Random seed

docs/user/FlowVariables.md

@@ -160,6 +160,7 @@ configuration file.
 | <a name="GLOBAL_ROUTE_USE_CUGR"></a>GLOBAL_ROUTE_USE_CUGR| Passed as -use_cugr to global_route. Uses CUGR as the global routing solver instead of the default FastRoute solver. NOTE: CUGR is not ready for production.| 0|
 | <a name="GND_NETS_VOLTAGES"></a>GND_NETS_VOLTAGES| Used for IR Drop calculation.| |
 | <a name="GPL_KEEP_OVERFLOW"></a>GPL_KEEP_OVERFLOW| Passed as -keep_resize_below_overflow to global_placement. Only used when GPL_TIMING_DRIVEN is enabled.| |
+| <a name="GPL_RANDOM_SEED"></a>GPL_RANDOM_SEED| Specifies a random seed for global placement.  Useful for perturbation studies.| |
 | <a name="GPL_ROUTABILITY_DRIVEN"></a>GPL_ROUTABILITY_DRIVEN| Specifies whether the placer should use routability driven placement.| 1|
 | <a name="GPL_TIMING_DRIVEN"></a>GPL_TIMING_DRIVEN| Specifies whether the placer should use timing driven placement.| 1|
 | <a name="GUI_TIMING"></a>GUI_TIMING| Load timing information when opening GUI. For large designs, this can be quite time consuming. Useful to disable when investigating non-timing aspects like floorplan, placement, routing, etc.| 1|
@@ -472,6 +473,7 @@ configuration file.
 - [FLOORPLAN_DEF](#FLOORPLAN_DEF)
 - [GLOBAL_PLACEMENT_ARGS](#GLOBAL_PLACEMENT_ARGS)
 - [GPL_KEEP_OVERFLOW](#GPL_KEEP_OVERFLOW)
+- [GPL_RANDOM_SEED](#GPL_RANDOM_SEED)
 - [GPL_ROUTABILITY_DRIVEN](#GPL_ROUTABILITY_DRIVEN)
 - [GPL_TIMING_DRIVEN](#GPL_TIMING_DRIVEN)
 - [IO_PLACER_H](#IO_PLACER_H)

flow/designs/asap7/swerv_wrapper/config.mk

@@ -61,3 +61,4 @@ export ROUTING_LAYER_ADJUSTMENT = 0.2
 export SWAP_ARITH_OPERATORS = 1
 export OPENROAD_HIERARCHICAL = 1
 
+export GPL_RANDOM_SEED = 2

flow/designs/nangate45/ariane133/config.mk

@@ -27,3 +27,5 @@ export RTLMP_MAX_MACRO = 30
 export RTLMP_MIN_MACRO = 10
 export RTLMP_MAX_INST = 80000
 export RTLMP_MIN_INST = 8000
+
+export GPL_RANDOM_SEED = 3

flow/designs/nangate45/ariane133/rules-base.json

@@ -1,11 +1,11 @@
 {
     "synth__canonical_netlist__hash": {
-        "value": "7af2e5d516717525c8e4b86fbe5c8c0fc7e3e6b0",
+        "value": "608c7e7060b1b403c0e893101b0bd83a23b7f306",
         "compare": "==",
         "level": "warning"
     },
     "synth__netlist__hash": {
-        "value": "0925e491023b71ddf98d5a9d92664c9607d38b85",
+        "value": "624023bd257848127135daf0c0d20528d8fb9315",
         "compare": "==",
         "level": "warning"
     },
@@ -38,11 +38,11 @@
         "compare": "<="
     },
     "cts__timing__setup__ws": {
-        "value": -0.579,
+        "value": -0.574,
         "compare": ">="
     },
     "cts__timing__setup__tns": {
-        "value": -929.0,
+        "value": -743.0,
         "compare": ">="
     },
     "cts__timing__hold__ws": {
@@ -62,7 +62,7 @@
         "compare": ">="
     },
     "globalroute__timing__setup__tns": {
-        "value": -755.0,
+        "value": -880.0,
         "compare": ">="
     },
     "globalroute__timing__hold__ws": {
@@ -94,7 +94,7 @@
         "compare": ">="
     },
     "finish__timing__setup__tns": {
-        "value": -801.0,
+        "value": -964.0,
         "compare": ">="
     },
     "finish__timing__hold__ws": {

flow/scripts/global_place.tcl

@@ -26,6 +26,8 @@ set global_placement_args {}
 # Parameters for routability mode in global placement
 append_env_var global_placement_args GPL_ROUTABILITY_DRIVEN -routability_driven 0
 
+append_env_var global_placement_args GPL_RANDOM_SEED -random_seed 1
+
 # Parameters for timing driven mode in global placement
 if { $::env(GPL_TIMING_DRIVEN) } {
   lappend global_placement_args {-timing_driven}

flow/scripts/global_place_skip_io.tcl

@@ -8,10 +8,14 @@ if { [env_var_exists_and_non_empty FLOORPLAN_DEF] } {
 } elseif { [all_pins_placed] } {
   puts "All pins are placed. Skipping global placement without IOs"
 } else {
+  set global_placement_args {}
+  append_env_var global_placement_args GPL_RANDOM_SEED -random_seed 1
+
   log_cmd global_placement -skip_io -density [place_density_with_lb_addon] \
     -pad_left $::env(CELL_PAD_IN_SITES_GLOBAL_PLACEMENT) \
     -pad_right $::env(CELL_PAD_IN_SITES_GLOBAL_PLACEMENT) \
-    {*}[env_var_or_empty GLOBAL_PLACEMENT_ARGS]
+    {*}[env_var_or_empty GLOBAL_PLACEMENT_ARGS] \
+    {*}$global_placement_args
 }
 
 source_step_tcl POST GLOBAL_PLACE_SKIP_IO

flow/scripts/variables.yaml

@@ -643,6 +643,11 @@ USE_NEGOTIATION:
   description: |
     Enable using negotiation legalizer for detailed placement.
   default: 0
+GPL_RANDOM_SEED:
+  description: |
+    Specifies a random seed for global placement.  Useful for perturbation studies.
+  stages:
+    - place
 GPL_TIMING_DRIVEN:
   description: |
     Specifies whether the placer should use timing driven placement.