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Missing termination measures #675

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merged 3 commits into from
Sep 14, 2023
Merged

Missing termination measures #675

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b3d4f15
sadd termination
Dspil Sep 14, 2023
4d73949
sliceconstruct termination measure
Dspil Sep 14, 2023
0ab9faa
change dummy comment in synthesized
Dspil Sep 14, 2023
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4 changes: 3 additions & 1 deletion src/main/scala/viper/gobra/translator/encodings/slices/SliceEncoding.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -342,6 +342,7 @@ class SliceEncoding(arrayEmb : SharedArrayEmbedding) extends LeafTypeEncoding {
* ensures soffset(result) == offset
* ensures slen(result) == len
* ensures scap(result) == cap
* dereases _
* }}}
*/
private val constructGenerator : FunctionGenerator[vpr.Type] = new FunctionGenerator[vpr.Type] {
Expand All @@ -357,6 +358,7 @@ class SliceEncoding(arrayEmb : SharedArrayEmbedding) extends LeafTypeEncoding {
val pre2 = synthesized(vpr.LeCmp(vpr.IntLit(0)(), lenDecl.localVar))("Slice length might be negative")
val pre3 = synthesized(vpr.LeCmp(lenDecl.localVar, capDecl.localVar))("Slice length might exceed capacity")
val pre4 = synthesized(vpr.LeCmp(vpr.Add(offsetDecl.localVar, capDecl.localVar)(), ctx.array.len(aDecl.localVar)()))("Slice capacity might exceed the capacity of the underlying array")
val pre5 = synthesized(termination.DecreasesWildcard(None))("This function is assumed to terminate")

// postconditions
val result = vpr.Result(ctx.slice.typ(typ))()
Expand All @@ -369,7 +371,7 @@ class SliceEncoding(arrayEmb : SharedArrayEmbedding) extends LeafTypeEncoding {
s"${Names.sliceConstruct}_${Names.serializeType(typ)}",
Seq(aDecl, offsetDecl, lenDecl, capDecl),
ctx.slice.typ(typ),
Seq(pre1, pre2, pre3, pre4),
Seq(pre1, pre2, pre3, pre4, pre5),
Seq(post1, post2, post3, post4),
None
)()
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6 changes: 5 additions & 1 deletion src/main/scala/viper/gobra/translator/library/slices/SlicesImpl.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,8 @@
package viper.gobra.translator.library.slices

import viper.gobra.translator.library.arrays.Arrays
import viper.silver.plugin.standard.termination
import viper.gobra.translator.util.ViperUtil.synthesized
import viper.silver.{ast => vpr}

class SlicesImpl(val arrays : Arrays) extends Slices {
Expand Down Expand Up @@ -274,6 +276,7 @@ class SlicesImpl(val arrays : Arrays) extends Slices {
* {{{
* function sadd(left: Int, right: Int): Int
* ensures result == left + right
* decreases
* {
* left + right
* }
Expand All @@ -284,7 +287,8 @@ class SlicesImpl(val arrays : Arrays) extends Slices {
val rDecl = vpr.LocalVarDecl("right", vpr.Int)()
val body : vpr.Exp = vpr.Add(lDecl.localVar, rDecl.localVar)()
val post : vpr.Exp = vpr.EqCmp(vpr.Result(vpr.Int)(), body)()
vpr.Function("sadd", Seq(lDecl, rDecl), vpr.Int, Seq(), Seq(post), Some(body))()
val pre : vpr.Exp = synthesized(termination.DecreasesTuple(Seq.empty, None))("Termination measure")
vpr.Function("sadd", Seq(lDecl, rDecl), vpr.Int, Seq(pre), Seq(post), Some(body))()
}

/**
Expand Down
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