gas: Removes Linux entrypoint logic from function declaration

Before this commit, function declarations were making syscalls to
interrupt the flow. This is a fair approach considering all our examples
just have a main function. But won't work if the namespace has more then
a single function.

The return now always sets the return value on RAX and jumps to the
function return label.

The function return label, will restore RBP and jump back to callee's
next instruction using RET instruction.

Function labels are kept, which means that a function called my_fn will
have the assembly label my_fn, so then, they can have INTEROP with other
languages.

Signed-off-by: Carlos Maniero <carlos@maniero.me>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/gas_assembly_generator.h b/src/gas_assembly_generator.h
index e400d2c..18ffb7f 100644
--- a/src/gas_assembly_generator.h
+++ b/src/gas_assembly_generator.h
@@ -48,7 +48,8 @@ typedef struct gas_assembly_generator_t
   FILE *stream;
   vector_t *refs;
   int stack_offset;
-  uint64_t cur_label_index;
+  uint64_t counter_label_index;
+  uint64_t return_label_index;
   evaluation_result_t latest_evaluation;
 } gas_assembly_generator_t;
 
@@ -58,4 +59,7 @@ 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);
 
+void
+gas_assembly_generator_compile_linux_main(gas_assembly_generator_t *gen, ast_node_t *func);
+
 #endif /* GAS_ASSEMBLY_GENERATOR_H */