Add gpl min/max phi coefficients

docs/user/FlowVariables.md

@@ -168,11 +168,13 @@ configuration file.
 | <a name="MACRO_WRAPPERS"></a>MACRO_WRAPPERS| The wrapper file that replaces existing macros with their wrapped version.| |
 | <a name="MAKE_TRACKS"></a>MAKE_TRACKS| Tcl file that defines add routing tracks to a floorplan.| |
 | <a name="MATCH_CELL_FOOTPRINT"></a>MATCH_CELL_FOOTPRINT| Enforce sizing operations to only swap cells that have the same layout boundary.| 0|
+| <a name="MAX_PLACE_STEP_COEF"></a>MAX_PLACE_STEP_COEF| Sets the maximum phi coefficient (pcof_max / µ_k Upper Bound) for global placement optimization. This parameter controls the step size upper bound in the RePlAce Nesterov optimization algorithm. Higher values allow more aggressive optimization but may risk divergence. Valid range: 1.00-1.20| 1.05|
 | <a name="MAX_REPAIR_ANTENNAS_ITER_DRT"></a>MAX_REPAIR_ANTENNAS_ITER_DRT| Defines the maximum number of iterations post-detailed routing repair antennas will run.| 5|
 | <a name="MAX_REPAIR_ANTENNAS_ITER_GRT"></a>MAX_REPAIR_ANTENNAS_ITER_GRT| Defines the maximum number of iterations post global routing repair antennas will run.| 5|
 | <a name="MAX_REPAIR_TIMING_ITER"></a>MAX_REPAIR_TIMING_ITER| Maximum number of iterations for repair setup and repair hold.| |
 | <a name="MAX_ROUTING_LAYER"></a>MAX_ROUTING_LAYER| The highest metal layer name to be used in routing.| |
 | <a name="MIN_BUF_CELL_AND_PORTS"></a>MIN_BUF_CELL_AND_PORTS| Used to insert a buffer cell to pass through wires. Used in synthesis.| |
+| <a name="MIN_PLACE_STEP_COEF"></a>MIN_PLACE_STEP_COEF| Sets the minimum phi coefficient (pcof_min / µ_k Lower Bound) for global placement optimization. This parameter controls the step size lower bound in the RePlAce Nesterov optimization algorithm. Lower values may improve convergence but can increase runtime. Valid range: 0.95-1.05| 0.95|
 | <a name="MIN_ROUTING_LAYER"></a>MIN_ROUTING_LAYER| The lowest metal layer name to be used in routing.| |
 | <a name="OPENROAD_HIERARCHICAL"></a>OPENROAD_HIERARCHICAL| Feature toggle to enable to run OpenROAD in hierarchical mode, otherwise considered flat. Will eventually be the default and this option will be retired.| 0|
 | <a name="PDN_TCL"></a>PDN_TCL| File path which has a set of power grid policies used by pdn to be applied to the design, such as layers to use, stripe width and spacing to generate the actual metal straps.| |
@@ -382,8 +384,10 @@ configuration file.
 - [IO_PLACER_H](#IO_PLACER_H)
 - [IO_PLACER_V](#IO_PLACER_V)
 - [MATCH_CELL_FOOTPRINT](#MATCH_CELL_FOOTPRINT)
+- [MAX_PLACE_STEP_COEF](#MAX_PLACE_STEP_COEF)
 - [MAX_REPAIR_TIMING_ITER](#MAX_REPAIR_TIMING_ITER)
 - [MAX_ROUTING_LAYER](#MAX_ROUTING_LAYER)
+- [MIN_PLACE_STEP_COEF](#MIN_PLACE_STEP_COEF)
 - [MIN_ROUTING_LAYER](#MIN_ROUTING_LAYER)
 - [PLACE_DENSITY](#PLACE_DENSITY)
 - [PLACE_DENSITY_LB_ADDON](#PLACE_DENSITY_LB_ADDON)

flow/scripts/global_place.tcl

@@ -33,6 +33,19 @@ if { $::env(GPL_TIMING_DRIVEN) } {
   }
 }
 
+# Parameters for phi coefficients in global placement
+set min_phi $::env(MIN_PLACE_STEP_COEF)
+set max_phi $::env(MAX_PLACE_STEP_COEF)
+
+if { $min_phi > $max_phi } {
+  utl::error GPL 200 \
+    "MIN_PLACE_STEP_COEF ($min_phi) cannot be greater than \
+MAX_PLACE_STEP_COEF ($max_phi)"
+}
+
+lappend global_placement_args -min_phi_coef $::env(MIN_PLACE_STEP_COEF)
+lappend global_placement_args -max_phi_coef $::env(MAX_PLACE_STEP_COEF)
+
 proc do_placement { global_placement_args } {
   set all_args [concat [list -density [place_density_with_lb_addon] \
     -pad_left $::env(CELL_PAD_IN_SITES_GLOBAL_PLACEMENT) \

flow/scripts/variables.yaml

@@ -571,6 +571,30 @@ GPL_ROUTABILITY_DRIVEN:
   stages:
     - place
   default: 1
+MIN_PLACE_STEP_COEF:
+  description: >
+    Sets the minimum phi coefficient (pcof_min / µ_k Lower Bound) for global
+    placement optimization. This parameter controls the step size lower bound
+    in the RePlAce Nesterov optimization algorithm. Lower values may improve
+    convergence but can increase runtime.
+    Valid range: 0.95-1.05
+  default: 0.95
+  stages:
+    - place
+  tunable: 1
+  type: float
+MAX_PLACE_STEP_COEF:
+  description: >
+    Sets the maximum phi coefficient (pcof_max / µ_k Upper Bound) for global
+    placement optimization. This parameter controls the step size upper bound
+    in the RePlAce Nesterov optimization algorithm. Higher values allow more
+    aggressive optimization but may risk divergence.
+    Valid range: 1.00-1.20
+  default: 1.05
+  stages:
+    - place
+  tunable: 1
+  type: float
 CAP_MARGIN:
   description: >
     Specifies a capacitance margin when fixing max capacitance violations. This