public static bool isEqual(GenKillWeight w1, GenKillWeight w2) {
Contract.Requires(w2 != null);
Contract.Requires(w1 != null);
if (w1.isZero)
return w2.isZero;
if (w2.isZero)
return w1.isZero;
return (w1.gen.Equals(w2.gen) && w1.kill.Equals(w2.kill));
}
public ICFG(Implementation impl) {
Contract.Requires(impl != null);
this.graph = new Graph<Block/*!*/>();
this.procsCalled = new Dictionary<string/*!*/, List<Block/*!*/>/*!*/>();
this.nodes = new HashSet<Block/*!*/>();
this.succEdges = new Dictionary<Block/*!*/, HashSet<Block/*!*/>/*!*/>();
this.predEdges = new Dictionary<Block/*!*/, HashSet<Block/*!*/>/*!*/>();
this.priority = new Dictionary<Block/*!*/, int>();
this.srcNodes = new HashSet<Block/*!*/>();
this.exitNodes = new HashSet<Block/*!*/>();
this.weightBefore = new Dictionary<Block/*!*/, GenKillWeight/*!*/>();
this.weightAfter = new Dictionary<Block/*!*/, GenKillWeight/*!*/>();
this.liveVarsAfter = new Dictionary<Block/*!*/, HashSet<Variable/*!*/>/*!*/>();
this.liveVarsBefore = new Dictionary<Block/*!*/, HashSet<Variable/*!*/>/*!*/>();
summary = GenKillWeight.zero();
this.impl = impl;
Initialize(impl);
}
public static GenKillWeight combine(GenKillWeight w1, GenKillWeight w2) {
Contract.Requires(w2 != null);
Contract.Requires(w1 != null);
Contract.Ensures(Contract.Result<GenKillWeight>() != null);
if (w1.isZero)
return w2;
if (w2.isZero)
return w1;
HashSet<Variable> g = new HashSet<Variable>(w1.gen);
g.UnionWith(w2.gen);
HashSet<Variable> k = new HashSet<Variable>(w1.kill);
k.IntersectWith(w2.kill);
return new GenKillWeight(g, k);
//return new GenKillWeight(w1.gen.Union(w2.gen), w1.kill.Intersection(w2.kill));
}
public static GenKillWeight projectLocals(GenKillWeight w) {
Contract.Requires(w != null);
Contract.Ensures(Contract.Result<GenKillWeight>() != null);
HashSet<Variable/*!*/> gen = new HashSet<Variable>();
foreach (Variable v in w.gen)
{
if (isGlobal(v))
gen.Add(v);
}
HashSet<Variable/*!*/> kill = new HashSet<Variable>();
foreach (Variable v in w.kill)
{
if (isGlobal(v))
kill.Add(v);
}
return new GenKillWeight(gen, kill);
}
public static GenKillWeight extend(GenKillWeight w1, GenKillWeight w2) {
Contract.Requires(w2 != null);
Contract.Requires(w1 != null);
Contract.Ensures(Contract.Result<GenKillWeight>() != null);
if (w1.isZero || w2.isZero)
return zero();
HashSet<Variable> t = new HashSet<Variable>(w2.gen);
t.ExceptWith(w1.kill);
HashSet<Variable> g = new HashSet<Variable>(w1.gen);
g.UnionWith(t);
HashSet<Variable> k = new HashSet<Variable>(w1.kill);
k.UnionWith(w2.kill);
return new GenKillWeight(g, k);
//return new GenKillWeight(w1.gen.Union(w2.gen.Difference(w1.kill)), w1.kill.Union(w2.kill));
}
private static GenKillWeight getWeightBeforeCall(Cmd cmd) {
Contract.Requires(cmd != null);
Contract.Ensures(Contract.Result<GenKillWeight>() != null);
Contract.Assert((cmd is CallCmd));
if (weightCacheBeforeCall.ContainsKey(cmd))
return weightCacheBeforeCall[cmd];
HashSet<Variable/*!*/>/*!*/ gen = new HashSet<Variable/*!*/>();
HashSet<Variable/*!*/>/*!*/ kill = new HashSet<Variable/*!*/>();
CallCmd/*!*/ ccmd = cce.NonNull((CallCmd/*!*/)cmd);
foreach (Expr/*!*/ expr in ccmd.Ins) {
Contract.Assert(expr != null);
VariableCollector/*!*/ collector = new VariableCollector();
collector.Visit(expr);
gen.UnionWith(collector.usedVars);
}
Contract.Assert(ccmd.Proc != null);
// Variables in requires are considered as "read"
foreach (Requires/*!*/ re in ccmd.Proc.Requires) {
Contract.Assert(re != null);
VariableCollector/*!*/ collector = new VariableCollector();
collector.Visit(re.Condition);
foreach (Variable/*!*/ v in collector.usedVars) {
Contract.Assert(v != null);
if (v is GlobalVariable) {
gen.Add(v);
}
}
}
// Old variables in ensures are considered as "read"
foreach (Ensures/*!*/ re in ccmd.Proc.Ensures) {
Contract.Assert(re != null);
VariableCollector/*!*/ collector = new VariableCollector();
collector.Visit(re.Condition);
foreach (Variable/*!*/ v in collector.oldVarsUsed) {
Contract.Assert(v != null);
if (v is GlobalVariable) {
gen.Add(v);
}
}
}
GenKillWeight/*!*/ ret = new GenKillWeight(gen, kill);
Contract.Assert(ret != null);
weightCacheAfterCall[cmd] = ret;
return ret;
}
private static GenKillWeight getWeightAfterCall(Cmd cmd) {
Contract.Requires(cmd != null);
Contract.Ensures(Contract.Result<GenKillWeight>() != null);
if (weightCacheAfterCall.ContainsKey(cmd))
return weightCacheAfterCall[cmd];
HashSet<Variable/*!*/>/*!*/ gen = new HashSet<Variable/*!*/>();
HashSet<Variable/*!*/>/*!*/ kill = new HashSet<Variable/*!*/>();
Contract.Assert(cmd is CallCmd);
CallCmd/*!*/ ccmd = cce.NonNull((CallCmd)cmd);
foreach (IdentifierExpr/*!*/ ie in ccmd.Outs) {
Contract.Assert(ie != null);
if (ie.Decl != null)
kill.Add(ie.Decl);
}
// Variables in ensures are considered as "read"
foreach (Ensures/*!*/ re in cce.NonNull(ccmd.Proc).Ensures) {
Contract.Assert(re != null);
VariableCollector/*!*/ collector = new VariableCollector();
collector.Visit(re.Condition);
foreach (Variable/*!*/ v in collector.usedVars) {
Contract.Assert(v != null);
if (v is GlobalVariable) {
gen.Add(v);
}
}
}
GenKillWeight/*!*/ ret = new GenKillWeight(gen, kill);
Contract.Assert(ret != null);
weightCacheAfterCall[cmd] = ret;
return ret;
}
private static GenKillWeight getWeight(Cmd cmd, Implementation impl, Program prog) {
Contract.Requires(cmd != null);
Contract.Ensures(Contract.Result<GenKillWeight>() != null);
if (weightCache.ContainsKey(cmd))
return weightCache[cmd];
HashSet<Variable/*!*/>/*!*/ gen = new HashSet<Variable/*!*/>();
HashSet<Variable/*!*/>/*!*/ kill = new HashSet<Variable/*!*/>();
GenKillWeight/*!*/ ret;
if (cmd is AssignCmd) {
AssignCmd/*!*/ assignCmd = (AssignCmd)cmd;
Contract.Assert(cmd != null);
// I must first iterate over all the targets and remove the live ones.
// After the removals are done, I must add the variables referred on
// the right side of the removed targets
foreach (AssignLhs/*!*/ lhs in assignCmd.Lhss) {
Contract.Assert(lhs != null);
Variable var = lhs.DeepAssignedVariable;
if (var != null) {
if (lhs is SimpleAssignLhs) {
// we should only remove non-map target variables because there is an implicit
// read of a map variable in an assignment to it
kill.Add(var);
}
}
}
int index = 0;
foreach (Expr/*!*/ expr in assignCmd.Rhss) {
Contract.Assert(expr != null);
VariableCollector/*!*/ collector = new VariableCollector();
collector.Visit(expr);
gen.UnionWith(collector.usedVars);
AssignLhs lhs = assignCmd.Lhss[index];
if (lhs is MapAssignLhs) {
// If the target is a map, then all indices are also read
MapAssignLhs malhs = (MapAssignLhs)lhs;
foreach (Expr e in malhs.Indexes) {
VariableCollector/*!*/ c = new VariableCollector();
c.Visit(e);
gen.UnionWith(c.usedVars);
}
}
index++;
}
ret = new GenKillWeight(gen, kill);
} else if (cmd is HavocCmd) {
HavocCmd/*!*/ havocCmd = (HavocCmd)cce.NonNull(cmd);
foreach (IdentifierExpr/*!*/ expr in havocCmd.Vars) {
Contract.Assert(expr != null);
if (expr.Decl != null) {
kill.Add(expr.Decl);
}
}
ret = new GenKillWeight(gen, kill);
} else if (cmd is PredicateCmd) {
Contract.Assert((cmd is AssertCmd || cmd is AssumeCmd));
PredicateCmd/*!*/ predicateCmd = (PredicateCmd)cce.NonNull(cmd);
if (predicateCmd.Expr is LiteralExpr && prog != null && impl != null) {
LiteralExpr le = (LiteralExpr)predicateCmd.Expr;
if (le.IsFalse) {
var globals = prog.GlobalVariables;
Contract.Assert(cce.NonNullElements(globals));
foreach (Variable/*!*/ v in globals) {
Contract.Assert(v != null);
kill.Add(v);
}
foreach (Variable/*!*/ v in impl.LocVars) {
Contract.Assert(v != null);
kill.Add(v);
}
foreach (Variable/*!*/ v in impl.OutParams) {
Contract.Assert(v != null);
kill.Add(v);
}
}
} else {
VariableCollector/*!*/ collector = new VariableCollector();
collector.Visit(predicateCmd.Expr);
gen.UnionWith(collector.usedVars);
}
ret = new GenKillWeight(gen, kill);
} else if (cmd is CommentCmd) {
ret = new GenKillWeight(gen, kill);
// comments are just for debugging and don't affect verification
} else if (cmd is SugaredCmd) {
SugaredCmd/*!*/ sugCmd = (SugaredCmd)cmd;
Contract.Assert(sugCmd != null);
ret = getWeight(sugCmd.Desugaring, impl, prog);
} else if (cmd is StateCmd) {
StateCmd/*!*/ stCmd = (StateCmd)cmd;
Contract.Assert(stCmd != null);
List<Cmd>/*!*/ cmds = stCmd.Cmds;
Contract.Assert(cmds != null);
int len = cmds.Count;
ret = GenKillWeight.one();
for (int i = len - 1; i >= 0; i--) {
GenKillWeight/*!*/ w = getWeight(cmds[i], impl, prog);
Contract.Assert(w != null);
ret = GenKillWeight.extend(w, ret);
}
foreach (Variable/*!*/ v in stCmd.Locals) {
Contract.Assert(v != null);
kill.Add(v);
}
ret = GenKillWeight.extend(new GenKillWeight(gen, kill), ret);
} else {
{
Contract.Assert(false);
throw new cce.UnreachableException();
}
}
weightCache[cmd] = ret;
return ret;
}
public bool setWeightBefore(GenKillWeight w) {
Contract.Requires(w != null);
GenKillWeight/*!*/ prev = cfg.weightBefore[block];
Contract.Assert(prev != null);
GenKillWeight/*!*/ curr = GenKillWeight.combine(w, prev);
Contract.Assert(curr != null);
if (GenKillWeight.isEqual(prev, curr))
return false;
cfg.weightBefore[block] = curr;
return true;
}