Move one simplification call in lowering.

[mcourteaux]

When debugging some stuff not part of this PR, I spotted a missing simplification, which Andrew determined to be AFTER hoist_loop_invariant_xxx. This moves the simplification in the right spot.

Breaking changes

I hope none, let's see.

These do not necessarily disqualify a PR from being merged, but they should at
least be tagged with the release_notes label.

Checklist

• Tests added or updated (not required for docs, CI config, or typo fixes)
• Documentation updated (if public API changed)
• Python bindings updated (if public API changed)
• Benchmarks are included here if the change is intended to affect performance.
• Commits include AI attribution where applicable (see Code of Conduct)

[alexreinking]

This should be moved up above the now-final simplification

[mcourteaux]

Andrew argued that the string should change, instead of moving this. @abadams

[abadams]

Suggest moving it after the custom passes and changing string to "Conceptual stmt:", because it's what you get if you compile to conceptual_stmt.

[mcourteaux]

Named it:

     debug(1) << "Lowering after reaching conceptual Stmt:\n"
              << s << "\n\n";

As Claude is grepping for "Lowering after" to find the different sections of the lowering phase.

[codecov]

Codecov Report

❌ Patch coverage is 70.21277% with 42 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.10%. Comparing base (bb5426d) to head (1040bca).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/CheckGPUCrossTalk.cpp	69.29%	28 Missing and 11 partials ⚠️
src/Lower.cpp	40.00%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9355      +/-   ##
==========================================
+ Coverage   70.08%   70.10%   +0.01%     
==========================================
  Files         259      260       +1     
  Lines       79158    79295     +137     
  Branches    19293    19328      +35     
==========================================
+ Hits        55477    55587     +110     
- Misses      17886    17927      +41     
+ Partials     5795     5781      -14     

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[alexreinking]

Deadlocks exposed here fixed by #9372

[mcourteaux]

Waiting for #9372 to land to update this branch, but this seems to work now.

@abadams please take note of Claude's initiative to disable a lower pass in LLVM 21, due to a bug fixed in 22 regarding SVE on ARM. I'll open a PR separately for this LLVM pass skip and remove the skips in all the tests to see if that makes the test suite pass.

[abadams]

Looks like it needs to be rebased. A bunch of unrelated changes are in it now.