/**
* Before instruction s, insert code to adjust ESP so that it lies at a particular offset from its
* usual location.
*
* @param s the instruction before which ESP must have the desired offset
* @param desiredOffset the desired offset
*/
private void moveESPBefore(Instruction s, int desiredOffset) {
PhysicalRegisterSet phys = (PhysicalRegisterSet) ir.regpool.getPhysicalRegisterSet();
Register ESP = phys.getESP();
int delta = desiredOffset - ESPOffset;
if (delta != 0) {
if (canModifyEFLAGS(s)) {
s.insertBefore(
MIR_BinaryAcc.create(
IA32_ADD,
new RegisterOperand(ESP, PRIMITIVE_TYPE_FOR_WORD),
VM.BuildFor32Addr ? IC(delta) : LC(delta)));
} else {
MemoryOperand M =
MemoryOperand.BD(
new RegisterOperand(ESP, PRIMITIVE_TYPE_FOR_WORD),
Offset.fromIntSignExtend(delta),
(byte) WORDSIZE,
null,
null);
s.insertBefore(
MIR_Lea.create(IA32_LEA, new RegisterOperand(ESP, PRIMITIVE_TYPE_FOR_WORD), M));
}
ESPOffset = desiredOffset;
}
}
