PrimaDelayCalc::simulate1 SIGSEGV: SparseLU solve() on failed compute() (missing info() guard)

Summary

sta::PrimaDelayCalc::simulate1() calls Eigen::SparseLU::solve() without
checking that the preceding compute() succeeded. For some degenerate
reduced RC systems compute() returns a non-Success status, and calling
solve() on the unfactorized solver dereferences an uninitialized supernodal
structure and crashes with SIGSEGV.

The twin call site in the same file (primaReduce()) already guards this:

Eigen::SparseLU<MatrixSd> G_solver(G_);
if (G_solver.info() != Eigen::Success)
  report_->error(1752, "G matrix is singular.");

but simulate1() does not:

A.makeCompressed();
Eigen::SparseLU<MatrixSd> A_solver;
A_solver.compute(A);
...
x = A_solver.solve(rhs);   // <-- SIGSEGV when compute() failed

Crash

Signal 11 received
 ...
 Eigen::internal::MappedSuperNodalMatrix<double, int>::solveInPlace<...>(...)
 sta::PrimaDelayCalc::simulate1(...)
 sta::PrimaDelayCalc::simulate()
 sta::PrimaDelayCalc::gateDelay(...)
 sta::GraphDelayCalc::findVertexDelay(...)
 ...
 sta::Sta::updateTiming(bool)
 rsz::Resizer::swapArithModules(...)

How to reproduce

Design swerv_wrapper / asap7, at the post-global-place resize step
(3_4_place_resized), with the prima (CCS) delay calculator.

git clone https://github.com/The-OpenROAD-Project/OpenROAD-flow-scripts
cd OpenROAD-flow-scripts
git submodule update --init tools/OpenROAD         
git -C tools/OpenROAD fetch origin 17d1e1d0f2569fb9e61a3e983eef69fe339039a9
git -C tools/OpenROAD checkout 17d1e1d0f2569fb9e61a3e983eef69fe339039a9
git -C tools/OpenROAD submodule update --init --recursive  

Build

cd flow
make DESIGN_CONFIG=./designs/asap7/swerv_wrapper/config.mk place
# → SIGSEGV at 3_4_place_resized  (sta::GraphDelayCalc → PrimaDelayCalc::simulate1)

/home/mkim/prima_crash_repro/3_3_place_gp.odb.gz   (~18 MB)
/home/mkim/prima_crash_repro/2_floorplan.sdc.gz
/home/mkim/prima_crash_repro/replay.tcl            (resize preamble)