private bool AssertDecodeBranchArguments(
IEnumerable <LNode> nodes,
Dictionary <Symbol, ValueTag> valueTags,
out IReadOnlyList <BranchArgument> args)
{
var results = new List <BranchArgument>();
foreach (var argNode in nodes)
{
if (!FeedbackHelpers.AssertIsId(argNode, Log))
{
args = null;
return(false);
}
var name = argNode.Name;
if (name == CodeSymbols.Result)
{
results.Add(BranchArgument.TryResult);
}
else if (name == EncoderState.tryFlowExceptionSymbol)
{
results.Add(BranchArgument.TryException);
}
else
{
results.Add(BranchArgument.FromValue(GetValueTag(argNode.Name, valueTags)));
}
}
args = results;
return(true);
}
private BasicBlockBuilder DecodeBasicBlock(
LNode node,
FlowGraphBuilder graph,
Dictionary <Symbol, BasicBlockBuilder> blocks,
Dictionary <Symbol, ValueTag> valueTags)
{
// Each basic block is essentially a
// (name, parameters, instructions, flow) tuple.
// We just parse all four elements and call it a day.
// Parse the block's name and create the block.
var name = FeedbackHelpers.AssertIsId(node.Args[0], Log)
? node.Args[0].Name
: GSymbol.Empty;
var blockBuilder = GetBasicBlock(name, graph, blocks);
// Parse the block's parameter list.
foreach (var paramNode in node.Args[1].Args)
{
if (FeedbackHelpers.AssertArgCount(paramNode, 2, Log))
{
blockBuilder.AppendParameter(
new BlockParameter(
DecodeType(paramNode.Args[0]),
FeedbackHelpers.AssertIsId(paramNode.Args[1], Log)
? GetValueTag(paramNode.Args[1].Name, valueTags)
: new ValueTag()));
}
else
{
blockBuilder.AppendParameter(new BlockParameter(ErrorType.Instance));
}
}
// Parse the block's instructions.
foreach (var valueNode in node.Args[2].Args)
{
// Decode the instruction.
Instruction insn;
if (!FeedbackHelpers.AssertIsCall(valueNode, Log) ||
!FeedbackHelpers.AssertArgCount(valueNode, 2, Log) ||
!FeedbackHelpers.AssertIsId(valueNode.Args[0], Log) ||
!AssertDecodeInstruction(valueNode.Args[1], valueTags, out insn))
{
continue;
}
// Append the instruction to the basic block.
blockBuilder.AppendInstruction(
insn,
GetValueTag(valueNode.Args[0].Name, valueTags));
}
// Parse the block's flow.
blockBuilder.Flow = DecodeBlockFlow(node.Args[3], graph, blocks, valueTags);
return(blockBuilder);
}
private static IntrinsicPrototype DecodeIntrinsic(IReadOnlyList <LNode> data, DecoderState state)
{
// TODO: decode exception specifications.
return(IntrinsicPrototype.Create(
FeedbackHelpers.AssertIsId(data[0], state.Log)
? data[0].Name.Name
: "error",
state.DecodeType(data[1]),
data[2].Args.EagerSelect <LNode, IType>(state.DecodeType)));
}
/// <summary>
/// Decodes a particular piece of data.
/// </summary>
/// <param name="data">
/// Encoded data to decode.
/// </param>
/// <param name="state">
/// The decoder's state.
/// </param>
/// <returns>
/// A decoded object.
/// </returns>
public override TObj Decode(LNode data, DecoderState state)
{
if (!FeedbackHelpers.AssertIsCall(data, state.Log) &&
!FeedbackHelpers.AssertIsId(data.Target, state.Log))
{
return(default(TObj));
}
var identifier = data.Name;
var args = data.Args;
return(Decode(identifier, data, state));
}
private bool AssertDecodeValueTags(
IEnumerable <LNode> nodes,
Dictionary <Symbol, ValueTag> valueTags,
out IReadOnlyList <ValueTag> tags)
{
var results = new List <ValueTag>();
foreach (var argNode in nodes)
{
if (!FeedbackHelpers.AssertIsId(argNode, Log))
{
tags = null;
return(false);
}
results.Add(GetValueTag(argNode.Name, valueTags));
}
tags = results;
return(true);
}
/// <summary>
/// Decodes an LNode as a simple name. Logs an error if the decoding
/// process fails.
/// </summary>
/// <param name="node">A node to decode as a simple name.</param>
/// <param name="name">The name described by <paramref name="node"/>.</param>
/// <returns>
/// <c>true</c> if <paramref name="node"/> can be decoded as a simple
/// name; otherwise, <c>false</c>.
/// </returns>
public bool AssertDecodeSimpleName(LNode node, out SimpleName name)
{
if (node.IsId)
{
name = new SimpleName(node.Name.Name);
return(true);
}
else if (node.IsCall)
{
var nameNode = node.Target;
int arity;
if (!FeedbackHelpers.AssertIsId(nameNode, Log) ||
!FeedbackHelpers.AssertArgCount(node, 1, Log) ||
!AssertDecodeInt32(node.Args[0], out arity))
{
name = null;
return(false);
}
name = new SimpleName(nameNode.Name.Name, arity);
return(true);
}
else
{
FeedbackHelpers.LogSyntaxError(
Log,
node,
FeedbackHelpers.QuoteEven(
"expected a simple name, which can either be a simple id (e.g., ",
"Name",
") or a call to an id that specifies the number of generic parameters (e.g., ",
"Name(2)",
")."));
name = null;
return(false);
}
}
private bool AssertDecodeBranch(
LNode node,
FlowGraphBuilder graph,
Dictionary <Symbol, BasicBlockBuilder> blocks,
Dictionary <Symbol, ValueTag> valueTags,
out Branch result)
{
IReadOnlyList <BranchArgument> args;
if (FeedbackHelpers.AssertIsCall(node, Log) &&
FeedbackHelpers.AssertIsId(node.Target, Log) &&
AssertDecodeBranchArguments(node.Args, valueTags, out args))
{
result = new Branch(
GetBasicBlock(node.Target.Name, graph, blocks).Tag,
args);
return(true);
}
else
{
result = default(Branch);
return(false);
}
}
/// <summary>
/// Decodes a control-flow graph as a method body.
/// </summary>
/// <param name="node">An encoded control-flow graph.</param>
/// <returns>
/// A new method body that includes the decoded control-flow graph.
/// </returns>
public FlowGraph DecodeFlowGraph(LNode node)
{
// A CFG consists of a list of basic blocks and a specially
// marked entry point block.
var graph = new FlowGraphBuilder();
var blocks = new Dictionary <Symbol, BasicBlockBuilder>();
var valueTags = new Dictionary <Symbol, ValueTag>();
var parsedEntryPoint = false;
// Do a quick pass through all blocks for determinism: we want
// to define the blocks in the same order as the original IR.
foreach (var blockNode in node.Args)
{
if (!FeedbackHelpers.AssertArgCount(blockNode, 4, Log))
{
// Log the error and return an empty flow graph.
return(new FlowGraph());
}
var name = FeedbackHelpers.AssertIsId(blockNode.Args[0], Log)
? blockNode.Args[0].Name
: GSymbol.Empty;
// Define the basic block for determinism.
GetBasicBlock(name, graph, blocks);
}
foreach (var blockNode in node.Args)
{
// Parse the basic block.
var blockBuilder = DecodeBasicBlock(blockNode, graph, blocks, valueTags);
// Entry points get special treatment.
if (blockNode.Calls(EncoderState.entryPointBlockSymbol))
{
if (parsedEntryPoint)
{
Log.LogSyntaxError(
blockNode,
"there can be only one entry point block in a control-flow graph.");
}
parsedEntryPoint = true;
// Update the graph's entry point.
var oldEntryPointTag = graph.EntryPointTag;
graph.EntryPointTag = blockBuilder.Tag;
graph.RemoveBasicBlock(oldEntryPointTag);
}
}
if (!parsedEntryPoint)
{
Log.LogSyntaxError(
node,
"all control-flow graphs must define exactly one " +
"entry point, but this one doesn't.");
}
return(graph.ToImmutable());
}
/// <inheritdoc/>
public override ITypeMember Decode(LNode data, DecoderState state)
{
if (data.Calls(accessorSymbol))
{
if (!FeedbackHelpers.AssertArgCount(data, 2, state.Log) ||
!FeedbackHelpers.AssertIsId(data.Args[1], state.Log))
{
return(null);
}
var property = state.DecodeProperty(data.Args[0]);
if (property == null)
{
return(null);
}
else
{
var kindName = data.Args[1].Name.Name;
var accessor = property.Accessors.FirstOrDefault(
acc => accessorKindEncodings[acc.Kind] == kindName);
if (accessor == null)
{
FeedbackHelpers.LogSyntaxError(
state.Log,
data.Args[1],
Quotation.QuoteEvenInBold(
"property ",
FeedbackHelpers.Print(data.Args[0]),
" does not define a ",
kindName,
" accessor."));
}
return(accessor);
}
}
else if (data.Calls(CodeSymbols.Dot))
{
// Simple dot indicates a field.
IType parentType;
SimpleName name;
if (!AssertDecodeTypeAndName(data, state, out parentType, out name))
{
return(null);
}
var candidates = state.TypeMemberIndex
.GetAll(parentType, name)
.OfType <IField>()
.ToArray();
return(CheckSingleCandidate(
candidates,
data.Args[0],
data.Args[1],
"field",
state));
}
else if (data.CallsMin(CodeSymbols.IndexBracks, 1))
{
IType parentType;
SimpleName name;
if (!AssertDecodeTypeAndName(data.Args[0], state, out parentType, out name))
{
return(null);
}
var indexTypes = data.Args
.Slice(1)
.EagerSelect(state.DecodeType);
var candidates = state.TypeMemberIndex
.GetAll(parentType, name)
.OfType <IProperty>()
.Where(prop =>
prop.IndexerParameters
.Select(p => p.Type)
.SequenceEqual(indexTypes))
.ToArray();
return(CheckSingleCandidate(
candidates,
data.Args[0].Args[0],
data,
"property",
state));
}
else if (data.Calls(CodeSymbols.Lambda))
{
IType parentType;
SimpleName name;
if (!FeedbackHelpers.AssertArgCount(data, 2, state.Log) ||
!FeedbackHelpers.AssertIsCall(data.Args[0], state.Log) ||
!AssertDecodeTypeAndName(data.Args[0].Target, state, out parentType, out name))
{
return(null);
}
// TODO: implement generic parameter decoding, use generic
// parameters in resolution process.
var paramTypes = data.Args[0].Args
.EagerSelect(state.DecodeType);
var retType = state.DecodeType(data.Args[1]);
var candidates = state.TypeMemberIndex
.GetAll(parentType, name)
.OfType <IMethod>()
.Where(method =>
method.Parameters
.Select(p => p.Type)
.SequenceEqual(paramTypes) &&
object.Equals(
method.ReturnParameter.Type,
retType))
.ToArray();
return(CheckSingleCandidate(
candidates,
data.Args[0].Target.Args[0],
data,
"method",
state));
}
else if (data.Calls(CodeSymbols.Of))
{
if (!FeedbackHelpers.AssertMinArgCount(data, 1, state.Log))
{
return(null);
}
var func = state.DecodeMethod(data.Args[0]);
var args = data.Args.Slice(1).EagerSelect(state.DecodeType);
if (func.GenericParameters.Count == args.Count)
{
return(func.MakeGenericMethod(args));
}
else
{
state.Log.LogSyntaxError(
data,
Quotation.QuoteEvenInBold(
"generic arity mismatch; expected ",
func.GenericParameters.Count.ToString(),
" parameters but got ",
args.Count.ToString(),
"."));
return(null);
}
}
else
{
state.Log.LogSyntaxError(
data,
Quotation.QuoteEvenInBold(
"cannot interpret ",
FeedbackHelpers.Print(data),
" as a type member; expected a call to one of ",
accessorSymbol.Name, ", ",
CodeSymbols.Dot.Name, ", ",
CodeSymbols.IndexBracks.Name, ", ",
CodeSymbols.Of.Name, " or ",
CodeSymbols.Lambda.Name));
return(null);
}
}
