[AutoTuner] Replace failed metric string "-" with ERROR_METRIC

When AutoTuner trials fail, sub-metrics (effective_clk_period, num_drc,
die_area) were returned as the string "-". This caused TensorBoard
HPARAMS to silently drop entire metric columns because of mixed
string/numeric data types across trials.

Replace "-" with ERROR_METRIC (9e99) in all error return paths so
TensorBoard consistently receives numeric values. Also add the missing
die_area key in AutoTunerBase.step() invalid config return to match the
success path.

Fixes #3482

Signed-off-by: Harsh Kumar <harshkumar3446@gmail.com>

Author: harsh-kumar-patwa

tools/AutoTuner/src/autotuner/distributed.py

@@ -147,7 +147,12 @@ def step(self):
 
         # if not a valid config, then don't run and pass back an error
         if not self.is_valid_config:
-            return {METRIC: ERROR_METRIC, "effective_clk_period": "-", "num_drc": "-"}
+            return {
+                METRIC: ERROR_METRIC,
+                "effective_clk_period": ERROR_METRIC,
+                "num_drc": ERROR_METRIC,
+                "die_area": ERROR_METRIC,
+            }
         self._variant = f"{self.variant}-{self.step_}"
         metrics_file = openroad(
             args=args,
@@ -242,7 +247,7 @@ def evaluate(self, metrics):
         error = "ERR" in metrics.values() or "ERR" in reference.values()
         not_found = "N/A" in metrics.values() or "N/A" in reference.values()
         if error or not_found:
-            return (ERROR_METRIC, "-", "-", "-")
+            return (ERROR_METRIC, ERROR_METRIC, ERROR_METRIC, ERROR_METRIC)
         ppa = self.get_ppa(metrics)
         gamma = ppa / 10
         score = ppa * (self.step_ / 100) ** (-1) + (gamma * metrics["num_drc"])

tools/AutoTuner/src/autotuner/utils.py

@@ -79,7 +79,7 @@ def calculate_score(metrics, step=1):
     not_found = "N/A" in metrics.values()
 
     if error or not_found:
-        return (ERROR_METRIC, "-", "-", "-")
+        return (ERROR_METRIC, ERROR_METRIC, ERROR_METRIC, ERROR_METRIC)
 
     effective_clk_period = metrics["clk_period"] - metrics["worst_slack"]
     num_drc = metrics["num_drc"]