py, compiler: When just bytecode, make explicit calls instead of table.

When just the bytecode emitter is needed there is no need to have a
dynamic method table for the emitter back-end, and we can instead
directly call the mp_emit_bc_XXX functions.  This gives a significant
reduction in code size and a very slight performance boost for the
compiler.

This patch saves 1160 bytes code on Thumb2 and 972 bytes on x86, when
native emitters are disabled.

Overall savings in code over the last 3 commits are:

bare-arm: 1664 bytes.
minimal:  2136 bytes.
stmhal:    584 bytes (it has native emitter enabled).
cc3200:   1736 bytes.

1 files changed, 34 insertions, 1 deletions

diff --git a/py/compile.c b/py/compile.c
index a41851c3a..62b6f0510 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -49,6 +49,11 @@ typedef enum {
     PN_const_object, // special node for a constant, generic Python object
 } pn_kind_t;
 
+#define NEED_METHOD_TABLE (MICROPY_EMIT_CPYTHON || MICROPY_EMIT_NATIVE)
+
+#if NEED_METHOD_TABLE
+
+// we need a method table to do the lookup for the emitter functions
 #define EMIT(fun) (comp->emit_method_table->fun(comp->emit))
 #define EMIT_ARG(fun, ...) (comp->emit_method_table->fun(comp->emit, __VA_ARGS__))
 #define EMIT_LOAD_FAST(qst, local_num) (comp->emit_method_table->load_id.fast(comp->emit, qst, local_num))
@@ -56,6 +61,16 @@ typedef enum {
 #define EMIT_INLINE_ASM(fun) (comp->emit_inline_asm_method_table->fun(comp->emit_inline_asm))
 #define EMIT_INLINE_ASM_ARG(fun, ...) (comp->emit_inline_asm_method_table->fun(comp->emit_inline_asm, __VA_ARGS__))
 
+#else
+
+// if we only have the bytecode emitter enabled then we can do a direct call to the functions
+#define EMIT(fun) (mp_emit_bc_##fun(comp->emit))
+#define EMIT_ARG(fun, ...) (mp_emit_bc_##fun(comp->emit, __VA_ARGS__))
+#define EMIT_LOAD_FAST(qst, local_num) (mp_emit_bc_load_fast(comp->emit, qst, local_num))
+#define EMIT_LOAD_GLOBAL(qst) (mp_emit_bc_load_global(comp->emit, qst))
+
+#endif
+
 // elements in this struct are ordered to make it compact
 typedef struct _compiler_t {
     qstr source_file;
@@ -83,7 +98,9 @@ typedef struct _compiler_t {
     scope_t *scope_cur;
 
     emit_t *emit;                                   // current emitter
+    #if NEED_METHOD_TABLE
     const emit_method_table_t *emit_method_table;   // current emit method table
+    #endif
 
     #if MICROPY_EMIT_INLINE_THUMB
     emit_inline_asm_t *emit_inline_asm;                                   // current emitter for inline asm
@@ -406,7 +423,11 @@ STATIC void compile_load_id(compiler_t *comp, qstr qst) {
     if (comp->pass == MP_PASS_SCOPE) {
         mp_emit_common_get_id_for_load(comp->scope_cur, qst);
     } else {
+        #if NEED_METHOD_TABLE
         mp_emit_common_id_op(comp->emit, &comp->emit_method_table->load_id, comp->scope_cur, qst);
+        #else
+        mp_emit_common_id_op(comp->emit, &mp_emit_bc_method_table_load_id_ops, comp->scope_cur, qst);
+        #endif
     }
 }
 
@@ -414,7 +435,11 @@ STATIC void compile_store_id(compiler_t *comp, qstr qst) {
     if (comp->pass == MP_PASS_SCOPE) {
         mp_emit_common_get_id_for_modification(comp->scope_cur, qst);
     } else {
+        #if NEED_METHOD_TABLE
         mp_emit_common_id_op(comp->emit, &comp->emit_method_table->store_id, comp->scope_cur, qst);
+        #else
+        mp_emit_common_id_op(comp->emit, &mp_emit_bc_method_table_store_id_ops, comp->scope_cur, qst);
+        #endif
     }
 }
 
@@ -422,7 +447,11 @@ STATIC void compile_delete_id(compiler_t *comp, qstr qst) {
     if (comp->pass == MP_PASS_SCOPE) {
         mp_emit_common_get_id_for_modification(comp->scope_cur, qst);
     } else {
+        #if NEED_METHOD_TABLE
         mp_emit_common_id_op(comp->emit, &comp->emit_method_table->delete_id, comp->scope_cur, qst);
+        #else
+        mp_emit_common_id_op(comp->emit, &mp_emit_bc_method_table_delete_id_ops, comp->scope_cur, qst);
+        #endif
     }
 }
 
@@ -2963,7 +2992,7 @@ STATIC void compile_node(compiler_t *comp, mp_parse_node_t pn) {
         }
     } else {
         mp_parse_node_struct_t *pns = (mp_parse_node_struct_t*)pn;
-        EMIT_ARG(set_line_number, pns->source_line);
+        EMIT_ARG(set_source_line, pns->source_line);
         compile_function_t f = compile_function[MP_PARSE_NODE_STRUCT_KIND(pns)];
         if (f == NULL) {
 #if MICROPY_DEBUG_PRINTERS
@@ -3660,8 +3689,10 @@ mp_obj_t mp_compile(mp_parse_node_t pn, qstr source_file, uint emit_opt, bool is
     comp->emit_method_table = &emit_cpython_method_table;
     #else
     comp->emit = emit_bc;
+    #if MICROPY_EMIT_NATIVE
     comp->emit_method_table = &emit_bc_method_table;
     #endif
+    #endif
     #if MICROPY_EMIT_INLINE_THUMB
     comp->emit_inline_asm = NULL;
     comp->emit_inline_asm_method_table = NULL;
@@ -3765,7 +3796,9 @@ mp_obj_t mp_compile(mp_parse_node_t pn, qstr source_file, uint emit_opt, bool is
 
                 default:
                     comp->emit = emit_bc;
+                    #if MICROPY_EMIT_NATIVE
                     comp->emit_method_table = &emit_bc_method_table;
+                    #endif
                     break;
             }
 #endif // !MICROPY_EMIT_CPYTHON