[llvm] [WebAssembly] [Backend] Wasm optimize illegal bitmask (PR #145627)

[via llvm-commits]

badumbatish wrote:

failing random flang test here with some new warnings added, will rebase and repush
```
2025-06-30T18:31:24.6800369Z ******************** TEST 'Flang :: Semantics/bug1046.f90' FAILED ********************
2025-06-30T18:31:24.6801254Z Exit Code: 1
2025-06-30T18:31:24.6801893Z 
2025-06-30T18:31:24.6802076Z Command Output (stdout):
2025-06-30T18:31:24.6802481Z --
2025-06-30T18:31:24.6802834Z --- 
2025-06-30T18:31:24.6803179Z +++ 
2025-06-30T18:31:24.6803578Z @@ -1,6 +1,6 @@
2025-06-30T18:31:24.6803814Z 
2025-06-30T18:31:24.6804187Z actual at 3: INTEGER(4) 0**0 is not defined [-Wfolding-exception]
2025-06-30T18:31:24.6805084Z actual at 5: REAL/COMPLEX 0**0 is not defined [-Wfolding-exception]
2025-06-30T18:31:24.6806033Z actual at 7: invalid argument on power with INTEGER exponent [-Wfolding-exception]
2025-06-30T18:31:24.6806997Z actual at 9: REAL/COMPLEX 0**0 is not defined [-Wfolding-exception]
2025-06-30T18:31:24.6808015Z actual at 11: invalid argument on power with INTEGER exponent [-Wfolding-exception]
2025-06-30T18:31:24.6809220Z actual at 13: REAL/COMPLEX 0**0 is not defined [-Wfolding-exception]
2025-06-30T18:31:24.6810263Z expect at 3: INTEGER(4) 0**0 is not defined
2025-06-30T18:31:24.6810815Z expect at 5: REAL/COMPLEX 0**0 is not defined
2025-06-30T18:31:24.6811600Z expect at 7: invalid argument on power with INTEGER exponent
2025-06-30T18:31:24.6812295Z expect at 9: REAL/COMPLEX 0**0 is not defined
2025-06-30T18:31:24.6812993Z expect at 11: invalid argument on power with INTEGER exponent
2025-06-30T18:31:24.6813731Z expect at 13: REAL/COMPLEX 0**0 is not defined
2025-06-30T18:31:24.6814138Z 
2025-06-30T18:31:24.6814280Z FAIL
2025-06-30T18:31:24.6814472Z 
2025-06-30T18:31:24.6814637Z --
2025-06-30T18:31:24.6814978Z Command Output (stderr):
2025-06-30T18:31:24.6815427Z --
2025-06-30T18:31:24.6818250Z "/usr/bin/python3" /home/gha/actions-runner/_work/llvm-project/llvm-project/flang/test/Semantics/test_errors.py /home/gha/actions-runner/_work/llvm-project/llvm-project/flang/test/Semantics/bug1046.f90 /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/flang -fc1 -pedantic -Werror # RUN: at line 1
2025-06-30T18:31:24.6823327Z + /usr/bin/python3 /home/gha/actions-runner/_work/llvm-project/llvm-project/flang/test/Semantics/test_errors.py /home/gha/actions-runner/_work/llvm-project/llvm-project/flang/test/Semantics/bug1046.f90 /home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/flang -fc1 -pedantic -Werror
```

https://github.com/llvm/llvm-project/pull/145627