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Print evaluator type and values of free variable of assertion failure predicate #1084

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Print evaluator type and values of free variable of assertion failure predicate #1084

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efac9ba
Print evaluator type and values of free variable of assertion failure…
vkuncak May 29, 2021
375c3f1
Display require failure with a similar binding
vkuncak May 29, 2021
0a44f0d
Use asString on id and pred instead of toString
vkuncak May 30, 2021
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12 changes: 9 additions & 3 deletions core/src/main/scala/stainless/evaluators/Evaluator.scala
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Expand Up @@ -8,9 +8,15 @@ import inox.evaluators.DeterministicEvaluator
object optCodeGen extends inox.FlagOptionDef("codegen", false)

object Evaluator {
val RecursiveEvaluatorName: String = "default recursive evaluator"
val CodeGenEvaluatorName: String = "codegen evaluator"
var kind: String = RecursiveEvaluatorName
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Could we include the names into the evaluators instead of using the global variable kind? I'm afraid this requires changing Inox though to add a name field.

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Yes, I did not want to chage Inox this time. Maybe later.

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Instead of storing this in a global var, you could also compute the evaluator name to output inside the EvaluatorComponent based on ctx.options.findOptionOrDefault(optCodeGen) (especially since the property isn't really global).

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@vkuncak vkuncak May 31, 2021 •
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I don't like checking the option since it's not telling me what the evaluator actually is, but what it should have been set to and there is complex initialization logic that determines that. Unfortunately I cannot use reflection and print dynamic class name e.g.with .getClass.getSimpleName() because somewhere in the code an anonymous class is created and the actual class name is lost.

Another question: how do I make --check-models benefit from this?

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Reflection should work, I think there's something like getClass.getSimpleName which isn't too mangled.

Model checking currently takes place in Inox. The easiest way to get it to benefit from the new behavior would be to always disable optCheckModels in Inox (like here) and check models inside Stainless. The logic on the Inox side is here. Model checking in Stainless could actually be more powerful because we have access to the type checker, but you might need to be careful about running into loops.

def apply(p: StainlessProgram, ctx: inox.Context):
DeterministicEvaluator { val program: p.type } = {
if (ctx.options.findOptionOrDefault(optCodeGen)) CodeGenEvaluator(p, ctx)
else RecursiveEvaluator(p, ctx)
DeterministicEvaluator { val program: p.type } =
{
if (ctx.options.findOptionOrDefault(optCodeGen)) {
kind = CodeGenEvaluatorName
CodeGenEvaluator(p, ctx)
} else RecursiveEvaluator(p, ctx)
}
}
6 changes: 5 additions & 1 deletion core/src/main/scala/stainless/evaluators/EvaluatorComponent.scala
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Expand Up @@ -93,7 +93,11 @@ class EvaluatorRun(override val pipeline: extraction.StainlessPipeline)
}

// Build an evaluator once and only if there is something to evaluate
lazy val evaluator = p.getSemantics.getEvaluator
lazy val evaluator = {
val e = p.getSemantics.getEvaluator
reporter.info(s"using ${Evaluator.kind}")
e
}

// Evaluate an expression, logging events
def evaluate(title: String, e: Expr): Either[String, Expr] = evaluator eval e match {
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34 changes: 28 additions & 6 deletions core/src/main/scala/stainless/evaluators/RecursiveEvaluator.scala
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Expand Up @@ -3,6 +3,7 @@
package stainless
package evaluators


trait RecursiveEvaluator extends inox.evaluators.RecursiveEvaluator {
val program: Program

Expand All @@ -11,11 +12,31 @@ trait RecursiveEvaluator extends inox.evaluators.RecursiveEvaluator {
import program.trees._
import program.symbols._

import inox.utils.Position

def showPredicateFailure(kind: String, pred: Expr, err: Option[String])(implicit rctx: RC): Unit = {
val msg = (err match {
case Some(m) => m + ": "
case None => ""
}) + pred.asString
reporter.info(s"${Position.smartPos(pred.getPos)} ${kind} failure of ${msg}")
reporter.info(s"Relevant variables at ${kind} failure point:")
val m = rctx.mappings
val fvs = exprOps.variablesOf(pred)
def showBinding(v: Variable): String = {
" " + v.id.asString + " -> " + m.get(v.toVal).getOrElse("?").toString
}
val fvDump: String = fvs.map(showBinding).mkString("\n")
reporter.info(fvDump)
}


override def e(expr: Expr)(implicit rctx: RC, gctx: GC): Expr = expr match {
case Require(pred, body) =>
if (!ignoreContracts && e(pred) != BooleanLiteral(true))
throw RuntimeError("Requirement did not hold @" + expr.getPos)
e(body)
if (!ignoreContracts && e(pred) != BooleanLiteral(true)) {
showPredicateFailure("require", pred, None)
throw RuntimeError("Requirement did not hold @" + Position.smartPos(expr.getPos))
} else e(body)

case en @ Ensuring(body, pred) =>
e(en.toAssert)
Expand All @@ -24,9 +45,10 @@ trait RecursiveEvaluator extends inox.evaluators.RecursiveEvaluator {
e(body)

case Assert(pred, err, body) =>
if (!ignoreContracts && e(pred) != BooleanLiteral(true))
throw RuntimeError(err.getOrElse("Assertion failed @" + expr.getPos))
e(body)
if (!ignoreContracts && e(pred) != BooleanLiteral(true)) {
showPredicateFailure("assertion", pred, err)
throw RuntimeError(err.getOrElse("Assertion failed @" + Position.smartPos(pred.getPos)))
} else e(body)

case MatchExpr(scrut, cases) =>
val rscrut = e(scrut)
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