/**
* Insert the epilogue before a particular return instruction.
*
* @param ret the return instruction.
*/
private void insertEpilogue(Instruction ret) {
// 1. Restore any saved registers
if (ir.compiledMethod.isSaveVolatile()) {
restoreVolatileRegisters(ret);
restoreFloatingPointState(ret);
}
restoreNonVolatiles(ret);
// 2. Restore caller's stackpointer and framepointer
int frameSize = getFrameFixedSize();
ret.insertBefore(MIR_UnaryNoRes.create(REQUIRE_ESP, IC(frameSize)));
MemoryOperand fpHome =
MemoryOperand.BD(
ir.regpool.makeTROp(),
ArchEntrypoints.framePointerField.getOffset(),
(byte) WORDSIZE,
null,
null);
ret.insertBefore(MIR_Nullary.create(IA32_POP, fpHome));
}
/**
* Insert the prologue for a normal method.
*
* <p>Assume we are inserting the prologue for method B called from method A.
*
* <ul>
* <li>Perform a stack overflow check.
* <li>Store a back pointer to A's frame
* <li>Store B's compiled method id
* <li>Adjust frame pointer to point to B's frame
* <li>Save any used non-volatile registers
* </ul>
*/
@Override
public void insertNormalPrologue() {
PhysicalRegisterSet phys = (PhysicalRegisterSet) ir.regpool.getPhysicalRegisterSet();
Register ESP = phys.getESP();
MemoryOperand fpHome =
MemoryOperand.BD(
ir.regpool.makeTROp(),
ArchEntrypoints.framePointerField.getOffset(),
(byte) WORDSIZE,
null,
null);
// the prologue instruction
Instruction plg = ir.firstInstructionInCodeOrder().nextInstructionInCodeOrder();
// inst is the instruction immediately after the IR_PROLOGUE
// instruction
Instruction inst = plg.nextInstructionInCodeOrder();
int frameFixedSize = getFrameFixedSize();
ir.compiledMethod.setFrameFixedSize(frameFixedSize);
// I. Buy a stackframe (including overflow check)
// NOTE: We play a little game here. If the frame we are buying is
// very small (less than 256) then we can be sloppy with the
// stackoverflow check and actually allocate the frame in the guard
// region. We'll notice when this frame calls someone and take the
// stackoverflow in the callee. We can't do this if the frame is too big,
// because growing the stack in the callee and/or handling a hardware trap
// in this frame will require most of the guard region to complete.
// See libvm.C.
if (frameFixedSize >= 256) {
// 1. Insert Stack overflow check.
insertBigFrameStackOverflowCheck(plg);
// 2. Save caller's frame pointer
inst.insertBefore(MIR_UnaryNoRes.create(IA32_PUSH, fpHome));
// 3. Set my frame pointer to current value of stackpointer
inst.insertBefore(
MIR_Move.create(
IA32_MOV, fpHome.copy(), new RegisterOperand(ESP, PRIMITIVE_TYPE_FOR_WORD)));
// 4. Store my compiled method id
int cmid = ir.compiledMethod.getId();
inst.insertBefore(MIR_UnaryNoRes.create(IA32_PUSH, VM.BuildFor32Addr ? IC(cmid) : LC(cmid)));
} else {
// 1. Save caller's frame pointer
inst.insertBefore(MIR_UnaryNoRes.create(IA32_PUSH, fpHome));
// 2. Set my frame pointer to current value of stackpointer
inst.insertBefore(
MIR_Move.create(
IA32_MOV, fpHome.copy(), new RegisterOperand(ESP, PRIMITIVE_TYPE_FOR_WORD)));
// 3. Store my compiled method id
int cmid = ir.compiledMethod.getId();
inst.insertBefore(MIR_UnaryNoRes.create(IA32_PUSH, VM.BuildFor32Addr ? IC(cmid) : LC(cmid)));
// 4. Insert Stack overflow check.
insertNormalStackOverflowCheck(plg);
}
// II. Save any used volatile and non-volatile registers
if (ir.compiledMethod.isSaveVolatile()) {
saveVolatiles(inst);
saveFloatingPointState(inst);
}
saveNonVolatiles(inst);
}