[llvm] [DFAJumpThreading] Unify equivalent states (PR #162447)

[Hongyu Chen via llvm-commits]

XChy wrote:

Some metrics:
```
Tests: 2463
Metric: dfa-jump-threading.NumTransforms

Program                                       dfa-jump-threading.NumTransforms                   
                                              result_before                    result_after diff 
Benchmarks...gs-C/TimberWolfMC/timberwolfmc     4.00                             5.00       25.0%
Benchmarks/7zip/7zip-benchmark                 14.00                            16.00       14.3%
Applications/ClamAV/clamscan                    6.00                             6.00        0.0%
Applications/SPASS/SPASS                        2.00                             2.00        0.0%
Applications/kimwitu++/kc                       1.00                             1.00        0.0%
Applications/lua/lua                            1.00                             1.00        0.0%
Applications/obsequi/Obsequi                    2.00                             2.00        0.0%
Applications/spiff/spiff                        1.00                             1.00        0.0%
Applications/sqlite3/sqlite3                    5.00                             5.00        0.0%
Benchmarks.../DOE-ProxyApps-C++/CLAMR/CLAMR     3.00                             3.00        0.0%
Benchmarks/MallocBench/gs/gs                    2.00                             2.00        0.0%
Benchmarks...ch/consumer-jpeg/consumer-jpeg     1.00                             1.00        0.0%
Benchmarks...sumer-typeset/consumer-typeset     3.00                             3.00        0.0%
Benchmarks/Prolangs-C/football/football         1.00                             1.00        0.0%
Benchmarks/Ptrdist/bc/bc                        1.00                             1.00        0.0%
```

```
Tests: 2463
Metric: dfa-jump-threading.NumCloned

Program                                       dfa-jump-threading.NumCloned                    
                                              result_before                result_after diff  
Benchmarks...gs-C/TimberWolfMC/timberwolfmc    42.00                        51.00        21.4%
Benchmarks/7zip/7zip-benchmark                154.00                       170.00        10.4%
Applications/SPASS/SPASS                        7.00                         7.00         0.0%
Applications/kimwitu++/kc                       3.00                         3.00         0.0%
Applications/spiff/spiff                       13.00                        13.00         0.0%
Benchmarks...ch/consumer-jpeg/consumer-jpeg    12.00                        12.00         0.0%
Benchmarks...sumer-typeset/consumer-typeset    26.00                        26.00         0.0%
Benchmarks/Prolangs-C/football/football        12.00                        12.00         0.0%
Benchmarks/Ptrdist/bc/bc                        4.00                         4.00         0.0%
Benchmarks.../mediabench/jpeg/jpeg-6a/cjpeg    12.00                        12.00         0.0%
Applications/ClamAV/clamscan                   89.00                        88.00        -1.1%
Benchmarks/MallocBench/gs/gs                   32.00                        31.00        -3.1%
Applications/sqlite3/sqlite3                   50.00                        42.00       -16.0%
Applications/obsequi/Obsequi                   29.00                        23.00       -20.7%
Applications/lua/lua                            3.00                         2.00       -33.3%
```

https://github.com/llvm/llvm-project/pull/162447