//Optimization for a simple 'for' cycle
private bool TryOptimizeFor(DFor node, Hints hints, CompilerContext ctx)
{
if (options.NoOptimizations ||
node.Guard is not null ||
node.Pattern.NodeType is not NodeType.NamePattern and not NodeType.WildcardPattern ||
node.Target.NodeType is not NodeType.Range)
{
return(false);
}
var incName = node.Pattern is INamedNode nn ? nn.NodeName : null;
if (incName is not null && incName.Length > 0 && char.IsUpper(incName[0]))
{
return(false);
}
var range = (DRange)node.Target;
if (range.From is null)
{
return(false);
}
long step;
var downTo = false;
if (range.Step is not null && range.Step.NodeType is not NodeType.Integer)
{
if (range.Step is not DUnaryOperation u ||
u.Operator is not UnaryOperator.Neg ||
u.Node.NodeType is not NodeType.Integer)
{
return(false);
}
step = -((DIntegerLiteral)u.Node).Value;
downTo = true;
}
private void Build(DFor node, Hints hints, CompilerContext ctx)
{
ctx = new(ctx)
{
BlockSkip = cw.DefineLabel(),
BlockExit = cw.DefineLabel(),
BlockBreakExit = cw.DefineLabel()
};
if (TryOptimizeFor(node, hints, ctx))
{
return;
}
StartScope(ScopeKind.Loop, node.Location);
hints = hints.Remove(Last);
var inc = false;
if (node.Pattern.NodeType == NodeType.NamePattern && !char.IsUpper(((DNamePattern)node.Pattern).Name[0] !))
{
inc = true;
}
var sys = AddVariable();
var initSkip = cw.DefineLabel();
Build(node.Target, hints.Append(Push), ctx);
cw.Briter(initSkip);
cw.GetMember(Builtins.Iterate);
cw.CallNullaryFunction();
cw.MarkLabel(initSkip);
cw.GetIter();
cw.PopVar(sys);
var iter = cw.DefineLabel();
cw.MarkLabel(iter);
cw.PushVar(new ScopeVar(sys));
cw.CallNullaryFunction();
cw.Brterm(ctx.BlockExit);
if (inc)
{
var ai = AddVariable(((DNamePattern)node.Pattern).Name !, node.Pattern.Location, VarFlags.None);
cw.PopVar(ai);
}
else
{
BuildPattern(node.Pattern, hints, ctx);
cw.Brfalse(ctx.BlockSkip);
}
if (node.Guard != null)
{
Build(node.Guard, hints.Append(Push), ctx);
cw.Brfalse(ctx.BlockSkip);
}
var nh = hints.Remove(Push);
Build(node.Body, nh, ctx);
cw.MarkLabel(ctx.BlockSkip);
cw.Br(iter);
cw.MarkLabel(ctx.BlockExit);
cw.Pop();
cw.PushNil();
AddLinePragma(node);
cw.MarkLabel(ctx.BlockBreakExit);
PopIf(hints);
cw.Nop();
EndScope();
}
private void Build(DFor node, Hints hints, CompilerContext ctx)
{
ctx = new CompilerContext(ctx)
{
BlockSkip = cw.DefineLabel(),
BlockExit = cw.DefineLabel(),
BlockBreakExit = cw.DefineLabel()
};
StartScope(false, node.Location);
hints = hints.Remove(Last);
var inc = -1;
if (node.Pattern.NodeType == NodeType.NamePattern &&
GetTypeHandle(null, node.Pattern.GetName(), out var _, out var _) != CompilerError.None)
{
inc = AddVariable(node.Pattern.GetName(), node.Pattern, VarFlags.None);
}
var sys = AddVariable();
var initSkip = cw.DefineLabel();
Build(node.Target, hints.Append(Push), ctx);
cw.Briter(initSkip);
cw.GetMember(GetMemberNameId(Builtins.Iterator));
cw.FunPrep(0);
cw.FunCall(0);
cw.MarkLabel(initSkip);
cw.PopVar(sys);
var iter = cw.DefineLabel();
cw.MarkLabel(iter);
cw.PushVar(new ScopeVar(sys));
cw.FunPrep(0);
cw.FunCall(0);
cw.Brterm(ctx.BlockExit);
if (inc > -1)
{
cw.PopVar(inc);
}
else
{
BuildPattern(node.Pattern, hints, ctx);
cw.Brfalse(ctx.BlockSkip);
}
if (node.Guard != null)
{
Build(node.Guard, hints.Append(Push), ctx);
cw.Brfalse(ctx.BlockSkip);
}
var nh = hints.Has(Push) ? hints.Remove(Push).Append(ExpectPush) : hints.Remove(ExpectPush);
Build(node.Body, nh, ctx);
cw.MarkLabel(ctx.BlockSkip);
cw.Br(iter);
cw.MarkLabel(ctx.BlockExit);
cw.Pop();
PushIf(hints);
AddLinePragma(node);
cw.MarkLabel(ctx.BlockBreakExit);
cw.Nop();
EndScope();
}
