private void BuildAstBlocks(ILCompilationUnit result, IDictionary <int, ILVariable> resultVariables)
{
foreach (var node in result.ControlFlowGraph.Nodes)
{
var ilBlock = (ILBasicBlock)node.UserData[ILBasicBlock.BasicBlockProperty];
var astBlock = new ILAstBlock(node);
foreach (var instruction in ilBlock.Instructions)
{
// Build expression.
var expression = BuildExpression(instruction, result);
switch (instruction.OpCode.Code)
{
case ILCode.POP:
{
// Since we treat registers as variables, we should treat POP instructions as assignment
// statements instead of a normal ILExpressionStatement. This makes it easier to apply
// analysis and transformations (such as variable inlining) later, in the same way we do
// that with normal variables.
var registerVar = result.GetOrCreateVariable(instruction.Operand.ToString());
var value = (ILExpression)((IILArgumentsProvider)expression).Arguments[0].Remove();
var assignment = new ILAssignmentStatement(registerVar, value);
astBlock.Statements.Add(assignment);
break;
}
case ILCode.CALL:
{
// CALL instructions that call non-void methods store the result in R0.
// TODO: Respect frame layout instead of hardcoding R0 as return value.
var callAnnotation = (CallAnnotation)instruction.Annotation;
var statement = callAnnotation.Function.FrameLayout.ReturnsValue
? (ILStatement) new ILAssignmentStatement(
result.GetOrCreateVariable(VMRegisters.R0.ToString()), expression)
: new ILExpressionStatement(expression);
astBlock.Statements.Add(statement);
break;
}
case ILCode.RET:
{
// TODO: Respect frame layout instead of hardcoding R0 as return value.
var returnExpr = (IILArgumentsProvider)expression;
foreach (var use in expression.AcceptVisitor(VariableUsageCollector.Instance))
{
use.Variable = null;
}
returnExpr.Arguments.Clear();
if (result.FrameLayout.ReturnsValue && !instruction.ProgramState.IgnoreExitKey)
{
var registerVar = result.GetOrCreateVariable(VMRegisters.R0.ToString());
returnExpr.Arguments.Add(new ILVariableExpression(registerVar));
}
astBlock.Statements.Add(new ILExpressionStatement(expression));
break;
}
default:
{
// Build statement around expression.
var statement = resultVariables.TryGetValue(instruction.Offset, out var resultVariable)
? (ILStatement) new ILAssignmentStatement(resultVariable, expression)
: new ILExpressionStatement(expression);
astBlock.Statements.Add(statement);
break;
}
}
}
node.UserData[ILAstBlock.AstBlockProperty] = astBlock;
}
}
public IEnumerable <ILVariableExpression> VisitAssignmentStatement(ILAssignmentStatement statement)
{
return(statement.Value.AcceptVisitor(this));
}