void
TR::AMD64ABILinkage::mapIncomingParms(
TR::ResolvedMethodSymbol *method,
uint32_t &stackIndex)
{
ListIterator<TR::ParameterSymbol> parameterIterator(&method->getParameterList());
TR::ParameterSymbol *parmCursor = parameterIterator.getFirst();
if (!parmCursor) return;
if (parmCursor->getLinkageRegisterIndex() < 0)
{
copyLinkageInfoToParameterSymbols();
}
// 1st: handle parameters which are passed through stack
//
TR::X86SystemLinkage::mapIncomingParms(method);
// 2nd: handle parameters which are passed through linkage registers, but are
// not assigned any register after RA (or say, by their first usage point,
// a MOV is needed to load it from stack to register).
//
// AMD64 SysV ABI says that: a parameter is placed either in registers or
// pushed on the stack, but can't take both. So, for parms passed through
// linkage registers but don't have physical registers assigned after RA,
// we will allocate stack space in local variable region.
//
for (parmCursor = parameterIterator.getFirst(); parmCursor; parmCursor = parameterIterator.getNext())
{
if ((parmCursor->getLinkageRegisterIndex() >= 0) && (parmCursor->getAllocatedIndex() < 0 || hasToBeOnStack(parmCursor)))
{
uint32_t align = getAlignment(parmCursor->getDataType());
uint32_t alignMinus1 = (align <= AMD64_STACK_SLOT_SIZE) ? (AMD64_STACK_SLOT_SIZE - 1) : (align - 1);
uint32_t pos = -stackIndex;
pos += parmCursor->getSize();
pos = (pos + alignMinus1) & (~alignMinus1);
stackIndex = -pos;
parmCursor->setParameterOffset(stackIndex);
if (comp()->getOption(TR_TraceCG))
traceMsg(comp(), "mapIncomingParms setParameterOffset %d for param symbol (reg param without home location) %p, hasToBeOnStack() %d\n", parmCursor->getParameterOffset(), parmCursor, hasToBeOnStack(parmCursor));
}
else if (parmCursor->getLinkageRegisterIndex() >=0 && parmCursor->getAllocatedIndex() >= 0)
{
//parmCursor->setDontHaveStackSlot(0); // this is a hack , so as we could print stack layout table in createPrologue
if (comp()->getOption(TR_TraceCG))
traceMsg(comp(), "mapIncomingParms no need to set parm %p, for it has got register %d assigned\n", parmCursor, parmCursor->getAllocatedIndex());
}
}
}
// Copies parameters from where they enter the method (either on stack or in a
// linkage register) to their "home location" where the method body will expect
// to find them (either on stack or in a global register).
//
TR::Instruction *
TR::X86SystemLinkage::copyParametersToHomeLocation(TR::Instruction *cursor)
{
TR::Machine *machine = cg()->machine();
TR::RealRegister *framePointer = machine->getX86RealRegister(TR::RealRegister::vfp);
TR::ResolvedMethodSymbol *bodySymbol = comp()->getJittedMethodSymbol();
ListIterator<TR::ParameterSymbol> paramIterator(&(bodySymbol->getParameterList()));
TR::ParameterSymbol *paramCursor;
const TR::RealRegister::RegNum noReg = TR::RealRegister::NoReg;
TR_ASSERT(noReg == 0, "noReg must be zero so zero-initializing movStatus will work");
TR::MovStatus movStatus[TR::RealRegister::NumRegisters] = {{(TR::RealRegister::RegNum)0,(TR::RealRegister::RegNum)0,(TR_MovDataTypes)0}};
// We must always do the stores first, then the reg-reg copies, then the
// loads, so that we never clobber a register we will need later. However,
// the logic is simpler if we do the loads and stores in the same loop.
// Therefore, we maintain a separate instruction cursor for the loads.
//
// We defer the initialization of loadCursor until we generate the first
// load. Otherwise, if we happen to generate some stores first, then the
// store cursor would get ahead of the loadCursor, and the instructions
// would end up in the wrong order despite our efforts.
//
TR::Instruction *loadCursor = NULL;
// Phase 1: generate RegMem and MemReg movs, and collect information about
// the required RegReg movs.
//
for (paramCursor = paramIterator.getFirst();
paramCursor != NULL;
paramCursor = paramIterator.getNext())
{
int8_t lri = paramCursor->getLinkageRegisterIndex(); // How the parameter enters the method
TR::RealRegister::RegNum ai // Where method body expects to find it
= (TR::RealRegister::RegNum)paramCursor->getAllocatedIndex();
int32_t offset = paramCursor->getParameterOffset(); // Location of the parameter's stack slot
TR_MovDataTypes movDataType = paramMovType(paramCursor); // What sort of MOV instruction does it need?
// Copy the parameter to wherever it should be
//
if (lri == NOT_LINKAGE) // It's on the stack
{
if (ai == NOT_ASSIGNED) // It only needs to be on the stack
{
// Nothing to do
}
else // Method body expects it to be in the ai register
{
if (loadCursor == NULL)
loadCursor = cursor;
if (debug("traceCopyParametersToHomeLocation"))
diagnostic("copyParametersToHomeLocation: Loading %d\n", ai);
// ai := stack
loadCursor = generateRegMemInstruction(
loadCursor,
TR::Linkage::movOpcodes(RegMem, movDataType),
machine->getX86RealRegister(ai),
generateX86MemoryReference(framePointer, offset, cg()),
cg()
);
}
}
else // It's in a linkage register
{
TR::RealRegister::RegNum sourceIndex = getProperties().getArgumentRegister(lri, isFloat(movDataType));
// Copy to the stack if necessary
//
if (ai == NOT_ASSIGNED || hasToBeOnStack(paramCursor))
{
if (comp()->getOption(TR_TraceCG))
traceMsg(comp(), "copyToHomeLocation param %p, linkage reg index %d, allocated index %d, parameter offset %d, hasToBeOnStack %d, parm->isParmHasToBeOnStack() %d.\n", paramCursor, lri, ai, offset, hasToBeOnStack(paramCursor), paramCursor->isParmHasToBeOnStack());
if (debug("traceCopyParametersToHomeLocation"))
diagnostic("copyParametersToHomeLocation: Storing %d\n", sourceIndex);
// stack := lri
cursor = generateMemRegInstruction(
cursor,
TR::Linkage::movOpcodes(MemReg, movDataType),
generateX86MemoryReference(framePointer, offset, cg()),
machine->getX86RealRegister(sourceIndex),
cg()
);
}
// Copy to the ai register if necessary
//
if (ai != NOT_ASSIGNED && ai != sourceIndex)
{
// This parameter needs a RegReg move. We don't know yet whether
// we need the value in the target register, so for now we just
// remember that we need to do this and keep going.
//
TR_ASSERT(movStatus[ai ].sourceReg == noReg, "Each target reg must have only one source");
TR_ASSERT(movStatus[sourceIndex].targetReg == noReg, "Each source reg must have only one target");
if (debug("traceCopyParametersToHomeLocation"))
diagnostic("copyParametersToHomeLocation: Planning to move %d to %d\n", sourceIndex, ai);
movStatus[ai].sourceReg = sourceIndex;
movStatus[sourceIndex].targetReg = ai;
movStatus[sourceIndex].outgoingDataType = movDataType;
}
if (debug("traceCopyParametersToHomeLocation") && ai == sourceIndex)
{
diagnostic("copyParametersToHomeLocation: Parameter #%d already in register %d\n", lri, ai);
}
}
}
// Phase 2: Iterate through the parameters again to insert the RegReg moves.
//
for (paramCursor = paramIterator.getFirst();
paramCursor != NULL;
paramCursor = paramIterator.getNext())
{
if (paramCursor->getLinkageRegisterIndex() == NOT_LINKAGE)
continue;
const TR::RealRegister::RegNum paramReg =
getProperties().getArgumentRegister(paramCursor->getLinkageRegisterIndex(), isFloat(paramMovType(paramCursor)));
if (movStatus[paramReg].targetReg == 0)
{
// This parameter does not need to be copied anywhere
if (debug("traceCopyParametersToHomeLocation"))
diagnostic("copyParametersToHomeLocation: Not moving %d\n", paramReg);
}
else
{
if (debug("traceCopyParametersToHomeLocation"))
diagnostic("copyParametersToHomeLocation: Preparing to move %d\n", paramReg);
// If a mov's target register is the source for another mov, we need
// to do that other mov first. The idea is to find the end point of
// the chain of movs starting with paramReg and ending with a
// register whose current value is not needed; then do that chain of
// movs in reverse order.
//
TR_ASSERT(noReg == 0, "noReg must be zero (not %d) for zero-filled initialization to work", noReg);
TR::RealRegister::RegNum regCursor;
// Find the last target in the chain
//
regCursor = movStatus[paramReg].targetReg;
while(movStatus[regCursor].targetReg != noReg)
{
// Haven't found the end yet
regCursor = movStatus[regCursor].targetReg;
TR_ASSERT(regCursor != paramReg, "Can't yet handle cyclic dependencies");
// TODO:AMD64 Use scratch register to break cycles
// A properly-written pickRegister should never
// cause cycles to occur in the first place. However, we may want
// to consider adding cycle-breaking logic so that (1) pickRegister
// has more flexibility, and (2) we're more robust against
// otherwise harmless bugs in pickRegister.
}
// Work our way backward along the chain, generating all the necessary movs
//
while(movStatus[regCursor].sourceReg != noReg)
{
TR::RealRegister::RegNum source = movStatus[regCursor].sourceReg;
if (debug("traceCopyParametersToHomeLocation"))
diagnostic("copyParametersToHomeLocation: Moving %d to %d\n", source, regCursor);
// regCursor := regCursor.sourceReg
cursor = generateRegRegInstruction(
cursor,
TR::Linkage::movOpcodes(RegReg, movStatus[source].outgoingDataType),
machine->getX86RealRegister(regCursor),
machine->getX86RealRegister(source),
cg()
);
// Update movStatus as we go so we don't generate redundant movs
movStatus[regCursor].sourceReg = noReg;
movStatus[source ].targetReg = noReg;
// Continue with the next register in the chain
regCursor = source;
}
}
}
// Return the last instruction we inserted, whether or not it was a load.
//
return loadCursor? loadCursor : cursor;
}
