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Unroll first and last iteration in encoding #399

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Unroll first and last iteration in encoding #399

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d992181
Unroll first and last iteration in encoding
JonasAlaif Dec 6, 2021
6300c10
Merge branch 'master' into loop-unrolling
JonasAlaif Jun 30, 2022
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17 changes: 11 additions & 6 deletions src/main/scala/viper/carbon/modules/impls/DefaultLoopModule.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -422,9 +422,11 @@ class DefaultLoopModule(val verifier: Verifier) extends LoopModule with StmtComp
}

private def handleWhile(w: sil.While): Stmt = {
val guard = translateExp(w.cond)
val (invs, writtenVars) = getWhileInformation(w)
val guard = translateExp(w.cond)
val (invs, writtenVars) = getWhileInformation(w)

If(
guard,
beforeLoopHead(invs, w.info.getUniqueInfo[LoopInfo].map(loopInfo => loopInfo.head.get)) ++
MaybeCommentBlock("Havoc loop written variables (except locals)",
Havoc((writtenVars map translateExp).asInstanceOf[Seq[Var]]) ++
Expand All @@ -448,10 +450,13 @@ class DefaultLoopModule(val verifier: Verifier) extends LoopModule with StmtComp
stmts
}
)) ++
MaybeCommentBlock("Inhale loop invariant after loop, and assume guard",
Assume(guard.not) ++ stateModule.assumeGoodState ++
inhale(invs map (x => (x, errors.WhileFailed(x)))) ++ executeUnfoldings(invs, (inv => errors.Internal(inv)))
)
MaybeCommentBlock("Unroll last loop iteration; inhale loop invariant and assume guard, execute body and lastly assume !guard",
stateModule.assumeGoodState ++
inhale(invs map (x => (x, errors.WhileFailed(x)))) ++ executeUnfoldings(invs, (inv => errors.Internal(inv))) ++
Assume(guard) ++ MaybeCommentBlock("Translate loop body", stmtModule.translateStmt(w.body)) ++ Assume(guard.not)
),
Statements.EmptyStmt
)
}

override def handleStmt(s: sil.Stmt, statesStackOfPackageStmt: List[Any] = null, allStateAssms: Exp = TrueLit(), insidePackageStmt: Boolean = false): (Seqn => Seqn) = {
Expand Down