Dafny: continued translation of "parallel" statements (Assign and Proof forms are mostly there, Call is missing and so is compilation)

Dafny: included some test cases for the "parallel" statement
Dafny: starting changing old "foreach" statements to the new "parallel" statement

6 files changed, 373 insertions, 191 deletions

diff --git a/Source/Dafny/Translator.cs b/Source/Dafny/Translator.cs
index 45817bdc..52449d81 100644
--- a/Source/Dafny/Translator.cs
+++ b/Source/Dafny/Translator.cs
@@ -3348,159 +3348,24 @@ namespace Microsoft.Dafny {
         if (s.Kind == ParallelStmt.ParBodyKind.Assign) {

           Contract.Assert(s.Ens.Count == 0);

           var s0 = (AssignStmt)s.S0;

-

-          // The statement:

-          //   parallel (x,y | Range(x,y)) {

-          //     (a)   E(x,y) . f :=  G(x,y);

-          //     (b)   A(x,y) [ I0(x,y), I1(x,y), ... ] :=  G(x,y);

-          //   }

-          // translate into:

-          //   if (*) {

-          //     // check definedness of Range

-          //     var x,y;

-          //     havoc x,y;

-          //     CheckWellDefined( Range );

-          //     assume Range;

-          //     // check definedness of the other expressions

-          //     (a)

-          //       CheckWellDefined( E.F );

-          //       check that E.f is in the modifies frame;

-          //       CheckWellDefined( G );

-          //       check nat restrictions for the RHS

-          //     (b)

-          //       CheckWellDefined( A[I0,I1,...] );

-          //       check that A[I0,I1,...] is in the modifies frame;

-          //       CheckWellDefined( G );

-          //       check nat restrictions for the RHS

-          //     // check for duplicate LHSs

-          //     var x', y';

-          //     havoc x', y';

-          //     assume Range[x,y := x',y'];

-          //     assume !(x == x' && y == y');

-          //     (a)

-          //       assert E(x,y) != E(x',y');

-          //     (b)

-          //       assert !( A(x,y)==A(x',y') && I0(x,y)==I0(x',y') && I1(x,y)==I1(x',y') && ... );

-          //

-          //     assume false;

-          //

-          //   } else {

-          //     var oldHeap := $Heap;

-          //     havoc $Heap;

-          //     assume $HeapSucc(oldHeap, $Heap);

-          //     (a)

-          //       assume (forall<alpha> o: ref, F: Field alpha ::

-          //         $Heap[o,F] = oldHeap[o,F] ||

-          //         (exists x,y :: Range(x,y) && o == E(x,y) && F = f));

-          //       assume (forall x,y ::  Range ==> $Heap[ E[$Heap:=oldHeap], F] == G[$Heap:=oldHeap]);

-          //     (b)

-          //       assume (forall<alpha> o: ref, F: Field alpha ::

-          //         $Heap[o,F] = oldHeap[o,F] ||

-          //         (exists x,y :: Range(x,y) && o == A(x,y) && F = Index(I0,I1,...)));

-          //       assume (forall x,y ::  Range ==> $Heap[ A[$Heap:=oldHeap], Index(I0,I1,...)] == G[$Heap:=oldHeap]);

-          //   }

-

-          var definedness = new StmtListBuilder();

-          var substMap = SetupBoundVarsAsLocals(s.BoundVars, definedness, locals, etran);

-          if (s.Range != null) {

-            Expression range = Substitute(s.Range, null, substMap);

-            TrStmt_CheckWellformed(range, definedness, locals, etran, false);

-            definedness.Add(new Bpl.AssumeCmd(s.Range.tok, etran.TrExpr(range)));

-          }

-

-          var lhs = Substitute(s0.Lhs.Resolved, null, substMap);

-          TrStmt_CheckWellformed(lhs, definedness, locals, etran, false);

-          Bpl.Expr obj, F;

-          string description = GetObjFieldDetails(lhs, etran, out obj, out F);

-          definedness.Add(Assert(lhs.tok, Bpl.Expr.SelectTok(lhs.tok, etran.TheFrame(lhs.tok), obj, F),

-            "assignment may update " + description + " not in the enclosing context's modifies clause"));

-          if (s0.Rhs is ExprRhs) {

-            var rhs = Substitute(((ExprRhs)s0.Rhs).Expr, null, substMap);

-            TrStmt_CheckWellformed(rhs, definedness, locals, etran, false);

-            // TODO: check nat restrictions for the RHS

-          }

-

-          // check for duplicate LHSs

-          var substMapPrime = SetupBoundVarsAsLocals(s.BoundVars, definedness, locals, etran);

-          var lhsPrime = Substitute(s0.Lhs.Resolved, null, substMapPrime);

-          if (s.Range != null) {

-            Expression range = Substitute(s.Range, null, substMapPrime);

-            definedness.Add(new Bpl.AssumeCmd(range.tok, etran.TrExpr(range)));

-          }

-          // assume !(x == x' && y == y');

-          Bpl.Expr eqs = Bpl.Expr.True;

-          foreach (var bv in s.BoundVars) {

-            var x = substMap[bv];

-            var xPrime = substMapPrime[bv];

-            // TODO: in the following line, is the term equality okay, or does it have to include things like Set#Equal sometimes too?

-            eqs = BplAnd(eqs, Bpl.Expr.Eq(etran.TrExpr(x), etran.TrExpr(xPrime)));

-          }

-          definedness.Add(new Bpl.AssumeCmd(s.Tok, Bpl.Expr.Not(eqs)));

-          Bpl.Expr objPrime, FPrime;

-          GetObjFieldDetails(lhsPrime, etran, out objPrime, out FPrime);

-          definedness.Add(Assert(s0.Tok,

-            Bpl.Expr.Or(Bpl.Expr.Neq(obj, objPrime), Bpl.Expr.Neq(F, FPrime)),

-            "left-hand sides for different parallel-statement bound variables may refer to the same location"));

-

-          definedness.Add(new Bpl.AssumeCmd(s.Tok, Bpl.Expr.False));

-

-          // Now for the translation of the update itself 

-

+          var definedness = new Bpl.StmtListBuilder();

           var updater = new Bpl.StmtListBuilder();

-          Bpl.IdentifierExpr prevHeap = GetPrevHeapVar_IdExpr(stmt.Tok, locals);

-          var prevEtran = new ExpressionTranslator(this, predef, prevHeap);

-          updater.Add(Bpl.Cmd.SimpleAssign(stmt.Tok, prevHeap, etran.HeapExpr));

-          updater.Add(new Bpl.HavocCmd(stmt.Tok, new Bpl.IdentifierExprSeq((Bpl.IdentifierExpr/*TODO: this cast is rather dubious*/)etran.HeapExpr)));

-          updater.Add(new Bpl.AssumeCmd(stmt.Tok, FunctionCall(stmt.Tok, BuiltinFunction.HeapSucc, null, prevHeap, etran.HeapExpr)));

-

-          // Here comes:

-          //   assume (forall<alpha> o: ref, f: Field alpha ::

-          //     $Heap[o,f] = oldHeap[o,f] ||

-          //     (exists x,y :: Range(x,y)[$Heap:=oldHeap] &&

-          //                    o == Object(x,y)[$Heap:=oldHeap] && f == Field(x,y)[$Heap:=oldHeap]));

-          Bpl.TypeVariable alpha = new Bpl.TypeVariable(stmt.Tok, "alpha");

-          Bpl.BoundVariable oVar = new Bpl.BoundVariable(stmt.Tok, new Bpl.TypedIdent(stmt.Tok, "$o", predef.RefType));

-          Bpl.IdentifierExpr o = new Bpl.IdentifierExpr(stmt.Tok, oVar);

-          Bpl.BoundVariable fVar = new Bpl.BoundVariable(stmt.Tok, new Bpl.TypedIdent(stmt.Tok, "$f", predef.FieldName(stmt.Tok, alpha)));

-          Bpl.IdentifierExpr f = new Bpl.IdentifierExpr(stmt.Tok, fVar);

-          Bpl.Expr heapOF = ExpressionTranslator.ReadHeap(stmt.Tok, etran.HeapExpr, o, f);

-          Bpl.Expr oldHeapOF = ExpressionTranslator.ReadHeap(stmt.Tok, prevHeap, o, f);

-          Bpl.VariableSeq xBvars = new Bpl.VariableSeq();

-          var xBody = etran.TrBoundVariables(s.BoundVars, xBvars);

-          if (s.Range != null) {

-            xBody = BplAnd(xBody, prevEtran.TrExpr(s.Range));

-          }

-          Bpl.Expr xObj, xField;

-          GetObjFieldDetails(s0.Lhs.Resolved, prevEtran, out xObj, out xField);

-          xBody = BplAnd(xBody, Bpl.Expr.Eq(o, xObj));

-          xBody = BplAnd(xBody, Bpl.Expr.Eq(f, xField));

-          Bpl.Expr xObjField = new Bpl.ExistsExpr(s.Tok, xBvars, xBody);

-          Bpl.Expr body = Bpl.Expr.Or(Bpl.Expr.Eq(heapOF, oldHeapOF), xObjField);

-          Bpl.Expr qq = new Bpl.ForallExpr(stmt.Tok, new Bpl.TypeVariableSeq(alpha), new Bpl.VariableSeq(oVar, fVar), body);

-          updater.Add(new Bpl.AssumeCmd(stmt.Tok, qq));

-

-          if (s0.Rhs is ExprRhs) {

-            //   assume (forall x,y :: Range(x,y)[$Heap:=oldHeap] ==>

-            //                         $Heap[ Object(x,y)[$Heap:=oldHeap], Field(x,y)[$Heap:=oldHeap] ] == G[$Heap:=oldHeap] ));

-            xBvars = new Bpl.VariableSeq();

-            Bpl.Expr xAnte = etran.TrBoundVariables(s.BoundVars, xBvars);

-            if (s.Range != null) {

-              xAnte = BplAnd(xAnte, prevEtran.TrExpr(s.Range));

-            }

-            GetObjFieldDetails(s0.Lhs.Resolved, prevEtran, out xObj, out xField);

-            var xHeapOF = ExpressionTranslator.ReadHeap(stmt.Tok, etran.HeapExpr, xObj, xField);

-            var g = prevEtran.TrExpr(((ExprRhs)s0.Rhs).Expr);

-            qq = new Bpl.ForallExpr(stmt.Tok, xBvars, Bpl.Expr.Imp(xAnte, Bpl.Expr.Eq(xHeapOF, g)));

-            updater.Add(new Bpl.AssumeCmd(stmt.Tok, qq));

-          }

+          TrParallelAssign(s, s0, definedness, updater, locals, etran);

           // All done, so put the two pieces together

           builder.Add(new Bpl.IfCmd(s.Tok, null, definedness.Collect(s.Tok), null, updater.Collect(s.Tok)));

           builder.Add(CaptureState(stmt.Tok));

 

         } else if (s.Kind == ParallelStmt.ParBodyKind.Call) {

           // TODO: call forall

+

         } else if (s.Kind == ParallelStmt.ParBodyKind.Proof) {

-          // TODO

+          var definedness = new Bpl.StmtListBuilder();

+          var exporter = new Bpl.StmtListBuilder();

+          TrParallelProof(s, definedness, exporter, locals, etran);

+          // All done, so put the two pieces together

+          builder.Add(new Bpl.IfCmd(s.Tok, null, definedness.Collect(s.Tok), null, exporter.Collect(s.Tok)));

+          builder.Add(CaptureState(stmt.Tok));

+

         } else {

           Contract.Assert(false);  // unexpected kind

         }

@@ -3573,6 +3438,240 @@ namespace Microsoft.Dafny {
       }

     }

 

+    void TrParallelAssign(ParallelStmt s, AssignStmt s0,

+      Bpl.StmtListBuilder definedness, Bpl.StmtListBuilder updater, Bpl.VariableSeq locals, ExpressionTranslator etran) {

+      // The statement:

+      //   parallel (x,y | Range(x,y)) {

+      //     (a)   E(x,y) . f :=  G(x,y);

+      //     (b)   A(x,y) [ I0(x,y), I1(x,y), ... ] :=  G(x,y);

+      //   }

+      // translate into:

+      //   if (*) {

+      //     // check definedness of Range

+      //     var x,y;

+      //     havoc x,y;

+      //     CheckWellDefined( Range );

+      //     assume Range;

+      //     // check definedness of the other expressions

+      //     (a)

+      //       CheckWellDefined( E.F );

+      //       check that E.f is in the modifies frame;

+      //       CheckWellDefined( G );

+      //       check nat restrictions for the RHS

+      //     (b)

+      //       CheckWellDefined( A[I0,I1,...] );

+      //       check that A[I0,I1,...] is in the modifies frame;

+      //       CheckWellDefined( G );

+      //       check nat restrictions for the RHS

+      //     // check for duplicate LHSs

+      //     var x', y';

+      //     havoc x', y';

+      //     assume Range[x,y := x',y'];

+      //     assume !(x == x' && y == y');

+      //     (a)

+      //       assert E(x,y) != E(x',y');

+      //     (b)

+      //       assert !( A(x,y)==A(x',y') && I0(x,y)==I0(x',y') && I1(x,y)==I1(x',y') && ... );

+      //

+      //     assume false;

+      //

+      //   } else {

+      //     var oldHeap := $Heap;

+      //     havoc $Heap;

+      //     assume $HeapSucc(oldHeap, $Heap);

+      //     (a)

+      //       assume (forall<alpha> o: ref, F: Field alpha ::

+      //         $Heap[o,F] = oldHeap[o,F] ||

+      //         (exists x,y :: Range(x,y) && o == E(x,y) && F = f));

+      //       assume (forall x,y ::  Range ==> $Heap[ E[$Heap:=oldHeap], F] == G[$Heap:=oldHeap]);

+      //     (b)

+      //       assume (forall<alpha> o: ref, F: Field alpha ::

+      //         $Heap[o,F] = oldHeap[o,F] ||

+      //         (exists x,y :: Range(x,y) && o == A(x,y) && F = Index(I0,I1,...)));

+      //       assume (forall x,y ::  Range ==> $Heap[ A[$Heap:=oldHeap], Index(I0,I1,...)] == G[$Heap:=oldHeap]);

+      //   }

+

+      var substMap = SetupBoundVarsAsLocals(s.BoundVars, definedness, locals, etran);

+      if (s.Range != null) {

+        Expression range = Substitute(s.Range, null, substMap);

+        TrStmt_CheckWellformed(range, definedness, locals, etran, false);

+        definedness.Add(new Bpl.AssumeCmd(s.Range.tok, etran.TrExpr(range)));

+      }

+

+      var lhs = Substitute(s0.Lhs.Resolved, null, substMap);

+      TrStmt_CheckWellformed(lhs, definedness, locals, etran, false);

+      Bpl.Expr obj, F;

+      string description = GetObjFieldDetails(lhs, etran, out obj, out F);

+      definedness.Add(Assert(lhs.tok, Bpl.Expr.SelectTok(lhs.tok, etran.TheFrame(lhs.tok), obj, F),

+        "assignment may update " + description + " not in the enclosing context's modifies clause"));

+      if (s0.Rhs is ExprRhs) {

+        var r = (ExprRhs)s0.Rhs;

+        var rhs = Substitute(r.Expr, null, substMap);

+        TrStmt_CheckWellformed(rhs, definedness, locals, etran, false);

+        // TODO: check nat restrictions for the RHS

+        //   CheckSubrange(rhs.tok, bRhs, checkSubrangeType, definedness);

+      }

+

+      // check for duplicate LHSs

+      var substMapPrime = SetupBoundVarsAsLocals(s.BoundVars, definedness, locals, etran);

+      var lhsPrime = Substitute(s0.Lhs.Resolved, null, substMapPrime);

+      if (s.Range != null) {

+        Expression range = Substitute(s.Range, null, substMapPrime);

+        definedness.Add(new Bpl.AssumeCmd(range.tok, etran.TrExpr(range)));

+      }

+      // assume !(x == x' && y == y');

+      Bpl.Expr eqs = Bpl.Expr.True;

+      foreach (var bv in s.BoundVars) {

+        var x = substMap[bv];

+        var xPrime = substMapPrime[bv];

+        // TODO: in the following line, is the term equality okay, or does it have to include things like Set#Equal sometimes too?

+        eqs = BplAnd(eqs, Bpl.Expr.Eq(etran.TrExpr(x), etran.TrExpr(xPrime)));

+      }

+      definedness.Add(new Bpl.AssumeCmd(s.Tok, Bpl.Expr.Not(eqs)));

+      Bpl.Expr objPrime, FPrime;

+      GetObjFieldDetails(lhsPrime, etran, out objPrime, out FPrime);

+      definedness.Add(Assert(s0.Tok,

+        Bpl.Expr.Or(Bpl.Expr.Neq(obj, objPrime), Bpl.Expr.Neq(F, FPrime)),

+        "left-hand sides for different parallel-statement bound variables may refer to the same location"));

+

+      definedness.Add(new Bpl.AssumeCmd(s.Tok, Bpl.Expr.False));

+

+      // Now for the translation of the update itself 

+

+      Bpl.IdentifierExpr prevHeap = GetPrevHeapVar_IdExpr(s.Tok, locals);

+      var prevEtran = new ExpressionTranslator(this, predef, prevHeap);

+      updater.Add(Bpl.Cmd.SimpleAssign(s.Tok, prevHeap, etran.HeapExpr));

+      updater.Add(new Bpl.HavocCmd(s.Tok, new Bpl.IdentifierExprSeq((Bpl.IdentifierExpr/*TODO: this cast is rather dubious*/)etran.HeapExpr)));

+      updater.Add(new Bpl.AssumeCmd(s.Tok, FunctionCall(s.Tok, BuiltinFunction.HeapSucc, null, prevHeap, etran.HeapExpr)));

+

+      // Here comes:

+      //   assume (forall<alpha> o: ref, f: Field alpha ::

+      //     $Heap[o,f] = oldHeap[o,f] ||

+      //     (exists x,y :: Range(x,y)[$Heap:=oldHeap] &&

+      //                    o == Object(x,y)[$Heap:=oldHeap] && f == Field(x,y)[$Heap:=oldHeap]));

+      Bpl.TypeVariable alpha = new Bpl.TypeVariable(s.Tok, "alpha");

+      Bpl.BoundVariable oVar = new Bpl.BoundVariable(s.Tok, new Bpl.TypedIdent(s.Tok, "$o", predef.RefType));

+      Bpl.IdentifierExpr o = new Bpl.IdentifierExpr(s.Tok, oVar);

+      Bpl.BoundVariable fVar = new Bpl.BoundVariable(s.Tok, new Bpl.TypedIdent(s.Tok, "$f", predef.FieldName(s.Tok, alpha)));

+      Bpl.IdentifierExpr f = new Bpl.IdentifierExpr(s.Tok, fVar);

+      Bpl.Expr heapOF = ExpressionTranslator.ReadHeap(s.Tok, etran.HeapExpr, o, f);

+      Bpl.Expr oldHeapOF = ExpressionTranslator.ReadHeap(s.Tok, prevHeap, o, f);

+      Bpl.VariableSeq xBvars = new Bpl.VariableSeq();

+      var xBody = etran.TrBoundVariables(s.BoundVars, xBvars);

+      if (s.Range != null) {

+        xBody = BplAnd(xBody, prevEtran.TrExpr(s.Range));

+      }

+      Bpl.Expr xObj, xField;

+      GetObjFieldDetails(s0.Lhs.Resolved, prevEtran, out xObj, out xField);

+      xBody = BplAnd(xBody, Bpl.Expr.Eq(o, xObj));

+      xBody = BplAnd(xBody, Bpl.Expr.Eq(f, xField));

+      Bpl.Expr xObjField = new Bpl.ExistsExpr(s.Tok, xBvars, xBody);

+      Bpl.Expr body = Bpl.Expr.Or(Bpl.Expr.Eq(heapOF, oldHeapOF), xObjField);

+      Bpl.Expr qq = new Bpl.ForallExpr(s.Tok, new Bpl.TypeVariableSeq(alpha), new Bpl.VariableSeq(oVar, fVar), body);

+      updater.Add(new Bpl.AssumeCmd(s.Tok, qq));

+

+      if (s0.Rhs is ExprRhs) {

+        //   assume (forall x,y :: Range(x,y)[$Heap:=oldHeap] ==>

+        //                         $Heap[ Object(x,y)[$Heap:=oldHeap], Field(x,y)[$Heap:=oldHeap] ] == G[$Heap:=oldHeap] ));

+        xBvars = new Bpl.VariableSeq();

+        Bpl.Expr xAnte = etran.TrBoundVariables(s.BoundVars, xBvars);

+        if (s.Range != null) {

+          xAnte = BplAnd(xAnte, prevEtran.TrExpr(s.Range));

+        }

+        var rhs = ((ExprRhs)s0.Rhs).Expr;

+        var g = prevEtran.TrExpr(rhs);

+        GetObjFieldDetails(s0.Lhs.Resolved, prevEtran, out xObj, out xField);

+        var xHeapOF = ExpressionTranslator.ReadHeap(s.Tok, etran.HeapExpr, xObj, xField);

+

+        Type lhsType;

+        if (lhs is FieldSelectExpr) {

+          lhsType = ((FieldSelectExpr)lhs).Type;

+        } else {

+          lhsType = null;

+        }

+        g = etran.CondApplyBox(rhs.tok, g, rhs.Type, lhsType);

+

+        qq = new Bpl.ForallExpr(s.Tok, xBvars, Bpl.Expr.Imp(xAnte, Bpl.Expr.Eq(xHeapOF, g)));

+        updater.Add(new Bpl.AssumeCmd(s.Tok, qq));

+      }

+    }

+

+    void TrParallelProof(ParallelStmt s, Bpl.StmtListBuilder definedness, Bpl.StmtListBuilder exporter, Bpl.VariableSeq locals, ExpressionTranslator etran) {

+      // Translate:

+      //   parallel (x,y | Range(x,y))

+      //     ensures Post(x,y);

+      //   {

+      //     Body;

+      //   }

+      // as:

+      //   if (*) {

+      //     var x,y;

+      //     havoc x,y;

+      //     CheckWellDefined( Range );

+      //     assume Range(x,y);

+      //     Tr( Body );

+      //     CheckWellDefined( Post );

+      //     assert Post;

+      //     assume false;

+      //   } else {

+      //     assume (forall x,y :: Range(x,y) ==> Post(x,y));

+      //   }

+

+      // Note, it would be nicer (and arguably more appropriate) to do a SetupBoundVarsAsLocals

+      // here (rather than a TrBoundVariables).  However, there is currently no way to apply

+      // a substMap to a statement (in particular, to s.Body), so that doesn't work here.

+      Bpl.VariableSeq bvars = new Bpl.VariableSeq();

+      var ante = etran.TrBoundVariables(s.BoundVars, bvars, true);

+      locals.AddRange(bvars);

+      var havocIds = new Bpl.IdentifierExprSeq();

+      foreach (Bpl.Variable bv in bvars) {

+        havocIds.Add(new Bpl.IdentifierExpr(s.Tok, bv));

+      }

+      definedness.Add(new Bpl.HavocCmd(s.Tok, havocIds));

+      definedness.Add(new Bpl.AssumeCmd(s.Tok, ante));

+      if (s.Range != null) {

+        TrStmt_CheckWellformed(s.Range, definedness, locals, etran, false);

+        definedness.Add(new Bpl.AssumeCmd(s.Range.tok, etran.TrExpr(s.Range)));

+      }

+

+      TrStmt(s.Body, definedness, locals, etran);

+

+      // check that postconditions hold

+      foreach (var ens in s.Ens) {

+        TrStmt_CheckWellformed(ens.E, definedness, locals, etran, false);

+        if (!ens.IsFree) {

+          bool splitHappened;  // we actually don't care

+          foreach (var split in TrSplitExpr(ens.E, etran, out splitHappened)) {

+            if (!split.IsFree) {

+              definedness.Add(Assert(split.E.tok, split.E, "possible violation of postcondition of parallel statement"));

+            }

+          }

+        }

+      }

+

+      definedness.Add(new Bpl.AssumeCmd(s.Tok, Bpl.Expr.False));

+

+      // Now for the other branch, where the ensures clauses are exported.

+

+      bvars = new Bpl.VariableSeq();

+      Dictionary<IVariable, Expression> substMap;

+      ante = etran.TrBoundVariablesRename(s.BoundVars, bvars, out substMap);

+      if (s.Range != null) {

+        var range = Substitute(s.Range, null, substMap);

+        TrStmt_CheckWellformed(range, definedness, locals, etran, false);

+        ante = BplAnd(ante, etran.TrExpr(range));

+      }

+

+      Bpl.Expr post = Bpl.Expr.True;

+      foreach (var ens in s.Ens) {

+        var p = Substitute(ens.E, null, substMap);

+        post = BplAnd(post, etran.TrExpr(p));

+      }

+

+      Bpl.Expr qq = new Bpl.ForallExpr(s.Tok, bvars, Bpl.Expr.Imp(ante, post));

+      exporter.Add(new Bpl.AssumeCmd(s.Tok, qq));

+    }

+

     private string GetObjFieldDetails(Expression lhs, ExpressionTranslator etran, out Bpl.Expr obj, out Bpl.Expr F) {

       string description;

       if (lhs is FieldSelectExpr) {

@@ -5326,12 +5425,22 @@ namespace Microsoft.Dafny {
       }

 

       public Bpl.Expr TrBoundVariables(List<BoundVar/*!*/> boundVars, Bpl.VariableSeq bvars) {

+        return TrBoundVariables(boundVars, bvars, false);

+      }

+

+      public Bpl.Expr TrBoundVariables(List<BoundVar/*!*/> boundVars, Bpl.VariableSeq bvars, bool translateAsLocals) {

         Contract.Requires(boundVars != null);

         Contract.Ensures(Contract.Result<Bpl.Expr>() != null);

 

         Bpl.Expr typeAntecedent = Bpl.Expr.True;

         foreach (BoundVar bv in boundVars) {

-          Bpl.Variable bvar = new Bpl.BoundVariable(bv.tok, new Bpl.TypedIdent(bv.tok, bv.UniqueName, translator.TrType(bv.Type)));

+          var tid = new Bpl.TypedIdent(bv.tok, bv.UniqueName, translator.TrType(bv.Type));

+          Bpl.Variable bvar;

+          if (translateAsLocals) {

+            bvar = new Bpl.LocalVariable(bv.tok, tid);

+          } else {

+            bvar = new Bpl.BoundVariable(bv.tok, tid);

+          }

           bvars.Add(bvar);

           Bpl.Expr wh = translator.GetWhereClause(bv.tok, new Bpl.IdentifierExpr(bv.tok, bvar), bv.Type, this);

           if (wh != null) {

@@ -5341,6 +5450,28 @@ namespace Microsoft.Dafny {
         return typeAntecedent;

       }

 

+      public Bpl.Expr TrBoundVariablesRename(List<BoundVar> boundVars, Bpl.VariableSeq bvars, out Dictionary<IVariable, Expression> substMap) {

+        Contract.Requires(boundVars != null);

+        Contract.Requires(bvars != null);

+

+        substMap = new Dictionary<IVariable, Expression>();

+        Bpl.Expr typeAntecedent = Bpl.Expr.True;

+        foreach (BoundVar bv in boundVars) {

+          var newBoundVar = new BoundVar(bv.tok, bv.Name, bv.Type);

+          IdentifierExpr ie = new IdentifierExpr(newBoundVar.tok, newBoundVar.UniqueName);

+          ie.Var = newBoundVar; ie.Type = ie.Var.Type;  // resolve ie here

+          substMap.Add(bv, ie);

+          Bpl.Variable bvar = new Bpl.BoundVariable(newBoundVar.tok, new Bpl.TypedIdent(newBoundVar.tok, newBoundVar.UniqueName, translator.TrType(newBoundVar.Type)));

+          bvars.Add(bvar);

+          var bIe = new Bpl.IdentifierExpr(bvar.tok, bvar);

+          Bpl.Expr wh = translator.GetWhereClause(bv.tok, bIe, newBoundVar.Type, this);

+          if (wh != null) {

+            typeAntecedent = translator.BplAnd(typeAntecedent, wh);

+          }

+        }

+        return typeAntecedent;

+      }

+

       public ExprSeq FunctionInvocationArguments(FunctionCallExpr e) {

         Contract.Requires(e != null);

         Contract.Ensures(Contract.Result<ExprSeq>() != null);

diff --git a/Test/VSI-Benchmarks/b5.dfy b/Test/VSI-Benchmarks/b5.dfy
index cd132ef3..612b96ba 100644
--- a/Test/VSI-Benchmarks/b5.dfy
+++ b/Test/VSI-Benchmarks/b5.dfy
@@ -57,12 +57,12 @@ class Queue<T> {
     tail.next := n;

     tail := n;

 

-    foreach (m in spine) {

+    parallel (m | m in spine) {

       m.tailContents := m.tailContents + [t];

     }

     contents := head.tailContents;

 

-    foreach (m in spine) {

+    parallel (m | m in spine) {

       m.footprint := m.footprint + n.footprint;

     }

     footprint := footprint + n.footprint;

diff --git a/Test/dafny0/Answer b/Test/dafny0/Answer
index a3e5e11f..4b3d9814 100644
--- a/Test/dafny0/Answer
+++ b/Test/dafny0/Answer
@@ -947,6 +947,42 @@ Execution trace:
 

 Dafny program verifier finished with 27 verified, 6 errors

 

+-------------------- Parallel.dfy --------------------

+Parallel.dfy(29,18): Error: possible violation of postcondition of parallel statement

+Execution trace:

+    (0,0): anon0

+    (0,0): anon17_Else

+    (0,0): anon7

+    (0,0): anon20_Else

+    (0,0): anon10

+    (0,0): anon21_Then

+    (0,0): anon22_Then

+    (0,0): anon14

+Parallel.dfy(34,19): Error: assertion violation

+Execution trace:

+    (0,0): anon0

+    (0,0): anon17_Else

+    (0,0): anon7

+    (0,0): anon20_Else

+    (0,0): anon10

+    (0,0): anon21_Then

+    (0,0): anon22_Then

+Parallel.dfy(76,19): Error: assertion violation

+Execution trace:

+    (0,0): anon0

+    (0,0): anon10_Else

+    (0,0): anon3

+    (0,0): anon11_Then

+Parallel.dfy(82,20): Error: possible violation of postcondition of parallel statement

+Execution trace:

+    (0,0): anon0

+    (0,0): anon10_Else

+    (0,0): anon3

+    (0,0): anon11_Then

+    (0,0): anon12_Then

+

+Dafny program verifier finished with 12 verified, 4 errors

+

 -------------------- TypeParameters.dfy --------------------

 TypeParameters.dfy(44,22): Error: assertion violation

 Execution trace:

diff --git a/Test/dafny0/Parallel.dfy b/Test/dafny0/Parallel.dfy
index 0928c070..88a67957 100644
--- a/Test/dafny0/Parallel.dfy
+++ b/Test/dafny0/Parallel.dfy
@@ -1,48 +1,16 @@
-/*

-method ParallelStatement_Syntax()

-{

-  parallel (i: int | 0 <= i < a.Length && i % 2 == 0) {

-    a[i] := a[(i + 1) % a.Length] + 3;

-  }

-

-  parallel (o | o in spine) {

-    o.f := o.f + Repr;

-  }

-

-  parallel (x, y | x in S && 0 <= y+x < 100) {

-    Lemma(x, y);

-  }

-

-  parallel (p | 0 <= p)

-    ensures F(p) <= Sum(p) * (p-1) + 100;

-  {

-    assert G(p);

-    ghost var t;

-    if (p % 2 == 0) {

-      assert G(p) == F(p+2);

-      t := p*p;

-    } else {

-      assume H(p, 20) < 100;  // don't know how to justify this

-      t := p;

-    }

-    PowerLemma(p, t);

-    t := t + 1;

-    PowerLemma(p, t);

-  }

-}

-*/

-

 class C {

-  var f: set<object>;

+  var data: int;

+  var st: set<object>;

 }

 

+// This method more or less just tests the syntax, resolution, and basic verification

 method ParallelStatement_Resolve(

     a: array<int>,

     spine: set<C>,

     Repr: set<object>,

     S: set<int>

   )

-  requires a != null;

+  requires a != null && null !in spine;

   modifies a, spine;

 {

   parallel (i: int | 0 <= i < a.Length && i % 2 == 0) {

@@ -50,7 +18,7 @@ method ParallelStatement_Resolve(
   }

 

   parallel (o | o in spine) {

-    o.f := o.f + Repr;

+    o.st := o.st + Repr;

   }

 

   parallel (x, y | x in S && 0 <= y+x < 100) {

@@ -58,12 +26,12 @@ method ParallelStatement_Resolve(
   }

 

   parallel (p | 0 <= p)

-    ensures F(p) <= Sum(p) * (p-1) + 100;

+    ensures F(p) <= Sum(p) * (p-1) + 100;  // error (no connection is known between F and Sum)

   {

     assert 0 <= G(p);

     ghost var t;

     if (p % 2 == 0) {

-      assert G(p) == F(p+2);

+      assert G(p) == F(p+2);  // error (there's nothing that gives any relation between F and G)

       t := p*p;

     } else {

       assume H(p, 20) < 100;  // don't know how to justify this

@@ -79,6 +47,53 @@ method Lemma(x: int, y: int)
 ghost method PowerLemma(x: int, y: int)

 

 function F(x: int): int

-function G(x: int): int

+function G(x: int): nat

 function H(x: int, y: int): int

 function Sum(x: int): int

+

+// ---------------------------------------------------------------------

+

+method M0(S: set<C>)

+  requires null !in S;

+  modifies S;

+  ensures forall o :: o in S ==> o.data == 85;

+  ensures forall o :: o != null && o !in S ==> o.data == old(o.data);

+{

+  parallel (s | s in S) {

+    s.data := 85;

+  }

+}

+

+method M1(S: set<C>, x: C)

+  requires null !in S && x in S;

+{

+  parallel (s | s in S)

+    ensures s.data < 100;

+  {

+    assume s.data == 85;

+  }

+  if (*) {

+    assert x.data == 85;  // error (cannot be inferred from parallel ensures clause)

+  } else {

+    assert x.data < 120;

+  }

+

+  parallel (s | s in S)

+    ensures s.data < 70;  // error

+  {

+    assume s.data == 85;

+  }

+}

+

+method M2() returns (a: array<int>)

+  ensures a != null;

+  ensures forall i,j :: 0 <= i < a.Length/2 <= j < a.Length ==> a[i] < a[j];

+{

+  a := new int[250];

+  parallel (i: nat | i < 125) {

+    a[i] := 423;

+  }

+  parallel (i | 125 <= i < 250) {

+    a[i] := 300 + i;

+  }

+}

diff --git a/Test/dafny0/runtest.bat b/Test/dafny0/runtest.bat
index bfa88b54..a670ced5 100644
--- a/Test/dafny0/runtest.bat
+++ b/Test/dafny0/runtest.bat
@@ -16,7 +16,7 @@ for %%f in (TypeTests.dfy NatTypes.dfy SmallTests.dfy Definedness.dfy
             Array.dfy MultiDimArray.dfy NonGhostQuantifiers.dfy AdvancedLHS.dfy

             Modules0.dfy Modules1.dfy BadFunction.dfy

             Comprehensions.dfy Basics.dfy ControlStructures.dfy

-            Termination.dfy DTypes.dfy

+            Termination.dfy DTypes.dfy Parallel.dfy

             TypeParameters.dfy Datatypes.dfy TypeAntecedents.dfy SplitExpr.dfy

             Refinement.dfy RefinementErrors.dfy LoopModifies.dfy

             ReturnErrors.dfy ReturnTests.dfy ChainingDisjointTests.dfy

diff --git a/Test/dafny1/Queue.dfy b/Test/dafny1/Queue.dfy
index bfb588be..0edfab81 100644
--- a/Test/dafny1/Queue.dfy
+++ b/Test/dafny1/Queue.dfy
@@ -85,12 +85,12 @@ class Queue<T> {
     tail.next := n;

     tail := n;

 

-    foreach (m in spine) {

+    parallel (m | m in spine) {

       m.tailContents := m.tailContents + [t];

     }

     contents := head.tailContents;

 

-    foreach (m in spine) {

+    parallel (m | m in spine) {

       m.footprint := m.footprint + n.footprint;

     }

     footprint := footprint + n.footprint;