string CBackendx86::Operand(const CTac *op)
{
string operand;
// TODO
// return a string representing op
// hint: take special care of references (op of type CTacReference)
std::stringstream buffer ;
buffer << op ;
CScope *cs = GetScope();
CSymtab *st = cs->GetSymbolTable();
vector<CSymbol*> slist = st->GetSymbols();
vector< CSymbol * > symbols = st->GetSymbols() ;
//CTacName
if (st->FindSymbol(buffer.str()) != NULL){
operand = buffer.str() ;
}
//CTacConstant
else if (buffer.str()[0] > 47 && buffer.str()[0] < 58){
operand = Imm(atoi(buffer.str().c_str())) ;
}
//CTacReference
else {
}
return operand ;
}
void CBackendx86::EmitInstruction(CTacInstr *i)
{
assert(i != NULL);
ostringstream cmt;
string mnm;
cmt << i;
EOperation op = i->GetOperation();
CScope* sc = GetScope() ;
const CSymbol* symbol ;
int size ;
switch (op) {
// binary operators
// dst = src1 op src2
// TODO
case opAdd :
//case opSub :
case opMul :
//case opDiv :
//case opAnd :
//case opOr :
EmitInstruction("movl", Operand(i->GetSrc(1)) + ", %eax", cmt.str());
EmitInstruction("movl", Operand(i->GetSrc(2)) + ", %ebx");
if (op == opAdd)
EmitInstruction("addl", "%ebx, %eax");
else if (op == opMul)
EmitInstruction("imull", "%ebx");
symbol = sc->GetSymbolTable()->FindSymbol(Operand(i->GetSrc(1)));
size = symbol->GetOffset() ;
cmt.str("");
cmt << size ;
EmitInstruction("movl", "%eax, -" + cmt.str() + "(%ebp)" );
break ;
// unary operators
// dst = op src1
// TODO
case opNeg :
//case opPos :
//case opNot :
symbol = sc->GetSymbolTable()->FindSymbol(Operand(i->GetSrc(1)));
if (symbol != NULL){
EmitInstruction("movl", Operand(i->GetSrc(1)) + ", %eax", cmt.str());
EmitInstruction("negl", "%eax");
size = symbol->GetOffset() ;cmt.str("");
cmt << size ;
EmitInstruction("movl", "%eax, -" + cmt.str() + "(%ebp)" );
}
else {
EmitInstruction("movl", Operand(i->GetSrc(1)) + ", %eax", cmt.str());
EmitInstruction("negl", "%eax");
}
break ;
// memory operations
// dst = src1
// TODO
case opAssign :
if (false) {
}else {
//cmt << " assign\t" + Operand(i->GetDest()) + " <- " << i->GetSrc(1) ;
Load(i->GetSrc(1), "%eax", cmt.str() ) ;
Store(i->GetDest(), 'a', "") ;
}
break ;
// pointer operations
// dst = &src1
// TODO
// dst = *src1
case opDeref:
// opDeref not generated for now
EmitInstruction("# opDeref", "not implemented", cmt.str());
break;
// unconditional branching
// goto dst
// TODO
// conditional branching
// if src1 relOp src2 then goto dst
// TODO
// function call-related operations
// TODO
// special
case opLabel:
_out << Label(dynamic_cast<CTacLabel*>(i)) << ":" << endl;
break;
case opNop:
EmitInstruction("nop", "", cmt.str());
break;
default:
EmitInstruction("# ???", "not implemented", cmt.str());
}
}
