[llvm] [TableGen] Introduce MatcherList to manage a linked list of Matchers. NFC (PR #177875)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `openmp-offload-amdgpu-runtime-2` running on `rocm-worker-hw-02` while building `llvm` at step 5 "compile-openmp".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/10/builds/22624

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 5 (compile-openmp) failure: build (failure)
...
9.137 [1063/64/3722] Creating library symlink lib/libLLVMInstCombine.so
9.147 [1062/64/3723] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/NullabilityChecker.cpp.o
9.153 [1061/64/3724] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/ObjCContainersChecker.cpp.o
9.157 [1060/64/3725] Linking CXX shared library lib/libLLVMInstrumentation.so.23.0git
9.166 [1059/64/3726] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/ObjCAtSyncChecker.cpp.o
9.167 [1058/64/3727] Creating library symlink lib/libLLVMInstrumentation.so
9.171 [1057/64/3728] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/ObjCMissingSuperCallChecker.cpp.o
9.176 [1056/64/3729] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/ObjCPropertyChecker.cpp.o
9.177 [1055/64/3730] Building CXX object tools/clang/lib/StaticAnalyzer/Checkers/CMakeFiles/obj.clangStaticAnalyzerCheckers.dir/ObjCSelfInitChecker.cpp.o
9.186 [1054/64/3731] Building X86GenDAGISel.inc...
FAILED: lib/Target/X86/X86GenDAGISel.inc /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/lib/Target/X86/X86GenDAGISel.inc 
cd /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/lib/Target/X86 && /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/llvm-tblgen -gen-dag-isel -I/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/lib/Target/X86 -I/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/include -I/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/include -I /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/lib/Target -omit-comments /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/lib/Target/X86/X86.td --write-if-changed -o /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/lib/Target/X86/X86GenDAGISel.inc
llvm-tblgen: /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/utils/TableGen/DAGISelMatcherOpt.cpp:486: void FactorScope(llvm::MatcherList&, llvm::MatcherList::iterator): Assertion `!Optn == !Tmp && "Expected all to be null if any are null"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
Stack dump:
0.	Program arguments: /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/bin/llvm-tblgen -gen-dag-isel -I/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/lib/Target/X86 -I/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/include -I/home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/include -I /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/lib/Target -omit-comments /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.src/llvm/lib/Target/X86/X86.td --write-if-changed -o /home/botworker/builds/openmp-offload-amdgpu-runtime-2/llvm.build/lib/Target/X86/X86GenDAGISel.inc
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  libLLVMSupport.so.23.0git  0x000075f088016960 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 240
1  libLLVMSupport.so.23.0git  0x000075f08801363f llvm::sys::RunSignalHandlers() + 47
2  libLLVMSupport.so.23.0git  0x000075f088013792
3  libc.so.6                  0x000075f087642520
4  libc.so.6                  0x000075f0876969fc pthread_kill + 300
5  libc.so.6                  0x000075f087642476 raise + 22
6  libc.so.6                  0x000075f0876287f3 abort + 211
7  libc.so.6                  0x000075f08762871b
8  libc.so.6                  0x000075f087639e96
9  llvm-tblgen                0x000058bb46c3dc16
10 llvm-tblgen                0x000058bb46c3ce27
11 llvm-tblgen                0x000058bb46c3ce27
12 llvm-tblgen                0x000058bb46c3ce27
13 llvm-tblgen                0x000058bb46c3ce27
14 llvm-tblgen                0x000058bb46c3ce27
15 llvm-tblgen                0x000058bb46c3ce27
16 llvm-tblgen                0x000058bb46c3ce27
17 llvm-tblgen                0x000058bb46c3ce27
18 llvm-tblgen                0x000058bb46c3ce27
19 llvm-tblgen                0x000058bb46c3ce27
20 llvm-tblgen                0x000058bb46c3ce27
21 llvm-tblgen                0x000058bb46c3ce27
22 llvm-tblgen                0x000058bb46c3ce27
23 llvm-tblgen                0x000058bb46c3ce27
24 llvm-tblgen                0x000058bb46c3ce27
25 llvm-tblgen                0x000058bb46c3ce27
26 llvm-tblgen                0x000058bb46c3ce27
27 llvm-tblgen                0x000058bb46c3ce27
28 llvm-tblgen                0x000058bb46c3ce27
29 llvm-tblgen                0x000058bb46c3ce27
30 llvm-tblgen                0x000058bb46c3ce27
31 llvm-tblgen                0x000058bb46c3ce27

```

</details>

https://github.com/llvm/llvm-project/pull/177875