[llvm] [GlobalISel] Refactor Combiner MatchData & Apply C++ Code Handling (PR #92239)

[Amara Emerson via llvm-commits]

aemerson wrote:

A non-LTO release w/o asserts build:
```
Program                                       compile_time
                                              lhs          rhs    diff
7zip/7zip-benchmark                            14.76        14.75 -0.1%
Bullet/bullet                                  10.98        10.97 -0.1%
tramp3d-v4/tramp3d-v4                           5.68         5.67 -0.1%
kimwitu++/kc                                    6.65         6.64 -0.2%
SPASS/SPASS                                     4.57         4.56 -0.3%
lencod/lencod                                   4.65         4.64 -0.3%
mafft/pairlocalalign                            2.68         2.67 -0.4%
consumer-typeset/consumer-typeset               3.59         3.58 -0.4%
sqlite3/sqlite3                                 2.49         2.48 -0.5%
                           Geomean difference                     -0.3%
```

A huge improvement, fantastic!

https://github.com/llvm/llvm-project/pull/92239