protected override ICode VisitIf(StmtIf s)
{
if (!VisitorFindContinuations.Any(s))
{
// 'If' contains no continuations, so no distribution can be done
return(s);
}
if (VisitorOnlyStatements.Only(s, Stmt.NodeType.If, Stmt.NodeType.Continuation) && this.ifInfo == null)
{
// 'If' only contains continuations, so no distribution can be done
// Must visit base method to find contained continuations
return(base.VisitIf(s));
}
bool finalise = false;
if (this.ifInfo == null)
{
finalise = true;
this.ifInfo = new IfInfo();
}
this.ifInfo.Conditions.Push(s.Condition);
var then = this.Visit(s.Then);
this.ifInfo.Conditions.Pop();
this.ifInfo.Conditions.Push(this.ctx.ExprGen.NotAutoSimplify(s.Condition));
var @else = this.Visit(s.Else);
this.ifInfo.Conditions.Pop();
if (then != s.Then || @else != s.Else)
{
var @if = new StmtIf(s.Ctx, s.Condition, (Stmt)then, (Stmt)@else);
if (finalise && this.ifInfo.AddToIf.Any())
{
var ifStmts = this.ifInfo.AddToIf.GroupBy(x => x.Item1.To, x => x.Item2).Select(x =>
new StmtIf(s.Ctx, x.Aggregate((a, b) => this.ctx.ExprGen.Or(a, b)),
this.ifInfo.AddToIf.First(y => y.Item1.To == x.Key).Item1, null)
);
var stmts = new Stmt[] { @if }.Concat(ifStmts).ToArray();
this.ifInfo = null;
return(new StmtBlock(s.Ctx, stmts));
}
else
{
if (finalise)
{
this.ifInfo = null;
}
return(@if);
}
}
else
{
// In this case, no continuations will have been found, so there cannot be any conditions to add
if (finalise)
{
this.ifInfo = null;
}
return(s);
}
}
public static IEnumerable <StmtContinuation> Get(ICode root)
{
var v = new VisitorFindContinuations();
v.Visit(root);
return(v.Continuations);
}
public static bool Any(ICode root)
{
var v = new VisitorFindContinuations();
v.Visit(root);
return(v.Continuations.Any());
}
protected override ICode VisitCil(StmtCil s)
{
var bsi = this.blockStartInfos[s];
var stack = new Stack <Expr>(bsi.Stack.Reverse());
var locals = bsi.Locals.Cast <Expr>().ToArray();
var args = bsi.Args.Cast <Expr>().ToArray();
var orgStack = stack.ToArray();
var orgLocals = locals.ToArray();
var orgArgs = args.ToArray();
var cil = new CilProcessor(this.ctx, stack, locals, args, this.instResults);
var stmts = new List <Stmt>();
switch (s.BlockType)
{
case StmtCil.SpecialBlock.Normal:
foreach (var inst in s.Insts)
{
var stmt = cil.Process(inst);
if (stmt != null)
{
stmts.Add(stmt);
}
}
break;
case StmtCil.SpecialBlock.Start:
// Do nothing
break;
case StmtCil.SpecialBlock.End:
stmts.Add(cil.ProcessReturn());
break;
default:
throw new InvalidOperationException("Invalid block type: " + s.BlockType);
}
this.stmtVarsChanged.Add(s, new StmtVarChanged {
Stack = stack.Zip(orgStack, (a, b) => a == b).ToArray(),
Locals = locals.Zip(orgLocals, (a, b) => a == b).ToArray(),
Args = args.Zip(orgArgs, (a, b) => a == b).ToArray(),
});
// Merge phi's
var continuations = VisitorFindContinuations.Get(s);
foreach (var continuation in continuations)
{
this.CreateOrMergeBsi(continuation.To, stack.ToArray(), locals, args);
}
// End
var next = (Stmt)this.Visit(s.EndCil);
stmts.Add(next);
return(new StmtBlock(this.ctx, stmts));
}
private Tuple <Stmt, Stmt> RemoveContinuation(Stmt s)
{
// Return Item1 = Statement 's' with continuation removed
// Return Item2 = Block that only continuation in 's' points to, otherwise null
// This must not return a null statement if empty, as then the 'try' statements won't know
// if it is a 'catch' or 'finally' statement. Uses a StmtEmpty instead.
var contCount = VisitorFindContinuations.Get(s).Count();
if (contCount == 0)
{
// Blocks with no continuations must end with a 'throw'
return(Tuple.Create(s, (Stmt)null));
}
if (contCount != 1)
{
return(null);
}
switch (s.StmtType)
{
case Stmt.NodeType.Block:
var statements = ((StmtBlock)s).Statements.ToArray();
if (statements.Length == 0)
{
return(null);
}
if (statements.Last().StmtType != Stmt.NodeType.Continuation)
{
return(null);
}
var cont = (StmtContinuation)statements.Last();
if (!cont.LeaveProtectedRegion)
{
return(null);
}
if (statements.Length == 1)
{
return(Tuple.Create((Stmt) new StmtEmpty(s.Ctx), cont.To));
}
return(Tuple.Create((Stmt) new StmtBlock(s.Ctx, statements.Take(statements.Length - 1)), cont.To));
case Stmt.NodeType.Continuation:
var sCont = (StmtContinuation)s;
if (!sCont.LeaveProtectedRegion)
{
return(null);
}
return(Tuple.Create((Stmt) new StmtEmpty(s.Ctx), sCont.To));
default:
return(null);
}
}
protected override ICode VisitCil(StmtCil s)
{
var endStackSize = this.StackSizeAnalysis(s.Insts, s.StartStackSize);
s.EndStackSize = endStackSize;
var conts = VisitorFindContinuations.Get(s.EndCil);
Action <Stmt, int> setStackSize = null;
setStackSize = (stmt, stackSize) => {
// Set all try and catch stacksizes recursively, to handle multiple trys start on the same instruction
switch (stmt.StmtType)
{
case Stmt.NodeType.Cil:
((StmtCil)stmt).StartStackSize = stackSize;
return;
case Stmt.NodeType.Try:
var stmtTry = (StmtTry)stmt;
setStackSize(stmtTry.Try, stackSize);
if (stmtTry.Catches != null)
{
setStackSize(stmtTry.Catches.First().Stmt, 1);
}
// 'Finally' stack sizes do not need setting, as they will have defaulted to 0
// and this will always be correct
return;
case Stmt.NodeType.Return:
// do nothing
return;
default:
throw new NotSupportedException("Should not be seeing: " + stmt.StmtType);
}
};
foreach (var cont in conts)
{
setStackSize(cont.To, endStackSize);
}
return(base.VisitCil(s));
}
public static bool Any(ICode root) {
var v = new VisitorFindContinuations();
v.Visit(root);
return v.Continuations.Any();
}
public static IEnumerable<StmtContinuation> Get(ICode root) {
var v = new VisitorFindContinuations();
v.Visit(root);
return v.Continuations;
}
protected override ICode VisitTry(StmtTry s)
{
var @try = this.RemoveContinuation(s.Try);
if (@try != null)
{
if (s.Catches != null)
{
if (s.Catches.Count() != 1)
{
throw new InvalidOperationException("Should only ever see 1 catch here");
}
var sCatch = s.Catches.First();
var @catch = this.RemoveContinuation(sCatch.Stmt);
if (@catch != null)
{
if ((@try.Item2 == null || @catch.Item2 == null || @try.Item2 == @catch.Item2) && (@try.Item2 != null || @catch.Item2 != null))
{
var newTry = new StmtTry(s.Ctx, @try.Item1, new[] { new StmtTry.Catch(@catch.Item1, sCatch.ExceptionVar) }, null);
var newCont = new StmtContinuation(s.Ctx, @try.Item2 ?? @catch.Item2, false);
return(new StmtBlock(s.Ctx, newTry, newCont));
}
}
// Special case
// When 'leave' CIL branch to different instructions, allow specific code to be
// moved inside the 'try' or 'catch' block. It should be impossible for this code to throw an exception
var tryTos = VisitorFindContinuations.Get(@try.Item2);
if (tryTos.Count() == 1 && tryTos.First().To == @catch.Item2 && @try.Item2.StmtType == Stmt.NodeType.Block)
{
var try2Stmts = ((StmtBlock)@try.Item2).Statements.ToArray();
var s0 = try2Stmts.Take(try2Stmts.Length - 1);
if (s0.All(x => x.StmtType == Stmt.NodeType.Assignment))
{
var sN = try2Stmts.Last();
if (sN.StmtType == Stmt.NodeType.Continuation)
{
var newTry = new StmtTry(s.Ctx,
new StmtBlock(s.Ctx, @try.Item1, new StmtBlock(s.Ctx, s0), new StmtContinuation(s.Ctx, ((StmtContinuation)sN).To, true)),
s.Catches, null);
return(newTry);
}
}
}
}
if (s.Finally != null)
{
var @finally = this.RemoveContinuation(s.Finally);
if (@finally != null)
{
if ((@try.Item2 == null || @finally.Item2 == null || @try.Item2 == @finally.Item2) && (@try.Item2 != null || @finally.Item2 != null))
{
var newTry = new StmtTry(s.Ctx, @try.Item1, null, @finally.Item1);
var newCont = new StmtContinuation(s.Ctx, @try.Item2 ?? @finally.Item2, false);
return(new StmtBlock(s.Ctx, newTry, newCont));
}
}
}
// TODO: This is a hack for badly handling fault handlers. They are ignored at the moment
if (s.Catches == null && s.Finally == null)
{
var cont = @try.Item2 == null ? null : new StmtContinuation(s.Ctx, @try.Item2, false);
return(new StmtBlock(s.Ctx, @try.Item1, cont));
}
}
return(base.VisitTry(s));
}
protected override ICode VisitContinuation(StmtContinuation s)
{
// TODO: Why is this de-recursing blocks in continuations? Why doesn't it just derecurse itself (if possible)???
if (s.To.StmtType != Stmt.NodeType.Block)
{
return(base.VisitContinuation(s));
}
if (!this.seen.Add(s.To))
{
return(base.VisitContinuation(s));
}
var block = (StmtBlock)s.To;
foreach (var stmt in block.Statements)
{
if (stmt.StmtType == Stmt.NodeType.Continuation)
{
// Continuation not inside 'if'
var sCont = (StmtContinuation)stmt;
if (sCont.To == block)
{
// Recursive, so derecurse with no condition on loop
var body = new StmtBlock(s.Ctx, block.Statements.TakeWhile(x => x != stmt).ToArray());
var replaceWith = new StmtDoLoop(s.Ctx, body, new ExprLiteral(s.Ctx, true, s.Ctx.Boolean));
this.replaces.Add(s.To, replaceWith);
return(base.VisitContinuation(s));
}
}
if (stmt.StmtType == Stmt.NodeType.If)
{
// Continuation only statement within 'if' with only a 'then' clause
var sIf = (StmtIf)stmt;
if (sIf.Else == null && sIf.Then.StmtType == Stmt.NodeType.Continuation)
{
var sThen = (StmtContinuation)sIf.Then;
if (sThen.To == block)
{
// Recursive, so derecurse
var condition = sIf.Condition;
var bodyStmts = block.Statements.TakeWhile(x => x != stmt).ToArray();
var bodyLast = bodyStmts.LastOrDefault();
var body = new StmtBlock(s.Ctx, bodyStmts);
var loop = new StmtDoLoop(s.Ctx, body, condition);
var afterLoop = block.Statements.SkipWhile(x => x != stmt).Skip(1).ToArray();
if (VisitorFindContinuations.Get(new StmtBlock(s.Ctx, afterLoop)).Any(x => x.To == block))
{
// Cannot de-recurse yet, must wait for continuations to be merged
return(base.VisitContinuation(s));
}
Stmt replaceWith;
if (afterLoop.Any())
{
var loopAndAfter = new[] { loop }.Concat(afterLoop).ToArray();
replaceWith = new StmtBlock(s.Ctx, loopAndAfter);
}
else
{
replaceWith = loop;
}
this.replaces.Add(s.To, replaceWith);
return(base.VisitContinuation(s));
}
}
}
if (VisitorFindContinuations.Any(stmt))
{
// Another continuation present, cannot derecurse
break;
}
}
return(base.VisitContinuation(s));
}
protected override ICode VisitSwitch(StmtSwitch s)
{
// If switch statement contains no continuations then it doesn't need processing
if (!VisitorFindContinuations.Any(s))
{
return(base.VisitSwitch(s));
}
var ctx = s.Ctx;
// If any cases go to the same continuation as the default case, remove them
if (s.Default != null && s.Default.StmtType == Stmt.NodeType.Continuation)
{
var defaultCont = (StmtContinuation)s.Default;
var sameAsDefault = s.Cases
.Where(x => x.Stmt != null && x.Stmt.StmtType == Stmt.NodeType.Continuation && ((StmtContinuation)x.Stmt).To == defaultCont.To)
.ToArray();
if (sameAsDefault.Any())
{
var cases = s.Cases.Except(sameAsDefault);
return(new StmtSwitch(ctx, s.Expr, cases, s.Default));
}
}
// If multiple case statements all go the same continuation, then put them consecutively
var groupedByTo = s.Cases
.Where(x => x.Stmt != null && x.Stmt.StmtType == Stmt.NodeType.Continuation)
.GroupBy(x => ((StmtContinuation)x.Stmt).To)
.Where(x => x.Count() >= 2)
.ToArray();
if (groupedByTo.Any())
{
var cases = s.Cases.Except(groupedByTo.SelectMany(x => x));
var combinedCases = groupedByTo.SelectMany(x => {
var same = x.ToArray();
var last = same.Last();
var sameCases = same.Take(same.Length - 1).Select(y => new StmtSwitch.Case(y.Value, null))
.Concat(new StmtSwitch.Case(last.Value, last.Stmt));
return(sameCases);
});
var allCases = cases.Concat(combinedCases).ToArray();
return(new StmtSwitch(ctx, s.Expr, allCases, s.Default));
}
Func <Stmt, IEnumerable <StmtContinuation> > getSingleFinalContinuation = stmt => {
if (stmt == null)
{
return(Enumerable.Empty <StmtContinuation>());
}
var contCount = VisitorFindContinuations.Get(stmt).Count();
if (contCount == 0)
{
// Case contains return or throw
return(Enumerable.Empty <StmtContinuation>());
}
if (contCount == 1)
{
if (stmt.StmtType == Stmt.NodeType.Continuation)
{
return(new[] { (StmtContinuation)stmt });
}
if (stmt.StmtType == Stmt.NodeType.Block)
{
var stmtBlock = (StmtBlock)stmt;
var last = stmtBlock.Statements.LastOrDefault();
if (last != null && last.StmtType == Stmt.NodeType.Continuation)
{
return(new[] { (StmtContinuation)last });
}
}
}
return(new StmtContinuation[] { null });
};
var conts = s.Cases.Select(x => x.Stmt).Concat(s.Default).SelectMany(x => getSingleFinalContinuation(x)).ToArray();
if (conts.All(x => x != null))
{
// If all cases end with a continuation to the same stmt, then put that stmt after the switch and remove all continuations
if (conts.AllSame(x => x.To))
{
Func <Stmt, Stmt> removeCont = stmt => {
if (stmt == null)
{
return(null);
}
switch (stmt.StmtType)
{
case Stmt.NodeType.Continuation:
return(new StmtBreak(ctx));
case Stmt.NodeType.Block:
var sBlock = (StmtBlock)stmt;
var stmts = sBlock.Statements.ToArray();
if (stmts.Last().StmtType == Stmt.NodeType.Continuation)
{
stmts = stmts.Take(stmts.Length - 1).Concat(new StmtBreak(ctx)).ToArray();
return(new StmtBlock(ctx, stmts));
}
else
{
return(stmt);
}
default:
return(stmt);
}
};
var cases = s.Cases.Select(x => new StmtSwitch.Case(x.Value, removeCont(x.Stmt))).ToArray();
var @switch = new StmtSwitch(ctx, s.Expr, cases, removeCont(s.Default));
return(new StmtBlock(ctx, @switch, conts[0]));
}
else if (this.lastChance)
{
// HACK: Change it into multiple if statements
var multiValues = new List <int>();
var converted = s.Cases.Aggregate(s.Default, (@else, @case) => {
multiValues.Add(@case.Value);
if (@case.Stmt == null)
{
return(@else);
}
else
{
var cond = multiValues.Aggregate((Expr)ctx.Literal(false), (expr, caseValue) => {
return(ctx.ExprGen.Or(expr, ctx.ExprGen.Equal(s.Expr, ctx.Literal(caseValue))));
});
multiValues.Clear();
var @if = new StmtIf(ctx, cond, @case.Stmt, @else);
return(@if);
}
});
return(converted);
}
// If some cases end in a continuation that itself ends in a continuation that other cases end with
// then use an extra variable to store whether to execute the intermediate code
// TODO: This is too specific, need a more general-purpose solution to the problem where cases
// don't all end by going to the same place
//var contTos = conts.Select(x => x.To).Distinct().ToArray();
//var finalContTos = contTos.Select(x => getSingleFinalContinuation(x).Select(y => y.NullThru(z => z.To))).SelectMany(x => x).ToArray();
//if (!finalContTos.Any(x => x == null)) {
// // All continuations are fully substituted
// var distinctFinalContTos = finalContTos.Distinct().ToArray();
// if (distinctFinalContTos.Length == 1) {
// var selector = ctx.Local(ctx.Int32);
// var inIfCont = contTos.Single(x => x != distinctFinalContTos[0]);
// var inIf = new StmtContinuation(ctx, inIfCont, false);
// var afterIf = new StmtContinuation(ctx, distinctFinalContTos[0], false);
// var allCasesTo = new StmtBlock(ctx,
// new StmtIf(ctx, ctx.ExprGen.Equal(selector, ctx.Literal(1)), inIf, null),
// afterIf);
// Func<Stmt, Stmt> adjustCont = stmt => {
// var cont = VisitorFindContinuations.Get(stmt).Single();
// var newCont = new StmtContinuation(ctx, allCasesTo, false);
// var contChanged = (Stmt)VisitorReplace.V(stmt, cont, newCont);
// var sValue = cont.To == inIf.To ? 1 : 0;
// var withSelectorSet = new StmtBlock(ctx,
// new StmtAssignment(ctx, selector, ctx.Literal(sValue)),
// contChanged);
// return withSelectorSet;
// };
// var cases = s.Cases.Select(x => new StmtSwitch.Case(x.Value, adjustCont(x.Stmt))).ToArray();
// var @switch = new StmtSwitch(ctx, s.Expr, cases, adjustCont(s.Default));
// return @switch;
// } else {
// throw new NotImplementedException();
// }
//}
}
return(base.VisitSwitch(s));
}
private void CreateOrMergeBsi(Stmt s, Expr[] stack, Expr[] locals, Expr[] args)
{
if (s.StmtType == Stmt.NodeType.Try)
{
var sTry = (StmtTry)s;
// It is fine to use 'locals' and 'args' in catch/finally because the phi clustering performed later
// will conglomerate all the necessary variables
if (sTry.Catches != null)
{
var catch0 = sTry.Catches.First();
this.CreateOrMergeBsi(catch0.Stmt, new Expr[] { catch0.ExceptionVar }, locals, args);
}
if (sTry.Finally != null)
{
this.CreateOrMergeBsi(sTry.Finally, new Expr[0], locals, args);
}
this.CreateOrMergeBsi(sTry.Try, stack, locals, args);
return;
}
if (s.StmtType != Stmt.NodeType.Cil)
{
throw new InvalidCastException("Should not be seeing: " + s.StmtType);
}
// Perform create/merge
Func <Expr, IEnumerable <Expr> > flattenPhiExprs = null;
flattenPhiExprs = e => {
if (e.ExprType == Expr.NodeType.VarPhi)
{
return(((ExprVarPhi)e).Exprs.SelectMany(x => flattenPhiExprs(x)));
}
return(new[] { e });
};
Action <ExprVarPhi[], IEnumerable <Expr> > merge = (bsiVars, thisVars) => {
foreach (var v in bsiVars.Zip(thisVars, (a, b) => new { phi = a, add = b }))
{
if (v.add != null)
{
v.phi.Exprs = flattenPhiExprs(v.add).Concat(v.phi.Exprs).Where(x => x != null && x != v.phi).Distinct().ToArray();
}
}
};
BlockInitInfo bsi;
if (!this.blockStartInfos.TryGetValue(s, out bsi))
{
Func <IEnumerable <Expr>, ExprVarPhi[]> create = exprs => exprs.Select(x => {
if (x == null)
{
return(new ExprVarPhi(this.ctx)
{
Exprs = new Expr[0]
});
}
if (x.ExprType == Expr.NodeType.VarPhi)
{
return((ExprVarPhi)x);
}
return(new ExprVarPhi(this.ctx)
{
Exprs = new[] { x }
});
}).ToArray();
bsi = new BlockInitInfo {
Stack = create(stack),
Locals = create(locals),
Args = create(args),
};
this.blockStartInfos.Add(s, bsi);
}
else
{
merge(bsi.Stack, stack);
merge(bsi.Locals, locals);
merge(bsi.Args, args);
// Forward-merge through already-processed nodes for vars that are not changed in a node
var fmSeen = new HashSet <Stmt>();
Action <Stmt> forwardMerge = null;
forwardMerge = (stmt) => {
if (fmSeen.Add(stmt))
{
var fmBsi = this.blockStartInfos.ValueOrDefault(stmt);
var fmChanges = this.stmtVarsChanged.ValueOrDefault(stmt);
if (fmBsi != null && fmChanges != null)
{
var fmStack = fmBsi.Stack.Take(fmChanges.Stack.Length).Select((x, i) => fmChanges.Stack[i] ? x : null).ToArray();
var fmLocals = fmBsi.Locals.Take(fmChanges.Locals.Length).Select((x, i) => fmChanges.Locals[i] ? x : null).ToArray();
var fmArgs = fmBsi.Args.Take(fmChanges.Args.Length).Select((x, i) => fmChanges.Args[i] ? x : null).ToArray();
if (fmStack.Any(x => x != null) || fmLocals.Any(x => x != null) || fmArgs.Any(x => x != null))
{
var fmConts = VisitorFindContinuations.Get(stmt);
foreach (var fmCont in fmConts)
{
var fmContBsi = this.blockStartInfos.ValueOrDefault(fmCont.To);
if (fmContBsi != null)
{
merge(fmContBsi.Stack, fmStack);
merge(fmContBsi.Locals, fmLocals);
merge(fmContBsi.Args, fmArgs);
forwardMerge(fmCont.To);
}
}
}
}
}
};
forwardMerge(s);
}
}
