Innovus: CTS and post-CTS qualification Cheat Sheet

This stage covers clock tree synthesis and the post-CTS stage that follows it: confirming CCOpt prerequisites, reviewing the built clock trees and skew groups, checking clock DRVs and NDR routing, legalising cells after CTS, and running post-CTS setup and hold timing through to clock gating coverage.

Sanity check cheat sheet

One row per command card. Read left to right: the check, the command that answers it, then what a healthy result, a result to review and a hard stop look like.

Card	Check and when	Command	Healthy	Review	Hard stop
S-01	CTS prerequisites and specification Before ccopt_design	`ccopt_design -check_prerequisites` `check_design -type cts -out_file <report_file>` `get_ccopt_clock_trees`	Every functional clock has a clock tree and a skew group, and the checks report no errors.	The primary corner is the first setup view by default, which may not be the one you meant.	A clock in the constraints has no clock tree, or check_design -type cts reports an error on targets or route types.
S-02	CTS run and log After ccopt_design	`ccopt_design` `ccopt_design -cts` `report_message -errors -count`	The command returns with no errors, and every warning has been read and either fixed or explained.	Warnings about dont_touch nets or clock instances that cannot be resized, which can limit skew balancing and clock quality.	Any error message, or a run that leaves clocks ideal or clock nets unrouted.
S-03	Clock tree report and clock DRVs After CTS	`report_ccopt_clock_trees -summary` `report_ccopt_clock_trees -file <report_file>` `report_ccopt_clock_trees -histograms`	Each clock tree is present, its sink count matches the design, and every violation count is zero.	Fewer sinks than the clock has flops, or violations only on dont_touch or pre-routed nets that CTS may not be able to fix.	A clock tree with no sinks, or violations on fixable clock nets beyond your budget.
S-04	Skew groups and insertion delay After CTS	`report_ccopt_skew_groups -summary` `report_ccopt_skew_groups -file <report_file>` `report_ccopt_skew_groups -summarize_stage_depth {buffer inverter}`	Insertion delay and skew of every skew group meet your budget in every corner reported.	Skew meets the primary corner but another corner has no target or misses it.	A skew group beyond a target that CTS enforces, or a skew group with no active sinks.
S-05	Clock routes, NDR and shielding After CTS	`reportRouteTypeConstraints -summary` `reportRouteTypeConstraints -detailed -file <report_file>` `report_route -clock`	Every net class that asks for an NDR or a shield shows it in the routed result, with adherence you accept.	Adherence below 100 percent on a few nets. The preferred layers are soft limits that the router may leave.	A clock net with an NDR route type that routed at the default rule, or required shielding that is missing.
S-06	Clock cell legalisation After CTS	`checkPlace <report_file>` `checkPlace -inst <instances>` `refinePlace`	No clock halo violations, and checkPlace reports no violations on clock cells.	A message that a clock halo was disabled on a large cell, so the halo you set was not applied.	Overlapping or off-grid clock cells, or halo violations that remain after refinement.
S-07	Post-CTS setup timing and propagated clocks After CTS	`timeDesign -postCTS -outDir <dir>` `timeDesign -postCTS -expandedViews -outDir <dir>` `getAnalysisMode`	Setup WNS and TNS meet the budget in every view, and every intended clock is propagated.	A large jump in negative slack against pre-CTS timing at clock gating endpoints, where real skew now counts.	Setup slack beyond budget on register-to-register paths, or a clock still ideal after CTS.
S-08	Hold timing and hold fixing After C-07	`timeDesign -postCTS -hold -outDir <dir>` `optDesign -postCTS -hold -outDir <dir>` `optDesign -postCTS -hold -holdVioData <file>`	Hold WNS and TNS meet the budget after fixing, and setup WNS is no worse than before.	Hold violations left for post-route fixing, or a small setup TNS loss, which hold fixing allows by default.	Setup WNS worse after hold fixing, or large hold violations with no fix path shown in the log.
S-09	Analysis coverage and clock gating checks After C-07	`report_analysis_coverage -verbose {violated untested}` `report_analysis_coverage -check_type {clock_gating_setup clock_gating_hold} -verbose {violated untested}` `report_clock_gating_check`	Every untested check has a known, accepted reason, and no clock gating check is violated.	A few untested checks whose reasons are constants or disabled arcs, and that you have reviewed.	Untested checks that give no clock at a flop that should be clocked, or a violated clock gating check.

Command cheat sheet

Legacy UI commands. Angle brackets are placeholders, and values shown are examples, not project limits.

Before CTS: checks and configuration record
`ccopt_design -check_prerequisites`	Checks that CTS can run, without doing CTS.
`check_design -type cts -out_file <report_file>`	Checks clock tree definition such as targets and route types. Needs the specification loaded. Writes a file.
`get_ccopt_clock_trees`	The names of the defined clock trees.
`get_ccopt_skew_groups`	The names of the defined skew groups.
`get_ccopt_delay_corner`	The primary-half delay corner that CTS uses to balance the trees.
`get_ccopt_property primary_delay_corner`	The primary corner you set, or {} if unset; see get_ccopt_delay_corner.
`create_ccopt_clock_tree_spec -file <spec_file>`	Without -file, defines the trees in the session. With -file, only writes a script to load with source. Changes the database.
`save_ccopt_config <dir>`	Writes the CCOpt configuration to a directory, for restore_ccopt_config only. Writes files.
`create_route_type -name <type> -non_default_rule <ndr> -top_preferred_layer <layer> -shield_net <net>`	Defines a route type that binds an NDR, preferred layers and a shield net. Changes the session.
`set_ccopt_property -net_type trunk route_type <type>`	Selects the route type for trunk nets. Changes the CCOpt configuration.
Run CTS
`ccopt_design`	Clock tree synthesis with clock concurrent optimization. Changes the database and writes timing reports to ./timingReports.
`ccopt_design -cts`	Clock tree synthesis only, with no datapath optimization or useful skew. Changes the database.
`clock_opt_design`	CCOpt for a place_opt_design V2 database. Legalises placement first; uses -check_cts_config and -out_dir. Changes the database.
`ccopt_pro`	Repairs clock DRVs and skew after a routing step. After ccopt_design it also runs earlyGlobalRoute on datapath nets. Changes the database.
Log and messages
`report_message -errors -count`	{ID count} pairs for every error ID since the tool started.
`report_message -warnings -count`	{ID count} pairs for every warning ID since the tool started.
Clock tree reports
`report_ccopt_clock_trees -summary`	Only the summary table of all clock trees.
`report_ccopt_clock_trees -file <report_file>`	Per-tree statistics and violation counts. Recalculates timing unless -no_invalidate is given. Writes a file.
`report_ccopt_clock_tree_structure -file <report_file>`	The tree as text: levels, clock gates, macro sinks and the sink count. Timing details only with -update_timing. Writes a file.
`report_ccopt_clock_tree_convergence -file <report_file>`	Convergence above clock sinks, and the sinks with most paths. Writes a file.
Skew groups and insertion delay
`report_ccopt_skew_groups -summary`	The skew group tables: insertion delay and skew per corner, with the target where one exists.
`report_ccopt_skew_groups -file <report_file>`	Summary tables plus min and max path detail. Writes a file.
`report_ccopt_skew_groups -summarize_stage_depth {buffer inverter}`	Counts of buffers and inverters on the paths instead of delay.
`report_ccopt_pin_insertion_delays -file <report_file>`	Distribution of pin insertion delay values set at sinks, not measured delay. Writes a file.
`report_ccopt_worst_chain -check_type setup`	The chain with the worst negative slack path, and why it cannot improve.
Clock DRVs, routes and NDR
`report_ccopt_clock_tree_drv -num_nets all -file <report_file>`	Constraint summary, violation counts and every violating clock net. Writes a file.
`report_ccopt_clock_tree_drv -drv_types {transition max_cap max_source_to_sink_net_length}`	The same report limited to the listed violation types.
`reportRouteTypeConstraints -summary`	Route type constraints per layer, NDR and category, such as INNOVUS_CLK_NDR.
`reportRouteTypeConstraints -detailed -file <report_file>`	Nets with route type constraints and adherence; default only below 80 percent. Writes a file.
`report_route -clock`	Routing statistics of the clock nets.
`report_route -ndr`	NDR statistics of nets.
`report_route -shield`	Statistics of shielded nets only.
`dbGet -p1 top.nets.isCTSClock 1`	Pointers to all CTS clock nets.
Legalisation after CTS
`report_ccopt_cell_halo_violations -summary`	A summary of clock instances with halo violations.
`checkPlace <report_file>`	Placement violations such as overlap, grid and pin access, with markers. Writes a file.
`refinePlace`	Finds legal locations for instances. Changes the placement only if it is not legal.
`cts_refine_clock_tree_placement`	Refines placement against clock halo and density rules, non-clock then clock cells. Changes the database.
Post-CTS timing and propagated clocks
`getAnalysisMode`	The current analysis settings, including the clock propagation mode.
`get_clocks -filter "is_propagated_clock == true"`	The clocks that are in propagated mode.
`get_propagated_clock -clock <clock>`	Whether the clock is ideal or propagated.
`report_clock_timing -type summary`	A clock timing summary from the timing engine.
`timeDesign -postCTS -outDir <dir>`	Post-CTS setup timing reports. Runs early global route and extraction first. Writes files.
`timeDesign -postCTS -expandedViews -outDir <dir>`	The same, with one report directory per view. Writes files.
`timeDesign -postCTS -hold -outDir <dir>`	Post-CTS hold timing reports. Runs early global route and extraction first. Writes files.
`timeDesign -postCTS -reportOnly`	Reports from the extraction already in memory, with no new extraction.
Hold fixing
`getOptMode -opt_hold_target_slack`	The current hold target slack in nanoseconds.
`setOptMode -opt_hold_target_slack <ns>`	Sets the hold target slack. Changes the session; record the value.
`optDesign -postCTS -hold -outDir <dir>`	Fixes hold violations after CTS and writes prefix_hold.summary. Changes the database.
`optDesign -postCTS -hold -holdVioData <file>`	Fixes hold and writes the top 50 remaining hold paths as text and csv. Changes the database.
Coverage, clock gating and clock propagation
`report_analysis_coverage`	A coverage summary per check type: checks, met, violated and untested.
`report_analysis_coverage -verbose {violated untested}`	The coverage details limited to violated and untested checks.
`report_analysis_coverage -check_type {clock_gating_setup clock_gating_hold} -verbose {violated untested}`	Clock gating checks only, with details and slack of violated and untested checks.
`report_clock_gating_check`	Every clock gating check, I or L, with setup and hold margins. No path slack.
`report_clock_propagation -clock <clock> -to <pin>`	Why a clock does not propagate to a pin, for example an inactive timing arc.
`check_timing`	Consistency and completeness checks on the timing constraints.
Clock power
`report_power -clock_network all`	Power consumed by the clock networks, including generated clocks.
`report_power -clock_network all -count_seq_elements_in_clock_network`	The same, with the leaf flip-flop power included.
Only if the block uses UPF or CPF
`report_ccopt_cell_filtering_reasons -power_domain <domain>`	The filtering reasons within one power domain.