compiler: Improve scalar aliases detection and scheduling by mloubout · Pull Request #2858 · devitocodes/devito

mloubout · 2026-02-25T16:07:19Z

Quite a few more changes that I would have liked but this avoid being too drastic. This basically make scalar aliases more reobust

Remove guards from scalar aliases used in multiple clusters to avoid issue with scope of variable
No longer allow scalar aliases that depend on a condition
Make aliases const (tiny change but bit better technically)
Small fix on lifting that prevents detaching scalar clusters from cluster with same guard
Tiny change to cse dtype due to numpy integer upcasting

review-notebook-app · 2026-02-25T16:21:32Z

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codecov · 2026-02-25T17:20:05Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.03%. Comparing base (28ded5a) to head (eb3b4ea).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2858      +/-   ##
==========================================
+ Coverage   78.96%   79.03%   +0.06%     
==========================================
  Files         248      248              
  Lines       51089    51210     +121     
  Branches     4422     4426       +4     
==========================================
+ Hits        40342    40473     +131     
+ Misses       9938     9926      -12     
- Partials      809      811       +2

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devito/passes/clusters/aliases.py

FabioLuporini · 2026-03-04T14:00:51Z

devito/passes/clusters/misc.py


-            lifted.append(c.rebuild(ispace=ispace, properties=properties, guards=guards))
+            _lifted = c.rebuild(ispace=ispace, properties=properties, guards=guards)
+            if guards and clusters[max(n-1, 0)].guards != guards and _lifted.is_scalar:


this is very convoluted

if we don't pull outside of a guard (as I just wrote above) extra checks here might not be required after all

devito/passes/clusters/aliases.py

FabioLuporini · 2026-03-04T14:03:25Z

devito/passes/clusters/aliases.py

+            is_cond = any(isinstance(d, (SubsamplingFactor, ConditionalDimension))
+                          for d in pivot.free_symbols)
+            if meta.guards and is_cond and nclusters > 1:
+                # Scalar alias that depends on a guard, unsafe to lift out of the guard


this is the wrong place, they shouldn't have been collected in the first place.

Instead, you can drop this thing and rather add new rule here: https://github.com/devitocodes/devito/blob/main/devito/passes/clusters/aliases.py#L299-L300

devito/passes/clusters/aliases.py

FabioLuporini

LGTM

mloubout added the compiler label Feb 25, 2026

mloubout force-pushed the alias-multi-cond branch 2 times, most recently from 19254fd to 6af1a6b Compare February 25, 2026 16:21

mloubout force-pushed the alias-multi-cond branch from 6af1a6b to 53151e2 Compare February 25, 2026 16:25

mloubout changed the title ~~compiler: prevent undefined Temp through global init~~ compiler: Prevent undefined Temp through global init Feb 25, 2026

mloubout force-pushed the alias-multi-cond branch 3 times, most recently from e2045e5 to b859dc4 Compare February 25, 2026 17:02

mloubout force-pushed the alias-multi-cond branch 10 times, most recently from 7fa5e9a to 8c0a82b Compare February 26, 2026 17:19

mloubout changed the title ~~compiler: Prevent undefined Temp through global init~~ compiler: Improve scalar aliases detection and scheduling Feb 26, 2026

mloubout force-pushed the alias-multi-cond branch 3 times, most recently from 42387e7 to 1a3141e Compare February 26, 2026 20:04