[AIEX] Fix register rewriting failed: cycle in copy bundle#793
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F-Stuckmann merged 2 commits intoaie-publicfrom Mar 12, 2026
Merged
[AIEX] Fix register rewriting failed: cycle in copy bundle#793F-Stuckmann merged 2 commits intoaie-publicfrom
F-Stuckmann merged 2 commits intoaie-publicfrom
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andcarminati
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F-Stuckmann,
SagarMaheshwari99,
abhinay-anubola,
katerynamuts,
khallouh,
konstantinschwarz,
martien-de-jong,
mludevid,
niwinanto and
stephenneuendorffer
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nit: superreg (double r)
| LLVM_DEBUG(dbgs() << "Expandable (not rewritable) " | ||
| << printReg(Reg, &TRI, 0, &MRI) << ":" | ||
| << printRegClassOrBank(Reg, MRI, &TRI) << '\n'); | ||
| Info.ExpandableRegs.push_back({Reg, AllSubRegs}); |
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Why don't we just store a pointer to SubRegSplit? That's a const pointer. Now we create three copies, one to populate it, one to create the pair, and one to push it into the vector.
F-Stuckmann
reviewed
Mar 5, 2026
| if (Reg.isPhysical()) | ||
| return false; | ||
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| auto &SubRegSplit = TRI.getSubRegSplit(MRI.getRegClass(Reg)->getID()); |
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nit: we could return SubRegSplit as an optional
F-Stuckmann
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Mar 11, 2026
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Related to the expansion of copy bundles whose reg candidates cannot be rewritten.
Introduce infrastructure to distinguish between expandable and rewritable registers in the AIEUnallocatedSuperRegRewriter pass. Key changes: - Add `isExpandableRegister()` helper to check if a register has a subregister split, consolidating duplicate checks - Replace `RegRewriteInfo` typedef with a struct containing two lists: - `ExpandableRegs`: All registers with SubRegSplit (superset) - `RewritableRegs`: Subset that can be immediately rewritten - Rename `getRewriteCandidates()` to `getRewriteAndExpandCandidates()` to reflect the dual-list approach - Update `expandCopyBundles()` to process all expandable registers - Update `rewriteCandidates()` to process only rewritable registers
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To fix the problem, we introduce infrastructure to distinguish between expandable and rewritable registers in the AIEUnallocatedSuperRegRewriter pass.