public void Compile(
If statement,
ICompilationContext context
)
{
var preferredRegisterCondition = new PreferredRegister(Register64.RAX);
var ifConditionResult = context.CompileExpression(statement.Condition, preferredRegisterCondition);
ifConditionResult.GenerateMoveTo(preferredRegisterCondition.MakeFor(Constants.BoolType), context.Generator, context.Linking);
context.Generator.Test(Register8.AL, Register8.AL);
var ifBody = context.CreateChildContext();
var elseBody = context.CreateChildContext();
if (statement.ElseInstruction != null)
{
elseBody.CompileStatement(statement.ElseInstruction.StatementAsBlock());
}
ifBody.CompileStatement(statement.Instruction.StatementAsBlock());
var elseBodySpan = elseBody.Generator.GetBufferSpan();
if (elseBodySpan.Length > 0)
{
if (elseBodySpan.Length <= sbyte.MaxValue)
{
ifBody.Generator.Jmp((sbyte)elseBodySpan.Length);
}
else
{
ifBody.Generator.Jmp(elseBodySpan.Length);
}
}
var ifBodySpan = ifBody.Generator.GetBufferSpan();
if (ifBodySpan.Length <= sbyte.MaxValue)
{
context.Generator.Je((sbyte)ifBodySpan.Length);
}
else
{
context.Generator.Je(ifBodySpan.Length);
}
ifBody.CopyToContext(context);
elseBody.CopyToContext(context);
}
public void Compile(
While statement,
ICompilationContext context
)
{
var codeGen = context.Generator;
var conditionStart = codeGen.StreamPosition;
var whileConditionResult = context.CompileExpression(statement.Condition, new PreferredRegister(Register64.RAX));
var whileConditionRegister = whileConditionResult.GetOccupiedOrVolatile(Constants.BoolType);
whileConditionResult.GenerateMoveTo(whileConditionRegister, Constants.BoolType, codeGen, context.Linking);
codeGen.Test(whileConditionRegister, whileConditionRegister);
var childContext = context.CreateChildContext();
childContext.CompileStatement(statement.Instruction.StatementAsBlock());
var bodySpan = childContext.Generator.GetBufferSpan();
var bodyLength = bodySpan.Length + JmpIntSize; // assume far jmp will be generated
if (bodyLength <= sbyte.MaxValue)
{
codeGen.Je((sbyte)bodyLength);
}
else
{
codeGen.Je(bodyLength);
}
var farJmpGuessPos = codeGen.StreamPosition;
childContext.CopyToContext(context);
var offsetToStart = conditionStart - codeGen.StreamPosition;
if (offsetToStart >= sbyte.MinValue)
{
codeGen.Jmp((sbyte)(offsetToStart - JmpSbyteSize));
// near jmp has been generated, but we assume a far jmp above
// if this is a near jmp, the other has to be too
// so it's safe to say, we just need to edit the byte.
// The new value has to fit, because the jmp becomes even nearer.
codeGen.GetBufferSpan().Slice((int)farJmpGuessPos - 1, 1)[0] -= (byte)(JmpIntSize - JmpSbyteSize);
}
else
{
codeGen.Jmp((int)(offsetToStart - JmpIntSize));
}
}
