void DeclarationNode::GenCode(CodeEmitter &e, bool travSib, int virtualRegister, int toff) {
DeclarationNode *dPtr;
// Assign virtual register to 'real' register
int actualRegister = virtualRegister%MAX_EXP_REGISTERS+FIRST_REG_OFFSET;
// Don't generate code for IO functions
if (subKind == FuncK && name != "input" && name != "output" && name != "inputb" && name != "outputb") {
// Lookup in symbol table - we'll need to set the "offset" variable
dPtr = (DeclarationNode *)this;
dPtr->offset = e.emitSkip(0); // save the current location for calls later
// If this function is main, we need to backpatch in the jump from the prolog
if (name == "main") {
e.emitBackup(jumpMain);
e.emitRMAbs("LDA", pc, dPtr->offset, "jump to main");
e.emitRestore();
}
e.emitComment("Function " + name + " returns " + PrintType(type));
e.emitRM("ST", FIRST_REG_OFFSET, -1, fp, "store return address"); // return address is always -1 away from current frame
// Load up the foff variable with the function size
foff = size;
// Function Body
if (child[1] != NULL) {
child[1]->GenCode(e, true, virtualRegister, foff);
}
// Add Return Statement if the function doesn't return from all branches
if (!allPathsReturn) {
e.emitComment("This function requires a catch all return");
e.emitRM("LDC", rt, 0, 0, "Set return value to 0");
e.emitRM("LD", actualRegister, -1, fp, "Load return address");
e.emitRM("LD", fp, 0, fp, "Adjust fp");
e.emitRM("LDA", pc, 0, actualRegister, "Return");
}
else
e.emitComment("This function returns from all paths, no catch all return required");
e.emitComment("End Function " + name);
}
if (sibling != NULL)
sibling->GenCode(e, true, virtualRegister, toff);
}
void StatementNode::GenCode(CodeEmitter &e, bool travSib, int virtualRegister, int toff) {
int currLoc, skipLoc;
// Assign virtual register to 'real' register
int actualRegister = virtualRegister%MAX_EXP_REGISTERS+FIRST_REG_OFFSET;
switch (subKind) {
case IfK:
e.emitComment("IF");
// Test Condition
if (child[0] != NULL)
child[0]->GenCode(e, true, virtualRegister, toff);
e.emitRM("LDC", rt, 1, 0, "load constant 1");
e.emitRO("SUB", actualRegister, actualRegister, rt, "if condition check");
skipLoc = e.emitSkip(1);
e.emitComment("THEN");
// Then part
if (child[1] != NULL)
child[1]->GenCode(e, true, virtualRegister, toff);
// Else part
if (child[2] != NULL) {
currLoc = e.emitSkip(1);
e.emitBackup(skipLoc);
e.emitRMAbs("JLT", actualRegister, currLoc+1, "jump to else if false");
e.emitRestore();
skipLoc = currLoc;
child[2]->GenCode(e, true, virtualRegister, toff);
currLoc = e.emitSkip(0);
e.emitBackup(skipLoc);
e.emitRMAbs("LDA", pc, currLoc, "jump past else part");
e.emitRestore();
}
else {
currLoc = e.emitSkip(0);
e.emitBackup(skipLoc);
e.emitRMAbs("JLT", actualRegister, currLoc, "jump past then if false");
e.emitRestore();
}
e.emitComment("END IF");
break;
case CompK:
e.emitComment("BEGIN");
if (child[1] != NULL)
child[1]->GenCode(e, true, virtualRegister, toff);
e.emitComment("END");
break;
case WhileK:
e.emitComment("WHILE");
currLoc = e.emitSkip(0);
// Test Condition
if (child[0] != NULL)
child[0]->GenCode(e, true, virtualRegister, toff);
e.emitRM("LDC", rt, 1, 0, "load constant 1");
e.emitRO("SUB", actualRegister, actualRegister, rt, "while condition check");
skipLoc = e.emitSkip(1);
e.emitComment("WHILE BODY");
// While Body
if (child[1] != NULL)
child[1]->GenCode(e, true, virtualRegister, toff);
e.emitRMAbs("LDA", pc, currLoc, "go to beginning of loop");
// Save current location to jump when While cond. is false
currLoc = e.emitSkip(0);
e.emitBackup(skipLoc);
e.emitRMAbs("JLT", actualRegister, currLoc, "break out of loop if false");
e.emitRestore();
e.emitComment("END WHILE");
break;
case ReturnK:
e.emitComment("RETURN");
if (child[0] != NULL)
child[0]->GenCode(e, true, virtualRegister, toff);
e.emitRM("LDA", rt, 0, actualRegister, "copy result to rt register");
e.emitRM("LD", actualRegister, -1, fp, "load return address"); // Return address is one off from frame pointer
e.emitRM("LD", fp, 0, fp, "adjust fp");
e.emitRM("LDA", pc, 0, actualRegister, "Return");
break;
}
if (sibling != NULL) {
e.emitComment(NO_COMMENT);
sibling->GenCode(e, true, virtualRegister, toff);
}
}
void ExpressionNode::GenCode(CodeEmitter &e, bool travSib, int virtualRegister, int toff) {
DeclarationNode *dPtr;
ExpressionNode *argPtr;
int localToff, boolSkipLoc, currentLoc, currentReg;
bool isUnary = true;
// Assign virtual register to 'real' register
int actualRegister = virtualRegister%MAX_EXP_REGISTERS+FIRST_REG_OFFSET;
int nextRegister = (virtualRegister+1)%MAX_EXP_REGISTERS+FIRST_REG_OFFSET;
localToff = toff;
switch (subKind) {
case OpK:
// process left child
if (child[0] != NULL)
child[0]->GenCode(e, true, virtualRegister, toff);
// mark location for short circuit jump
if (op == "&&" || op == "||")
boolSkipLoc = e.emitSkip(1);
if (child[1] != NULL) {
isUnary = false;
// see if all of our registers are full...
if (virtualRegister+1 >= MAX_EXP_REGISTERS) {
// push value from "next" register
e.emitRM("ST", nextRegister, toff--, fp, "dump register"); // push
}
else
e.emitComment("Left side will remain in register");
/*
// save left side
localToff = toff--;
e.emitRM("ST", ac, localToff, fp, "save left side");
*/
// process right child
child[1]->GenCode(e, true, virtualRegister+1, toff);
/*
// load left back into the accumulator
toff = localToff;
e.emitRM("LD", ac1, localToff, fp, "load left into ac1");
*/
}
// process operators
// arithmetic operators
if (op == "+")
e.emitRO("ADD", actualRegister, actualRegister, nextRegister, "op +");
else if (op == "-" && !isUnary)
e.emitRO("SUB", actualRegister, actualRegister, nextRegister, "op -");
else if (op == "*")
e.emitRO("MUL", actualRegister, actualRegister, nextRegister, "op *");
else if (op == "/")
e.emitRO("DIV", actualRegister, actualRegister, nextRegister, "op /");
else if (op == "%") {
e.emitRO("DIV", rt, actualRegister, nextRegister, "begin op %");
e.emitRO("MUL", nextRegister, rt, nextRegister, "");
e.emitRO("SUB", actualRegister, actualRegister, nextRegister, "end op %");
}
else if (op == "&&") {
/**** Code for the non short circuit case ****
e.emitRO("ADD", actualRegister, actualRegister, nextRegister, "prepare for && op");
e.emitRM("LDC", nextRegister, 2, 0, "load constant for &&");
e.emitRO("SUB", actualRegister, nextRegister, actualRegister, "compute value");
e.emitRM("JEQ", actualRegister, 2, pc, "op &&");
e.emitRM("LDC", actualRegister, 0, 0, "load false into ac");
e.emitRM("LDA", pc, 1, pc, "jump past true case");
e.emitRM("LDC", actualRegister, 1, 0, "load true into ac");
**** Code for the non short circuit case *****/
e.emitRM("JGT", nextRegister, 2, pc, "op && (right side)");
// special case: If left side of && is false then whole expression is false
currentLoc = e.emitSkip(0);
e.emitBackup(boolSkipLoc);
e.emitRMAbs("JEQ", actualRegister, currentLoc, "Skip right child of && if left is false");
e.emitRestore();
e.emitRM("LDC", actualRegister, 0, 0, "load false into ac");
e.emitRM("LDA", pc, 1, pc, "jump past true case");
e.emitRM("LDC", actualRegister, 1, 0, "load true into ac");
}
else if (op == "||") {
/**** Code for the non short circuit case ****
e.emitRO("ADD", actualRegister, actualRegister, nextRegister, "prepare for || op");
e.emitRM("JGT", actualRegister, 2, pc, "op ||");
e.emitRM("LDC", actualRegister, 0, 0, "load false into ac");
e.emitRM("LDA", pc, 1, pc, "jump past true case");
e.emitRM("LDC", actualRegister, 1, 0, "load true into ac");
**** Code for the non short circuit case *****/
//e.emitRM("JEQ", nextRegister, 2, pc, "op || (right side)");
/* Since the left side is short circuited the right side alone will determine
whether the expression is true or false. Just make sure the RHS is int the right
register */
e.emitRM("LDA", actualRegister, 0, nextRegister, "Move RHS to current accumulator");
// special case: If left side of || is true then whole expression is true
currentLoc = e.emitSkip(0);
e.emitBackup(boolSkipLoc);
e.emitRMAbs("JGT", actualRegister, currentLoc, "Skip right child of || if left is true");
e.emitRestore();
//e.emitRM("LDC", actualRegister, 1, 0, "load true into ac");
//e.emitRM("LDA", pc, 1, pc, "jump past false case");
//e.emitRM("LDC", actualRegister, 0, 0, "load false into ac");
}
else if (op == "!") {
e.emitRM("JEQ", actualRegister, 2, pc, "op !");
e.emitRM("LDC", actualRegister, 0, 0, "load false into ac");
e.emitRM("LDA", pc, 1, pc, "jump past true case");
e.emitRM("LDC", actualRegister, 1, 0, "load true into ac");
}
else if (op == "-" and isUnary) {
e.emitRM("LDC", rt, 0, 0, "Load zero in rt for unary -");
e.emitRO("SUB", actualRegister, rt, actualRegister, "op unary -");
}
else { // comparison operators
e.emitRO("SUB", actualRegister, actualRegister, nextRegister, "prepare for comparison op");
if (op == "==")
e.emitRM("JEQ", actualRegister, 2, pc, "op ==");
else if (op == "!=")
e.emitRM("JNE", actualRegister, 2, pc, "op !=");
else if (op == "<")
e.emitRM("JLT", actualRegister, 2, pc, "op <");
else if (op == "<=")
e.emitRM("JLE", actualRegister, 2, pc, "op <=");
else if (op == ">")
e.emitRM("JGT", actualRegister, 2, pc, "op >");
else if (op == ">=")
e.emitRM("JGE", actualRegister, 2, pc, "op >=");
e.emitRM("LDC", actualRegister, 0, 0, "load false into ac");
e.emitRM("LDA", pc, 1, pc, "jump past true case");
e.emitRM("LDC", actualRegister, 1, 0, "load true into ac");
}
// if we dumped a register earlier we need to restore it here
if (virtualRegister+1 >= MAX_EXP_REGISTERS) {
// pop value from stack back into next register
e.emitRM("LD", nextRegister, ++toff, fp, "restore register"); // pop
}
break;
case AssignK:
// process RHS of assignment
if (child[1] != NULL)
child[1]->GenCode(e, true, virtualRegister, toff);
// call function to store in LHS
((ExpressionNode *)child[0])->GenAssignLHS(e, virtualRegister, toff);
break;
case ConstK:
e.emitRM("LDC", actualRegister, val, 0, "load constant");
break;
case IdK:
if (this->dPtr->isArray) {
// is this array indexed?
if (child[0] == NULL) { // must be a parameter
if (this->dPtr->theScope == TreeNode::Parameter)
e.emitRM("LD", actualRegister, this->dPtr->offset, (this->dPtr->theScope == TreeNode::Global)?gp:fp, "Load address of base of array " + this->name);
else
e.emitRM("LDA", actualRegister, this->dPtr->offset, (this->dPtr->theScope == TreeNode::Global)?gp:fp, "Load address of base of array " + this->name);
}
else {
child[0]->GenCode(e, true, virtualRegister, toff);
if (this->dPtr->theScope == TreeNode::Parameter)
e.emitRM("LD", rt, this->dPtr->offset, (this->dPtr->theScope == TreeNode::Global)?gp:fp, "Load address of base of array " + this->name);
else
e.emitRM("LDA", rt, this->dPtr->offset, (this->dPtr->theScope == TreeNode::Global)?gp:fp, "Load address of base of array " + this->name);
e.emitRO("SUB", actualRegister, rt, actualRegister, "index off of the base");
e.emitRM("LD", actualRegister, 0, actualRegister, "load the value");
}
}
else {
e.emitRM("LD", actualRegister, this->dPtr->offset, (this->dPtr->theScope == TreeNode::Global)?gp:fp, "load variable " + name);
}
break;
case CallK:
// dump any used registers to temps before calling a function
currentReg = actualRegister;
if (currentReg > FIRST_REG_OFFSET)
e.emitComment("Need to dump Registers before call");
while (currentReg > FIRST_REG_OFFSET)
e.emitRM("ST", --currentReg, toff--, fp, "Save register to temporaries");
dPtr = (DeclarationNode *)symtab->lookup(name.c_str());
currentLoc = toff--;
e.emitRM("ST", fp, currentLoc, fp, "Store old fp in ghost frame");
// leave room for return param
--toff;
// process function parameters
argPtr = (ExpressionNode *)this->child[0]; // set the parameter pointer to the function declaration parameters
//localToff = toff;
while (argPtr != NULL) {
//localToff--;
//toff--;
argPtr->GenCode(e, false, 0, toff);
// store expression result
e.emitRM("ST", FIRST_REG_OFFSET, toff-- , fp, "Save parameter");
argPtr = (ExpressionNode *)argPtr->sibling;
}
// prepare for jump
e.emitRM("LDA", fp, currentLoc, fp, "Load address of new frame");
e.emitRM("LDA", FIRST_REG_OFFSET, 1, pc, "Put return address in ac");
e.emitRMAbs("LDA", pc, dPtr->offset, "Call " + dPtr->name);
// save return value
e.emitRM("LDA", actualRegister, 0, rt, "Save the result in current accumulator");
// restore temps back to registers
if (currentReg < actualRegister)
e.emitComment("Need to restore registers after call");
toff = currentLoc;
while (currentReg < actualRegister)
e.emitRM("LD", currentReg++, ++toff, fp, "Load Register from Temporaries");
// restore toff
//toff = localToff;
break;
}
if (sibling != NULL && travSib) {
e.emitComment(NO_COMMENT);
sibling->GenCode(e, true, 0, localToff);
}
}