openroad coredumps during clock tree insertion

[MoonbaseOtago]

Describe the bug

I'm building a design with an external clock (and tree) and 2 internal clocks (and trees) derived from flops, in some recent openroad releases it works, in others it crashes (sort of sounds like a use after free sort of bug)

I'll attach a reproducible that fails consistently - have a look in files/home/paul/factory-test/src/project.sdc to see how I set up the clocks - note this web form wont take the upload, I'll try in the bug propper or give you a link to the file

I've added a GDB backtrace at the end here, it's 26,000 stack frames deep, might be a recursion problem .....

Expected Behavior

It doesn't crash, makes the clock trees

Environment

[WARNING] Your current OpenROAD version is outdated.
It is recommened to pull the latest changes.
If problem persists, file a github issue with the re-producible test case.
kernel: Linux 6.19.0-9-generic
os: Ubuntu 26.04 (Resolute Raccoon)
cmake version 4.2.3
-- The CXX compiler identification is GNU 15.2.0
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- OpenROAD version: 26Q1-1957-g9b0caf1a52
-- System name: Linux
-- Compiler: GNU 15.2.0
-- Build type: RELEASE
-- Install prefix: /usr/local
-- C++ Standard: 20
-- C++ Standard Required: ON
-- C++ Extensions: OFF
-- LTO/IPO is enabled
-- The C compiler identification is GNU 15.2.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Performing Test C_COMPILER_SUPPORTS__-Wno-array-bounds
-- Performing Test C_COMPILER_SUPPORTS__-Wno-array-bounds - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-array-bounds
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-array-bounds - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-nonnull
-- Performing Test C_COMPILER_SUPPORTS__-Wno-nonnull - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-nonnull
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-nonnull - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-maybe-uninitialized
-- Performing Test C_COMPILER_SUPPORTS__-Wno-maybe-uninitialized - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-maybe-uninitialized
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-maybe-uninitialized - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-format-overflow
-- Performing Test C_COMPILER_SUPPORTS__-Wno-format-overflow - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-format-overflow
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-format-overflow - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-unused-variable
-- Performing Test C_COMPILER_SUPPORTS__-Wno-unused-variable - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-unused-variable
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-unused-variable - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-unused-function
-- Performing Test C_COMPILER_SUPPORTS__-Wno-unused-function - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-unused-function
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-unused-function - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-write-strings
-- Performing Test C_COMPILER_SUPPORTS__-Wno-write-strings - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-write-strings
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-write-strings - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-sign-compare
-- Performing Test C_COMPILER_SUPPORTS__-Wno-sign-compare - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-sign-compare
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-sign-compare - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-sign-compare
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-sign-compare - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-deprecated
-- Performing Test C_COMPILER_SUPPORTS__-Wno-deprecated - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-deprecated
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-deprecated - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-c++11-narrowing
-- Performing Test C_COMPILER_SUPPORTS__-Wno-c++11-narrowing - Failed
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-c++11-narrowing
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-c++11-narrowing - Failed
-- Performing Test C_COMPILER_SUPPORTS__-Wno-register
-- Performing Test C_COMPILER_SUPPORTS__-Wno-register - Failed
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-register
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-register - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-format
-- Performing Test C_COMPILER_SUPPORTS__-Wno-format - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-format
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-format - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-reserved-user-defined-literal
-- Performing Test C_COMPILER_SUPPORTS__-Wno-reserved-user-defined-literal - Failed
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-reserved-user-defined-literal
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-reserved-user-defined-literal - Failed
-- Performing Test C_COMPILER_SUPPORTS__-Wno-alloc-size-larger-than
-- Performing Test C_COMPILER_SUPPORTS__-Wno-alloc-size-larger-than - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-alloc-size-larger-than
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-alloc-size-larger-than - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-attributes
-- Performing Test C_COMPILER_SUPPORTS__-Wno-attributes - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-attributes
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-attributes - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-aggressive-loop-optimizations
-- Performing Test C_COMPILER_SUPPORTS__-Wno-aggressive-loop-optimizations - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-aggressive-loop-optimizations
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-aggressive-loop-optimizations - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-stringop-overflow
-- Performing Test C_COMPILER_SUPPORTS__-Wno-stringop-overflow - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-stringop-overflow
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-stringop-overflow - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-changes-meaning
-- Performing Test C_COMPILER_SUPPORTS__-Wno-changes-meaning - Failed
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-changes-meaning
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-changes-meaning - Success
-- Performing Test C_COMPILER_SUPPORTS__-fpermissive
-- Performing Test C_COMPILER_SUPPORTS__-fpermissive - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-fpermissive
-- Performing Test CXX_COMPILER_SUPPORTS__-fpermissive - Success
-- Performing Test C_COMPILER_SUPPORTS__-x
-- Performing Test C_COMPILER_SUPPORTS__-x - Failed
-- Performing Test CXX_COMPILER_SUPPORTS__-x
-- Performing Test CXX_COMPILER_SUPPORTS__-x - Failed
-- Performing Test C_COMPILER_SUPPORTS__c++
-- Performing Test C_COMPILER_SUPPORTS__c++ - Failed
-- Performing Test CXX_COMPILER_SUPPORTS__c++
-- Performing Test CXX_COMPILER_SUPPORTS__c++ - Failed
-- Performing Test C_COMPILER_SUPPORTS__-std=c++17
-- Performing Test C_COMPILER_SUPPORTS__-std=c++17 - Failed
-- Performing Test CXX_COMPILER_SUPPORTS__-std=c++17
-- Performing Test CXX_COMPILER_SUPPORTS__-std=c++17 - Success
-- Performing Test C_COMPILER_SUPPORTS__-fno-exceptions
-- Performing Test C_COMPILER_SUPPORTS__-fno-exceptions - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-fno-exceptions
-- Performing Test CXX_COMPILER_SUPPORTS__-fno-exceptions - Success
-- Performing Test C_COMPILER_SUPPORTS__-Wno-unused-but-set-variable
-- Performing Test C_COMPILER_SUPPORTS__-Wno-unused-but-set-variable - Success
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-unused-but-set-variable
-- Performing Test CXX_COMPILER_SUPPORTS__-Wno-unused-but-set-variable - Success
-- TCL library: /usr/lib/x86_64-linux-gnu/libtcl.so
-- TCL header: /usr/include/tcl/tcl.h
-- TCL readline header: /usr/include/x86_64-linux-gnu
-- Found SWIG: /usr/bin/swig (found suitable version "4.4.0", minimum required is "4.0")
-- Using SWIG >= 4.4.0 -flatstaticmethod flag for python
-- boost: 1.90.0
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Success
-- Found Threads: TRUE
-- absl: 20260107
-- Found GTest: /home/paul/.local/lib/cmake/GTest/GTestConfig.cmake (found version "1.17.0")
-- GTest: 1.17.0
-- Found Python3: /usr/include/python3.14 (found version "3.14.3") found components: Development Development.Module Development.Embed
-- Found ZLIB: /usr/lib/x86_64-linux-gnu/libz.so (found version "1.3.1")
-- spdlog: 1.15.0
-- Found BISON: /usr/bin/bison (found version "3.8.2")
-- Found Doxygen: /usr/bin/doxygen (found version "1.15.0") found components: doxygen dot
-- STA version: 3.0.0
-- STA git sha: 83e1f9b77f35a953dbd3c01dba431a789a981803
-- System name: Linux
-- Compiler: GNU 15.2.0
-- Build type: RELEASE
-- Build CXX_FLAGS: -O3 -DNDEBUG
-- Install prefix: /usr/local
-- IPO/LTO: not supported - CMake doesn't support IPO for current C compiler
-- Found FLEX: /usr/biCMake Error at /usr/lib/x86_64-linux-gnu/cmake/Boost-1.90.0/BoostConfig.cmake:141 (find_package):
  Could not find a configuration file for package "boost_iostreams" that
  exactly matches requested version "1.90.0".

  The following configuration files were considered but not accepted:

    /home/paul/.local/lib/cmake/boost_iostreams-1.89.0/boost_iostreams-config.cmake, version: 1.89.0
      The version found is not compatible with the version requested.

Call Stack (most recent call first):
  /usr/lib/x86_64-linux-gnu/cmake/Boost-1.90.0/BoostConfig.cmake:262 (boost_find_component)
  src/utl/CMakeLists.txt:6 (find_package)


n/flex (found version "2.6.4")
-- TCL library: /usr/lib/x86_64-linux-gnu/libtcl.so
-- TCL header: /usr/include/tcl/tcl.h
-- TCL readline library: NOT FOUND
-- TCL readline header: /usr/include/x86_64-linux-gnu/tclreadline.h
-- CUDD library: /usr/local/lib/libcudd.a
-- CUDD header: /usr/local/include/cudd.h
-- SSTA: 0
-- Found SWIG: /usr/bin/swig (found suitable version "4.4.0", minimum required is "3.0")
-- STA library: /tmp/tmp.GktfBUEVWK/libOpenSTA.a
-- STA executable: /tmp/tmp.GktfBUEVWK/sta
-- Found BZip2: /usr/lib/x86_64-linux-gnu/libbz2.so (found version "1.0.8")
-- Looking for BZ2_bzCompressInit
-- Looking for BZ2_bzCompressInit - found
-- Found re2: /home/paul/.local/lib/cmake/re2/re2Config.cmake (found version "11.0.0")
-- Found Clp: /home/paul/.local/lib/cmake/Clp/ClpConfig.cmake (found version "1.17.10")
-- Found Cbc: /home/paul/.local/lib/cmake/Cbc/CbcConfig.cmake (found version "2.10.12")
-- Found SCIP: /home/paul/.local/lib/cmake/scip/scip-config.cmake (found version "9.2.2")
-- Found OpenMP_CXX: -fopenmp (found version "4.5")
-- Found OpenMP: TRUE (found version "4.5")
-- Found OR-Tools: /home/paul/.local/lib/cmake/ortools (version: 9.14.6206)
-- TCL library: /usr/lib/x86_64-linux-gnu/libtcl.so
-- TCL header: /usr/include/tcl/tcl.h
-- Found OpenMP_C: -fopenmp (found version "4.5")
-- Found OpenMP: TRUE (found version "4.5")
-- Found OpenMP: TRUE (found version "4.5")
-- Found OpenGL: /usr/lib/x86_64-linux-gnu/libOpenGL.so
-- GUI is enabled
-- Could NOT find VTune (missing: VTune_LIBRARIES VTune_INCLUDE_DIRS)
-- Configuring incomplete, errors occurred!

To Reproduce

grab the reproducable, run "tun.sh"

Relevant log output

Screenshots

No response

Additional Context

Here's a coredump - looks like a recursion issue - it's 26,000 stack frames deep :-)

Program received signal SIGSEGV, Segmentation fault.
0x000055555ba1585c in std::__get_helper<0ul, odb::Point&&> (__t=...) at /usr/include/c++/15/tuple:2429
2429 { return _Tuple_impl<__i, _Head, _Tail...>::_M_head(__t); }
(gdb) bt
#0 0x000055555ba1585c in std::__get_helper<0ul, odb::Point&&> (__t=...) at /usr/include/c++/15/tuple:2429
#1 0x000055555ba154bf in std::get<0ul, odb::Point&&> (__t=std::tuple containing = {...}) at /usr/include/c++/15/tuple:2445
#2 0x000055555dbe5940 in std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > >::pair<odb::Point&&, 0ul>(std::tupleodb::Point&&&, std::tuple<>&, std::_Index_tuple<0ul>, std::_Index_tuple<>) (this=0x555571b49d90,
__tuple1=std::tuple containing = {...}, __tuple2=empty std::tuple) at /usr/include/c++/15/tuple:2886
#3 0x000055555dbe4f63 in std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > >::pairodb::Point&&(std::piecewise_construct_t, std::tupleodb::Point&&, std::tuple<>) (this=0x555571b49d90,
__first=std::tuple containing = {...}, __second=empty std::tuple) at /usr/include/c++/15/tuple:2876
#4 0x000055555dbe4106 in construct_at<std::pair<const odb::Point, std::vectorodb::dbITerm* >, const std::piecewise_construct_t&, std::tupleodb::Point&&, std::tuple<> > (__location=0x555571b49d90) at /usr/include/c++/15/bits/stl_construct.h:110
#5 0x000055555dbdf3cc in std::allocator_traits<std::allocator<std::_Rb_tree_node<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > > > >::construct<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > >, std::piecewise_construct_t const&, std::tupleodb::Point&&, std::tuple<> >(std::allocator<std::_Rb_tree_node<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > > >&, std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > >, std::piecewise_construct_t const&, std::tupleodb::Point&&&&, std::tuple<>&&) (__a=..., __p=0x555571b49d90) at /usr/include/c++/15/bits/alloc_traits.h:676
#6 std::_Rb_tree<odb::Point, std::pair<odb::Point const, std::vector<odb::dbITerm, std::allocatorodb::dbITerm* > >, std::_Select1st<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > >, std::lessodb::Point, std::allocator<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > > >::_M_construct_node<std::piecewise_construct_t const&, std::tupleodb::Point&&, std::tuple<> >(std::_Rb_tree_node<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > >, std::piecewise_construct_t const&, std::tupleodb::Point&&&&, std::tuple<>&&) (this=0x7fffff7ff490, __node=0x555571b49d70) at /usr/include/c++/15/bits/stl_tree.h:1237
#7 0x000055555dbd80a5 in std::_Rb_tree<odb::Point, std::pair<odb::Point const, std::vector<odb::dbITerm, std::allocatorodb::dbITerm* > >, std::_Select1st<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > >, std::lessodb::Point, std::allocator<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > > >::_M_create_node<std::piecewise_construct_t const&, std::tupleodb::Point&&, std::tuple<> >(std::piecewise_construct_t const&, std::tupleodb::Point&&&&, std::tuple<>&&) (this=0x7fffff7ff490) at /usr/include/c++/15/bits/stl_tree.h:1254
#8 0x000055555dbd0659 in std::_Rb_tree<odb::Point, std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > >, std::_Select1st<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > >, std::lessodb::Point, std::allocator<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > > >::_Auto_node::_Auto_node<std::piecewise_construct_t const&, std::tupleodb::Point&&, std::tuple<> >(std::_Rb_tree<odb::Point, std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > >, std::_Select1st<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > >, std::lessodb::Point, std::allocator<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > > >&, std::piecewise_construct_t const&, std::tupleodb::Point&&&&, std::tuple<>&&) (this=0x7fffff7ff300, __t=...) at /usr/include/c++/15/bits/stl_tree.h:2285
#9 0x000055555dbc8bea in std::_Rb_tree<odb::Point, std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > >, std::_Select1st<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > >, std::lessodb::Point, std::allocator<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > > >::_M_emplace_hint_unique<std::piecewise_construct_t const&, std::tupleodb::Point&&, std::tuple<> >(std::_Rb_tree_const_iterator<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > >, std::piecewise_construct_t const&, std::tupleodb::Point&&&&, std::tuple<>&&) (this=0x7fffff7ff490, __pos={...})
at /usr/include/c++/15/bits/stl_tree.h:3084
#10 0x000055555dbc2b5b in std::map<odb::Point, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* >, std::lessodb::Point, std::allocator<std::pair<odb::Point const, std::vector<odb::dbITerm*, std::allocatorodb::dbITerm* > > > >::operator[]
(this=0x7fffff7ff490, __k=...) at /usr/include/c++/15/bits/stl_map.h:555
#11 0x000055555dbaacf0 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb4f0)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:871
#12 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb570)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#13 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb4f0)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#14 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb570)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#15 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb4f0)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#16 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb570)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#17 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb4f0)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#18 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb570)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#19 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb4f0)

............

#26169 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb4f0)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#26170 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb570)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#26171 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb4f0)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#26172 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb570)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891
#26173 0x000055555dbaae76 in cts::TritonCTS::cloneClockGaters (this=0x555562a4c7b0, clkNet=0x55556e9eb4f0)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:891

#26174 0x000055555dbad63a in cts::TritonCTS::populateTritonCTS (this=0x555562a4c7b0)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:1216
#26175 0x000055555dba4d07 in cts::TritonCTS::runTritonCts (this=0x555562a4c7b0)
at /home/paul/OpenROAD/src/cts/src/TritonCTS.cpp:93
#26176 0x000055555b5dd41b in run_triton_cts ()
at /home/paul/OpenROAD/build/src/cts/src/CMakeFiles/cts.dir/TritonCTSTCL_wrap.cxx:2076
#26177 0x000055555b5e7e1e in _wrap_run_triton_cts (clientData=0x0, interp=0x555562a76a20, objc=1, objv=0x555562a84bd0)
at /home/paul/OpenROAD/build/src/cts/src/CMakeFiles/cts.dir/TritonCTSTCL_wrap.cxx:4214
#26178 0x00007ffff7dfeab0 in TclNRRunCallbacks () from /usr/local/lib/libtcl8.6.so
#26179 0x00007ffff7e00e4e in TclEvalEx () from /usr/local/lib/libtcl8.6.so
#26180 0x00007ffff7e01797 in Tcl_EvalEx () from /usr/local/lib/libtcl8.6.so
#26181 0x00007ffff7e017ba in Tcl_Eval () from /usr/local/lib/libtcl8.6.so

#26182 0x000055555aaeac02 in sta::sourceTclFile (filename=0x7fffffffc563 "./scripts/openroad/cts.tcl", echo=false,
verbose=false, interp=0x555562a76a20) at /home/paul/OpenROAD/src/sta/app/StaMain.cc:104
#26183 0x000055555a6b3ada in tclAppInit (argc=@0x5555624b0fc0: 2, argv=0x7fffffffbf78,
init_filename=0x55555f47a668 ".openroad", interp=0x555562a76a20) at /home/paul/OpenROAD/src/Main.cc:564
#26184 0x000055555a6b3e61 in ord::tclInit (interp=0x555562a76a20) at /home/paul/OpenROAD/src/Main.cc:608
#26185 0x000055555a6b3e1a in ord::tclAppInit (interp=0x555562a76a20) at /home/paul/OpenROAD/src/Main.cc:603
#26186 0x00007ffff7ec771a in Tcl_MainEx () from /usr/local/lib/libtcl8.6.so

#26187 0x000055555a6b34bc in main (argc=4, argv=0x7fffffffbf78) at /home/paul/OpenROAD/src/Main.cc:311

[MoonbaseOtago]

Still couldn't upload it you can grab it from:

http://moonbaseotago.com/cts-bug-reproducible.tgz

[MoonbaseOtago]

I've been thinking more about this bug now that I see the backtrace .... let me explain more about what's going on in this block, it consists of 2 parts an 8b10 encoder and an 10b8 decoder, each part has a fast clock and a 1/10 internally generated slow clock. In this case both parts share the same fast clock which is connected to an external pin. It's probably only worth considering one part, the other probably has the same issues.

The slow clock is generated internally and comes off a flop, its made using the fast clock and a counter counting to 10, signals pass between the slow domain and the fast domain, there's no assumption about a timing or phase relation between the fast clock and the slow one, instead timing between the domains is correct by construction (signals only change or are sampled at particular locations in the 10 clock counter cycles (thereby creating appropriate setup and hold between domains) - this probably means that there are paths that could be followed between clock domains in a loop, possibly causing the recursion runaway we see in the backtrace

I knew that I needed to disconnect these potential timing paths and I tried to do it with the following in the .sdc file

set_clock_groups -asynchronous -group { rp2040_clk } -group { des_clk } -group { ser_clk }

I'm relatively new to openroad (but I've wrestled synopsys a lot) so maybe the above is the wrong way to tackle this problem (in synopsys I might create some sort of multi-cycle path in one direction).

Finally there's another issue here, sometimes it works, I'm building from Tiny Tapeout/Librelane, and some releases of Librelane reliably work (and I have a tapeout in the queue), but most reliably fail ..... so I'm confused here

[arthurjolo]

The issue is happening during the clock tree building and separating them into clock groups would not prevent the clock tree from being built. There is a bug in the clock tree building and I am looking into it.

On a side note, I am no expert user but to disconnect timing paths you I believe you should use set_false_path. Maybe set_clock_groups does disconnect them but I only know about set_false_path.

[gadfort]

@arthurjolo we use set_clock_groups extensively, it's perfectly legal and while you can use set_false_path to accomplish the same, openroad should handle it correctly.

[maliberty]

@arthurjolo the command defines groups of clocks that are asynchronous with respect to each other and therefore no timing path between them is checked. The effect is similar to set_false_path.

[arthurjolo]

I confirmed that the issue is a loop in the generated clocks. Both the 8b10 encoder and an 10b8 decoder clocks have it, the loop is from the output of the clock driver flop to its data input: eg10b8 decoder

This path does not cross clocks and when CTS was looking for clock gaters it got stuck in this loop. I was able to avoid this issue but I am having issues to run the testcase until the end. STA is very slow when updating the timing graph and can't confirm if there is no other issues further in CTS. I am investigating this to create a PR.

[arthurjolo]

PR #10163 will fix your crash. However the issue with STA that I mentioned is a bug in STA that creates a loop in the timing path of the generated clocks drivers. This bug has been fixed, but it is still not available in OR.

To work around the bug you can add this to your scripts:

set_disable_timing -from CLK -to CLK [get_cells s8b10.r_clk10_sky130_fd_sc_hd__dfxtp_2_Q]

set_disable_timing -from CLK -to CLK [get_cells d10b8.r_clk10_sky130_fd_sc_hd__dfxtp_2_Q]

This will prevent the issue in STA while the fix is not available.

[MoonbaseOtago]

Great! thanks! - Paul

…

On Fri, Apr 17, 2026 at 8:00 AM arthurjolo ***@***.***> wrote: *arthurjolo* left a comment (The-OpenROAD-Project/OpenROAD#9993) <#9993 (comment)> PR #10163 <#10163> will fix your crash. However the issue with STA that I mentioned is a bug in STA that creates a loop in the timing path of the generated clocks drivers. This bug has been fixed, but it is still not available in OR. To work around the bug you can add this to your scripts: set_disable_timing -from CLK -to CLK [get_cells s8b10.r_clk10_sky130_fd_sc_hd__dfxtp_2_Q] set_disable_timing -from CLK -to CLK [get_cells d10b8.r_clk10_sky130_fd_sc_hd__dfxtp_2_Q] This will prevent the issue in STA wile the fix is not available. — Reply to this email directly, view it on GitHub <#9993 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AANCY7NX7LXTWROSEZR3WAT4WE3V3AVCNFSM6AAAAACXF2EWDWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DENRTGAYTOOBZGU> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[dsengupta0628]

PR #10163 will fix your crash. However the issue with STA that I mentioned is a bug in STA that creates a loop in the timing path of the generated clocks drivers. This bug has been fixed, but it is still not available in OR.

To work around the bug you can add this to your scripts:

set_disable_timing -from CLK -to CLK [get_cells s8b10.r_clk10_sky130_fd_sc_hd__dfxtp_2_Q]

set_disable_timing -from CLK -to CLK [get_cells d10b8.r_clk10_sky130_fd_sc_hd__dfxtp_2_Q]

This will prevent the issue in STA while the fix is not available.

This STA bug is fixed and now available in OpenROAD too- could you please give it a try with latest OpenROAD master without the workaround commands?