gas: Compile boolean variable assignment

When the assignment value is a literal, it just assigns zero or one to
the variable stack's location. If the value is an expression, it
compiles the expression and assign zeros and ones based on expression
result.

2 files changed, 101 insertions, 36 deletions

diff --git a/src/gas_assembly_generator.c b/src/gas_assembly_generator.c
index c85d7a7..44467db 100644
--- a/src/gas_assembly_generator.c
+++ b/src/gas_assembly_generator.c
@@ -58,6 +58,13 @@ gas_assembly_generator_set_latest_evaluation_as_literal(gas_assembly_generator_t
 }
 
 static void
+gas_assembly_generator_set_latest_evaluation_as_literal_boolean(gas_assembly_generator_t *gen, bool value)
+{
+  gen->latest_evaluation =
+    (evaluation_result_t){ .kind = EVALUATION_RESULT_AS_LITERAL_BOOL, .data = { .literal_bool = value } };
+}
+
+static void
 gas_assembly_generator_set_latest_evaluation_to_rax(gas_assembly_generator_t *gen)
 {
   gen->latest_evaluation = (evaluation_result_t){ .kind = EVALUATION_RESULT_ON_RAX };
@@ -70,6 +77,14 @@ gas_assembly_generator_set_latest_evaluation_on_stack(gas_assembly_generator_t *
     (evaluation_result_t){ .kind = EVALUATION_RESULT_ON_STACK, .data = { .stack_offset = stack_offset } };
 }
 
+static void
+gas_assembly_generator_compile_condition(gas_assembly_generator_t *gen,
+                                         ast_node_t *condition,
+                                         uint64_t true_label_index,
+                                         bool jump_when_true,
+                                         uint64_t false_label_index,
+                                         bool jump_when_false);
+
 typedef struct ref_entry_t
 {
   ast_identifier_t *id;
@@ -178,25 +193,59 @@ gas_assembly_generator_compile_return_stmt(gas_assembly_generator_t *gen, ast_re
 
   gas_assembly_generator_compile(gen, return_stmt->argument);
 
-  if (gen->latest_evaluation.kind == EVALUATION_RESULT_AS_LITERAL_INTEGER) {
-    fprintf(gen->stream, "  mov $%ld, %%rdi\n", gen->latest_evaluation.data.literal_int);
-  } else {
-    fprintf(gen->stream, "  mov %%rax, %%rdi\n");
+  switch (gen->latest_evaluation.kind) {
+    case EVALUATION_RESULT_AS_LITERAL_INTEGER:
+      fprintf(gen->stream, "  mov $%ld, %%rdi\n", gen->latest_evaluation.data.literal_int);
+      break;
+    case EVALUATION_RESULT_ON_RAX:
+      fprintf(gen->stream, "  mov %%rax, %%rdi\n");
+      break;
+    case EVALUATION_RESULT_ON_STACK:
+      fprintf(gen->stream, "  mov %d(%%rbp), %%rdi\n", gen->latest_evaluation.data.stack_offset);
+      break;
+    case EVALUATION_RESULT_VOID:
+      fprintf(gen->stream, "  xor %%rdi, %%rdi\n");
+      break;
+    case EVALUATION_RESULT_AS_LITERAL_BOOL:
+      assert(false && "Unexpected");
+      break;
   }
+
   fprintf(gen->stream, "  mov $60, %%rax\n");
   fprintf(gen->stream, "  syscall\n");
 }
 
 static void
-gas_assembly_generator_compile_variable_declaration(gas_assembly_generator_t *gen,
-                                                    ast_variable_declaration_t *variable_declaration)
+gas_assembly_generator_compile_variable_assign_value(gas_assembly_generator_t *gen,
+                                                     ast_node_t *expression,
+                                                     ref_entry_t *entry)
 {
-  gen->stack_offset -= 8;
-  gas_assembly_generator_compile(gen, variable_declaration->value);
+  if (expression->result_type == TYPE_BOOL) {
+    if (expression->kind == AST_LITERAL) {
+      assert(expression->data.literal.kind == AST_LITERAL_BOOL);
 
-  ref_entry_t *entry = ref_entry_new();
-  *entry = (ref_entry_t){ .id = &variable_declaration->identifier, .stack_offset = gen->stack_offset };
-  vector_push_back(gen->refs, entry);
+      fprintf(gen->stream, "  movq $%d, %d(%%rbp)\n", expression->data.literal.value.boolean, entry->stack_offset);
+      return;
+    }
+
+    uint64_t true_label_index = gen->cur_label_index++;
+    uint64_t false_label_index = gen->cur_label_index++;
+    uint64_t after_assign_label_index = gen->cur_label_index++;
+
+    gas_assembly_generator_compile_condition(gen, expression, true_label_index, false, false_label_index, true);
+
+    fprintf(gen->stream, ".L_%ld:\n", true_label_index);
+    fprintf(gen->stream, "  movq $1, %d(%%rbp)\n", entry->stack_offset);
+    fprintf(gen->stream, "  jmp .L_%ld\n", after_assign_label_index);
+
+    fprintf(gen->stream, ".L_%ld:\n", false_label_index);
+    fprintf(gen->stream, "  movq $0, %d(%%rbp)\n", entry->stack_offset);
+
+    fprintf(gen->stream, ".L_%ld:\n", after_assign_label_index);
+    return;
+  }
+
+  gas_assembly_generator_compile(gen, expression);
 
   switch (gen->latest_evaluation.kind) {
     case EVALUATION_RESULT_AS_LITERAL_INTEGER:
@@ -209,6 +258,7 @@ gas_assembly_generator_compile_variable_declaration(gas_assembly_generator_t *ge
       fprintf(gen->stream, "  movq %d(%%rbp), %%rax\n", gen->latest_evaluation.data.stack_offset);
       fprintf(gen->stream, "  movq %%rax, %d(%%rbp)\n", entry->stack_offset);
       break;
+    case EVALUATION_RESULT_AS_LITERAL_BOOL:
     case EVALUATION_RESULT_VOID:
       assert(false && "Unexpected void result for variable declaration");
       // FIXME: store the latest node at latest evaluation and print_ast
@@ -216,36 +266,26 @@ gas_assembly_generator_compile_variable_declaration(gas_assembly_generator_t *ge
 }
 
 static void
+gas_assembly_generator_compile_variable_declaration(gas_assembly_generator_t *gen,
+                                                    ast_variable_declaration_t *variable_declaration)
+{
+  gen->stack_offset -= 8;
+
+  ref_entry_t *entry = ref_entry_new();
+  *entry = (ref_entry_t){ .id = &variable_declaration->identifier, .stack_offset = gen->stack_offset };
+  vector_push_back(gen->refs, entry);
+
+  gas_assembly_generator_compile_variable_assign_value(gen, variable_declaration->value, entry);
+}
+
+static void
 gas_assembly_generator_compile_variable_assignment(gas_assembly_generator_t *gen,
                                                    ast_variable_assignment_t *variable_assignment)
 {
   ref_entry_t *entry = find_ref_entry(gen->refs, variable_assignment->identifier);
   assert(entry && "reference not found");
 
-  gas_assembly_generator_compile(gen, variable_assignment->expression);
-
-  switch (gen->latest_evaluation.kind) {
-    case EVALUATION_RESULT_AS_LITERAL_INTEGER:
-      fprintf(gen->stream, "  movq $%ld, %d(%%rbp)\n", gen->latest_evaluation.data.literal_int, entry->stack_offset);
-      break;
-    case EVALUATION_RESULT_ON_RAX:
-      fprintf(gen->stream, "  mov %%rax, %d(%%rbp)\n", entry->stack_offset);
-      break;
-    case EVALUATION_RESULT_ON_STACK:
-      fprintf(gen->stream, "  movq %d(%%rbp), %%rax\n", gen->latest_evaluation.data.stack_offset);
-      fprintf(gen->stream, "  movq %%rax, %d(%%rbp)\n", entry->stack_offset);
-      break;
-    case EVALUATION_RESULT_VOID:
-      assert(false && "Unexpected void result for variable declaration");
-      // FIXME: store the latest node at latest evaluation and print_ast
-  }
-  // Today we dont't support chain-assignment like this:
-  //
-  //   a = b = 1;
-  //
-  // If we start supporting it, we need to change the latest evaluation kind to
-  // stack.
-  gen->latest_evaluation.kind = EVALUATION_RESULT_VOID;
+  gas_assembly_generator_compile_variable_assign_value(gen, variable_assignment->expression, entry);
 }
 
 static void
@@ -263,6 +303,9 @@ gas_assembly_generator_compile_literal(gas_assembly_generator_t *gen, ast_litera
     case AST_LITERAL_INTEGER:
       gas_assembly_generator_set_latest_evaluation_as_literal(gen, literal->value.integer);
       return;
+    case AST_LITERAL_BOOL:
+      gas_assembly_generator_set_latest_evaluation_as_literal_boolean(gen, literal->value.boolean);
+      return;
     default:
       assert(false && "no code generation strategy.");
   }
@@ -301,6 +344,9 @@ gas_assembly_generator_binary_operation(gas_assembly_generator_t *gen, ast_binar
     case EVALUATION_RESULT_ON_STACK:
       fprintf(gen->stream, "  movq %d(%%rbp), %%rcx\n", right_evaluation.data.stack_offset);
       break;
+    case EVALUATION_RESULT_AS_LITERAL_BOOL:
+      fprintf(gen->stream, "  mov $%d, %%rcx\n", right_evaluation.data.literal_bool);
+      break;
     case EVALUATION_RESULT_VOID:
       assert(false && "Unexpected void result for binary operation");
       // FIXME: store the latest node at latest evaluation and print_ast
@@ -317,6 +363,9 @@ gas_assembly_generator_binary_operation(gas_assembly_generator_t *gen, ast_binar
       break;
     case EVALUATION_RESULT_ON_RAX:
       break;
+    case EVALUATION_RESULT_AS_LITERAL_BOOL:
+      fprintf(gen->stream, "  mov $%d, %%rax\n", left_evaluation.data.literal_bool);
+      break;
     case EVALUATION_RESULT_VOID:
       assert(false && "Unexpected void result for binary operation");
   }
@@ -452,6 +501,20 @@ gas_assembly_generator_compile_if_stmt(gas_assembly_generator_t *gen, ast_if_stm
       fprintf(gen->stream, ".L_%ld:\n", false_label_index);
       break;
     }
+    case AST_VARIABLE: {
+      uint64_t false_label_index = gen->cur_label_index++;
+      ref_entry_t *entry = find_ref_entry(gen->refs, if_stmt->condition->data.variable.identifier);
+
+      fprintf(gen->stream, "  movq %d(%%rbp), %%rax\n", entry->stack_offset);
+      fprintf(gen->stream, "  cmpq $1, %%rax\n");
+      fprintf(gen->stream, "  jne .L_%ld\n", false_label_index);
+
+      gas_assembly_generator_compile(gen, if_stmt->body);
+
+      fprintf(gen->stream, ".L_%ld:\n", false_label_index);
+      assert(entry);
+      break;
+    }
     default:
       assert(false);
   }
diff --git a/src/gas_assembly_generator.h b/src/gas_assembly_generator.h
index 2e195fb..e400d2c 100644
--- a/src/gas_assembly_generator.h
+++ b/src/gas_assembly_generator.h
@@ -26,12 +26,14 @@ typedef enum evaluation_result_kind_t
   EVALUATION_RESULT_VOID,
   EVALUATION_RESULT_ON_RAX,
   EVALUATION_RESULT_ON_STACK,
-  EVALUATION_RESULT_AS_LITERAL_INTEGER
+  EVALUATION_RESULT_AS_LITERAL_INTEGER,
+  EVALUATION_RESULT_AS_LITERAL_BOOL
 } evaluation_result_kind_t;
 
 typedef union evaluation_result_data_t
 {
   int64_t literal_int;
+  bool literal_bool;
   int stack_offset;
 } evaluation_result_data_t;