Document ALLOW_DUPLICATE_CORNERS

Signed-off-by: Kareem Farid <[email protected]>

Changelog.md

@@ -38,15 +38,16 @@
 
 * `OpenROAD.*`
 
-  * Added `PNR_CORNERS`. An override for `DEFAULT_CORNER` for PnR steps except
-    for steps using `RSZ_CORNERS` and `CTS_CORNERS`.
+  * Added `PNR_CORNERS` which defaults to `STA_CORNERS`. An override for 
+    `DEFAULT_CORNER` for PnR steps except for steps using `RSZ_CORNERS` and 
+    `CTS_CORNERS`.
+  * Added `ALLOW_DUPLICATE_CORNERS` to avoid redundant corners definitions.
   * Added `LAYERS_RC`, `VIAS_R`: Unlike OpenLane 1.0.0 variables with similar
     names, these are mappings from corners to layer/via RC values.
     * `PNR_CORNERS`, `RSZ_CORNERS`, and `CTS_CORNERS` all now support multiple
       corners to have the same set of liberty files (as RC values may differ.)
   * Added `SET_RC_VERBOSE`, which (very noisily) logs set-RC-related commands to
     logs.
-  * Always read libs before reading odb.
   * Added `log_cmd` from OpenROAD-flow-scripts -- neat idea for consistency
   * Lib files are now *always* read BEFORE reading database files.
   * **Internal**: Steps now sensitive to `_OPENROAD_GUI` environment variable --

openlane/steps/openroad.py

@@ -255,10 +255,10 @@ class OpenROADStep(TclStep):
             "Points to the DEF file to be used as a template.",
         ),
         Variable(
-            "CORNERS_ALLOW_DUPLICATE",
+            "ALLOW_DUPLICATE_CORNERS",
             bool,
             "Allow duplicate IPVT corners definition for all *_CORNERS (except STA_CORNERS) variables. Duplicate corners have the same set of lib files and same set of values for LAYERS_RC and VIAS_R."
-            + " When off, the set of defined corners are reduced to to a unique set having different set of lib files, LAYERS_RC and VIAS_R values",
+            + " When false, corners are reduced to to a unique set of where each corner defines a unique mixture of lib files, LAYERS_RC and VIAS_R values",
             default=True,
         ),
     ]
@@ -371,7 +371,7 @@ def __hash__(self):
                     ipvt_corners[corner].vias_r = metal_layers
 
         filtered_ipvt_corners_names_sorted = corners
-        if not self.config["CORNERS_ALLOW_DUPLICATE"]:
+        if not self.config["ALLOW_DUPLICATE_CORNERS"]:
             filtered_ipvt_corners = {
                 k: v
                 for k, v in ipvt_corners.items()