ps5: implement operators in generate_expression

ps5/src/generator.c

@@ -166,6 +166,39 @@ static void generate_function_call(node_t* call)
   // TODO (Task 4.3)
 }
 
+#define UNARY_OP(OP, INST) \
+  if (strcmp(op, (OP)) == 0) { \
+    generate_expression(expression->children[0]); \
+    INST(RAX); \
+  }
+#define BINARY_OP(OP, INST) \
+  if (strcmp(op, (OP)) == 0) { \
+    generate_expression(left); \
+    PUSHQ(RAX); \
+    generate_expression(right); \
+    POPQ(RCX); \
+    INST(RCX, RAX); \
+  }
+#define DIVISION_OP \
+  if (strcmp(op, "/") == 0) { \
+    generate_expression(expression->children[1]); \
+    PUSHQ(RAX); \
+    generate_expression(expression->children[0]); \
+    CQO; \
+    POPQ(RCX); \
+    IDIVQ(RCX); \
+  }
+#define COMPARE_OP(OP, INST) \
+  if (strcmp(op, (OP)) == 0) { \
+    generate_expression(left); \
+    PUSHQ(RAX); \
+    generate_expression(right); \
+    POPQ(RCX); \
+    CMPQ(RAX, RCX); \
+    INST(AL); \
+    MOVZBQ(AL, RAX); \
+  }
+
 // Generates code to evaluate the expression, and place the result in %rax
 static void generate_expression(node_t* expression)
 {
@@ -187,6 +220,30 @@ static void generate_expression(node_t* expression)
     EMIT("movq (%s), %s", RAX, RAX);              // deref rax
     break;
   case OPERATOR:
+    char *op = expression->data.operator;
+    switch (expression->n_children) {
+    case 1:
+      UNARY_OP("-", NEGQ);
+      /* logical not "!" is omitted */
+      break;
+    case 2:
+      node_t *left = expression->children[0];
+      node_t *right = expression->children[1];
+      BINARY_OP("+", ADDQ);
+      BINARY_OP("-", SUBQ);
+      BINARY_OP("*", IMULQ);
+      DIVISION_OP; // special snowflake
+      COMPARE_OP("<",  SETL);
+      COMPARE_OP(">",  SETG);
+      COMPARE_OP("<=", SETLE);
+      COMPARE_OP(">=", SETGE);
+      COMPARE_OP("==", SETE);
+      COMPARE_OP("!=", SETNE);
+      break;
+    case 3:
+      /* ternary op "?:" is omitted */
+      break;
+    }
     break;
   case FUNCTION_CALL:
     break;