[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 `clang-x86_64-linux-abi-test` running on `sie-linux-worker2` while building `llvm` at step 6 "build-unified-tree".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/8/builds/26991

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

```
Step 6 (build-unified-tree) failure: build (failure)
...
16.076 [5498/10/2061] Building AArch64GenCallingConv.inc...
16.247 [5497/10/2062] Building AArch64GenAsmWriter1.inc...
17.048 [5496/10/2063] Building AArch64GenAsmMatcher.inc...
17.812 [5495/10/2064] Building AArch64GenMCPseudoLowering.inc...
17.971 [5494/10/2065] Building AArch64GenExegesis.inc...
18.057 [5493/10/2066] Building AArch64GenMCCodeEmitter.inc...
21.129 [5492/10/2067] Building CXX object lib/MC/MCParser/CMakeFiles/LLVMMCParser.dir/AsmParser.cpp.o
21.809 [5491/10/2068] Building AArch64GenFastISel.inc...
22.997 [5490/10/2069] Building AArch64GenO0PreLegalizeGICombiner.inc...
23.010 [5489/10/2070] Building AArch64GenDAGISel.inc...
FAILED: lib/Target/AArch64/AArch64GenDAGISel.inc /home/buildbot/buildbot-root/abi-test/build/lib/Target/AArch64/AArch64GenDAGISel.inc 
cd /home/buildbot/buildbot-root/abi-test/build/lib/Target/AArch64 && /home/buildbot/buildbot-root/abi-test/build/bin/llvm-tblgen -gen-dag-isel -I/home/buildbot/buildbot-root/abi-test/llvm/llvm/lib/Target/AArch64 -I/home/buildbot/buildbot-root/abi-test/build/include -I/home/buildbot/buildbot-root/abi-test/llvm/llvm/include -I /home/buildbot/buildbot-root/abi-test/llvm/llvm/lib/Target -omit-comments /home/buildbot/buildbot-root/abi-test/llvm/llvm/lib/Target/AArch64/AArch64.td --write-if-changed -o AArch64GenDAGISel.inc -d AArch64GenDAGISel.inc.d && /usr/bin/cmake/bin/cmake -E cmake_transform_depfile Ninja gccdepfile /home/buildbot/buildbot-root/abi-test/llvm/llvm /home/buildbot/buildbot-root/abi-test/llvm/llvm/lib/Target/AArch64 /home/buildbot/buildbot-root/abi-test/build /home/buildbot/buildbot-root/abi-test/build/lib/Target/AArch64 /home/buildbot/buildbot-root/abi-test/build/lib/Target/AArch64/AArch64GenDAGISel.inc.d /home/buildbot/buildbot-root/abi-test/build/CMakeFiles/d/44853bddfd4f6686b58fc02d771a417a61fbce8279dc73f0df8b37383aeb6521.d
llvm-tblgen: /home/buildbot/buildbot-root/abi-test/llvm/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/buildbot/buildbot-root/abi-test/build/bin/llvm-tblgen -gen-dag-isel -I/home/buildbot/buildbot-root/abi-test/llvm/llvm/lib/Target/AArch64 -I/home/buildbot/buildbot-root/abi-test/build/include -I/home/buildbot/buildbot-root/abi-test/llvm/llvm/include -I /home/buildbot/buildbot-root/abi-test/llvm/llvm/lib/Target -omit-comments /home/buildbot/buildbot-root/abi-test/llvm/llvm/lib/Target/AArch64/AArch64.td --write-if-changed -o AArch64GenDAGISel.inc -d AArch64GenDAGISel.inc.d
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  llvm-tblgen 0x000058f91b744510
1  llvm-tblgen 0x000058f91b7413bf
2  llvm-tblgen 0x000058f91b741512
3  libc.so.6   0x00007346f9c94520
4  libc.so.6   0x00007346f9ce89fc pthread_kill + 300
5  libc.so.6   0x00007346f9c94476 raise + 22
6  libc.so.6   0x00007346f9c7a7f3 abort + 211
7  libc.so.6   0x00007346f9c7a71b
8  libc.so.6   0x00007346f9c8be96
9  llvm-tblgen 0x000058f91b5a4176
10 llvm-tblgen 0x000058f91b5a3387
11 llvm-tblgen 0x000058f91b5a3387
12 llvm-tblgen 0x000058f91b5a3387
13 llvm-tblgen 0x000058f91b5a3387
14 llvm-tblgen 0x000058f91b5a3387
15 llvm-tblgen 0x000058f91b5a3387
16 llvm-tblgen 0x000058f91b5a3387
17 llvm-tblgen 0x000058f91b5a3387
18 llvm-tblgen 0x000058f91b5a3387
19 llvm-tblgen 0x000058f91b5a3387
20 llvm-tblgen 0x000058f91b5a3387
21 llvm-tblgen 0x000058f91b57b4cc
22 llvm-tblgen 0x000058f91b784c0f
23 llvm-tblgen 0x000058f91b750276
24 llvm-tblgen 0x000058f91b3fbaa5
25 libc.so.6   0x00007346f9c7bd90
26 libc.so.6   0x00007346f9c7be40 __libc_start_main + 128
27 llvm-tblgen 0x000058f91b3aa005
Aborted (core dumped)
23.542 [5489/9/2071] Building AArch64GenPostLegalizeGICombiner.inc...
23.685 [5489/8/2072] Building AArch64GenGlobalISel.inc...
24.621 [5489/7/2073] Building AArch64GenPostLegalizeGILowering.inc...

```

</details>

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