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Keep the whole dimension for a loop index that is not affine in the loop variable - #2621
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…oop variable The Python frontend offsets a nested SDFG's view of an array by f(min(range)) and sizes it by the trip count, which assumes the index f is affine in the loop variable. A modulo index such as tbl[(j + t) % 3] broke both: the nested array got shape k + 1 and an offset of j % 3 while the caller passed the table's base pointer, so the nested SDFG read the wrong entries.
tbennun
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Sep 30, 2026
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Good catch!
I am wondering if is_affine_in (and is_polynomial) is faster than Match(a*b+c). We need to benchmark and maybe propagation.py can improve too.
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newast.py: the non-affine index handling of #2621 patches the offset-and-squeeze logic that this branch removed, so the branch's version is kept. vector_inference.py: kept the Indices-to-Range conversion and adopted the name-based loop parameter lookup from main. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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The frontend offset a nested SDFG array by f(min(loop range)) and sized it by the trip count, which is only valid when the index f is affine in the loop variable; an index such as (j + t) % 3 read the wrong table entries. It now keeps the whole dimension for a non-affine index, with a reproducer that checks the nested connector shapes and the numerics.