdcClass.hh
@@ -67,6 +67,7 @@ class PortDelay;
 enum class AnalysisType { single, bc_wc, ocv };
 
 enum class ExceptionPathType { false_path, loop, multi_cycle, path_delay,
+			       path_margin,
 			       group_path, filter, any};
 
 enum class ClockSense { positive, negative, stop };
diff --git a/include/sta/Sta.hh b/include/sta/Sta.hh
index eff131a4b..063a178dd 100644
--- a/include/sta/Sta.hh
+++ b/include/sta/Sta.hh
@@ -517,6 +517,12 @@ public:
                      bool break_path,
 		     float delay,
 		     const char *comment);
+  void makePathMargin(ExceptionFrom *from,
+		      ExceptionThruSeq *thrus,
+		      ExceptionTo *to,
+		      const MinMaxAll *min_max,
+		      float margin,
+		      const char *comment);
   void makeGroupPath(const char *name,
 		     bool is_default,
 		     ExceptionFrom *from,
diff --git a/sdc/ExceptionPath.cc b/sdc/ExceptionPath.cc
index 163dcf653..011253ec3 100644
--- a/sdc/ExceptionPath.cc
+++ b/sdc/ExceptionPath.cc
@@ -564,6 +564,64 @@ PathDelay::overrides(ExceptionPath *exception) const
 
 ////////////////////////////////////////////////////////////////
 
+PathMargin::PathMargin(ExceptionFrom *from,
+		       ExceptionThruSeq *thrus,
+		       ExceptionTo *to,
+		       const MinMaxAll *min_max,
+		       float margin,
+		       bool own_pts,
+		       const char *comment) :
+  ExceptionPath(from, thrus, to, min_max, own_pts,
+		pathMarginPriority() + fromThruToPriority(from, thrus, to),
+		comment),
+  margin_(margin)
+{
+}
+
+ExceptionPath *
+PathMargin::clone(ExceptionFrom *from,
+		  ExceptionThruSeq *thrus,
+		  ExceptionTo *to,
+		  bool own_pts)
+{
+  return new PathMargin(from, thrus, to, min_max_, margin_, own_pts, comment_);
+}
+
+int
+PathMargin::typePriority() const
+{
+  return pathMarginPriority();
+}
+
+bool
+PathMargin::tighterThan(ExceptionPath *) const
+{
+  return false;
+}
+
+const char *
+PathMargin::typeString() const
+{
+  return "Margin";
+}
+
+bool
+PathMargin::mergeable(ExceptionPath *) const
+{
+  return false;
+}
+
+bool
+PathMargin::overrides(ExceptionPath *exception) const
+{
+  // A later set_path_margin with the same scope replaces the earlier one.
+  return exception->isPathMargin()
+    && exception->priority() == priority_
+    && exception->minMax() == min_max_;
+}
+
+////////////////////////////////////////////////////////////////
+
 FalsePath::FalsePath(ExceptionFrom *from,
 		     ExceptionThruSeq *thrus,
 		     ExceptionTo *to,
@@ -624,6 +682,7 @@ FalsePath::mergeable(ExceptionPath *exception) const
 bool
 FalsePath::overrides(ExceptionPath *exception) const
 {
+  // Most recent definition overrides earlier ones.
   return exception->priority() == priority()
     && exception->minMax() == min_max_;
 }
diff --git a/sdc/Sdc.cc b/sdc/Sdc.cc
index e105e3c9c..595ab61e6 100644
--- a/sdc/Sdc.cc
+++ b/sdc/Sdc.cc
@@ -4086,12 +4086,26 @@ Sdc::makePathDelay(ExceptionFrom *from,
 		   const char *comment)
 {
   checkFromThrusTo(from, thrus, to);
-  PathDelay *exception = new PathDelay(from, thrus, to, min_max, 
+  PathDelay *exception = new PathDelay(from, thrus, to, min_max,
 				       ignore_clk_latency, break_path,
                                        delay, true, comment);
   addException(exception);
 }
 
+void
+Sdc::makePathMargin(ExceptionFrom *from,
+		    ExceptionThruSeq *thrus,
+		    ExceptionTo *to,
+		    const MinMaxAll *min_max,
+		    float margin,
+		    const char *comment)
+{
+  checkFromThrusTo(from, thrus, to);
+  PathMargin *exception = new PathMargin(from, thrus, to, min_max,
+					 margin, true, comment);
+  addException(exception);
+}
+
 void
 Sdc::recordPathDelayInternalFrom(ExceptionPath *exception)
 {
@@ -4499,7 +4513,8 @@ Sdc::addException1(ExceptionPath *exception)
 void
 Sdc::addException2(ExceptionPath *exception)
 {
-  if (exception->isMultiCycle() || exception->isPathDelay())
+  if (exception->isMultiCycle() || exception->isPathDelay()
+      || exception->isPathMargin())
     deleteMatchingExceptions(exception);
   recordException(exception);
   mergeException(exception);
diff --git a/sdc/Sdc.i b/sdc/Sdc.i
index a1ee1e5a4..23519a314 100644
--- a/sdc/Sdc.i
+++ b/sdc/Sdc.i
@@ -720,6 +720,17 @@ make_path_delay(ExceptionFrom *from,
                             delay, comment);
 }
 
+void
+make_path_margin(ExceptionFrom *from,
+		 ExceptionThruSeq *thrus,
+		 ExceptionTo *to,
+		 const MinMaxAll *min_max,
+		 float margin,
+		 const char *comment)
+{
+  Sta::sta()->makePathMargin(from, thrus, to, min_max, margin, comment);
+}
+
 void
 reset_path_cmd(ExceptionFrom *
 	       from, ExceptionThruSeq *thrus,
diff --git a/sdc/WriteSdc.cc b/sdc/WriteSdc.cc
index b3095d915..b44d00790 100644
--- a/sdc/WriteSdc.cc
+++ b/sdc/WriteSdc.cc
@@ -1295,6 +1295,10 @@ WriteSdc::writeExceptionCmd(ExceptionPath *exception) const
     if (exception->ignoreClkLatency())
       gzprintf(stream_, " -ignore_clock_latency");
   }
+  else if (exception->isPathMargin()) {
+    gzprintf(stream_, "set_path_margin");
+    writeSetupHoldFlag(exception->minMax());
+  }
   else if (exception->isGroupPath()) {
     if (exception->isDefault())
       gzprintf(stream_, "group_path -default");
@@ -1315,6 +1319,10 @@ WriteSdc::writeExceptionValue(ExceptionPath *exception) const
     gzprintf(stream_, " ");
     writeTime(exception->delay());
   }
+  else if (exception->isPathMargin()) {
+    gzprintf(stream_, " ");
+    writeTime(exception->margin());
+  }
 }
 
 void
diff --git a/search/PathEnd.cc b/search/PathEnd.cc
index 12b539d4a..d13b1d4de 100644
--- a/search/PathEnd.cc
+++ b/search/PathEnd.cc
@@ -231,6 +231,12 @@ PathEnd::targetClkMcpAdjustment(const StaState *) const
   return 0.0;
 }
 
+float
+PathEnd::targetClkPathMargin(const StaState *) const
+{
+  return 0.0;
+}
+
 const TimingRole *
 PathEnd::checkRole(const StaState *) const
 {
@@ -641,7 +647,8 @@ PathEndClkConstrained::targetClkArrivalNoCrpr(const StaState *sta) const
  			  targetClkEdge(sta),
  			  targetClkPath(),
  			  checkRole(sta), sta)
-    + targetClkMcpAdjustment(sta);
+    + targetClkMcpAdjustment(sta)
+    + targetClkPathMargin(sta);
 }
 
 Delay
@@ -699,6 +706,30 @@ PathEndClkConstrained::targetClkUncertainty(const StaState *sta) const
 			     targetClkPath(), checkRole(sta), sta);
 }
 
+float
+PathEndClkConstrained::targetClkPathMargin(const StaState *sta) const
+{
+  const Sdc *sdc = sta->sdc();
+  const TimingRole *role = checkRole(sta);
+  ExceptionPath *exception = nullptr;
+  int hi_priority_exception = -1;
+  // Look up a path margin for the target
+  sdc->exceptionTo(ExceptionPathType::path_margin,
+                   path_->pin(sta),
+                   path_->transition(sta),
+                   targetClkEdge(sta),
+                   role->pathMinMax(),
+                   false,
+                   exception, hi_priority_exception);
+  if (!exception) // no path margin found
+    return 0.0;
+  float margin = exception->margin();
+  // Setup time margin is sign-flipped
+  if (role->genericRole() == TimingRole::setup())
+    margin = -margin;
+  return margin;
+}
+
 Crpr
 PathEndClkConstrained::crpr(const StaState *sta) const
 {
@@ -1426,7 +1457,8 @@ PathEndOutputDelay::targetClkArrivalNoCrpr(const StaState *sta) const
     return targetClkTime(sta)
       + tgtClkDelay(tgt_clk_edge, check_role, sta)
       + targetClkUncertainty(sta)
-      + checkMcpAdjustment(path_, tgt_clk_edge, sta);
+      + checkMcpAdjustment(path_, tgt_clk_edge, sta)
+      + targetClkPathMargin(sta);
   }
 }
 
@@ -1967,7 +1999,8 @@ PathEndPathDelay::targetClkArrivalNoCrpr(const StaState *sta) const
   const ClockEdge *tgt_clk_edge = targetClkEdge(sta);
   if (tgt_clk_edge)
     return targetClkDelay(sta)
-      + targetClkUncertainty(sta);
+      + targetClkUncertainty(sta)
+      + targetClkPathMargin(sta);
   else if (clk_path_)
     return clk_path_->arrival();
   else
diff --git a/search/ReportPath.cc b/search/ReportPath.cc
index eb775c841..487f6bae1 100644
--- a/search/ReportPath.cc
+++ b/search/ReportPath.cc
@@ -2653,6 +2653,10 @@ ReportPath::reportClkUncertainty(const PathEnd *end,
   if (inter_uncertainty != 0.0)
     reportLine("inter-clock uncertainty", inter_uncertainty,
                clk_arrival, early_late);
+  float margin = end->targetClkPathMargin(this);
+  clk_arrival += margin;
+  if (margin != 0.0)
+    reportLine("path margin", margin, clk_arrival, early_late);
 }
 
 ////////////////////////////////////////////////////////////////
diff --git a/search/Sta.cc b/search/Sta.cc
index d34ffecbd..345e46cbc 100644
--- a/search/Sta.cc
+++ b/search/Sta.cc
@@ -2000,13 +2000,25 @@ Sta::makePathDelay(ExceptionFrom *from,
 		   float delay,
 		   const char *comment)
 {
-  sdc_->makePathDelay(from, thrus, to, min_max, 
+  sdc_->makePathDelay(from, thrus, to, min_max,
 		      ignore_clk_latency, break_path,
                       delay, comment);
   search_->endpointsInvalid();
   search_->arrivalsInvalid();
 }
 
+void
+Sta::makePathMargin(ExceptionFrom *from,
+		    ExceptionThruSeq *thrus,
+		    ExceptionTo *to,
+		    const MinMaxAll *min_max,
+		    float margin,
+		    const char *comment)
+{
+  sdc_->makePathMargin(from, thrus, to, min_max, margin, comment);
+  search_->arrivalsInvalid();
+}
+
 void
 Sta::resetPath(ExceptionFrom *from,
 	       ExceptionThruSeq *thrus,
diff --git a/search/VisitPathEnds.cc b/search/VisitPathEnds.cc
index b5a762d54..ec914ce87 100644
--- a/search/VisitPathEnds.cc
+++ b/search/VisitPathEnds.cc
@@ -178,12 +178,12 @@ VisitPathEnds::visitCheckEnd(const Pin *pin,
                     && tgt_clk != sdc_->defaultArrivalClock()
                     && sdc_->sameClockGroup(src_clk, tgt_clk)
                     && !sdc_->clkStopPropagation(tgt_pin, tgt_clk)
-                    // False paths and path delays override
-                    // paths.
+                    // False paths, path delays, and path margins override
                     && (exception == nullptr
                         || exception->isFilter()
                         || exception->isGroupPath()
-                        || exception->isMultiCycle())) {
+                        || exception->isMultiCycle()
+                        || exception->isPathMargin())) {
                   MultiCyclePath *mcp=dynamic_cast<MultiCyclePath*>(exception);
                   if (network_->isLatchData(pin)
                       && check_role == TimingRole::setup()) {
@@ -359,11 +359,12 @@ VisitPathEnds::visitOutputDelayEnd1(OutputDelay *output_delay,
   else if (src_clk_edge
            && tgt_clk_edge
 	   && sdc_->sameClockGroup(path->clock(this), tgt_clk_edge->clock())
-	   // False paths and path delays override.
+	   // False paths, path delays, and path margins override.
 	   && (exception == nullptr
 	       || exception->isFilter()
 	       || exception->isGroupPath()
-	       || exception->isMultiCycle())) {
+	       || exception->isMultiCycle()
+	       || exception->isPathMargin())) {
     MultiCyclePath *mcp = dynamic_cast<MultiCyclePath*>(exception);
     PathEndOutputDelay path_end(output_delay, path, ref_path, mcp, this);
     visitor->visit(&path_end);
@@ -426,11 +427,12 @@ VisitPathEnds::visitGatedClkEnd(const Pin *pin,
 	  ExceptionPath *exception = exceptionTo(path, pin, end_rf,
 						 clk_edge, min_max);
 	  if (sdc_->sameClockGroup(src_clk, clk)
-	      // False paths and path delays override.
+	      // False paths, path delays, and path margins override.
 	      && (exception == nullptr
 		  || exception->isFilter()
 		  || exception->isGroupPath()
-		  || exception->isMultiCycle())
+		  || exception->isMultiCycle()
+		  || exception->isPathMargin())
 	      && (!filtered
 		  || search_->matchesFilter(path, clk_edge))) {
 	    MultiCyclePath *mcp =
@@ -548,11 +550,12 @@ VisitPathEnds::visitDataCheckEnd1(DataCheck *check,
                                              tgt_clk_edge, min_max);
       if (sdc_->sameClockGroup(src_clk, tgt_clk)
 	  && !sdc_->clkStopPropagation(from_pin, tgt_clk)
-	  // False paths and path delays override.
+	  // False paths, path delays, and path margins override.
 	  && (exception == 0
 	      || exception->isFilter()
 	      || exception->isGroupPath()
-	      || exception->isMultiCycle())
+	      || exception->isMultiCycle()
+	      || exception->isPathMargin())
 	  && (!filtered
 	      || search_->matchesFilter(path, tgt_clk_edge))) {
 	MultiCyclePath *mcp=dynamic_cast<MultiCyclePath*>(exception);

From 7c4c7d7b0abb2d06307309f79551346bebb22b02 Mon Sep 17 00:00:00 2001
From: Stan Lee <135666755+stanminlee@users.noreply.github.com>
Date: Thu, 21 May 2026 16:44:33 -0700
Subject: [PATCH 02/23] tcl wrapper

---
 sdc/Sdc.tcl | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/sdc/Sdc.tcl b/sdc/Sdc.tcl
index d23f8af89..67d96219b 100644
--- a/sdc/Sdc.tcl
+++ b/sdc/Sdc.tcl
@@ -2457,6 +2457,61 @@ proc set_min_delay { args } {
 
 ################################################################
 
+define_cmd_args "set_path_margin" \
+  {[-setup] [-hold] [-rise] [-fall] [-comment comment]\
+     [-from from_list] [-rise_from from_list] [-fall_from from_list]\
+     [-through|-thr|-th through_list] [-rise_through|-rise_thr|-rise_th through_list]\
+     [-fall_through|-fall_thr|-fall_th through_list]\
+     [-to to_list] [-rise_to to_list] [-fall_to to_list] margin}
+
+proc set_path_margin { args } {
+  parse_key_args "set_path_margin" args \
+    keys {-from -rise_from -fall_from -to -rise_to -fall_to -comment} \
+    flags {-rise -fall -setup -hold} 0
+
+  # Applies to setup, hold, or both.
+  set min_max "min_max"
+  if { [info exists flags(-setup)] && ![info exists flags(-hold)] } {
+    set min_max "max"
+  } elseif { [info exists flags(-hold)] && ![info exists flags(-setup)] } {
+    set min_max "min"
+  }
+
+  # Validate arguments.
+  set cmd "set_path_margin"
+  set arg_error 0
+  set from [parse_from_arg keys arg_error]
+  set thrus [parse_thrus_arg args arg_error]
+  set to [parse_to_arg keys flags arg_error]
+  check_exception_pins $from $to
+  if { $arg_error } {
+    delete_from_thrus_to $from $thrus $to
+    return
+  }
+
+  # Validate margin value count and argument type.
+  check_for_key_args $cmd args
+  if { [llength $args] == 0 } {
+    delete_from_thrus_to $from $thrus $to
+    sta_error 1800 "missing margin argument."
+  } elseif { [llength $args] > 1 } {
+    sta_warn 1801 "'$args' ignored."
+  }
+  if { $from == "NULL" && $thrus == "" && $to == "NULL" } {
+    delete_from_thrus_to $from $thrus $to
+    sta_error 1802 "-from, -through or -to required."
+  }
+
+  # Parse margin value.
+  set margin [lindex $args 0]
+  check_float "set_path_margin margin" $margin
+  set margin [time_ui_sta $margin]
+  set comment [parse_comment_key keys]
+  make_path_margin $from $thrus $to $min_max $margin $comment
+}
+
+################################################################
+
 define_cmd_args "set_min_pulse_width" {[-low] [-high] value [objects]}
 
 proc set_min_pulse_width { args } {

From cf17c558691efe4146d4e5ab54c64c478b96aef2 Mon Sep 17 00:00:00 2001
From: Stan Lee <135666755+stanminlee@users.noreply.github.com>
Date: Thu, 21 May 2026 17:03:10 -0700
Subject: [PATCH 03/23] test

---
 test/regression_vars.tcl |   1 +
 test/set_path_margin.ok  | 118 +++++++++++++++++++++++++++++++++++++++
 test/set_path_margin.tcl |  26 +++++++++
 3 files changed, 145 insertions(+)
 create mode 100644 test/set_path_margin.ok
 create mode 100644 test/set_path_margin.tcl

diff --git a/test/regression_vars.tcl b/test/regression_vars.tcl
index 405ac17e2..ef66af6cb 100644
--- a/test/regression_vars.tcl
+++ b/test/regression_vars.tcl
@@ -183,6 +183,7 @@ record_public_tests {
   power_json
   prima3
   report_checks_sorted
+  set_path_margin
   report_checks_src_attr
   report_json1
   report_json2
diff --git a/test/set_path_margin.ok b/test/set_path_margin.ok
new file mode 100644
index 000000000..a8ae88a7a
--- /dev/null
+++ b/test/set_path_margin.ok
@@ -0,0 +1,118 @@
+Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r2/CK (DFF_X1)
+   0.0772    0.0772 v r2/Q (DFF_X1)
+   0.0233    0.1006 v u1/Z (BUF_X1)
+   0.0273    0.1278 v u2/ZN (AND2_X1)
+   0.0000    0.1278 v r3/D (DFF_X1)
+             0.1278   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+  -0.5000    9.5000   path margin
+   0.0000    9.5000   clock reconvergence pessimism
+             9.5000 ^ r3/CK (DFF_X1)
+  -0.0390    9.4610   library setup time
+             9.4610   data required time
+-------------------------------------------------------------
+             9.4610   data required time
+            -0.1278   data arrival time
+-------------------------------------------------------------
+             9.3332   slack (MET)
+
+
+Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: min
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r1/CK (DFF_X1)
+   0.0772    0.0772 v r1/Q (DFF_X1)
+   0.0254    0.1026 v u2/ZN (AND2_X1)
+   0.0000    0.1026 v r3/D (DFF_X1)
+             0.1026   data arrival time
+
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.5000    0.5000   path margin
+   0.0000    0.5000   clock reconvergence pessimism
+             0.5000 ^ r3/CK (DFF_X1)
+   0.0016    0.5016   library hold time
+             0.5016   data required time
+-------------------------------------------------------------
+             0.5016   data required time
+            -0.1026   data arrival time
+-------------------------------------------------------------
+            -0.3990   slack (VIOLATED)
+
+
+Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r2/CK (DFF_X1)
+   0.0772    0.0772 v r2/Q (DFF_X1)
+   0.0233    0.1006 v u1/Z (BUF_X1)
+   0.0273    0.1278 v u2/ZN (AND2_X1)
+   0.0000    0.1278 v r3/D (DFF_X1)
+             0.1278   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+  67.0000   77.0000   path margin
+   0.0000   77.0000   clock reconvergence pessimism
+            77.0000 ^ r3/CK (DFF_X1)
+  -0.0390   76.9610   library setup time
+            76.9610   data required time
+-------------------------------------------------------------
+            76.9610   data required time
+            -0.1278   data arrival time
+-------------------------------------------------------------
+            76.8332   slack (MET)
+
+
+Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: min
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r1/CK (DFF_X1)
+   0.0772    0.0772 v r1/Q (DFF_X1)
+   0.0254    0.1026 v u2/ZN (AND2_X1)
+   0.0000    0.1026 v r3/D (DFF_X1)
+             0.1026   data arrival time
+
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+  -0.5000   -0.5000   path margin
+   0.0000   -0.5000   clock reconvergence pessimism
+            -0.5000 ^ r3/CK (DFF_X1)
+   0.0016   -0.4984   library hold time
+            -0.4984   data required time
+-------------------------------------------------------------
+            -0.4984   data required time
+            -0.1026   data arrival time
+-------------------------------------------------------------
+             0.6010   slack (MET)
+
+
diff --git a/test/set_path_margin.tcl b/test/set_path_margin.tcl
new file mode 100644
index 000000000..fd0a548a2
--- /dev/null
+++ b/test/set_path_margin.tcl
@@ -0,0 +1,26 @@
+# set_path_margin: per-path slack adjustment on the capture clock.
+
+read_liberty ../examples/nangate45_typ.lib.gz
+read_verilog ../examples/example1.v
+link_design top
+create_clock -name clk -period 10 {clk1 clk2 clk3}
+set_input_delay -clock clk 0 {in1 in2}
+
+proc setup_at { pin } {
+  report_checks -to $pin -path_delay max -digits 4 -fields {} -group_path_count 1
+}
+proc hold_at { pin } {
+  report_checks -to $pin -path_delay min -digits 4 -fields {} -group_path_count 1
+}
+
+set_path_margin -setup 0.50 -comment {tighten setup time} -to [get_pins r3/D]
+setup_at [get_pins r3/D]
+
+set_path_margin -hold 0.50 -comment {tighten hold time} -to [get_pins r3/D]
+hold_at [get_pins r3/D]
+
+set_path_margin -setup -67 -comment {loosen setup time} -to [get_pins r3/D]
+setup_at [get_pins r3/D]
+
+set_path_margin -hold -0.50 -comment {loosen hold time} -to [get_pins r3/D]
+hold_at [get_pins r3/D]

From f36f4f5e8fcbc4af0e23123651bd6da1ed8d1aee Mon Sep 17 00:00:00 2001
From: Stan Lee <135666755+stanminlee@users.noreply.github.com>
Date: Thu, 21 May 2026 22:34:49 -0700
Subject: [PATCH 04/23] smallfixes

---
 search/PathEnd.cc | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/search/PathEnd.cc b/search/PathEnd.cc
index d13b1d4de..09856a8ef 100644
--- a/search/PathEnd.cc
+++ b/search/PathEnd.cc
@@ -709,23 +709,17 @@ PathEndClkConstrained::targetClkUncertainty(const StaState *sta) const
 float
 PathEndClkConstrained::targetClkPathMargin(const StaState *sta) const
 {
-  const Sdc *sdc = sta->sdc();
-  const TimingRole *role = checkRole(sta);
-  ExceptionPath *exception = nullptr;
-  int hi_priority_exception = -1;
-  // Look up a path margin for the target
-  sdc->exceptionTo(ExceptionPathType::path_margin,
-                   path_->pin(sta),
-                   path_->transition(sta),
-                   targetClkEdge(sta),
-                   role->pathMinMax(),
-                   false,
-                   exception, hi_priority_exception);
-  if (!exception) // no path margin found
+  ExceptionPath *exception =
+    sta->search()->exceptionTo(ExceptionPathType::path_margin,
+                               path_, path_->pin(sta),
+                               path_->transition(sta),
+                               targetClkEdge(sta),
+                               checkRole(sta)->pathMinMax(),
+                               false, false);
+  if (!exception)
     return 0.0;
   float margin = exception->margin();
-  // Setup time margin is sign-flipped
-  if (role->genericRole() == TimingRole::setup())
+  if (checkRole(sta)->genericRole() == TimingRole::setup())
     margin = -margin;
   return margin;
 }

From 16be080324794e811bb8dfe7c33e0b53ecb551b1 Mon Sep 17 00:00:00 2001
From: Stan Lee <135666755+stanminlee@users.noreply.github.com>
Date: Thu, 21 May 2026 22:41:58 -0700
Subject: [PATCH 05/23] update test

---
 test/set_path_margin.ok  | 176 +++++++++++++++++++++++++++++++++++++++
 test/set_path_margin.tcl |  44 +++++++---
 2 files changed, 209 insertions(+), 11 deletions(-)

diff --git a/test/set_path_margin.ok b/test/set_path_margin.ok
index a8ae88a7a..d03b4bfe1 100644
--- a/test/set_path_margin.ok
+++ b/test/set_path_margin.ok
@@ -116,3 +116,179 @@ Path Type: min
              0.6010   slack (MET)
 
 
+Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r1/CK (DFF_X1)
+   0.0836    0.0836 ^ r1/Q (DFF_X1)
+   0.0277    0.1113 ^ u2/ZN (AND2_X1)
+   0.0000    0.1113 ^ r3/D (DFF_X1)
+             0.1113   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+  -2.0000    8.0000   path margin
+   0.0000    8.0000   clock reconvergence pessimism
+             8.0000 ^ r3/CK (DFF_X1)
+  -0.0311    7.9689   library setup time
+             7.9689   data required time
+-------------------------------------------------------------
+             7.9689   data required time
+            -0.1113   data arrival time
+-------------------------------------------------------------
+             7.8576   slack (MET)
+
+
+Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r2/CK (DFF_X1)
+   0.0772    0.0772 v r2/Q (DFF_X1)
+   0.0233    0.1006 v u1/Z (BUF_X1)
+   0.0273    0.1278 v u2/ZN (AND2_X1)
+   0.0000    0.1278 v r3/D (DFF_X1)
+             0.1278   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+  67.0000   77.0000   path margin
+   0.0000   77.0000   clock reconvergence pessimism
+            77.0000 ^ r3/CK (DFF_X1)
+  -0.0390   76.9610   library setup time
+            76.9610   data required time
+-------------------------------------------------------------
+            76.9610   data required time
+            -0.1278   data arrival time
+-------------------------------------------------------------
+            76.8332   slack (MET)
+
+
+Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r1/CK (DFF_X1)
+   0.0836    0.0836 ^ r1/Q (DFF_X1)
+   0.0277    0.1113 ^ u2/ZN (AND2_X1)
+   0.0000    0.1113 ^ r3/D (DFF_X1)
+             0.1113   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+  -5.0000    5.0000   path margin
+   0.0000    5.0000   clock reconvergence pessimism
+             5.0000 ^ r3/CK (DFF_X1)
+  -0.0311    4.9689   library setup time
+             4.9689   data required time
+-------------------------------------------------------------
+             4.9689   data required time
+            -0.1113   data arrival time
+-------------------------------------------------------------
+             4.8576   slack (MET)
+
+
+Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r2/CK (DFF_X1)
+   0.0772    0.0772 v r2/Q (DFF_X1)
+   0.0233    0.1006 v u1/Z (BUF_X1)
+   0.0273    0.1278 v u2/ZN (AND2_X1)
+   0.0000    0.1278 v r3/D (DFF_X1)
+             0.1278   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+   0.0000   10.0000   clock reconvergence pessimism
+            10.0000 ^ r3/CK (DFF_X1)
+  -0.0390    9.9610   library setup time
+             9.9610   data required time
+-------------------------------------------------------------
+             9.9610   data required time
+            -0.1278   data arrival time
+-------------------------------------------------------------
+             9.8332   slack (MET)
+
+
+Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r1/CK (DFF_X1)
+   0.0836    0.0836 ^ r1/Q (DFF_X1)
+   0.0277    0.1113 ^ u2/ZN (AND2_X1)
+   0.0000    0.1113 ^ r3/D (DFF_X1)
+             0.1113   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+  -2.0000    8.0000   path margin
+   0.0000    8.0000   clock reconvergence pessimism
+             8.0000 ^ r3/CK (DFF_X1)
+  -0.0311    7.9689   library setup time
+             7.9689   data required time
+-------------------------------------------------------------
+             7.9689   data required time
+            -0.1113   data arrival time
+-------------------------------------------------------------
+             7.8576   slack (MET)
+
+
+Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r2/CK (DFF_X1)
+   0.0772    0.0772 v r2/Q (DFF_X1)
+   0.0233    0.1006 v u1/Z (BUF_X1)
+   0.0273    0.1278 v u2/ZN (AND2_X1)
+   0.0000    0.1278 v r3/D (DFF_X1)
+             0.1278   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+  -3.0000    7.0000   path margin
+   0.0000    7.0000   clock reconvergence pessimism
+             7.0000 ^ r3/CK (DFF_X1)
+  -0.0390    6.9610   library setup time
+             6.9610   data required time
+-------------------------------------------------------------
+             6.9610   data required time
+            -0.1278   data arrival time
+-------------------------------------------------------------
+             6.8332   slack (MET)
+
+
diff --git a/test/set_path_margin.tcl b/test/set_path_margin.tcl
index fd0a548a2..a17d605ef 100644
--- a/test/set_path_margin.tcl
+++ b/test/set_path_margin.tcl
@@ -6,21 +6,43 @@ link_design top
 create_clock -name clk -period 10 {clk1 clk2 clk3}
 set_input_delay -clock clk 0 {in1 in2}
 
-proc setup_at { pin } {
-  report_checks -to $pin -path_delay max -digits 4 -fields {} -group_path_count 1
+proc setup_at { args } {
+  report_checks {*}$args -path_delay max -digits 4 -fields {} -group_path_count 1
 }
-proc hold_at { pin } {
-  report_checks -to $pin -path_delay min -digits 4 -fields {} -group_path_count 1
+proc hold_at { args } {
+  report_checks {*}$args -path_delay min -digits 4 -fields {} -group_path_count 1
 }
 
+# Test -to and that -setup and -hold are properly applied.
 set_path_margin -setup 0.50 -comment {tighten setup time} -to [get_pins r3/D]
-setup_at [get_pins r3/D]
-
+setup_at -to [get_pins r3/D]
 set_path_margin -hold 0.50 -comment {tighten hold time} -to [get_pins r3/D]
-hold_at [get_pins r3/D]
-
+hold_at -to [get_pins r3/D]
 set_path_margin -setup -67 -comment {loosen setup time} -to [get_pins r3/D]
-setup_at [get_pins r3/D]
-
+setup_at -to [get_pins r3/D]
 set_path_margin -hold -0.50 -comment {loosen hold time} -to [get_pins r3/D]
-hold_at [get_pins r3/D]
+hold_at -to [get_pins r3/D]
+
+# Test -from
+reset_path -through [get_pins u1/Z]
+set_path_margin -setup 2.0 -from [get_pins r1/CK]
+# Should see path margin.
+setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
+# Should not see path margin.
+setup_at -from [get_pins r2/CK] -to [get_pins r3/D]
+
+# Test -from and -to.
+reset_path -to [get_pins r3/D]
+set_path_margin -setup 5.0 -from [get_pins r1/CK] -to [get_pins r3/D]
+# Should see path margin.
+setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
+# Should not see path margin.
+setup_at -from [get_pins r2/CK] -to [get_pins r3/D]
+
+# Test -through.
+reset_path -to [get_pins r3/D]
+set_path_margin -setup 3.0 -through [get_pins u1/Z]
+# Should not see path margin.
+setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
+# Should see path margin.
+setup_at -from [get_pins r2/CK] -to [get_pins r3/D]

From dc507813ce89bec08b59154855e7fe6f78ad0abe Mon Sep 17 00:00:00 2001
From: Stan Lee <135666755+stanminlee@users.noreply.github.com>
Date: Thu, 21 May 2026 22:50:42 -0700
Subject: [PATCH 06/23] better testing

---
 test/set_path_margin.ok  | 117 +++++++++++++++++++++++++++++++++++++++
 test/set_path_margin.tcl |  18 ++++++
 2 files changed, 135 insertions(+)

diff --git a/test/set_path_margin.ok b/test/set_path_margin.ok
index d03b4bfe1..a674dd0de 100644
--- a/test/set_path_margin.ok
+++ b/test/set_path_margin.ok
@@ -292,3 +292,120 @@ Path Type: max
              6.8332   slack (MET)
 
 
+Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r1/CK (DFF_X1)
+   0.0836    0.0836 ^ r1/Q (DFF_X1)
+   0.0277    0.1113 ^ u2/ZN (AND2_X1)
+   0.0000    0.1113 ^ r3/D (DFF_X1)
+             0.1113   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+  -4.0000    6.0000   path margin
+   0.0000    6.0000   clock reconvergence pessimism
+             6.0000 ^ r3/CK (DFF_X1)
+  -0.0311    5.9689   library setup time
+             5.9689   data required time
+-------------------------------------------------------------
+             5.9689   data required time
+            -0.1113   data arrival time
+-------------------------------------------------------------
+             5.8576   slack (MET)
+
+
+Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r2/CK (DFF_X1)
+   0.0772    0.0772 v r2/Q (DFF_X1)
+   0.0233    0.1006 v u1/Z (BUF_X1)
+   0.0273    0.1278 v u2/ZN (AND2_X1)
+   0.0000    0.1278 v r3/D (DFF_X1)
+             0.1278   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+  -4.0000    6.0000   path margin
+   0.0000    6.0000   clock reconvergence pessimism
+             6.0000 ^ r3/CK (DFF_X1)
+  -0.0390    5.9610   library setup time
+             5.9610   data required time
+-------------------------------------------------------------
+             5.9610   data required time
+            -0.1278   data arrival time
+-------------------------------------------------------------
+             5.8332   slack (MET)
+
+
+Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r1/CK (DFF_X1)
+   0.0836    0.0836 ^ r1/Q (DFF_X1)
+   0.0277    0.1113 ^ u2/ZN (AND2_X1)
+   0.0000    0.1113 ^ r3/D (DFF_X1)
+             0.1113   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+  -6.0000    4.0000   path margin
+   0.0000    4.0000   clock reconvergence pessimism
+             4.0000 ^ r3/CK (DFF_X1)
+  -0.0311    3.9689   library setup time
+             3.9689   data required time
+-------------------------------------------------------------
+             3.9689   data required time
+            -0.1113   data arrival time
+-------------------------------------------------------------
+             3.8576   slack (MET)
+
+
+Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
+Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
+Path Group: clk
+Path Type: max
+
+    Delay      Time   Description
+-------------------------------------------------------------
+   0.0000    0.0000   clock clk (rise edge)
+   0.0000    0.0000   clock network delay (ideal)
+   0.0000    0.0000 ^ r2/CK (DFF_X1)
+   0.0772    0.0772 v r2/Q (DFF_X1)
+   0.0233    0.1006 v u1/Z (BUF_X1)
+   0.0273    0.1278 v u2/ZN (AND2_X1)
+   0.0000    0.1278 v r3/D (DFF_X1)
+             0.1278   data arrival time
+
+  10.0000   10.0000   clock clk (rise edge)
+   0.0000   10.0000   clock network delay (ideal)
+   0.0000   10.0000   clock reconvergence pessimism
+            10.0000 ^ r3/CK (DFF_X1)
+  -0.0390    9.9610   library setup time
+             9.9610   data required time
+-------------------------------------------------------------
+             9.9610   data required time
+            -0.1278   data arrival time
+-------------------------------------------------------------
+             9.8332   slack (MET)
+
+
diff --git a/test/set_path_margin.tcl b/test/set_path_margin.tcl
index a17d605ef..293e5cb2d 100644
--- a/test/set_path_margin.tcl
+++ b/test/set_path_margin.tcl
@@ -46,3 +46,21 @@ set_path_margin -setup 3.0 -through [get_pins u1/Z]
 setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
 # Should see path margin.
 setup_at -from [get_pins r2/CK] -to [get_pins r3/D]
+
+# Test a clock-scoped startpoint.
+reset_path -from [get_pins r1/CK]
+reset_path -through [get_pins u1/Z]
+set_path_margin -setup 4.0 -from [get_clocks clk]
+# Should see path margin on the clock.
+setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
+setup_at -from [get_pins r2/CK] -to [get_pins r3/D]
+
+# Test -from, -through, and -to.
+reset_path -from [get_clocks clk]
+set_path_margin -setup 6.0 -from [get_pins r1/CK] \
+                           -through [get_pins u2/A1] \
+                           -to [get_pins r3/D]
+# Should see path margin.
+setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
+# Should not see path margin.
+setup_at -from [get_pins r2/CK] -to [get_pins r3/D]

From 00bd442e6d80d09a70db454a123f4bbb8d98305c Mon Sep 17 00:00:00 2001
From: Akash Levy <akashlevy@gmail.com>
Date: Tue, 26 May 2026 01:42:01 -0700
Subject: [PATCH 07/23] Reformat makePathMargin function parameters

---
 include/sta/Sdc.hh | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/sta/Sdc.hh b/include/sta/Sdc.hh
index bcf79ba51..c49e7a64c 100644
--- a/include/sta/Sdc.hh
+++ b/include/sta/Sdc.hh
@@ -767,10 +767,10 @@ public:
                      std::string_view comment);
   void makePathMargin(ExceptionFrom *from,
                       ExceptionThruSeq *thrus,
-		                  ExceptionTo *to,
-		                  const MinMaxAll *min_max,
-		                  float margin,
-		                  const char *comment);
+                      ExceptionTo *to,
+                      const MinMaxAll *min_max,
+                      float margin,
+                      const char *comment);
   bool pathDelaysWithoutTo() const { return path_delays_without_to_; }
   // Delete matching false/multicycle/path_delay exceptions.
   // Caller owns from, thrus, to exception points (and must delete them).

From 45fe5b265a1f69e19d3fd6a487f916ba6bac9854 Mon Sep 17 00:00:00 2001
From: Akash Levy <akashlevy@gmail.com>
Date: Tue, 26 May 2026 01:42:41 -0700
Subject: [PATCH 08/23] Update Sta.hh

---
 include/sta/Sta.hh | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/sta/Sta.hh b/include/sta/Sta.hh
index aabb7bba2..44474a448 100644
--- a/include/sta/Sta.hh
+++ b/include/sta/Sta.hh
@@ -660,11 +660,11 @@ public:
                      std::string_view comment,
                      Sdc *sdc);
   void makePathMargin(ExceptionFrom *from,
-		                  ExceptionThruSeq *thrus,
-		                  ExceptionTo *to,
-		                  const MinMaxAll *min_max,
-		                  float margin,
-		                  const char *comment);
+                      ExceptionThruSeq *thrus,
+                      ExceptionTo *to,
+                      const MinMaxAll *min_max,
+                      float margin,
+                      const char *comment);
   void makeGroupPath(std::string_view name,
                      bool is_default,
                      ExceptionFrom *from,

From db0e0033ac8754e64fd11f978a4622e73f66b956 Mon Sep 17 00:00:00 2001
From: Akash Levy <akashlevy@gmail.com>
Date: Tue, 26 May 2026 01:46:30 -0700
Subject: [PATCH 09/23] Update Sdc.cc

---
 sdc/Sdc.cc | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/sdc/Sdc.cc b/sdc/Sdc.cc
index f717617da..68ee832ad 100644
--- a/sdc/Sdc.cc
+++ b/sdc/Sdc.cc
@@ -4105,15 +4105,15 @@ Sdc::makePathDelay(ExceptionFrom *from,
 
 void
 Sdc::makePathMargin(ExceptionFrom *from,
-		    ExceptionThruSeq *thrus,
-		    ExceptionTo *to,
-		    const MinMaxAll *min_max,
-		    float margin,
-		    const char *comment)
+                    ExceptionThruSeq *thrus,
+                    ExceptionTo *to,
+                    const MinMaxAll *min_max,
+                    float margin,
+                    const char *comment)
 {
   checkFromThrusTo(from, thrus, to);
   PathMargin *exception = new PathMargin(from, thrus, to, min_max,
-					 margin, true, comment);
+	                                     margin, true, comment);
   addException(exception);
 }
 

From de241e5e11bc4120960826ffb5226bb16e722a1d Mon Sep 17 00:00:00 2001
From: Akash Levy <akashlevy@gmail.com>
Date: Tue, 26 May 2026 01:51:16 -0700
Subject: [PATCH 10/23] Format constructor and clone method parameters

---
 include/sta/ExceptionPath.hh | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/sta/ExceptionPath.hh b/include/sta/ExceptionPath.hh
index 8273750db..eb5c04c22 100644
--- a/include/sta/ExceptionPath.hh
+++ b/include/sta/ExceptionPath.hh
@@ -235,16 +235,16 @@ class PathMargin : public ExceptionPath
 {
 public:
   PathMargin(ExceptionFrom *from,
-	     ExceptionThruSeq *thrus,
-	     ExceptionTo *to,
-	     const MinMaxAll *min_max,
-	     float margin,
-	     bool own_pts,
-	     const char *comment);
+             ExceptionThruSeq *thrus,
+             ExceptionTo *to,
+             const MinMaxAll *min_max,
+             float margin,
+             bool own_pts,
+             const char *comment);
   virtual ExceptionPath *clone(ExceptionFrom *from,
-			       ExceptionThruSeq *thrus,
-			       ExceptionTo *to,
-			       bool own_pts);
+                               ExceptionThruSeq *thrus,
+                               ExceptionTo *to,
+                               bool own_pts);
   virtual bool isPathMargin() const { return true; }
   virtual ExceptionPathType type() const { return ExceptionPathType::path_margin; }
   virtual const char *typeString() const;

From 68f25783c0a96a5ea99dac99b0c74836a12a4c85 Mon Sep 17 00:00:00 2001
From: Akash Levy <akashlevy@gmail.com>
Date: Tue, 26 May 2026 01:55:06 -0700
Subject: [PATCH 11/23] Update ExceptionPath.cc

---
 sdc/ExceptionPath.cc | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/sdc/ExceptionPath.cc b/sdc/ExceptionPath.cc
index 303a1faee..12f09c782 100644
--- a/sdc/ExceptionPath.cc
+++ b/sdc/ExceptionPath.cc
@@ -560,24 +560,24 @@ PathDelay::overrides(ExceptionPath *exception) const
 ////////////////////////////////////////////////////////////////
 
 PathMargin::PathMargin(ExceptionFrom *from,
-		       ExceptionThruSeq *thrus,
-		       ExceptionTo *to,
-		       const MinMaxAll *min_max,
-		       float margin,
-		       bool own_pts,
-		       const char *comment) :
+                       ExceptionThruSeq *thrus,
+                       ExceptionTo *to,
+                       const MinMaxAll *min_max,
+                       float margin,
+                       bool own_pts,
+                       const char *comment) :
   ExceptionPath(from, thrus, to, min_max, own_pts,
-		pathMarginPriority() + fromThruToPriority(from, thrus, to),
-		comment),
+                pathMarginPriority() + fromThruToPriority(from, thrus, to),
+                comment),
   margin_(margin)
 {
 }
 
 ExceptionPath *
 PathMargin::clone(ExceptionFrom *from,
-		  ExceptionThruSeq *thrus,
-		  ExceptionTo *to,
-		  bool own_pts)
+                  ExceptionThruSeq *thrus,
+                  ExceptionTo *to,
+                  bool own_pts)
 {
   return new PathMargin(from, thrus, to, min_max_, margin_, own_pts, comment_);
 }

From 5bfd662f53551c726a41ff3d406fcb8b3703ff85 Mon Sep 17 00:00:00 2001
From: Akash Levy <akashlevy@gmail.com>
Date: Tue, 26 May 2026 01:56:17 -0700
Subject: [PATCH 12/23] Refactor make_path_margin function parameters

---
 sdc/Sdc.i | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/sdc/Sdc.i b/sdc/Sdc.i
index 18fd3d7d0..238879654 100644
--- a/sdc/Sdc.i
+++ b/sdc/Sdc.i
@@ -857,11 +857,11 @@ make_path_delay(ExceptionFrom *from,
 
 void
 make_path_margin(ExceptionFrom *from,
-		 ExceptionThruSeq *thrus,
-		 ExceptionTo *to,
-		 const MinMaxAll *min_max,
-		 float margin,
-		 const char *comment)
+                 ExceptionThruSeq *thrus,
+                 ExceptionTo *to,
+                 const MinMaxAll *min_max,
+                 float margin,
+                 const char *comment)
 {
   Sta::sta()->makePathMargin(from, thrus, to, min_max, margin, comment);
 }

From 88123f88f8ce41dde59f7668c875eab46f3ca0e4 Mon Sep 17 00:00:00 2001
From: Akash Levy <akashlevy@gmail.com>
Date: Tue, 26 May 2026 02:00:55 -0700
Subject: [PATCH 13/23] Move set_path_margin to a different position

---
 test/regression_vars.tcl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/regression_vars.tcl b/test/regression_vars.tcl
index 0b1372cc3..79371c168 100644
--- a/test/regression_vars.tcl
+++ b/test/regression_vars.tcl
@@ -182,11 +182,11 @@ record_public_tests {
   prima3
   read_saif_null_instance
   report_checks_sorted
-  set_path_margin
   report_checks_src_attr
   report_json1
   report_json2
   sdc_strip_escaped_bus
+  set_path_margin
   slash_port_test
   suppress_msg
   vcd_timestamp

From 2dfbfd3392b5fb792d84672d19eca46afd815b20 Mon Sep 17 00:00:00 2001
From: Akash Levy <akashlevy@gmail.com>
Date: Tue, 26 May 2026 02:02:03 -0700
Subject: [PATCH 14/23] Fix formatting of makePathMargin function parameters

---
 search/Sta.cc | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/search/Sta.cc b/search/Sta.cc
index 157d7d85e..72a7eb3be 100644
--- a/search/Sta.cc
+++ b/search/Sta.cc
@@ -2071,11 +2071,11 @@ Sta::makePathDelay(ExceptionFrom *from,
 
 void
 Sta::makePathMargin(ExceptionFrom *from,
-		    ExceptionThruSeq *thrus,
-		    ExceptionTo *to,
-		    const MinMaxAll *min_max,
-		    float margin,
-		    const char *comment)
+                    ExceptionThruSeq *thrus,
+                    ExceptionTo *to,
+                    const MinMaxAll *min_max,
+                    float margin,
+                    const char *comment)
 {
   sdc_->makePathMargin(from, thrus, to, min_max, margin, comment);
   search_->arrivalsInvalid();

From f4e57aca5bb5510b60382531b4c4f59a1f26877a Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Tue, 26 May 2026 02:06:59 -0700
Subject: [PATCH 15/23] Smallfixes for typeString

---
 include/sta/ExceptionPath.hh | 2 +-
 sdc/ExceptionPath.cc         | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/sta/ExceptionPath.hh b/include/sta/ExceptionPath.hh
index eb5c04c22..4d748374d 100644
--- a/include/sta/ExceptionPath.hh
+++ b/include/sta/ExceptionPath.hh
@@ -247,7 +247,7 @@ public:
                                bool own_pts);
   virtual bool isPathMargin() const { return true; }
   virtual ExceptionPathType type() const { return ExceptionPathType::path_margin; }
-  virtual const char *typeString() const;
+  virtual std::string_view *typeString() const;
   virtual bool mergeable(ExceptionPath *exception) const;
   virtual bool overrides(ExceptionPath *exception) const;
   virtual float margin() const { return margin_; }
diff --git a/sdc/ExceptionPath.cc b/sdc/ExceptionPath.cc
index 12f09c782..cb0c8c0c4 100644
--- a/sdc/ExceptionPath.cc
+++ b/sdc/ExceptionPath.cc
@@ -594,7 +594,7 @@ PathMargin::tighterThan(ExceptionPath *) const
   return false;
 }
 
-const char *
+std::string_view
 PathMargin::typeString() const
 {
   return "Margin";

From b6b04e029a66936f97206747d31a7e51200f4250 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Tue, 26 May 2026 02:07:26 -0700
Subject: [PATCH 16/23] Oops

---
 include/sta/ExceptionPath.hh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/sta/ExceptionPath.hh b/include/sta/ExceptionPath.hh
index 4d748374d..78a48895d 100644
--- a/include/sta/ExceptionPath.hh
+++ b/include/sta/ExceptionPath.hh
@@ -247,7 +247,7 @@ public:
                                bool own_pts);
   virtual bool isPathMargin() const { return true; }
   virtual ExceptionPathType type() const { return ExceptionPathType::path_margin; }
-  virtual std::string_view *typeString() const;
+  virtual std::string_view typeString() const;
   virtual bool mergeable(ExceptionPath *exception) const;
   virtual bool overrides(ExceptionPath *exception) const;
   virtual float margin() const { return margin_; }

From 9231a44c76c7ca001f44a7cc7ad73fc96c5f7950 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Tue, 26 May 2026 02:09:18 -0700
Subject: [PATCH 17/23] Last string_view fix

---
 include/sta/ExceptionPath.hh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/sta/ExceptionPath.hh b/include/sta/ExceptionPath.hh
index 78a48895d..0b5e824e1 100644
--- a/include/sta/ExceptionPath.hh
+++ b/include/sta/ExceptionPath.hh
@@ -240,7 +240,7 @@ public:
              const MinMaxAll *min_max,
              float margin,
              bool own_pts,
-             const char *comment);
+             std::string_view comment);
   virtual ExceptionPath *clone(ExceptionFrom *from,
                                ExceptionThruSeq *thrus,
                                ExceptionTo *to,

From eede2fa28b7bc7dceff0c1cd9aed63f1f90172e5 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Tue, 26 May 2026 02:09:39 -0700
Subject: [PATCH 18/23] Actually one more

---
 sdc/ExceptionPath.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sdc/ExceptionPath.cc b/sdc/ExceptionPath.cc
index cb0c8c0c4..65f9f348a 100644
--- a/sdc/ExceptionPath.cc
+++ b/sdc/ExceptionPath.cc
@@ -565,7 +565,7 @@ PathMargin::PathMargin(ExceptionFrom *from,
                        const MinMaxAll *min_max,
                        float margin,
                        bool own_pts,
-                       const char *comment) :
+                       std::string_view comment) :
   ExceptionPath(from, thrus, to, min_max, own_pts,
                 pathMarginPriority() + fromThruToPriority(from, thrus, to),
                 comment),

From 527cd5ddca935776fce3847098675c6efde60f91 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Tue, 26 May 2026 02:11:04 -0700
Subject: [PATCH 19/23] Fix for reporting

---
 search/ReportPath.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/search/ReportPath.cc b/search/ReportPath.cc
index 6ac459041..44094ce2b 100644
--- a/search/ReportPath.cc
+++ b/search/ReportPath.cc
@@ -2682,7 +2682,7 @@ ReportPath::reportClkUncertainty(const PathEnd *end,
     reportLine("inter-clock uncertainty", inter_uncertainty,
                clk_arrival, early_late);
   float margin = end->targetClkPathMargin(this);
-  clk_arrival += margin;
+  clk_arrival = delaySum(clk_arrival, margin, this);
   if (margin != 0.0)
     reportLine("path margin", margin, clk_arrival, early_late);
 }

From 137aca28f62e0d235496ca9b0c67780c93e053de Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Tue, 26 May 2026 02:19:42 -0700
Subject: [PATCH 20/23] More fixups

---
 include/sta/PathEnd.hh | 1 +
 include/sta/Sdc.hh     | 2 +-
 include/sta/Sta.hh     | 3 ++-
 sdc/Sdc.cc             | 4 ++--
 sdc/Sdc.i              | 6 ++++--
 search/Sta.cc          | 5 +++--
 6 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/include/sta/PathEnd.hh b/include/sta/PathEnd.hh
index fb126f5d8..253277391 100644
--- a/include/sta/PathEnd.hh
+++ b/include/sta/PathEnd.hh
@@ -262,6 +262,7 @@ public:
   float targetNonInterClkUncertainty(const StaState *sta) const override;
   float interClkUncertainty(const StaState *sta) const override;
   float targetClkUncertainty(const StaState *sta) const override;
+  float targetClkPathMargin(const StaState *sta) const override;
   Crpr crpr(const StaState *sta) const override;
   Required requiredTime(const StaState *sta) const override;
   Slack slack(const StaState *sta) const override;
diff --git a/include/sta/Sdc.hh b/include/sta/Sdc.hh
index c49e7a64c..cf064c19d 100644
--- a/include/sta/Sdc.hh
+++ b/include/sta/Sdc.hh
@@ -770,7 +770,7 @@ public:
                       ExceptionTo *to,
                       const MinMaxAll *min_max,
                       float margin,
-                      const char *comment);
+                      std::string_view comment);
   bool pathDelaysWithoutTo() const { return path_delays_without_to_; }
   // Delete matching false/multicycle/path_delay exceptions.
   // Caller owns from, thrus, to exception points (and must delete them).
diff --git a/include/sta/Sta.hh b/include/sta/Sta.hh
index 44474a448..8e4a94dbb 100644
--- a/include/sta/Sta.hh
+++ b/include/sta/Sta.hh
@@ -664,7 +664,8 @@ public:
                       ExceptionTo *to,
                       const MinMaxAll *min_max,
                       float margin,
-                      const char *comment);
+                      std::string_view comment,
+                      Sdc *sdc);
   void makeGroupPath(std::string_view name,
                      bool is_default,
                      ExceptionFrom *from,
diff --git a/sdc/Sdc.cc b/sdc/Sdc.cc
index 68ee832ad..fc82ef54d 100644
--- a/sdc/Sdc.cc
+++ b/sdc/Sdc.cc
@@ -4109,11 +4109,11 @@ Sdc::makePathMargin(ExceptionFrom *from,
                     ExceptionTo *to,
                     const MinMaxAll *min_max,
                     float margin,
-                    const char *comment)
+                    std::string_view comment)
 {
   checkFromThrusTo(from, thrus, to);
   PathMargin *exception = new PathMargin(from, thrus, to, min_max,
-	                                     margin, true, comment);
+                                         margin, true, comment);
   addException(exception);
 }
 
diff --git a/sdc/Sdc.i b/sdc/Sdc.i
index 238879654..16e5bc409 100644
--- a/sdc/Sdc.i
+++ b/sdc/Sdc.i
@@ -861,9 +861,11 @@ make_path_margin(ExceptionFrom *from,
                  ExceptionTo *to,
                  const MinMaxAll *min_max,
                  float margin,
-                 const char *comment)
+                 std::string_view comment)
 {
-  Sta::sta()->makePathMargin(from, thrus, to, min_max, margin, comment);
+  Sta *sta = Sta::sta();
+  Sdc *sdc = sta->cmdSdc();
+  sta->makePathMargin(from, thrus, to, min_max, margin, comment, sdc);
 }
 
 void
diff --git a/search/Sta.cc b/search/Sta.cc
index 72a7eb3be..8b5f03738 100644
--- a/search/Sta.cc
+++ b/search/Sta.cc
@@ -2075,9 +2075,10 @@ Sta::makePathMargin(ExceptionFrom *from,
                     ExceptionTo *to,
                     const MinMaxAll *min_max,
                     float margin,
-                    const char *comment)
+                    std::string_view comment,
+                    Sdc *sdc)
 {
-  sdc_->makePathMargin(from, thrus, to, min_max, margin, comment);
+  sdc->makePathMargin(from, thrus, to, min_max, margin, comment);
   search_->arrivalsInvalid();
 }
 

From 5c16348fad72ef6a8e659a13280e85f940aa00f2 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Tue, 26 May 2026 02:19:49 -0700
Subject: [PATCH 21/23] Final fixup

---
 search/PathEnd.cc | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/search/PathEnd.cc b/search/PathEnd.cc
index d9431df92..8dd8d8450 100644
--- a/search/PathEnd.cc
+++ b/search/PathEnd.cc
@@ -701,13 +701,14 @@ PathEndClkConstrained::targetClkUncertainty(const StaState *sta) const
 float
 PathEndClkConstrained::targetClkPathMargin(const StaState *sta) const
 {
+  Sdc *sdc = path_->sdc(sta);
   ExceptionPath *exception =
     sta->search()->exceptionTo(ExceptionPathType::path_margin,
                                path_, path_->pin(sta),
                                path_->transition(sta),
                                targetClkEdge(sta),
                                checkRole(sta)->pathMinMax(),
-                               false, false);
+                               false, false, sdc);
   if (!exception)
     return 0.0;
   float margin = exception->margin();

From 9d2426b033bbb4f9202096ace8ea6541e56a3056 Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Tue, 26 May 2026 02:23:49 -0700
Subject: [PATCH 22/23] Remove comment

---
 sdc/ExceptionPath.cc | 1 -
 1 file changed, 1 deletion(-)

diff --git a/sdc/ExceptionPath.cc b/sdc/ExceptionPath.cc
index 65f9f348a..34aab4bc5 100644
--- a/sdc/ExceptionPath.cc
+++ b/sdc/ExceptionPath.cc
@@ -677,7 +677,6 @@ FalsePath::mergeable(ExceptionPath *exception) const
 bool
 FalsePath::overrides(ExceptionPath *exception) const
 {
-  // Most recent definition overrides earlier ones.
   return exception->priority() == priority()
     && exception->minMax() == min_max_;
 }

From 9fee88793d2ea5eff77b3b3cb92c199f8196d6fc Mon Sep 17 00:00:00 2001
From: Akash Levy <akash@silimate.com>
Date: Tue, 26 May 2026 02:33:10 -0700
Subject: [PATCH 23/23] Add JSON support and test for it

---
 search/ReportPath.cc     |  4 ++++
 test/set_path_margin.ok  | 14 ++++++++++++++
 test/set_path_margin.tcl | 24 ++++++++++++++++++++++++
 3 files changed, 42 insertions(+)

diff --git a/search/ReportPath.cc b/search/ReportPath.cc
index 44094ce2b..6ea84b93e 100644
--- a/search/ReportPath.cc
+++ b/search/ReportPath.cc
@@ -1246,6 +1246,10 @@ ReportPath::reportJson(const PathEnd *end,
                  delayAsFloat(end->checkCrpr(this)));
     result += sta::format("  \"margin\": {:.3e},\n",
                  delayAsFloat(end->margin(this)));
+    float path_margin = end->targetClkPathMargin(this);
+    if (path_margin != 0.0)
+      result += sta::format("  \"path_margin\": {:.3e},\n",
+                   path_margin);
     result += sta::format("  \"required_time\": {:.3e},\n",
                  delayAsFloat(end->requiredTimeOffset(this)));
     result += sta::format("  \"slack\": {:.3e}\n",
diff --git a/test/set_path_margin.ok b/test/set_path_margin.ok
index a674dd0de..14e88b1dd 100644
--- a/test/set_path_margin.ok
+++ b/test/set_path_margin.ok
@@ -28,6 +28,7 @@ Path Type: max
              9.3332   slack (MET)
 
 
+setup_to_tighten -5.000e-10
 Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -57,6 +58,7 @@ Path Type: min
             -0.3990   slack (VIOLATED)
 
 
+hold_to_tighten 5.000e-10
 Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -87,6 +89,7 @@ Path Type: max
             76.8332   slack (MET)
 
 
+setup_to_loosen 6.700e-08
 Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -116,6 +119,7 @@ Path Type: min
              0.6010   slack (MET)
 
 
+hold_to_loosen -5.000e-10
 Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -145,6 +149,7 @@ Path Type: max
              7.8576   slack (MET)
 
 
+setup_from_r1 -2.000e-09
 Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -175,6 +180,7 @@ Path Type: max
             76.8332   slack (MET)
 
 
+setup_from_r2 6.700e-08
 Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -204,6 +210,7 @@ Path Type: max
              4.8576   slack (MET)
 
 
+setup_from_to_r1 -5.000e-09
 Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -233,6 +240,7 @@ Path Type: max
              9.8332   slack (MET)
 
 
+setup_from_to_r2 none
 Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -262,6 +270,7 @@ Path Type: max
              7.8576   slack (MET)
 
 
+setup_through_r1 -2.000e-09
 Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -292,6 +301,7 @@ Path Type: max
              6.8332   slack (MET)
 
 
+setup_through_r2 -3.000e-09
 Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -321,6 +331,7 @@ Path Type: max
              5.8576   slack (MET)
 
 
+setup_from_clk_r1 -4.000e-09
 Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -351,6 +362,7 @@ Path Type: max
              5.8332   slack (MET)
 
 
+setup_from_clk_r2 -4.000e-09
 Startpoint: r1 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -380,6 +392,7 @@ Path Type: max
              3.8576   slack (MET)
 
 
+setup_combo_r1 -6.000e-09
 Startpoint: r2 (rising edge-triggered flip-flop clocked by clk)
 Endpoint: r3 (rising edge-triggered flip-flop clocked by clk)
 Path Group: clk
@@ -409,3 +422,4 @@ Path Type: max
              9.8332   slack (MET)
 
 
+setup_combo_r2 none
diff --git a/test/set_path_margin.tcl b/test/set_path_margin.tcl
index 293e5cb2d..e84378cfe 100644
--- a/test/set_path_margin.tcl
+++ b/test/set_path_margin.tcl
@@ -12,40 +12,60 @@ proc setup_at { args } {
 proc hold_at { args } {
   report_checks {*}$args -path_delay min -digits 4 -fields {} -group_path_count 1
 }
+proc report_json_path_margin { label path_delay args } {
+  set cmd [concat [list report_checks] $args \
+    [list -path_delay $path_delay -format json -group_path_count 1]]
+  with_output_to_variable json $cmd
+  if { [regexp {"path_margin": ([^,\n]+)} $json match margin] } {
+    puts "$label $margin"
+  } else {
+    puts "$label none"
+  }
+}
 
 # Test -to and that -setup and -hold are properly applied.
 set_path_margin -setup 0.50 -comment {tighten setup time} -to [get_pins r3/D]
 setup_at -to [get_pins r3/D]
+report_json_path_margin setup_to_tighten max -to [get_pins r3/D]
 set_path_margin -hold 0.50 -comment {tighten hold time} -to [get_pins r3/D]
 hold_at -to [get_pins r3/D]
+report_json_path_margin hold_to_tighten min -to [get_pins r3/D]
 set_path_margin -setup -67 -comment {loosen setup time} -to [get_pins r3/D]
 setup_at -to [get_pins r3/D]
+report_json_path_margin setup_to_loosen max -to [get_pins r3/D]
 set_path_margin -hold -0.50 -comment {loosen hold time} -to [get_pins r3/D]
 hold_at -to [get_pins r3/D]
+report_json_path_margin hold_to_loosen min -to [get_pins r3/D]
 
 # Test -from
 reset_path -through [get_pins u1/Z]
 set_path_margin -setup 2.0 -from [get_pins r1/CK]
 # Should see path margin.
 setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
+report_json_path_margin setup_from_r1 max -from [get_pins r1/CK] -to [get_pins r3/D]
 # Should not see path margin.
 setup_at -from [get_pins r2/CK] -to [get_pins r3/D]
+report_json_path_margin setup_from_r2 max -from [get_pins r2/CK] -to [get_pins r3/D]
 
 # Test -from and -to.
 reset_path -to [get_pins r3/D]
 set_path_margin -setup 5.0 -from [get_pins r1/CK] -to [get_pins r3/D]
 # Should see path margin.
 setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
+report_json_path_margin setup_from_to_r1 max -from [get_pins r1/CK] -to [get_pins r3/D]
 # Should not see path margin.
 setup_at -from [get_pins r2/CK] -to [get_pins r3/D]
+report_json_path_margin setup_from_to_r2 max -from [get_pins r2/CK] -to [get_pins r3/D]
 
 # Test -through.
 reset_path -to [get_pins r3/D]
 set_path_margin -setup 3.0 -through [get_pins u1/Z]
 # Should not see path margin.
 setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
+report_json_path_margin setup_through_r1 max -from [get_pins r1/CK] -to [get_pins r3/D]
 # Should see path margin.
 setup_at -from [get_pins r2/CK] -to [get_pins r3/D]
+report_json_path_margin setup_through_r2 max -from [get_pins r2/CK] -to [get_pins r3/D]
 
 # Test a clock-scoped startpoint.
 reset_path -from [get_pins r1/CK]
@@ -53,7 +73,9 @@ reset_path -through [get_pins u1/Z]
 set_path_margin -setup 4.0 -from [get_clocks clk]
 # Should see path margin on the clock.
 setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
+report_json_path_margin setup_from_clk_r1 max -from [get_pins r1/CK] -to [get_pins r3/D]
 setup_at -from [get_pins r2/CK] -to [get_pins r3/D]
+report_json_path_margin setup_from_clk_r2 max -from [get_pins r2/CK] -to [get_pins r3/D]
 
 # Test -from, -through, and -to.
 reset_path -from [get_clocks clk]
@@ -62,5 +84,7 @@ set_path_margin -setup 6.0 -from [get_pins r1/CK] \
                            -to [get_pins r3/D]
 # Should see path margin.
 setup_at -from [get_pins r1/CK] -to [get_pins r3/D]
+report_json_path_margin setup_combo_r1 max -from [get_pins r1/CK] -to [get_pins r3/D]
 # Should not see path margin.
 setup_at -from [get_pins r2/CK] -to [get_pins r3/D]
+report_json_path_margin setup_combo_r2 max -from [get_pins r2/CK] -to [get_pins r3/D]