ENG-1889

[AdvaySingh1]

No description provided.

[linear]

ENG-1889

[greptile-apps]

Greptile Summary

This PR replaces an assert in Gia_ManAppendAnd that fired when both literals referenced the same variable with a graceful handler that reclaims the appended object and returns the simplified result (x & x = x, x & !x = 0).

• The --p->nObjs reclamation does not roll back the Vec_IntPush(&p->vHash, 0) that Gia_ManAppendObj performs when structural hashing is active, leaving p->vHash permanently one entry ahead of p->nObjs and corrupting hash lookups for all subsequently appended nodes.

Confidence Score: 3/5

Not safe to merge as-is — the missing vHash rollback silently corrupts structural hashing for all subsequent AND nodes when a degenerate AND is encountered.

A P1 correctness bug exists: the object-count decrement (--p->nObjs) is not paired with Vec_IntPop(&p->vHash), leaving the hash vector out-of-sync. This desynchronisation causes incorrect hash slot assignments for every node appended after a degenerate AND is detected.

src/aig/gia/gia.h — specifically the early-return block in Gia_ManAppendAnd around lines 733–737.

Important Files Changed

Filename	Overview
src/aig/gia/gia.h	Replaces a same-variable literal assertion in Gia_ManAppendAnd with a graceful handler, but the --p->nObjs reclamation omits the matching Vec_IntPop(&p->vHash) rollback, leaving p->vHash out-of-sync when structural hashing is active.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["Gia_ManAppendAnd(p, iLit0, iLit1)"] --> B["Gia_ManAppendObj(p)\n• vHash.push(0) if hashing active\n• return pObjs[nObjs++]"]
    B --> C{assertions pass?}
    C -- No --> FAIL[abort]
    C -- Yes --> D{"!fGiaSimple &&\nLit2Var(iLit0)==Lit2Var(iLit1)?"}
    D -- Yes --> E["print WARNING\n--p->nObjs  ⚠️ vHash NOT popped"]
    E --> F{iLit0 == iLit1?}
    F -- Yes --> G["return iLit0\n(x & x = x)"]
    F -- No --> H["return 0\n(x & !x = false)"]
    D -- No --> I["fill pObj fields\n(iDiff0/1, fCompl0/1)"]
    I --> J["handle pFanData / fSweeper / fBuiltInSim"]
    J --> K["return Gia_ObjToLit(p, pObj)"]

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