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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using Microsoft.Boogie;
using System.Diagnostics.Contracts;
namespace GPUVerify {
class AdversarialAbstraction {
private GPUVerifier verifier;
internal AdversarialAbstraction(GPUVerifier verifier) {
this.verifier = verifier;
}
internal void Abstract() {
List<Declaration> NewTopLevelDeclarations = new List<Declaration>();
foreach (Declaration d in verifier.Program.TopLevelDeclarations) {
if (d is Variable && verifier.KernelArrayInfo.Contains(d as Variable) &&
verifier.ArrayModelledAdversarially(d as Variable)) {
continue;
}
if (d is Implementation) {
Abstract(d as Implementation);
}
if (d is Procedure) {
Abstract(d as Procedure);
}
NewTopLevelDeclarations.Add(d);
}
verifier.Program.TopLevelDeclarations = NewTopLevelDeclarations;
AbstractRequiresClauses(verifier.KernelProcedure);
}
private void AbstractRequiresClauses(Procedure proc) {
RequiresSeq newRequires = new RequiresSeq();
foreach (Requires r in proc.Requires) {
var visitor = new AccessesAdversarialArrayVisitor(verifier);
visitor.VisitRequires(r);
if (!visitor.found) {
newRequires.Add(r);
}
}
proc.Requires = newRequires;
}
private void Abstract(Procedure proc) {
AbstractModifiesSet(proc);
}
private void AbstractModifiesSet(Procedure proc) {
IdentifierExprSeq NewModifies = new IdentifierExprSeq();
foreach (IdentifierExpr e in proc.Modifies) {
var visitor = new AccessesAdversarialArrayVisitor(verifier);
visitor.VisitIdentifierExpr(e);
if(!visitor.found) {
NewModifies.Add(e);
}
}
proc.Modifies = NewModifies;
}
private void Abstract(Implementation impl) {
VariableSeq NewLocVars = new VariableSeq();
foreach (Variable v in impl.LocVars) {
Debug.Assert(!verifier.KernelArrayInfo.getGroupSharedArrays().Contains(v));
NewLocVars.Add(v);
}
impl.LocVars = NewLocVars;
if (CommandLineOptions.Unstructured)
impl.Blocks = impl.Blocks.Select(Abstract).ToList();
else
impl.StructuredStmts = Abstract(impl.StructuredStmts);
}
private StmtList Abstract(StmtList stmtList) {
Contract.Requires(stmtList != null);
StmtList result = new StmtList(new List<BigBlock>(), stmtList.EndCurly);
foreach (BigBlock bodyBlock in stmtList.BigBlocks) {
result.BigBlocks.Add(Abstract(bodyBlock));
}
return result;
}
private CmdSeq Abstract(CmdSeq cs) {
var result = new CmdSeq();
foreach (Cmd c in cs) {
if (c is AssignCmd) {
AssignCmd assign = c as AssignCmd;
var lhss = new List<AssignLhs>();
var rhss = new List<Expr>();
for (int i = 0; i != assign.Lhss.Count; i++) {
AssignLhs lhs = assign.Lhss[i];
Expr rhs = assign.Rhss[i];
ReadCollector rc = new ReadCollector(verifier.KernelArrayInfo);
rc.Visit(rhs);
bool foundAdversarial = false;
foreach (AccessRecord ar in rc.accesses) {
if (verifier.ArrayModelledAdversarially(ar.v)) {
foundAdversarial = true;
break;
}
}
if (foundAdversarial) {
Debug.Assert(lhs is SimpleAssignLhs);
result.Add(new HavocCmd(c.tok, new IdentifierExprSeq(new IdentifierExpr[] { (lhs as SimpleAssignLhs).AssignedVariable })));
continue;
}
WriteCollector wc = new WriteCollector(verifier.KernelArrayInfo);
wc.Visit(lhs);
if (wc.GetAccess() != null && verifier.ArrayModelledAdversarially(wc.GetAccess().v)) {
continue; // Just remove the write
}
lhss.Add(lhs);
rhss.Add(rhs);
}
if (lhss.Count != 0) {
result.Add(new AssignCmd(assign.tok, lhss, rhss));
}
continue;
}
result.Add(c);
}
return result;
}
private Block Abstract(Block b) {
b.Cmds = Abstract(b.Cmds);
return b;
}
private BigBlock Abstract(BigBlock bb) {
BigBlock result = new BigBlock(bb.tok, bb.LabelName, new CmdSeq(), null, bb.tc);
result.simpleCmds = Abstract(bb.simpleCmds);
if (bb.ec is WhileCmd) {
WhileCmd WhileCommand = bb.ec as WhileCmd;
result.ec =
new WhileCmd(WhileCommand.tok, WhileCommand.Guard, WhileCommand.Invariants, Abstract(WhileCommand.Body));
}
else if (bb.ec is IfCmd) {
IfCmd IfCommand = bb.ec as IfCmd;
Debug.Assert(IfCommand.elseIf == null);
result.ec = new IfCmd(IfCommand.tok, IfCommand.Guard, Abstract(IfCommand.thn), IfCommand.elseIf, IfCommand.elseBlock != null ? Abstract(IfCommand.elseBlock) : null);
}
else {
Debug.Assert(bb.ec == null || bb.ec is BreakCmd);
}
return result;
}
class AccessesAdversarialArrayVisitor : StandardVisitor {
internal bool found;
private GPUVerifier verifier;
internal AccessesAdversarialArrayVisitor(GPUVerifier verifier) {
this.found = false;
this.verifier = verifier;
}
public override Variable VisitVariable(Variable v) {
if (verifier.KernelArrayInfo.Contains(v)) {
if (verifier.ArrayModelledAdversarially(v)) {
found = true;
}
}
return base.VisitVariable(v);
}
}
}
}
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