ps6: task 4

ps6/src/generator.c

@@ -240,12 +240,37 @@ static const char* generate_array_access(node_t* node)
   return MEM(RCX);
 }
 
+int ternary_counter = 0;
+
 // Generates code to evaluate expressions on the form A ? B : C
 // If A is non-zero, B is evaluated. Otherwise C is evaluated.
 // The final result is placed in %rax
 static void generate_ternary_operator(node_t* op)
 {
   // TODO (Task 4): Implement the ternary operator
+  assert(op->n_children == 3);
+
+  node_t *a, *b, *c;
+  a = op->children[0];
+  b = op->children[1];
+  c = op->children[2];
+
+  char endif_label[8];
+  snprintf(endif_label, 8, "ENDTY%d", ternary_counter);
+  char else_label[8];
+  snprintf(else_label, 8, "ELSY%d", ternary_counter);
+
+  ternary_counter++;
+
+  generate_expression(a);
+  CMPQ("$0", RAX);
+  JE(else_label);
+  generate_expression(b);
+  JMP(endif_label);
+  
+  LABEL("%s", else_label);
+  generate_expression(c);
+  LABEL("%s", endif_label);
 }
 
 // Generates code to evaluate the expression, and place the result in %rax