Physical design sanity checks

Sanity Checks in Physical Design Flow

1. check_library
2. check_timing
3. report_constraint
4. report_timing
5. report_qor
6. check_design
7. check_legality

check_library:

 check_library validates the libraries i.e., it performs consistency checks between logical and physical libraries, across logical libraries, and within physical libraries. This command checks library qualities in three main areas: Physical library quality Logic versus physical library consistency Logic versus logic library consistency

check_timing 

PNR tool wont optimize the paths which are not constrained. So we have to check any unconstrained paths are exist in the design. check_timing command reports unconstrained paths. If there are any unconstrained paths in the design, run the report_timing_requirements command to verify that the unconstrained paths are false paths.

No clock_relative delay specified for input ports ____________

Unconstrained_endpoints. _________________

End-points are not constrained for maximum delay ___________________

report_constraints

 It reports to check the following parameters. Worst Negative Slack (WNS) Total Negative Slack (TNS) Design Rule Constraint Violations

 report_timing

report_timing displays timing information about a design. The report_timing command provides a report of timing information for the current design. By default, the report_timing command reports the single worst setup path in each clock group. 

report_qor

 report_qor displays QoR information and statistics for the current design. This command reports timing-path group and cell count details, along with current design statistics such as combinational, noncombinational, and total area. The command also reports static power, design rule violations, and compile-time details.

check_design

 check_design checks the current design for consistency. The check_design command checks the internal representation of the current design for consistency, and issues error and warning messages as appropriate. 

a. inputs/Outputs 300

b. Undriven outputs (LINT-5) 505

c. Unloaded inputs (LINT-8) 162

d. Feedthrough (LINT-29) 174

e. Shorted outputs (LINT-31) 52

f. Constant outputs (LINT-52) 24

g. Cells 152

h. Cells do not drive (LINT-1) 1

i. Connected to power or ground (LINT-32) 118

j. Nets connected to multiple pins on same cell (LINT-33) 33

k. Nets 1226

l. Unloaded nets (LINT-2) 721

Error messages indicate design problems of such severity that the compile command does not accept the design Warning messages are informational and do not necessarily indicate design problems. However, these messages should be investigated.

Warnings

Potential problems detected by this command include Unloaded input ports or undriven output ports Nets without loads or drivers or with multiple drivers

Cells or designs without inputs or outputs 

Mismatched pin counts between an instance and its reference 

Tristate buses with non-tristate drivers wire loops across hierarchies

 check_legality 

reports overlap and cells placement related violation like orientation, overlaps etc.