/// <summary>
/// Allocate a low register and map it to the given original register.
/// </summary>
private LowRegisterState AllocateLowRegister(Instruction ins, Register register, MethodBody body)
{
// Prepare
var type = GetType(register);
var isWide = (type == RType.Wide);
var regsNeeded = isWide ? 2 : 1;
LowRegisterState regState = null;
HashSet <Register> allRegistersUsedInIns = null;
while (true)
{
// Try to allocate free spilling register
regState = lowRegisters.FirstOrDefault(x => x.IsFreeFor(type));
if (regState != null)
{
break; // Found a free low register
}
// No spilling register is available.
// Free another register first
// If wide, free 2 registers
if (nextSpillIndex + regsNeeded > lowRegisters.Length)
{
nextSpillIndex = 0;
}
regState = lowRegisters[nextSpillIndex];
var regStateNext = isWide ? lowRegisters[nextSpillIndex + 1] : null;
// Update index so we take another the next time
nextSpillIndex = (nextSpillIndex + regsNeeded) % (lowRegisters.Length - 1);
// Do not allocate registers already used in the current instruction
allRegistersUsedInIns = allRegistersUsedInIns ?? GetAllUsedRegisters(ins);
if (allRegistersUsedInIns.Contains(regState.LowRegister))
{
continue;
}
if ((regStateNext != null) && allRegistersUsedInIns.Contains(regStateNext.LowRegister))
{
continue;
}
// Save sReg back to original register
var map = mapper.RegisterSpillingMap;
regState.SaveToOriginalAndClear(ins, block, body, map);
if (regStateNext != null)
{
regStateNext.SaveToOriginalAndClear(ins, block, body, map);
}
}
// Add mapping
regState.SetInUseBy(register, type);
return(regState);
}
/// <summary>
/// Mark this low register state as no longer in use.
/// </summary>
private void Clear()
{
if (isWide)
{
next.Clear();
}
OriginalRegister = null;
SaveToOriginalNeeded = false;
isWide = false;
type = RType.Value;
wideStart = null;
Mapping = null;
}
/// <summary>
/// Default ctor.
/// </summary>
internal BlockSpillCodeGenerator(BasicBlock block, RegisterMapper mapper, List <Register> lowRegisters, List <Register> invokeFrame, List <Register> allRegisters)
{
this.block = block;
this.mapper = mapper;
this.lowRegisters = new LowRegisterState[lowRegisters.Count];
LowRegisterState next = null;
for (var i = lowRegisters.Count - 1; i >= 0; i--)
{
this.lowRegisters[i] = new LowRegisterState(lowRegisters[i], next);
next = this.lowRegisters[i];
}
this.invokeFrame = invokeFrame;
this.allRegisters = allRegisters;
}
/// <summary>
/// Default ctor
/// </summary>
public LowRegisterState(Register lowRegister, LowRegisterState next)
{
LowRegister = lowRegister;
this.next = next;
}
/// <summary>
/// Try to get the low register that the given original register is mapped onto.
/// </summary>
private bool TryGetLowRegister(Register originalRegister, out Register lowRegister, out LowRegisterState lowRegisterState)
{
lowRegisterState = lowRegisters.FirstOrDefault(x => x.OriginalRegister == originalRegister);
lowRegister = (lowRegisterState != null) ? lowRegisterState.LowRegister : null;
return(lowRegister != null);
}
/// <summary>
/// Mark this low register state as no longer in use.
/// </summary>
private void Clear()
{
if (isWide) next.Clear();
OriginalRegister = null;
SaveToOriginalNeeded = false;
isWide = false;
type = RType.Value;
wideStart = null;
Mapping = null;
}
/// <summary>
/// Default ctor
/// </summary>
public LowRegisterState(Register lowRegister, LowRegisterState next)
{
LowRegister = lowRegister;
this.next = next;
}
/// <summary>
/// Try to get the low register that the given original register is mapped onto.
/// </summary>
private bool TryGetLowRegister(Register originalRegister, out Register lowRegister, out LowRegisterState lowRegisterState)
{
lowRegisterState = lowRegisters.FirstOrDefault(x => x.OriginalRegister == originalRegister);
lowRegister = (lowRegisterState != null) ? lowRegisterState.LowRegister : null;
return (lowRegister != null);
}
