1 files changed, 57 insertions, 8 deletions

diff --git a/src/gas_assembly_generator.c b/src/gas_assembly_generator.c
index 5091120..fab4cd2 100644
--- a/src/gas_assembly_generator.c
+++ b/src/gas_assembly_generator.c
@@ -41,6 +41,19 @@ gas_assembly_generator_compile_variable_declaration(gas_assembly_generator_t *ge
 static void
 gas_assembly_generator_compile_variable(gas_assembly_generator_t *gen, ast_variable_t *variable);
 
+static void
+gas_assembly_generator_set_latest_evaluation_as_literal(gas_assembly_generator_t *gen, int64_t value)
+{
+  gen->latest_evaluation =
+    (evaluation_result_t){ .kind = EVALUATION_RESULT_LITERAL_INTEGER, .data = { .literal_int = value } };
+}
+
+static void
+gas_assembly_generator_set_latest_evaluation_as_register(gas_assembly_generator_t *gen)
+{
+  gen->latest_evaluation = (evaluation_result_t){ .kind = EVALUATION_RESULT_REGISTER };
+}
+
 typedef struct ref_entry_t
 {
   ast_identifier_t *id;
@@ -61,7 +74,6 @@ ref_entry_new(void)
   return entry;
 }
 
-
 void
 gas_assembly_generator_init(gas_assembly_generator_t *gen, FILE *stream)
 {
@@ -74,6 +86,8 @@ gas_assembly_generator_init(gas_assembly_generator_t *gen, FILE *stream)
 void
 gas_assembly_generator_compile(gas_assembly_generator_t *gen, ast_node_t *ast)
 {
+  gen->latest_evaluation.kind = EVALUATION_RESULT_VOID;
+
   switch (ast->kind) {
     case AST_BINARY_OPERATION:
       gas_assembly_generator_binary_operation(gen, &ast->data.binary_operation);
@@ -131,7 +145,11 @@ gas_assembly_generator_compile_return_stmt(gas_assembly_generator_t *gen, ast_re
 
   gas_assembly_generator_compile(gen, return_stmt->argument);
 
-  fprintf(gen->stream, "  mov %%rax, %%rdi\n");
+  if (gen->latest_evaluation.kind == EVALUATION_RESULT_LITERAL_INTEGER) {
+    fprintf(gen->stream, "  mov $%ld, %%rdi\n", gen->latest_evaluation.data.literal_int);
+  } else {
+    fprintf(gen->stream, "  mov %%rax, %%rdi\n");
+  }
   fprintf(gen->stream, "  mov $60, %%rax\n");
   fprintf(gen->stream, "  syscall\n");
 }
@@ -147,7 +165,17 @@ gas_assembly_generator_compile_variable_declaration(gas_assembly_generator_t *ge
   *entry = (ref_entry_t){ .id = &variable_declaration->identifier, .stack_offset = gen->stack_offset };
   vector_push_back(gen->refs, entry);
 
-  fprintf(gen->stream, "  mov %%rax, %d(%%rbp)\n", entry->stack_offset);
+  switch (gen->latest_evaluation.kind) {
+    case EVALUATION_RESULT_LITERAL_INTEGER:
+      fprintf(gen->stream, "  mov $%ld, %d(%%rbp)\n", gen->latest_evaluation.data.literal_int, entry->stack_offset);
+      break;
+    case EVALUATION_RESULT_REGISTER:
+      fprintf(gen->stream, "  mov %%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
+  }
 }
 
 static void
@@ -163,6 +191,7 @@ gas_assembly_generator_compile_variable(gas_assembly_generator_t *gen, ast_varia
   }
   assert(entry && "reference not found");
   fprintf(gen->stream, "  mov %d(%%rbp), %%rax\n", entry->stack_offset);
+  gas_assembly_generator_set_latest_evaluation_as_register(gen);
 }
 
 static void
@@ -170,7 +199,7 @@ gas_assembly_generator_compile_literal(gas_assembly_generator_t *gen, ast_litera
 {
   switch (literal->kind) {
     case AST_LITERAL_INTEGER:
-      fprintf(gen->stream, "  mov $%d, %%rax\n", literal->value.integer);
+      gas_assembly_generator_set_latest_evaluation_as_literal(gen, literal->value.integer);
       return;
     default:
       assert(false && "no code generation strategy.");
@@ -181,14 +210,34 @@ static void
 gas_assembly_generator_binary_operation(gas_assembly_generator_t *gen, ast_binary_operation_t *binary_operation)
 {
   gas_assembly_generator_compile(gen, binary_operation->right);
+  evaluation_result_t right_evaluation = gen->latest_evaluation;
 
-  gen->stack_offset -= 8;
-  fprintf(gen->stream, "  mov %%rax, %d(%%rbp)\n", gen->stack_offset);
+  if (right_evaluation.kind == EVALUATION_RESULT_REGISTER) {
+    gen->stack_offset -= 8;
+    fprintf(gen->stream, "  mov %%rax, %d(%%rbp)\n", gen->stack_offset);
+  }
 
   gas_assembly_generator_compile(gen, binary_operation->left);
+  evaluation_result_t left_evaluation = gen->latest_evaluation;
 
-  fprintf(gen->stream, "  mov %d(%%rbp), %%rcx\n", gen->stack_offset);
-  gen->stack_offset += 8;
+  switch (right_evaluation.kind) {
+    case EVALUATION_RESULT_LITERAL_INTEGER:
+      fprintf(gen->stream, "  mov $%ld, %%rcx\n", right_evaluation.data.literal_int);
+      break;
+    case EVALUATION_RESULT_REGISTER:
+      fprintf(gen->stream, "  mov %d(%%rbp), %%rcx\n", gen->stack_offset);
+      gen->stack_offset += 8;
+      break;
+    case EVALUATION_RESULT_VOID:
+      assert(false && "Unexpected void result for variable declaration");
+      // FIXME: store the latest node at latest evaluation and print_ast
+  }
+
+  gas_assembly_generator_set_latest_evaluation_as_register(gen);
+
+  if (left_evaluation.kind == EVALUATION_RESULT_LITERAL_INTEGER) {
+    fprintf(gen->stream, "  mov $%ld, %%rax\n", left_evaluation.data.literal_int);
+  }
 
   if (binary_operation->kind == AST_BINOP_ADITION) {
     fprintf(gen->stream, "  add %%rcx, %%rax\n");