compiler: Do not CSE-capture IndexedPointer indices

[ggorman]

Problem

IndexedPointer (ptr->field[idx]) had no handler in CSE's _catch, so the generic handler recursed into its index. When an integer index expression repeats inside a floating-point Cluster, CSE binds it to a CTemp, and cse_dtype promotes an integer expression in a float Cluster to the Cluster's float type. The result is a floating-point array subscript:

float r4 = (time / ct0f) + static_cast<int>(time >= 3)*static_cast<int>((3)%(ct0f) != 0);
f_vec->sizes[r4] = f_vec->sizes[r4];   // nvcc: expression must have integral or unscoped enum type
                                        // hipcc: array subscript is not an integer

This surfaced after #3043: the CondEq snapshot shift turned a bare IntDiv index (never captured) into an Add that CSE does capture. Any backend that lowers metadata lookups to IndexedPointer inside a float Cluster hits it.

Fix

Register IndexedPointer with the same _catch handler as Indexed/Symbol/Reserved, so CSE treats it as an opaque terminal and never looks inside its index. Two executable lines; no change to cse_dtype, whose promotion rule affects unrelated arithmetic.

Test

tests/test_cse.py::test_indexedpointer_index_not_captured: two IndexedPointers sharing a repeated integer index in a float32 Cluster; asserts no CTemp ends up inside an IndexedPointer index.

• Negative control: with devito/passes/clusters/cse.py reverted the test fails (assert not True: the index was captured); with the change it passes.
• tests/test_cse.py, test_dse.py, test_buffering.py: 306 passed, 2 xfailed (one MPI test fails identically without this change on the host used, due to a missing mpirun).
• Generated CUDA source compiled with nvcc 12.4: 5 errors before, 0 after; the same case runs on an RTX 3090 (CUDA 12.9).

🤖 Generated with Claude Code

---

CI note. pytest-osx-py312-clang-omp-base fails on this PR for a reason unrelated to the change: the runner it drew is a non-M1 Apple chip, which get_platform() does not classify as AppleArm, so test_nested_nthreads is not skipped and emits x86 intrinsics headers. Fixed in #3048. pytest-gpu-omp-amd segfaults in the examples step (test_tti_stability[staggered]); the generated code for that operator is byte-identical with and without this change, and a concurrent unrelated PR run failed the same job (runner contention, tracked in #3049).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.15%. Comparing base (a9964bb) to head (5c8ec26).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3047      +/-   ##
==========================================
- Coverage   84.26%   84.15%   -0.12%     
==========================================
  Files         258      258              
  Lines       56982    56999      +17     
  Branches     4854     4856       +2     
==========================================
- Hits        48018    47967      -51     
- Misses       8138     8202      +64     
- Partials      826      830       +4     

Flag	Coverage Δ
pytest-gpu-aomp-amdgpuX	68.56% <100.00%> (-0.01%)	⬇️
pytest-gpu-gcc-	79.04% <100.00%> (+0.01%)	⬆️
pytest-gpu-icx-	79.00% <100.00%> (+<0.01%)	⬆️
pytest-gpu-nvc-nvidiaX	69.14% <100.00%> (+<0.01%)	⬆️

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[FabioLuporini]

thanks

closing since @mloubout has already cherry-picked this commit inside #3050 so we'll merge it via that