protected override ICode VisitAssignment(StmtAssignment s) {
var ctx = s.Ctx;
var newTarget = ctx.Local(s.Target.Type);
var phi = new ExprVarPhi(ctx) { Exprs = new[] { s.Target, newTarget } };
this.phiMap.Add(s.Target, phi);
return new StmtAssignment(s.Ctx, newTarget, (Expr)this.Visit(s.Expr));
}
protected override ICode VisitVarPhi(ExprVarPhi e) {
if (e.Type.IsBoolean()) {
List<Expr> newExprs = null;
foreach (var expr in e.Exprs) {
var mustConvert = !expr.Type.IsBoolean();
var newExpr = mustConvert ? this.ConvertToBoolean(expr) : expr;
if (mustConvert && newExprs == null) {
newExprs = new List<Expr>(e.Exprs.TakeWhile(x => x != expr));
}
if (newExprs != null) {
newExprs.Add(newExpr);
}
}
if (newExprs != null) {
return new ExprVarPhi(e.Ctx) { Exprs = newExprs };
}
}
return e;
}
protected override ICode VisitIf(StmtIf s) {
var ctx = s.Ctx;
var condition = (Expr)this.Visit(s.Condition);
this.stack.Push(new List<ExprVar>());
var then = (Stmt)this.Visit(s.Then);
var thenDA = this.stack.Pop();
this.stack.Push(new List<ExprVar>());
var @else = (Stmt)this.Visit(s.Else);
var elseDA = this.stack.Pop();
var intersection = thenDA.Intersect(elseDA, (IEqualityComparer<ExprVar>)this.phiComparer).ToArray();
this.stack.Peek().AddRange(intersection);
var conditionVars = VisitorFindVars.V(condition);
var needAssigning = conditionVars.Except(this.stack.SelectMany(x => x), (IEqualityComparer<ExprVar>)this.phiComparer).ToArray();
if (needAssigning.Any()) {
var replacements = needAssigning.Select(x => {
var newExpr = ctx.Local(x.Type);
var phi = new ExprVarPhi(ctx) { Exprs = new[] { x, newExpr } };
return new { orgExpr = x, newExpr, phi };
}).ToArray();
foreach (var replace in replacements) {
this.stack.Peek().Add(replace.newExpr);
this.stack.Peek().Add(replace.phi);
condition = (Expr)VisitorReplace.V(condition, replace.orgExpr, replace.phi);
}
this.ensureAssigned.Add(s, replacements.Select(x => x.newExpr).ToArray());
}
if (condition != s.Condition || then != s.Then || @else != s.Else) {
var newS = new StmtIf(ctx, condition, then, @else);
this.stmtMap.Add(newS,s);
return newS;
} else {
return s;
}
}
protected override ICode VisitVarPhi(ExprVarPhi e) {
if (e.Exprs.Count() == 1) {
return this.Visit(e.Exprs.First());
}
var exprNew = e.Exprs.Select(x => (Expr)this.Visit(x)).ToArray();
var exprs = exprNew
.SelectMany(x => {
if (x == null) {
return Enumerable.Empty<Expr>();
}
if (x.ExprType == Expr.NodeType.VarPhi) {
return ((ExprVarPhi)x).Exprs;
}
return new[] { x };
})
.Distinct(Expr.EqComparerExact)
.ToArray();
if (exprs.SequenceEqual(e.Exprs)) {
return e;
} else {
return new ExprVarPhi(e.Ctx) { Exprs = exprs };
}
}
protected override ICode VisitVarPhi(ExprVarPhi e) {
// Variables within phi's cannot be removed
this.inPhiCount++;
var ret = base.VisitVarPhi(e);
this.inPhiCount--;
return ret;
}
protected override ICode VisitVarPhi(ExprVarPhi e) {
bool finalise = false;
if (this.phiSeen == null) {
this.phiSeen = new HashSet<ExprVarPhi>();
finalise = true;
}
this.code.AppendFormat("phi<{0}>(", e.GetHashCode());
if (this.phiSeen.Add(e)) {
foreach (var v in e.Exprs) {
this.Visit(v);
this.code.Append(",");
}
this.code.Length--;
} else {
this.code.AppendFormat("<rec-{0}>", e.GetHashCode());
}
this.code.Append(")");
if (finalise) {
this.phiSeen = null;
}
return e;
}
protected override ICode VisitVarPhi(ExprVarPhi e) {
this.clusters.Add(e.Exprs.OfType<ExprVar>().Concat(e).ToArray());
return e;
}
public static ICode V(ICode ast) {
var ctx = ast.Ctx;
var blockInfo = FindSuitableBlocks.GetInfo(ast);
var bestBlock = blockInfo
.Where(x => !x.Value.containsLeaveProtectedRegion && x.Value.numConts <= 1)
.OrderBy(x => x.Value.numConts == 0 ? 1000 : x.Value.numConts)
.ThenBy(x => x.Value.numICodes)
.FirstOrDefault();
if (bestBlock.Key == null) {
return ast;
}
if (bestBlock.Value.numConts > 1) {
// Best block must have just one continuation
return ast;
}
Stmt addContTo = null;
if (bestBlock.Value.numConts == 0) {
addContTo = (Stmt)blockInfo.FirstOrDefault(x => x.Value.numConts == 0 && x.Key != bestBlock.Key).Key;
if (addContTo == null) {
return ast;
}
}
var blockAst = (Stmt)bestBlock.Key;
if (blockAst.StmtType != Stmt.NodeType.Block) {
// Best block must be StmtBlock
return ast;
}
var stmtBlock = (StmtBlock)blockAst;
var stmts = stmtBlock.Statements.ToArray();
var cont = bestBlock.Value.numConts == 0 ? new StmtContinuation(ctx, addContTo, false) : (StmtContinuation)stmts.Last();
var ifSkipContentPhi = new ExprVarPhi(ctx);
var ifSkipInitialVar = ctx.Local(ctx.Boolean);
var ifSkipContentVar = ctx.Local(ctx.Boolean);
var ifSkipContentPhiExprs = new List<Expr> { ifSkipInitialVar, ifSkipContentVar };
var ifSkipReset = new StmtAssignment(ctx, ifSkipContentVar, ctx.Literal(false));
var inIfBlock = new StmtBlock(ctx, stmts.Take(stmts.Length - (bestBlock.Value.numConts == 0 ? 0 : 1)));
var ifBlock = new StmtIf(ctx, ctx.ExprGen.Not(ifSkipContentPhi), inIfBlock, null);
var newBlock = new StmtBlock(ctx, ifBlock, ifSkipReset, cont);
ast = VisitorReplace.V(ast, blockAst, newBlock);
var allConts = VisitorFindContinuationsRecursive.Get(ast);
var contsNeedChanging = allConts.Where(x => x != cont && x.To == cont.To).ToArray();
var contsReplaceInfo = contsNeedChanging
.Select(x => {
var ifVar = ctx.Local(ctx.Boolean);
var newCont = new StmtBlock(ctx,
new StmtAssignment(ctx, ifVar, ctx.Literal(true)),
new StmtContinuation(ctx, newBlock, x.LeaveProtectedRegion));
return new { oldCont = x, ifVar, newCont };
})
.ToArray();
foreach (var contReplace in contsReplaceInfo) {
ifSkipContentPhiExprs.Add(contReplace.ifVar);
ast = VisitorReplace.V(ast, contReplace.oldCont, contReplace.newCont);
}
ifSkipContentPhi.Exprs = ifSkipContentPhiExprs;
// TODO: Shouldn't be required, but definite-assignment doesn't quite work properly, so is required
var initalSkipVarAssignment = new StmtAssignment(ctx, ifSkipInitialVar, ctx.Literal(false));
var newAst = new StmtBlock(ctx, initalSkipVarAssignment, (Stmt)ast);
return newAst;
}
protected override ICode VisitDoLoop(StmtDoLoop s) {
var ctx = s.Ctx;
var body = (Stmt)this.Visit(s.Body);
var @while = (Expr)this.Visit(s.While);
var conditionVars = VisitorFindVars.V(@while);
var needAssigning = conditionVars.Except(this.stack.SelectMany(x => x), (IEqualityComparer<ExprVar>)this.phiComparer).ToArray();
if (needAssigning.Any()) {
var replacements = needAssigning.Select(x => {
var newExpr = ctx.Local(x.Type);
var phi = new ExprVarPhi(ctx) { Exprs = new[] { x, newExpr } };
return new { orgExpr = x, newExpr, phi };
}).ToArray();
foreach (var replace in replacements) {
this.stack.Peek().Add(replace.newExpr);
this.stack.Peek().Add(replace.phi);
@while = (Expr)VisitorReplace.V(@while, replace.orgExpr, replace.phi);
}
var assignmentStmts = replacements
.Select(x=>new StmtAssignment(ctx, x.newExpr, new ExprDefaultValue(ctx, x.newExpr.Type)))
.ToArray();
body = new StmtBlock(ctx, assignmentStmts.Concat(body));
}
if (body != s.Body || @while != s.While) {
return new StmtDoLoop(ctx, body, @while);
} else {
return s;
}
}