[AIE] Fix sub-register index composition in split instruction rewriter#968
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Add a test case for when a tuple operand already has a sub-register index (e.g., %R.sub_hi_dim). The aie-split-instrs-create pass should compose the indices correctly (e.g., sub_hi_dim_then_sub_mod instead of sub_mod). The current CHECK lines reflect the buggy behavior where the existing sub-register index is overwritten instead of composed.
When splitting a tuple instruction operand that already has a sub-register index (e.g., %R.sub_hi_dim), the aie-split-instrs-create pass was overwriting the existing index with the new split sub-register (e.g., sub_mod) instead of composing them (sub_hi_dim_then_sub_mod). This caused downstream passes to reference wrong sub-register lanes. For example, a PADD_2D_pseudo using the high dimension of an eds register would have its split operands reference the low dimension sub-registers, leading to undefined uses that later crashed in the AIESuperRegRewriter pass with 'Virtual register defs don't dominate all uses'. Fix by using TRI.composeSubRegIndices() to properly compose the existing sub-register index with the new split sub-register index.
konstantinschwarz
requested review from
F-Stuckmann,
SagarMaheshwari99,
abhinay-anubola,
abnikant,
andcarminati,
katerynamuts,
khallouh,
martien-de-jong,
mludevid,
niwinanto and
stephenneuendorffer
as code owners
SagarMaheshwari99
approved these changes
Apr 24, 2026
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When splitting a tuple instruction operand that already has a
sub-register index (e.g., %R.sub_hi_dim), the aie-split-instrs-create
pass was overwriting the existing index with the new split sub-register
(e.g., sub_mod) instead of composing them (sub_hi_dim_then_sub_mod).
This caused downstream passes to reference wrong sub-register lanes.
For example, a PADD_2D_pseudo using the high dimension of an eds
register would have its split operands reference the low dimension
sub-registers, leading to undefined uses that later crashed in
the AIESuperRegRewriter pass with 'Virtual register defs don't
dominate all uses'.
Fix by using TRI.composeSubRegIndices() to properly compose the
existing sub-register index with the new split sub-register index.