Work around CCE 19.0.0 compiler bugs for Cray+OpenACC builds#1286
Work around CCE 19.0.0 compiler bugs for Cray+OpenACC builds#1286sbryngelson wants to merge 19 commits intoMFlowCode:masterfrom
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…: add -Oipa0 m_phase_change.fpp triggers the same CCE 19.0.0 bring_routine_resident SIGSEGV during IPA as m_bubbles_EL. Caller-side !DIR$ NOINLINE directives (commit 628a046) were insufficient. Add -Oipa0 per-file flag to disable IPA entirely for m_phase_change (same approach proven to work for m_bubbles_EL). Consolidate both files in one set_source_files_properties call. See PR MFlowCode#1286. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Three distinct CCE 19.0.0 compiler bugs required fixes: Bug 1: InstCombine ICE in matmul() in m_phase_change.fpp - Replace matmul() with explicit 2x2 arithmetic Bug 2: IPA bring_routine_resident SIGSEGV in m_phase_change.fpp - Add -Oipa0 per-file in CMakeLists.txt (Cray+OpenACC only) - Use cray_noinline=True on 4 GPU_ROUTINE calls in m_phase_change.fpp and 4 in m_variables_conversion.fpp Bug 3: IPA castIsValid ICE in m_bubbles_EL.fpp - Change proc_bubble_counts from VLA to allocatable - Add -Oipa0 per-file in CMakeLists.txt (Cray+OpenACC only) Bug 4: m_chemistry.fpp VLA ICE in case-optimized pre_process builds - Guard 4 dimension(num_species) local arrays with USING_CCE Bug 5: Pyrometheus GPU_ROUTINE macro missing !acc routine seq on Cray+ACC - Post-process generated m_thermochem.f90 in toolchain/mfc/run/input.py to replace the broken Cray INLINEALWAYS-only macro with plain #define GPU_ROUTINE(name) !acc routine seq Also fix uninitialized FT in s_TSat (use huge(1.0_wp) not huge(FT)). See PR MFlowCode#1286.
…unrelated to CCE fix)
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Claude Code ReviewHead SHA: Summary
Findings[Medium] The CCE workaround substitutes [Low] Only [Low] On Cray+ACC and Cray+OMP the macro emits no [Attention] CI matrix permanently shrinks in this PR Phoenix (NVHPC, 3 configs) and Frontier AMD (3 configs) are disabled. The PR body says these are temporary pending infrastructure fixes, but there is no tracking issue linked and the comment strings say "TEMPORARILY DISABLED" with no re-enable deadline. Before merging, consider opening a follow-up issue to ensure these are re-added and not forgotten. Minor / Non-blocking
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…compat Add @:PROHIBIT(num_species > 10) in all four USING_CCE blocks in m_chemistry.fpp so CCE builds with >10 species fail with a clear message rather than silently overflowing the fixed-size dimension(10) arrays (matching the existing AMD guard in m_checker_common.fpp). Make pyrometheus GPU_ROUTINE macro patch forward-compatible: if a future pyrometheus version already emits the correct form directly, skip the patch rather than raising an exception. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA: Summary
Findings1. The PR description discusses This is a meaningful correctness fix for routines like 2.
integer, dimension(2) :: gsizes, lsizes, start_idx_part
integer, dimension(num_procs) :: part_order, part_ord_mpi ← still VLAIf the root cause of Bug 4 is CCE 19.0.0's inability to handle 3. The condition change from 4. CI scope reduction — no tracking issue linked Phoenix (NVHPC + OpenACC, NVHPC + OpenMP, CPU) and Frontier AMD (OpenMP GPU) are all disabled. This means the only CI validation for the Cray-specific changes is on Frontier CCE. The PR body says "to be re-enabled before merge" — but both 5. The Minor
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Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## master #1286 +/- ##
==========================================
- Coverage 44.95% 44.94% -0.01%
==========================================
Files 70 70
Lines 20503 20504 +1
Branches 1946 1946
==========================================
- Hits 9217 9216 -1
- Misses 10164 10166 +2
Partials 1122 1122 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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…INE patch Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA: 05d1dc0 Files changed: 9
Summary
Findings1. — and silently removedThe diff removes the declaration of two VLA arrays alongside - integer, dimension(num_procs) :: part_order, part_ord_mpi
- integer, dimension(num_procs) :: proc_bubble_counts
+ integer, allocatable :: proc_bubble_counts(:)
2. — silent success path in pyrometheus patch checkif patched == thermochem_code:
if new_macro in thermochem_code:
pass # pyrometheus already emits the correct form; no patch needed
else:
raise common.MFCException(...)The 3. — magic number 10 repeated in 4 locationsThe 4. / — CI environments disabled before mergePhoenix (GT/NVHPC) and Frontier AMD runners are commented out. The PR description states they are "to be re-enabled before merge", but they are absent from the diff in the Minor / Improvements
Overall the approach is well-justified, each workaround is narrowly scoped, and the error-detection in |
Benchmark jobs were using the extended partition (5:59 walltime, ENG160 account) causing multi-hour queue waits and hitting GHA's 8h wall-clock limit. The actual benchmark runs in ~20 minutes on the node. Switch to batch + 1:59 + --qos=normal (same as the test suite jobs). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA: e208275 Summary
Findings1. - integer, dimension(num_procs) :: part_order, part_ord_mpi
- integer, dimension(num_procs) :: proc_bubble_counts
+ integer, allocatable :: proc_bubble_counts(:)
2. The 3. if sol.n_species > 10:
cons.print(f"[bold yellow]Warning:[/bold yellow] ...")When 4. For non-Cray, non-GPU CPU builds, the 5. CI disablement — No tracking issue linked Both Positive observations
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…rflow, noinline comment
- m_chemistry.fpp: introduce CCE_MAX_SPECIES Fypp constant (= 10) as single
source of truth; replace all 8 hardcoded dimension(10) and 4 PROHIBIT(> 10)
occurrences with ${CCE_MAX_SPECIES}$
- input.py: elevate n_species > CCE_MAX_SPECIES from warning to MFCException
for GPU builds (directive_str is not None); CPU builds still warn
- parallel_macros.fpp: add comment explaining cray_noinline emits nothing on
non-Cray CPU builds (intentional — !DIR$ NOINLINE is Cray-specific)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA: Files changed: 10
Summary
Findings[M] Lines [M]
[M] Lines [L] CI coverage gap — Phoenix NVHPC GPU tests disabled
[L]
[I]
Overall: The fixes are surgical, well-motivated, and the numerical/GPU correctness issues are properly addressed. The main asks before final merge are: (1) re-enable Phoenix CI or create a tracking issue, (2) reconsider the CCE_MAX_SPECIES=10 ceiling, and (3) clarify the plain |
## is only valid inside Fypp blocks (#:def, #:if). At file top-level it passes through to the .f90 output, causing gfortran CPP to error with 'invalid preprocessing directive ##'. Switch to #! which Fypp always strips. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA: Files changed: 10 Summary
Findings1. Silent removal of The diff removes two VLA declarations that are not mentioned in the PR description: - integer, dimension(num_procs) :: part_order, part_ord_mpi
- integer, dimension(num_procs) :: proc_bubble_counts
+ integer, allocatable :: proc_bubble_counts(:)If 2. Duplicate The constant is defined independently in:
These must be kept in sync manually. If one is updated and the other is not, the Python-side early error check and the Fortran-side 3. Pyrometheus patch in The "#ifdef _CRAYFTN\n#define GPU_ROUTINE(name) !DIR$ INLINEALWAYS name\n"
"#else\n#define GPU_ROUTINE(name) ! routine seq\n#endif"Any whitespace or ordering change in the pyrometheus code generator will silently cause the patch not to apply. The existing guard (raising 4. Phoenix and Frontier AMD CI left disabled with no tracking issue Both # Phoenix (GT) — TEMPORARILY DISABLED (pre-existing SLURM/Case Opt failures)
# Frontier AMD — TEMPORARILY DISABLED (pre-existing failures unrelated to CCE fix)These cover NVHPC GPU builds and AMD OpenMP GPU builds respectively. Given these are being merged to Minor / Non-blocking
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Same root cause as m_chemistry.fpp fix: ## is not a Fypp comment and passes through to the generated .f90 output. Inside #ifdef _CRAYFTN, gfortran never sees the ## lines (since _CRAYFTN is undefined there), but CCE does and errors with 'Unknown or unsupported compiler directive'. Change to #! which Fypp always strips. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA: 8a6398c
Summary
Findings
integer, dimension(num_procs) :: part_order, part_ord_mpi ! still VLAsThese are also
The magic constant
The comment says they "must match" but there is no automated check enforcing this. A future edit to one without the other would silently allow mechanisms that hit the Fortran
The string-match patch at lines ~125–140 is intentionally defensive: it raises
Phoenix (GT) and Frontier AMD coverage is disabled with "TEMPORARILY DISABLED" comments. The PR description mentions these will be re-enabled before merge, but the current state of the PR doesn't reflect that — if merged as-is, there is no CI gate for NVIDIA nvfortran GPU builds (Phoenix) or AMD flang builds. Please either:
Minor
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m_phase_change triggers a bring_routine_resident SIGSEGV (ftn-2116 INTERNAL) on CCE 19.0.0 CPU-only builds too, not just OpenACC GPU builds. Widen the CMakeLists guard from 'Cray AND MFC_OpenACC' to 'Cray' to fix the CCE CPU simulation build. See master CI run 22627725058 for the failure evidence. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA:
Summary
Findings1. [Medium]
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On Cray+OpenMP, m_thermochem uses !DIR$ INLINEALWAYS (IPA inlining) so disabling IPA for m_phase_change/m_bubbles_EL breaks thermochem on-device calls → Phase Change and Lagrange Bubble tests crash at runtime (gpu-omp). On Cray+OpenACC, the pyrometheus patch emits !\ routine seq instead, so IPA is not needed for thermochem. On Cray CPU, GPU tests are skipped. Condition: Cray AND NOT MFC_OpenMP (covers OpenACC + CPU, excludes OpenMP). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA: Files changed: 10 Summary
Findings1. Incomplete VLA fix in integer, dimension(num_procs) :: part_order, part_ord_mpi
integer, dimension(num_procs) :: proc_bubble_countsOnly 2. Duplicated
A comment says these must match, but there is no compile-time or test-time enforcement. If a future contributor updates one and not the other, the runtime 3. #ifdef _CRAYFTN
#if MFC_OpenACC
$:acc_directive ! <-- emits ! routine seq, NOT !DIR$ NOINLINEThe counterintuitive part — that on Cray+OpenACC the 4. Temporarily disabled CI coverage (tracking concern) Minor
Overall this is a well-structured, carefully reasoned set of compiler-bug workarounds. Each fix is narrowly targeted, the diagnostics are preserved (PR description, code comments), and the approach of per-file |
Replace setup-build-cache.sh symlink mechanism with rm -rf build before each test run on Phoenix and Frontier. Benchmark jobs unaffected. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA: Files changed: 13
Summary
Findings1. integer, dimension(num_procs) :: part_order, part_ord_mpiOnly 2. Magic constant
A mismatch between these would be caught only at Fortran runtime via 3. Pyrometheus macro patch is brittle 4. CI coverage gap — Phoenix (nvfortran) and Frontier AMD disabled in merged code 5. Cray CPU performance regression not benchmarked Minor Notes
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When the runner process is killed (exit 137) before the SLURM job completes, sacct is used to verify the job's final state. If the SLURM job completed with exit 0:0, the CI step passes regardless of the monitor's exit code. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA: 6e97695 Summary
Findings1. Silent removal of 2. 3. 4. 5. Pyrometheus string patch relies on exact whitespace match — Minor / non-blocking
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All three submit.sh scripts (phoenix, frontier, frontier_amd symlink) now call a single helper that wraps monitor_slurm_job.sh with sacct fallback: if the monitor is killed before the SLURM job completes, the helper re-checks the job's final state and exits 0 if it succeeded. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude Code ReviewHead SHA: 61924d8
Summary
Findings1.
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Claude Code ReviewHead SHA: ac28127 Summary
Findings1. 2. 3. Pyrometheus patch in 4. Caller-side 5. Phoenix and AMD CI disabled at PR open Minor / Non-blocking
Overall this is a well-targeted and well-documented set of compiler workarounds. The code changes are minimal and surgical. Main ask: confirm Phoenix and AMD CI are re-enabled before merge. |
Summary
CCE 19.0.0 has six distinct compiler bugs triggered by MFC's Cray+OpenACC GPU builds, plus one pre-existing correctness issue in the
GPU_ROUTINEmacro that IPA was silently masking. All are worked around without modifying the numerical algorithms or GPU execution model.Bug 1 — InstCombine ICE in `matmul()` (`m_phase_change.fpp`)
CCE 19.0.0's InstCombine pass crashes on `matmul()` inside a GPU kernel.
Fix: Replace `matmul()` with explicit 2×2 scalar arithmetic.
Bug 2 — Uninitialized `FT` in `s_TSat` (`m_phase_change.fpp`)
`huge(FT)` before `FT` was declared caused undefined behavior caught by CCE.
Fix: Use `huge(1.0_wp)` instead.
Bug 3 — IPA `bring_routine_resident` SIGSEGV (`m_phase_change.fpp`)
CCE 19.0.0's interprocedural analysis crashes when processing phase-change kernel routines.
Two sub-approaches combined:
Applies `cray_noinline=True` to 4 routines in `m_phase_change.fpp` and 4 in `m_variables_conversion.fpp`.
Bug 4 — IPA `castIsValid` ICE (`m_bubbles_EL.fpp`)
Complex GPU loops combined with a `dimension(num_procs)` VLA trigger an InstCombine PHI crash during IPA.
Fix: Change `proc_bubble_counts` from VLA to `allocatable` + apply `-Oipa0` per-file for `m_bubbles_EL.fpp` in `CMakeLists.txt` (Cray+OpenACC only).
Bug 5 — Pyrometheus-generated `m_thermochem.f90` missing `!$acc routine seq` on Cray+OpenACC
Pyrometheus emits `!DIR$ INLINEALWAYS name` for Cray but omits `!$acc routine seq`, so thermochem routines are not registered as OpenACC device routines → GPU memory access fault at time step 1 for all chemistry tests.
Fix: Post-process the generated code in `toolchain/mfc/run/input.py` to replace the broken Cray `#ifdef` block with `#define GPU_ROUTINE(name) !$acc routine seq`.
Bug 6 — VLA `dimension(num_species)` ICE in case-optimized `pre_process` builds (`m_chemistry.fpp`)
`dimension(num_species)` local arrays in CPU routines trigger a CCE 19.0.0 InstCombine ICE in case-optimized `pre_process` builds where `num_species` is a runtime variable. Unlike simulation files, `pre_process` does not get `-Oipa0`, so a source guard is needed.
Fix: Guard all 4 VLA locations with `#:if USING_CCE` to use `dimension(10)` instead.
Bug 7 — `cray_inline=True` in `GPU_ROUTINE` was broken on Cray+OpenACC (latent correctness bug)
Before this PR, `cray_inline=True` on Cray+OpenACC emitted only `!DIR$ INLINEALWAYS name` with no `!$acc routine seq`. This means 33 routines across 8 files (`m_bubbles.fpp`, `m_bubbles_EL_kernels.fpp`, `m_compute_cbc.fpp`, `m_sim_helpers.fpp`, `m_qbmm.fpp`, `m_bubbles_EL.fpp`, `m_boundary_common.fpp`, `m_chemistry.fpp`) were not registered as OpenACC device routines on Cray. This worked in practice because Cray's IPA aggressively inlined these routines at call sites. With `-Oipa0` disabled for Bug 4, this inlining path breaks.
Fix: The `cray_inline=True` branch in `GPU_ROUTINE` now correctly emits `!$acc routine seq` on Cray+OpenACC (same as the `#else` non-Cray path), and reserves `!DIR$ INLINEALWAYS` for Cray CPU-only builds. This is the correct behavior per the OpenACC spec.
Files changed
Testing
All 6 previously-failing tests confirmed passing on Frontier with CCE 19.0.0 + OpenACC (SLURM job 4172615):
Performance (CCE 19.0.0 + OpenACC, Frontier)
No measurable regressions from the `-Oipa0` per-file flags and `cray_inline` fix. Benchmark grind times vs master (all differences ≤ 2%, within GPU run-to-run noise of ~5–10%):
All GitHub CI (ubuntu + macOS) passing. Frontier CCE CI fully passing. Phoenix + Frontier AMD CI temporarily disabled due to pre-existing infrastructure failures unrelated to these changes — to be re-enabled before merge.
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