metrics: report what is free unconditionally

With SKIP_REPORT_METRICS=1, report_metrics reported nothing at all, so a
flow that skips it for speed also lost design area, instance counts and
utilization, though those are a walk over the instances that needs no
timer.

Report them unconditionally, before the skip. SKIP_REPORT_METRICS now
skips only what costs time: the timing update behind setup and hold WS
and TNS, fmax, the max slew/cap/fanout checks and clock skew; the power
analysis; and the reports/<stage>_*.rpt text reports.

The calls that take measurable time even on asap7/gcd, 5 to 200 ms each
on a few hundred cells, run under log_cmd, so on a large design the log
names any that takes five seconds or more. The four register path
searches go through `log_cmd eval { ... }`, so the log prints the
command rather than the expanded register list.

On asap7/gcd, metrics on (DETAILED_METRICS=1) and off give
byte-identical .odb files at every stage; with SKIP_REPORT_METRICS=1
every stage's metrics .json has the design area and no timing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Øyvind Harboe <oyvind.harboe@zylin.com>

Author: oharboe

docs/user/FlowVariables.md

@@ -291,7 +291,7 @@ configuration file.
 | <a name="SKIP_LAST_GASP"></a>SKIP_LAST_GASP| Do not use last gasp optimization to fix timing violations (default: use gate last gasp).| |
 | <a name="SKIP_PIN_SWAP"></a>SKIP_PIN_SWAP| Do not use pin swapping as a transform to fix timing violations (default: use pin swapping).| |
 | <a name="SKIP_REPAIR_TIE_FANOUT"></a>SKIP_REPAIR_TIE_FANOUT| Skip repair_tie_fanout at floorplan step.| 0|
-| <a name="SKIP_REPORT_METRICS"></a>SKIP_REPORT_METRICS| If set to 1, then metrics, report_metrics does nothing. Useful to speed up builds.| 0|
+| <a name="SKIP_REPORT_METRICS"></a>SKIP_REPORT_METRICS| If set to 1, report_metrics writes only the metrics that cost no analysis: design area, instance counts and utilization. Timing, power, clock skew, the max slew/cap/fanout checks and the reports/<stage>_*.rpt text reports are skipped; they need a timing update and a power analysis at every stage that calls it. The counters the tools record as they run (placement, legalization, routing, repair, warnings) are written either way.| 0|
 | <a name="SKIP_VT_SWAP"></a>SKIP_VT_SWAP| Do not perform VT swap to improve QoR (default: do VT swap).| |
 | <a name="SLEW_MARGIN"></a>SLEW_MARGIN| Specifies a slew margin when fixing max slew violations. This option allows you to overfix.| |
 | <a name="SWAP_ARITH_OPERATORS"></a>SWAP_ARITH_OPERATORS| Improve timing QoR by swapping ALU and MULT arithmetic operators.| 0|

flow/scripts/report_metrics.tcl

@@ -7,6 +7,7 @@ proc report_puts { out } {
 }
 
 proc report_metrics { stage when { include_erc true } { include_clock_skew true } } {
+  report_design_area_metrics
   if { $::env(SKIP_REPORT_METRICS) } {
     return
   }
@@ -17,7 +18,7 @@ proc report_metrics { stage when { include_erc true } { include_clock_skew true
   report_puts "\n=========================================================================="
   report_puts "$when report_tns"
   report_puts "--------------------------------------------------------------------------"
-  report_tns >> $filename
+  log_cmd report_tns >> $filename
   report_tns_metric
   report_tns_metric -hold
 
@@ -36,7 +37,7 @@ proc report_metrics { stage when { include_erc true } { include_clock_skew true
   report_puts "\n=========================================================================="
   report_puts "$when report_clock_min_period"
   report_puts "--------------------------------------------------------------------------"
-  report_clock_min_period -include_port_paths >> $filename
+  log_cmd report_clock_min_period -include_port_paths >> $filename
   report_fmax_metric
 
   if { $include_clock_skew && $::env(REPORT_CLOCK_SKEW) } {
@@ -70,9 +71,9 @@ proc report_metrics { stage when { include_erc true } { include_clock_skew true
     report_puts "\n=========================================================================="
     report_puts "$when report_check_types -max_slew -max_cap -max_fanout -violators"
     report_puts "--------------------------------------------------------------------------"
-    report_check_types -max_slew -max_capacitance -max_fanout -violators >> $filename
+    log_cmd report_check_types -max_slew -max_capacitance -max_fanout -violators >> $filename
 
-    report_erc_metrics
+    log_cmd report_erc_metrics
 
     report_puts "\n=========================================================================="
     report_puts "$when max_slew_check_slack"
@@ -163,16 +164,18 @@ proc report_metrics { stage when { include_erc true } { include_clock_skew true
       report_puts "\n=========================================================================="
       report_puts "$when report_checks -path_delay max reg to reg"
       report_puts "--------------------------------------------------------------------------"
-      report_checks -path_delay max -from [all_registers] -to [all_registers] \
-        -format full_clock_expanded >> $filename
+      log_cmd eval { report_checks -path_delay max -from [all_registers] -to [all_registers] \
+        -format full_clock_expanded >> $filename }
       report_puts "\n=========================================================================="
       report_puts "$when report_checks -path_delay min reg to reg"
       report_puts "--------------------------------------------------------------------------"
-      report_checks -path_delay min -from [all_registers] -to [all_registers] \
-        -format full_clock_expanded >> $filename
+      log_cmd eval { report_checks -path_delay min -from [all_registers] -to [all_registers] \
+        -format full_clock_expanded >> $filename }
 
       set inp_to_reg_critical_path \
-        [lindex [find_timing_paths -path_delay max -from [all_inputs] -to [all_registers]] 0]
+        [lindex [log_cmd eval {
+          find_timing_paths -path_delay max -from [all_inputs] -to [all_registers]
+        }] 0]
       if { $inp_to_reg_critical_path != "" } {
         set target_clock_latency_max \
           [sta::format_time [$inp_to_reg_critical_path target_clk_delay] 4]
@@ -182,7 +185,9 @@ proc report_metrics { stage when { include_erc true } { include_clock_skew true
 
 
       set inp_to_reg_critical_path [lindex \
-        [find_timing_paths -path_delay min -from [all_inputs] -to [all_registers]] 0]
+        [log_cmd eval {
+          find_timing_paths -path_delay min -from [all_inputs] -to [all_registers]
+        }] 0]
       if { $inp_to_reg_critical_path != "" } {
         set target_clock_latency_min \
           [sta::format_time [$inp_to_reg_critical_path target_clk_delay] 4]
@@ -237,12 +242,12 @@ proc report_metrics { stage when { include_erc true } { include_clock_skew true
   if { [env_var_exists_and_non_empty CORNERS] } {
     foreach corner $::env(CORNERS) {
       report_puts "Corner: $corner"
-      report_power -corner $corner >> $filename
+      log_cmd report_power -corner $corner >> $filename
       report_power_metric -corner $corner
     }
     unset corner
   } else {
-    report_power >> $filename
+    log_cmd report_power >> $filename
     report_power_metric
   }
 
@@ -251,5 +256,4 @@ proc report_metrics { stage when { include_erc true } { include_clock_skew true
   puts "$when report_design_area"
   puts "--------------------------------------------------------------------------"
   report_design_area
-  report_design_area_metrics
 }

flow/scripts/variables.json

@@ -128,8 +128,13 @@ REPORT_ENDPOINT_SLACK:
   default: 0
 SKIP_REPORT_METRICS:
   description: >
-    If set to 1, then metrics, report_metrics does nothing. Useful to speed up
-    builds.
+    If set to 1, report_metrics writes only the metrics that cost no
+    analysis: design area, instance counts and utilization. Timing, power,
+    clock skew, the max slew/cap/fanout checks and the
+    reports/<stage>_*.rpt text reports are skipped; they need a timing
+    update and a power analysis at every stage that calls it. The
+    counters the tools record as they run (placement, legalization,
+    routing, repair, warnings) are written either way.
   stages:
     - synth
     - floorplan