update nangate45 layer resistance with segment-based regression results

[AcKoucher]

Correlation Data

Mode: segment
Designs (15): aes, ariane133, ariane136, bp, bp_be, bp_fe, bp_multi, dynamic_node, gcd, ibex, jpeg, mempool_group, swerv, swerv_wrapper, tinyRocket.
OR Version: 390e0d62
Units: R [kΩ/μm], C [fF/μm]

The resistance values that we were using weren't actually precise. Probably something off with the net-based regression script. The resistance fits obtained with new segment-based regression have perfect (1.00) R².

I cleaned up the setRC.tcl script so that the data w.r.t. the correlation is tracked here rather than having comments in the file.

Observations Regarding M1

• There was no regression data for this layer (nangate45 doesn't route on M1 — pins only).
• The old values were kept.

Updated Rules

[WARNING] Multiple clocks not supported. Will use first clock: mrx_clk_pad_i: 300.0000.
[WARNING] Multiple clocks not supported. Will use first clock: mrx_clk_pad_i: 300.0000.
[WARNING] Multiple clocks not supported. Will use first clock: clk: 333.0000.
designs/nangate45/aes/rules-base.json updates:

Metric	Old	New	Type
globalroute__timing__hold__tns	-0.398	-0.726	Failing

designs/nangate45/ariane133/rules-base.json updates:

Metric	Old	New	Type
globalroute__timing__setup__tns	-556.0	-570.0	Failing
finish__timing__setup__tns	-549.0	-577.0	Failing

[WARNING] Multiple clocks not supported. Will use first clock: clk_i: 3.0000.
designs/nangate45/swerv/rules-base.json updates:

Metric	Old	New	Type
cts__timing__setup__tns	-363.0	-497.0	Failing
globalroute__timing__setup__tns	-420.0	-512.0	Failing
finish__timing__setup__tns	-396.0	-460.0	Failing

designs/nangate45/tinyRocket/rules-base.json updates:

Metric	Old	New	Type
cts__timing__setup__tns	-30.0	-32.4	Failing
globalroute__timing__setup__tns	-50.3	-53.9	Failing
finish__timing__setup__tns	-42.8	-46.0	Failing

[WARNING] Multiple clocks not supported. Will use first clock: ext_clk: 15.0000.

Messages from CI

[INFO] asap7/minimal not included in CI.
[INFO] gf12 not included in the update.
[INFO] gf55 not included in the update.
[INFO] nangate45/bp_quad not included in CI.

[gemini-code-assist]

Code Review

This pull request updates the resistance values for metal layers in the Nangate45 platform's RC configuration. The reviewer identified minor inconsistencies in the resistance values for layers with identical physical characteristics (metal4-6, metal7-8, and metal9-10) and suggested using consistent, rounded values to improve maintainability and accurately reflect the PDK's physical symmetry.