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assembly.c
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assembly.c
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#include "assembly.h"
/*
Recursively generates code for an astnode
*/
void generateCode(FILE *fp,ASTNode *currASTNode){
// base case
if(currASTNode==NULL) return;
int numberOfChildren = calculateChildrenCount(currASTNode);
int isScopeChanged = 0;
int current_scope_previous;
if(currASTNode->astScopeNode->scope > current_scope){
isScopeChanged = 1;
fprintf(fp,"\tli $t0, %d\n\tsub $sp, $sp, $t0\n\tmove $t2, $sp\n",currASTNode->astScopeNode->tableSize);
current_scope_previous = current_scope;
current_scope = currASTNode->astScopeNode->scope;
}
if(currASTNode->progType >= IDEN_RELATED){
load_spill_array_identifier(fp,currASTNode,0);
}
else if(currASTNode->progType == CONSTANTS ){
if(currASTNode->type == INT){
fprintf(fp,"\tli $t1, %s\n",currASTNode->lexeme); //load number
} else if(currASTNode->type == CHAR){
fprintf(fp,"\tli $t1, %d\n",currASTNode->lexeme[1]); // load character
} else if(currASTNode->type == STRING){
fprintf(fp,"\tla $t1, %d\n",currASTNode->lexeme[1]); // load character
}
// decrement current stack pointer $t2
fprintf(fp,"\tli $t3,4\n\tsub $t2,$t2,$t3\n\tsw $t1,0($t2)\n\n"); // store result in $t2
}
else if(!strcmp(currASTNode->lexeme,"output")){
symbolTable* curr_table = getSymbolTable(currASTNode->child[1]->lexeme, currASTNode);
loadFromStack(fp,"$a0",curr_table,currASTNode->child[1]->astScopeNode,0);
if(currASTNode->child[0]->type == INT){
fprintf(fp,"\tli $v0,1\n\tsyscall\n\tli $a0,32\n\tli $v0,11\n\tsyscall\n");
} else if(currASTNode->child[0]->type == CHAR){
fprintf(fp,"\tli $v0,11\n\tsyscall\n\tli $a0,32\n\tsyscall\n");
} else if(currASTNode->child[0]->type == STRING){
fprintf(fp,"\tli $v0,4\n\tla $a0,%s\n\tsyscall\n",currASTNode->child[1]->lexeme);
}
}
else if(!strcmp(currASTNode->lexeme,"input")){
if(currASTNode->child[0]->type == INT){
fprintf(fp,"\tli $v0,5\n\tsyscall\n");
}
else if(currASTNode->child[0]->type == CHAR){
fprintf(fp,"\tli $v0,12\n\tsyscall\n");
}
else if(currASTNode->child[0]->type == STRING){
fprintf(fp,"\tli $v0,8\n\t\n\tla $a0, %s\n\tsyscall\n",currASTNode->child[1]->lexeme);
}
symbolTable* curr_table = getSymbolTable(currASTNode->child[1]->lexeme, currASTNode);
spill(fp,"$v0",curr_table,currASTNode->child[1]->astScopeNode,0);
}
else if(numberOfChildren == 2 && checkIfOperator(currASTNode->lexeme)==1 ) {
for(int child_index=0;child_index<numberOfChildren;child_index++) generateCode(fp,currASTNode->child[child_index]);
fprintf(fp,"\tlw $t1,0($t2)\n\tlw $t0,4($t2)\n\tli $t3,4\n\tadd $t2,$t2,$t3\n"); // right operand $t1, left operand $t0, t3 temp stack for calculations
operationsCode(fp,currASTNode->lexeme);
fprintf(fp,"\tsw $t1,0($t2)\n\n");
}
else if(numberOfChildren == 1 && checkIfOperator(currASTNode->lexeme)==1 ){
generateCode(fp,currASTNode->child[0]);
fprintf(fp,"\tlw $t1,0($t2)\n");
if(strcmp(currASTNode->lexeme, "-") == 0){
fprintf(fp,"\tsub $t1,$0,$t1\n");
}
else{
fprintf(fp,"\tseq $t1,$0,$t1\n");
}
fprintf(fp,"\tsw $t1,0($t2)\n\n");
}
else if(!strcmp(currASTNode->lexeme,"Newline")){
fprintf(fp,"\n\tmove $s1,$a0\n\tla $a0, newline_FIXED\n\tli $v0,4\n\tsyscall\n\tmove $a0,$s1\n\t");
}
else if(currASTNode->type==STRING_ASSIGN_CONCAT){
char labelHere[100];
getNewLabel(labelHere);
fprintf(fp,"\n\tla $s1, %s\n\tli $t6,10\n\tla $s2, %s\n\tloop%s:\n\tlb $t5, 0($s1)\n\tbeqz $t5, next%s\n\tbeq $t5, $t6, next%s\n\tsb $t5, 0($s2)\n\taddi $s1,$s1,1\n\taddi $s2,$s2,1\n\tj loop%s\n\tnext%s:\n\tla $s1, %s\n\tloop2%s: \n\tlb $t5, 0($s1) \n\tbeqz $t5, next2%s \n\tbeq $t5, $t6 next2%s\n\tsb $t5, 0($s2) \n\taddi $s1,$s1,1\n\taddi $s2,$s2,1\n\tj loop2%s\n\tsb $zero,0($s2)\n\tnext2%s:\n\tsb $zero,0($s2)\n\t",currASTNode->child[1]->child[0]->lexeme,currASTNode->child[0]->lexeme,labelHere,labelHere,labelHere,labelHere,labelHere,currASTNode->child[1]->child[1]->lexeme,labelHere,labelHere,labelHere,labelHere,labelHere);
}
else if(!strcmp(currASTNode->lexeme,"=")){
if(currASTNode->type==MUTATE_STRING){
fprintf(fp,"\n\tla $s1, %s\n\tla $t6, constant%s\n\taddi $s1,$s1,%s\n\tlb $t5,0($t6)\n\tsb $t5,0($s1)\n\t",currASTNode->child[0]->lexeme,currASTNode->child[1]->lexeme,currASTNode->child[0]->child[0]->lexeme);
}
else if(currASTNode->type==STRING_ASSIGN_VAR){
char labelHere[100];
getNewLabel(labelHere);
fprintf(fp,"\n\tli $s2,0\n\tla $t5, %s\n\tla $s1, %s\n\tloopss%s:\n\tlb $t6, 0($t5)\n\tsb $t6, 0($s1)\n\taddi $t5, $t5,1\n\taddi $s1,$s1,1\n\taddi $s2,$s2,1\n\tblt $s2, 100, loopss%s\n",currASTNode->child[1]->lexeme,currASTNode->child[0]->lexeme,labelHere,labelHere);
}
else if(currASTNode->child[0]->type==STRING){
char labelHere[100];
getNewLabel(labelHere);
fprintf(fp,"\n\tli $s2,0\n\tla $t5, constant%s\n\tla $s1, %s\n\tloop%s:\n\tlb $t6, 0($t5)\n\tsb $t6, 0($s1)\n\taddi $t5, $t5,1\n\taddi $s1,$s1,1\n\taddi $s2,$s2,1\n\tblt $s2, 100, loop%s\n",currASTNode->child[1]->lexeme,currASTNode->child[0]->lexeme,labelHere,labelHere);
}
else{
generateCode(fp,currASTNode->child[1]);
fprintf(fp,"\tlw $t1,0($t2)\n");
load_spill_array_identifier(fp,currASTNode->child[0],1);
if(strcmp(currASTNode->parent->lexeme,currASTNode->lexeme)){
fprintf(fp,"\tadd $t2,$t2,4\n" );
}
}
}
else if(currASTNode->progType == WHILE_LOOP){
char while_expression[100],while_body_outer[100];// these should not leave anything in 0($t2)
getNewLabel(while_expression);
getNewLabel(while_body_outer);
strcpy(currASTNode->labels[0],while_expression);
strcpy(currASTNode->labels[1],while_body_outer);
fprintf(fp,"%s:\n",while_expression);
generateCode(fp,currASTNode->child[0]); // generate code for expression evaluation
fprintf(fp,"\tlw $t0,0($t2)\n\tbeq $0, $t0,%s\n",while_body_outer);
generateCode(fp,currASTNode->child[1]); // generate code for body of the loop
fprintf(fp,"b %s\n%s:\n",while_expression,while_body_outer);
}
else if(currASTNode->progType == FOR_TYPE_ONE || currASTNode->progType==FOR_TYPE_TWO){
char for_condition[100],for_body_outer[100];
getNewLabel(for_condition);
getNewLabel(for_body_outer);
strcpy(currASTNode->labels[0],for_condition);
strcpy(currASTNode->labels[1],for_body_outer);
generateCode(fp,currASTNode->child[0]); // for declaration
fprintf(fp,"%s:",for_condition);
generateCode(fp,currASTNode->child[1]); // for condition code generation
fprintf(fp,"\tlw $t1,0($t2)\n\tadd $t2,$t2,4\n\tbeq $t1,$0,%s\n",for_body_outer); // if false leave out of for
if(currASTNode->progType==FOR_TYPE_ONE) generateCode(fp,currASTNode->child[2]); // for loop body
else {
generateCode(fp,currASTNode->child[3]); // for loop body
generateCode(fp,currASTNode->child[2]); // for loop increment / decrement expression
}
fprintf(fp,"\tb %s\n%s:\n",for_condition,for_body_outer); // go back to for condition , for outer body
}
else if(currASTNode->progType == IF_TYPE_ONE || currASTNode->progType == IF_TYPE_TWO){
char if_body_outer[100]; // to go out of in if(){}
char else_body[100];// to go inside else of if(){}else{}
getNewLabel(if_body_outer);
getNewLabel(else_body);
generateCode(fp,currASTNode->child[0]);
fprintf(fp,"\tlw $t0,0($t2)\n\tadd $t2,$t2,4\n");
if(currASTNode->progType == IF_TYPE_ONE){
fprintf(fp,"\tbeq $0, $t0,%s\n",if_body_outer); // in if(){} type of statements go out of 'if' if condition is false
} else {
fprintf(fp,"\tbeq $0, $t0,%s\n",else_body); // in if(){}else{} type of statements go to 'else' if condition is false
}
generateCode(fp,currASTNode->child[1]); // if body
if(currASTNode->progType == IF_TYPE_TWO){
fprintf(fp,"\tb %s\n%s:\n",if_body_outer,else_body); // do not go in else part if coming from 'if' part
generateCode(fp,currASTNode->child[2]);
}
fprintf(fp,"%s:\n",if_body_outer);
}
else if(currASTNode->type == CONTINUE || currASTNode->type == BREAK){
int label_index = 0; // 0-> go to next iteration label
if(currASTNode->type == BREAK) label_index = 1; // 1-> exit while/for loop label
ASTNode *for_or_while_loop = getClosestForOrWhile(currASTNode);
if(for_or_while_loop!=NULL){
fprintf(fp,"\tb %s\n",for_or_while_loop->labels[label_index]);
}
}
else if(currASTNode->type == RETURN){
if(numberOfChildren == 1){
generateCode(fp,currASTNode->child[0]);
fprintf(fp,"\tlw $v0,0($t2)\n");
}
int sizeDifference = currASTNode->astScopeNode->sizeSum - globalSymNode->sizeSum;
fprintf(fp,"\tadd $sp, $sp, %d\n\tmove $t2, $sp\n\tjr $ra\n",sizeDifference);
}
else if(currASTNode->progType == FUNCTION_WITHOUT_ARGUMENT){ //function calls
fprintf(fp,"\tli $t0,4\n\tsub $sp,$sp,$t0\n\tsw $ra,0($sp)\n\tmove $t2,$sp\n\tjal %s\n\n",currASTNode->lexeme);
fprintf(fp,"\tlw $ra,0($sp)\n\tadd $sp,$sp,4\n\tmove $t2,$sp\n");
if(currASTNode->type != VOID){
fprintf(fp,"\tli $t0,4\n\tsub $t2,$t2,$t0\n\tsw $v0,0($t2)\n");
}
}
else if(currASTNode->progType == FUNCTION_WITH_ARGUMENT){
processFunctionArguments(fp,currASTNode->child[0]);
fprintf(fp,"\tli $t0,4\n\tsub $sp,$sp,$t0\n\tsw $ra,0($sp)\n\tmove $t2,$sp\n\tli $t0,12\n\tsub $sp,$sp,$t0\n");
fprintf(fp,"\tjal %s\n\n\tadd $sp,$sp,12\n\tlw $ra,0($sp)\n\tadd $sp,$sp,4\n\tmove $t2,$sp\n",currASTNode->lexeme);
if(currASTNode->type != VOID){
fprintf(fp,"\tli $t0,4\n\tsub $t2,$t2,$t0\n\tsw $v0,0($t2)\n");
}
}
else {
for(int child_index=0;child_index<numberOfChildren;child_index++)
generateCode(fp,currASTNode->child[child_index]);
}
if(isScopeChanged == 1){
fprintf(fp,"\tli $t0, %d\n\tadd $sp, $sp, $t0\n\tmove $t2, $sp\n",currASTNode->astScopeNode->tableSize);
current_scope = current_scope_previous;
}
}
/*
Generates code for instructions that perform mathematical operations
*/
void operationsCode(FILE *fp,char *s){
for(int index=0;index<OPERATORS_COUNT;index++){
if(strcmp(s,operators[index])==0){
if((strcmp(s,"&&") == 0) || (strcmp(s,"||") == 0)) {
fprintf(fp,"\t%s $t9,$t0,$t1\n\tsne $t1,$t9,$0\n",instruction_for_operators[index]);
} else {
fprintf(fp,"\t%s $t1,$t0,$t1\n",instruction_for_operators[index]);
}
return;
}
}
}
void spill(FILE *fp,char *reg,symbolTable *currSymbolNode,tableNode *currTableNode,int isArr){
if(currSymbolNode->parentTableNode->scope == 0){
fprintf(fp,"\tla $t9,global\n\tadd $t9,$t9,%d\n",currSymbolNode->offset);
if(isArr==1) fprintf(fp,"\tadd $t9,$t9,$t8\n"); // to add the base address of array
fprintf(fp,"\tsw %s, 0($t9)\n",reg); // otherwise there is no offset
}
else if(currTableNode->scope == currSymbolNode->parentTableNode->scope){
fprintf(fp,"\tadd $t9,$sp,%d\n",currSymbolNode->offset);
if(isArr==1) fprintf(fp,"\tadd $t9,$t9,$t8\n");
fprintf(fp,"\tsw %s, 0($t9)\n",reg);
}
else{
int sizeDifference = currTableNode->sizeSum + currSymbolNode->offset - currSymbolNode->parentTableNode->sizeSum ;
fprintf(fp,"\tadd $t9,$sp,%d\n",sizeDifference);
if(isArr==1) fprintf(fp,"\tadd $t9,$t9,$t8\n");
fprintf(fp,"\tsw %s, 0($t9)\n",reg);
}
}
void loadFromStack(FILE *fp,char *reg,symbolTable *currSymbolNode,tableNode *currTableNode,int isArr){
if(currSymbolNode->parentTableNode->scope == 0){
fprintf(fp,"\tla $t9,global\n\tadd $t9,$t9,%d\n",currSymbolNode->offset);
if(isArr==1) fprintf(fp,"\tadd $t9,$t9,$t8\n");
fprintf(fp,"\tlw %s, 0($t9)\n",reg);
}
else if(currTableNode->scope == currSymbolNode->parentTableNode->scope){
fprintf(fp,"\tadd $t9,$sp,%d\n",currSymbolNode->offset);
if(isArr==1) fprintf(fp,"\tadd $t9,$t9,$t8\n");
fprintf(fp,"\tlw %s, 0($t9)\n",reg);
}
else{
int sizeDifference = currTableNode->sizeSum - currSymbolNode->parentTableNode->sizeSum + currSymbolNode->offset;
fprintf(fp,"\tadd $t9,$sp,%d\n",sizeDifference);
if(isArr==1) fprintf(fp,"\tadd $t9,$t9,$t8\n");
fprintf(fp,"\tlw %s, 0($t9)\n",reg);
}
}
void load_spill_array_identifier(FILE *fp,ASTNode*curr_node,int type){ // 0 == loadFromStack from stack , 1 == store to stack
int offset; // there is value in $t1 ,, save before calling generateCode
if(curr_node->progType==IDEN_RELATED){
offset = 0;
if(type==0){
fprintf(fp,"\tli $t3,4\n\tsub $t2,$t2,$t3\n");
symbolTable* curr_table = getSymbolTable(curr_node->lexeme, curr_node);
loadFromStack(fp,"$t4",curr_table,curr_node->astScopeNode,offset);
fprintf(fp,"\tsw $t4,0($t2)\n\n" );
}
}
else if(curr_node->progType == ARRAY_SINGLE_DIM){
fprintf(fp,"move $s0,$t1\n");
generateCode(fp,curr_node->child[0]);
fprintf(fp,"move $t1,$s0\n\tlw $t8,0($t2)\n\tli $t9,4\n\tmul $t8,$t8,$t9\n"); // add $t8 in offset
offset = 1;
if(type==0){
symbolTable* curr_table = getSymbolTable(curr_node->lexeme,curr_node);
loadFromStack(fp,"$t4",curr_table,curr_node->astScopeNode,offset); // load variable from sp and put on current stack pointed by $t3
fprintf(fp,"\tsw $t4,0($t2)\n\n");
}
if(type==1)
fprintf(fp,"\tadd $t2,$t2,4\n");
}
if(type == 1){
symbolTable* curr_table = getSymbolTable(curr_node->lexeme, curr_node);
spill(fp,"$t1",curr_table,curr_node->astScopeNode,offset);
}
}
/*
Generates code for putting all arguments in place
*/
void processFunctionArguments(FILE *fp,ASTNode *currASTNode){
// arguments is a tree like (ifmultiple arguments)-
// node
// / \
// node arg4
// / \
// node arg3
// / \
// arg1 arg2
// arguments is a tree like (if one)-
// arg1
ASTNode *currArgumentNode=currASTNode;
int index = findIndexInFunTree(currASTNode);
// assuming index!=-1
// go to leftmost child i.e. first argument
while(strcmp(currArgumentNode->lexeme,",")==0)
currArgumentNode = currArgumentNode->child[0];
int recordSpace = 0;
int recordSize;
int is_first_argument = 1;
if(currASTNode == currArgumentNode){
// case when only one argument
generateCode(fp,currArgumentNode);
// size of activation record
recordSize = funTree->children[index]->funcScopeNode->tableSize - recordSpace + 16;
fprintf(fp,"\tmove $t0,$sp\n\tli $t1, %d\n\tsub $t0,$t0,$t1\n\tlw $t4,0($t2)\n",recordSize);
recordSpace += 4;
fprintf(fp,"\tsw $t4,0($t0)\n");
}
else{
while(currArgumentNode != currASTNode->parent){
if(is_first_argument==0){
// rest of the arguments from 2 are right child of the node
generateCode(fp,currArgumentNode->child[1]);
}
else {
// first argument is the node itself
generateCode(fp,currArgumentNode);
is_first_argument=0;
}
recordSize = funTree->children[index]->funcScopeNode->tableSize - recordSpace + 16;
fprintf(fp,"\tmove $t8,$sp\n\tli $t7, %d\n\tsub $t8,$t8,$t7\n\tlw $t4,0($t2)\n\tadd $t2,$t2,4\n",recordSize);
recordSpace += 4;
fprintf(fp,"\tsw $t4,0($t8)\n");
// go to next argument, travel up the tree
currArgumentNode = currArgumentNode->parent;
}
}
}
/*
Calculates count of children in astnode
*/
int calculateChildrenCount(ASTNode* currASTNode){
int index = 0;
while(currASTNode->child[index]!=NULL) index++;
return index;
}
/*
Generates a new label
*/
void getNewLabel(char *s){
sprintf(s,"%s_%d",funTree->children[current_function_index]->functionName,global_labels_count++);
}
/*
Checks if lexeme if one of the operators defined
*/
int checkIfOperator(char* lexeme){
for(int index=0;index<OPERATORS_COUNT;index++){
if(strcmp(lexeme, operators[index])==0) return 1;
}
return 0;
}
/*
Finds index of a function from funTree that stores all global functions
*/
int findIndexInFunTree(ASTNode* currASTNode){
for(int index=0;index<funTree->numberOfChilds;index++){
if(strcmp(currASTNode->parent->lexeme,funTree->children[index]->functionName)==0){
return index;
}
}
return -1;
}
/*
Returns the astnode for closest outside for or while loop
*/
ASTNode * getClosestForOrWhile(ASTNode *currASTNode){
ASTNode* iteration_node = currASTNode;
while(iteration_node!=NULL){
if((strcmp(iteration_node->lexeme, "for")==0) || (strcmp(iteration_node->lexeme, "while")==0)) return iteration_node;
// check in parent node
iteration_node = iteration_node->parent;
}
return NULL;
}
/*
Generates MIPS code into a file
*/
void createAssembly(){
FILE *fp = fopen("target.s","w");
global_labels_count = 0; // assign unique labels
current_scope = 0; // scope level
// Initial code
fprintf(fp,".data\n");
// allocate space for strings
fprintf(fp,"\n\tnewline_FIXED: .asciiz \"\n\"\n");
for(int i=0;i<stringInd;i++){
fprintf(fp,"\t%s: .space 100\n",strings[i]);
}
for(int i=0;i<ConstantStringInd;i++){
fprintf(fp,"\tconstant%d: .asciiz %s\n",i,ConstantStrings[i]);
}
fprintf(fp,"global: .word %d\n",globalSymNode->tableSize);
fprintf(fp,".text\n");
// for each function generate individual code
for(int i=0;i<funTree->numberOfChilds;++i){
current_function_index = i;
// start function by creating the stack frame of the total size of all variable, store sp in t2
fprintf(fp,"%s:\n\tli $t0, %d\n\tsub $sp, $sp, $t0\n\tmove $t2, $sp\n",funTree->children[i]->functionName,funTree->children[i]->funcScopeNode->tableSize);
current_scope = funTree->children[i]->funcScopeNode->scope;
// generate code for this function, second child or child[1] contains the tree of statements inside function
generateCode(fp,funTree->children[i]->astNode->child[1]);
// remove stack frame, jump back to the address in return address register
fprintf(fp,"\tli $t0, %d\n\tadd $sp, $sp, $t0\n\tmove $t2, $sp\n\tjr $ra\n",funTree->children[i]->funcScopeNode->tableSize);
}
fclose(fp);
}