/// <summary>
/// Compile a line of Yolol into a runnable C# function
/// </summary>
/// <param name="line">The line of code to convert</param>
/// <param name="lineNumber">The number of this line</param>
/// <param name="maxLines">The max number of lines in a valid program (20, in standard Yolol)</param>
/// <param name="maxStringLength"></param>
/// <param name="internalVariableMap">A dictionary used for mapping variables to integers in all lines in this script</param>
/// <param name="externalVariableMap">A dictionary used for mapping externals to integers in all lines in this script</param>
/// <param name="staticTypes">Statically known types for variables</param>
/// <param name="changeDetection"></param>
/// <returns>A function which runs this line of code. Accepts two sections of memory, internal variables and external variables. Returns the line number to go to next</returns>
public static Func <ArraySegment <Value>, ArraySegment <Value>, LineResult> Compile(
this Line line,
int lineNumber,
int maxLines,
int maxStringLength,
InternalsMap internalVariableMap,
ExternalsMap externalVariableMap,
IReadOnlyDictionary <VariableName, Type>?staticTypes = null,
bool changeDetection = false
)
{
// Locate all accessed variables and load them into the maps
var stored = new FindAssignedVariables();
stored.Visit(line);
var loaded = new FindReadVariables();
loaded.Visit(line);
foreach (var name in stored.Names.Concat(loaded.Names).Distinct())
{
var dict = name.IsExternal ? (Dictionary <VariableName, int>)externalVariableMap : internalVariableMap;
if (!dict.TryGetValue(name, out _))
{
dict[name] = dict.Count;
}
}
return(line.Compile(lineNumber, maxLines, maxStringLength, (IReadonlyInternalsMap)internalVariableMap, externalVariableMap, staticTypes, changeDetection));
}
[NotNull] public static IEnumerable <VariableName> FindWrites([NotNull] this IBasicBlock block, ISingleStaticAssignmentTable ssa)
{
var r = new FindAssignedVariables();
r.Visit(block);
return(r.Names);
}
/// <summary>
/// Replace reads from variables which are never assigned with a constant `0` (the default value for unassigned vars)
/// </summary>
/// <param name="cfg"></param>
/// <returns></returns>
public static IControlFlowGraph ReplaceUnassignedReads(this IControlFlowGraph cfg)
{
var v = new FindAssignedVariables();
foreach (var vertex in cfg.Vertices)
{
v.Visit(vertex);
}
return(cfg.VisitBlocks(() => new ReplaceUnassignedReads(new HashSet <VariableName>(v.Names))));
}
public static Program FoldSingleUseVariables(this Program prog)
{
// Find all variables associated with a count of how many times they are read
var readsInProgram = new FindReadVariables();
readsInProgram.Visit(prog);
// Find all variables associated with a count of how many times they are assigned
var writesInProgram = new FindAssignedVariables();
writesInProgram.Visit(prog);
var lines = new List <Line>();
foreach (var item in prog.Lines)
{
lines.Add(item.Fixpoint(20, line => {
// Find all reads in this line
var readsInLine = new FindReadVariables();
readsInLine.Visit(line);
// Find all writes in this line
var writesInLine = new FindAssignedVariables();
writesInLine.Visit(line);
// Find variables that can be folded away
var toReplace = (from v in readsInLine.Counts
where !v.Key.IsExternal
where v.Value == 1 // Filter to things only read once in this line
where readsInProgram.Counts[v.Key] == 1 // Filter to things only read once in the entire program
where writesInProgram.Counts[v.Key] == 1 // Filter to things on written once in the entire program
where writesInLine.Counts[v.Key] == 1 // Filter to things written once in this line
select v.Key).FirstOrDefault();
// If nothing was found to fold we can break out of the loop
if (toReplace == null)
{
return(line);
}
// Find the value that was assigned to this
var expr = writesInLine.Expressions[toReplace].Single();
// Substitute it into the line
var result = new SubstituteVariable(toReplace, expr).Visit(line);
return(result);
}));
}
return(new Program(lines));
}
public void EmitLoad(Line line)
{
// Find every variable that is loaded anywhere in the line
var loadFinder = new FindReadVariables();
loadFinder.Visit(line);
// Find every variable that is written to anywhere in the line
var storeFinder = new FindAssignedVariables();
storeFinder.Visit(line);
_mutated.UnionWith(storeFinder.Names);
// Only cache things which read or written more than once in the line
var toCache = new HashSet <VariableName>();
foreach (var(name, count) in loadFinder.Counts)
{
if (count > 1)
{
toCache.Add(name);
}
}
foreach (var(name, count) in storeFinder.Counts)
{
if (count > 1)
{
toCache.Add(name);
}
}
// Load up everything that will be read later in the line
// The `IsDirty` flags protect against writing back uninitialised variables at the end
foreach (var variable in toCache)
{
var type = _types.TypeOf(variable) ?? StackType.YololValue;
var local = _emitter.DeclareLocal(type.ToType(), $"CacheFor_{variable.Name}", false);
EmitLoadValue(variable);
StaticUnbox(type);
_emitter.StoreLocal(local);
_cache.Add(variable, new TypedLocal(type, local));
var dirty = _emitter.DeclareLocal(typeof(bool), $"CacheFor_{variable.Name}_IsDirty");
_emitter.LoadConstant(false);
_emitter.StoreLocal(dirty);
_cacheDirty.Add(variable, dirty);
}
}
[NotNull] public static IReadOnlyCollection <VariableName> FindUnreadAssignments([NotNull] this IControlFlowGraph cfg)
{
var assigned = new FindAssignedVariables();
var read = new FindReadVariables();
foreach (var bb in cfg.Vertices)
{
assigned.Visit(bb);
read.Visit(bb);
}
var result = new HashSet <VariableName>(assigned.Names.Where(n => !n.IsExternal));
result.ExceptWith(read.Names);
return(result);
}
