dpl: modify negotiation drc penalty and debug mode options

[gudeh]

Summary

Modify default DRC penalty value. Parametrize search window range and DRC penalty. A few debug mode changes. Some variables renamings.

Functional changes:
Tunable DRC penalty. Modifiable via the new -drc_penalty option; default is kDrcPenalty = 5.0. Reduce the previous default DRC penalty relative to the previous hardcoded value of 1000. This means we allow for DRCs occurrences during initial negotiation iterations, while solving them on later iterations.

New TCL options:

• -drc_penalty: base DRC penalty, scaled per iteration.
• -site_search_window / -row_search_window: parametrize the former kHorizWindow (20) / kAdjWindow (5) constants (renamed to site_search_window_ / row_search_window_. Defaults unchanged).

Debug / visualization

• Reworked iterative mode: stops every major iteration; adds -iterative_start and an iterative_jump interval.
• Prior-iteration moves drawn in grey; current-iteration movers colored.
• Stuck-cell counters and printing.
  • For some corner cases cells may not move (they get "stuck", for example if it is on top of a macro and the search window can't reach outside the macro), for such cases we report with printStuckSummary().
• Renamed setDplPositions→commitNegotiationPosToDpl and flushToDb→commitNegotiationPosToOdb.

Reporting

• gpl-style violations table (total violations / illegal cells / illegal sites) with capped line count.
• "overflow" terminology renamed to "violations".

Type of Change

• Bug fix
• Refactoring

Impact

The previous behavior of focusing on DRCs at initial iterations when there are multiple overlaps does not make sense. DRCs should be solved later on.

At least one private design wasn't converging because of this.

Verification

• I have verified that the local build succeeds (./etc/Build.sh).
• I have run the relevant tests and they pass.
• My code follows the repository's formatting guidelines.
• I have signed my commits (DCO).

Related Issues

This is one of multiple PRs splitting up PR #10226 to make Negotiation the default algorithm at DPL.

[gemini-code-assist]

Code Review

This pull request introduces configurable search windows and DRC penalties for the NegotiationLegalizer, adds new debugging parameters, and integrates a GUI chart to visualize legalization progress. Feedback on the changes highlights two issues: a logic bug in findBestLocation that causes stuck cells to be double-counted when no valid candidate is found, and an overly restrictive TCL validation check on -iterative_start that incorrectly rejects the valid value of 0.

[gemini-code-assist]

The -iterative_start option specifies the iteration from which debugging/visualization should start. The default value is 0 (start from the very first iteration), and Opendp::setNegotiationDebugStart explicitly clamps the value to std::max(0, iterative_start), making 0 a perfectly valid value.

However, using sta::check_positive_integer on -iterative_start will reject 0 as an invalid value, preventing users from explicitly specifying -iterative_start 0 in their scripts. Using sta::check_integer and manually verifying that the value is non-negative is a more robust approach.

  set iterative_start 0
  if { [info exists keys(-iterative_start)] } {
    set iterative_start $keys(-iterative_start)
    sta::check_integer "-iterative_start" $iterative_start
    if { $iterative_start < 0 } {
      sta::error DPL 33 "-iterative_start must be non-negative"
    }
  }

[eder-matheus]

@codex review

[gudeh]

This one includes a parametrization of the search window because there was some overlap with code change on the DRC penalty.

There should be another PR after this one to make the search window dynamically adjustable with the instance size. The base value should be the one modifiable by TCL

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Bravo.

Reviewed commit: 7fc4d0a401

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[eder-matheus]

@gudeh Please check clang-tidy and bazel unit tests failures.