Merge pull request #4143 from The-OpenROAD-Project-staging/update-cluster-flops-check

updated cluster_flops enablement check

Author: maliberty

docs/user/FlowVariables.md

@@ -109,7 +109,8 @@ configuration file.
 | <a name="CELL_PAD_IN_SITES_DETAIL_PLACEMENT"></a>CELL_PAD_IN_SITES_DETAIL_PLACEMENT| Cell padding on both sides in site widths to ease routability in detail placement.| 0|
 | <a name="CELL_PAD_IN_SITES_GLOBAL_PLACEMENT"></a>CELL_PAD_IN_SITES_GLOBAL_PLACEMENT| Cell padding on both sides in site widths to ease routability during global placement.| 0|
 | <a name="CLKGATE_MAP_FILE"></a>CLKGATE_MAP_FILE| Optional mapping file supplied to Yosys to map clock gating cells| |
-| <a name="CLUSTER_FLOPS"></a>CLUSTER_FLOPS| Minimum number of flip-flops per sink cluster.| 0|
+| <a name="CLUSTER_FLOPS"></a>CLUSTER_FLOPS| Enable clustering of flip-flops into multi-bit flip-flops, if the platform PDK includes multi-bit flip-flops| 0|
+| <a name="CLUSTER_FLOPS_ARGS"></a>CLUSTER_FLOPS_ARGS| Additional arguments passed to the cluster_flops command.| |
 | <a name="CORE_AREA"></a>CORE_AREA| The core area specified as a list of lower-left and upper-right corners in microns (X1 Y1 X2 Y2).| |
 | <a name="CORE_ASPECT_RATIO"></a>CORE_ASPECT_RATIO| The core aspect ratio (height / width). This variable is only used when `CORE_UTILIZATION` is set.| 1.0|
 | <a name="CORE_MARGIN"></a>CORE_MARGIN| The margin between the core area and die area, specified in microns. Allowed values are either one value for all margins or a set of four values, one for each margin. The order of the four values are: `{bottom top left right}`. This variable is only used when `CORE_UTILIZATION` is set.| 1.0|
@@ -434,6 +435,7 @@ configuration file.
 - [CELL_PAD_IN_SITES_DETAIL_PLACEMENT](#CELL_PAD_IN_SITES_DETAIL_PLACEMENT)
 - [CELL_PAD_IN_SITES_GLOBAL_PLACEMENT](#CELL_PAD_IN_SITES_GLOBAL_PLACEMENT)
 - [CLUSTER_FLOPS](#CLUSTER_FLOPS)
+- [CLUSTER_FLOPS_ARGS](#CLUSTER_FLOPS_ARGS)
 - [DETAIL_PLACEMENT_ARGS](#DETAIL_PLACEMENT_ARGS)
 - [DONT_BUFFER_PORTS](#DONT_BUFFER_PORTS)
 - [EARLY_SIZING_CAP_RATIO](#EARLY_SIZING_CAP_RATIO)

flow/scripts/global_place.tcl

@@ -68,8 +68,8 @@ if { $result != 0 } {
 
 log_cmd estimate_parasitics -placement
 
-if { [env_var_exists_and_non_empty CLUSTER_FLOPS] } {
-  cluster_flops {*}[env_var_or_empty CLUSTER_FLOPS_ARGS]
+if { $::env(CLUSTER_FLOPS) } {
+  log_cmd cluster_flops {*}[env_var_or_empty CLUSTER_FLOPS_ARGS]
   log_cmd estimate_parasitics -placement
 }
 

flow/scripts/variables.yaml

@@ -1001,10 +1001,17 @@ CTS_BUF_LIST:
     - cts
 CLUSTER_FLOPS:
   description: >
-    Minimum number of flip-flops per sink cluster.
+    Enable clustering of flip-flops into multi-bit flip-flops, if the platform
+    PDK includes multi-bit flip-flops
   stages:
     - place
   default: 0
+CLUSTER_FLOPS_ARGS:
+  description: >
+    Additional arguments passed to the cluster_flops command.
+  stages:
+    - place
+  default: ""
 CTS_CLUSTER_DIAMETER:
   description: >
     Maximum diameter (in microns) of sink cluster.